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May 2016 • Vol 6 Issue 1

SADTJ ISSN 2077-2793

• Obstructive Sleep Apnea and Mandibular Advancement Splints:Occlusal Effects and Progression of Changes Associated with a Decade of Treatment • Safe Approach in “All-on-four” technique: A Case Report • Fit accuracy of metal partial removable dental prosthesis frameworks fabricated by traditional or light curing modeling material technique: An in vitro study

The Southern African Dental Technology Journal

• Influence of bruxism on survival of porcelain laminate veneers

DENTASA Summit & Annual General Meeting Showcasing Our Local Talent The Interaction Between the Laboratory Technician and the Orthodontist (Class II Cases) Dr MPS Sethusa

Digital Design of Screw Retained Implant Structures Mr MJ de Beer

Digital Dental Equipment- Return on Investment? Mr Zarius Marx

Complete System Performance is the Key for Predictable Long-Term Results Dr Anton Grotius

All-Ceramic Restorations in the Aesthetic Zone: Layered vs Full-Contour Mr André Buys.

Maxillofacial Prosthodontics: A South African Dilemma or Predicament Dr Matshediso ‘Kuki’ Mothopi-Peri

CPD 17


Invitation to write articles and case presentations The Southern African Dental Technology Journal invites all dental technicians/technologists and dentists, who have original articles or case presentations to submit their work. The SADTJ is a peer review publication, and all original articles will be reviewed by our Associate Editors. Do not let this scare you off, you will receive constructive criticism and suggestions on how to improve your writing, should your article not be published the first time round.

Length of Manuscripts: •

• • •

Technical Article: 1500-2000 words and 15-20 photos or diagrams. These articles should be up-to-date accounts of interesting and noteworthy developments in techniques. They should be case specific and engage the intermediate and advanced-level technologies as well as new techniques. Articles should give step by step information on how to do something, but also provide insight on the why and how of a particular technique or product. Please include a 10 question, multiple choice quiz, about the contents of the article, when submitting a technical article. All technical articles submitted to the journal must be written or co-written by a Certified Dental Technician, a foreign technician with a SADTC approval to work in South Africa, or a dentist. Photo Technical Article (Case presentation): 1000 words maximum and 10-26 photos. These articles should be up-to-date accounts of interesting and noteworthy developments in techniques. This kind of article is usually a case presentation sharing tips or a quick technique with others. The photos should be accompanied by a written explanation (maximum 1000 words) of how the final results were accomplished. Research Article: 6000 words. Here the criteria of intelligibility and wider interest are strictly applied. Review Articles: up to 6000 words long. These articles should be up-to-date surveys of important current developments in dentistry. News Articles: 250-700 words, photos optional. We are interested in all news-worthy events that involved or impact dental technicians, or their laboratories. Please keep us up to date so we can share the news.

Manuscripts and Photo Requirements: • • • •

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Articles submitted should be in the proper format for scientific papers. All submissions should be the original work of the author/s as noted. Articles should be submitted in Microsoft Word. Images should be in JPEG format. It should have a resolution of no less than, 300dpi, should be uncompressed, be of high quality and clarity and should have no copyright. You are not allowed to reproduce any images without the proper copyright releases. If the images are not your own, please make sure that you obtain the copyright release on the images before submitting it to the SADTJ, as this remains your responsibility. The journal reserves the right to edit your article, for the sake of clarity. Articles that have been submitted to the Journal of Dental Technology in Southern Africa, may not be submitted to another publication for a period of four months. Include a photograph of the authors as well as a short biography. Include copies of the completed authors release form, conflict of interest and photo release forms with the submission, of your article. Include the cover page for your article.

Presentation of Content: • • • • • •

Use Arial or Times Roman as font. Number each page clearly. No footnotes will be allowed. Keep your presentation clear and simple. Tables, figures and images (including photographs), should be presented on a separate page at the end of the document, separate from other documents. All tables, figures and images must be clearly marked using Arabic numerals.

All manuscripts must be submitted in English. Remember to include all your contact details when submitting your work. Make use of this invitation, and submit your work today, we look forward to hear from you. 2

SADTJ Vol 6 Issue 1


In This Issue SADTJ Vol 6 Issue 1 March 2016

Editor

Axel Grabowski

Managing Editor Mariaan Roets

PUBLISHED BY

The Dental Technicians Association of South Africa

LAYOUT AND DESIGN Nicola van Rensburg

ADVERTISING ENQUIRIES m.roets@dentiworks.com

ADDRESS CHANGES

Elize Morris: dentasa@absamail.co.za

ACCOUNTS Elize Morris: dentasa@absamail.co.za Tell: 012 460 1155 Fax: 086 233 7122

DENTASA

PO Box 95340, Waterkloof, 0145 Tel: 012 460 1155 Fax: 012 460 9481

Obstructive Sleep Apnea and Mandibular Advancement Splints: Occlusal Effects and Progression of Changes Associated with a Decade of Treatment Vol 6 Issue 1.

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Safe Approach in “All-on-four” technique: A Case Report Vol 6 Issue 1.

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Fit Accuracy of Metal Partial Removable Dental Prosthesis Frameworks Fabricated by Traditional or Light Curing Modeling Material Technique: An In Vitro Study Vol 6 Issue 1.

19

Influence of Bruxism On Survival of Porcelain Laminate Veneers Vol 6 Issue 1.

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A Comparison of Masticatory Performance and Efficiency of Complete Dentures Made with High Impact and Felxible Resins: A Pilot Study Vol 6 Issue 1.

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Pneumoconiosis and Respiratory Problems in Dental Laboratory Technicians: Analysis of 893 Dental Technicians Vol 6 Issue 1.

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STATEMENT OF INTENT The Southern African Dental Technology Journal is published quarterly. The main objective of the Journal is to provide the professional with the opportunity to earn CDP credits through completing the questionnaires, or writing articles. All papers in English, on any aspect of dental laboratory science or related disciplines, will be considered on merit and subject to the review of the editorial board and the CPD accreditation committee.

EDITORIAL, ADVERTISING AND COPYRIGHT POLICY Copyright of individual articles appearing in this publication reside with the individual authors. No article appearing in this publication may be reproduced in any manner, or in any format without the express written permission of its author and a release from this publication. All rights are reserved. Opinions and statements, of whatever nature, are published under the authority of the submitting author and should not be taken as the official policy of the Dental Technology Association of South Africa.

SADTJ Vol 6 Issue 1

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Editor’s Page As they say in the classics “Doesn’t time fly when you are having fun?” Here we are just over a month away from the DENTASA Summit and AGM. The AGM team has been very busy to ensure that it is going to be an excellent two days. We have for the first time succeeded in our drive to have more local speakers than overseas speakers. One thing is for sure, we here in South Africa do not have to stand back for quality and local is lekker. Please make every effort to join us on the 3rd and 4th June 2016. This has been a very busy year, and lots has happened in the profession of dental technology. Most important was the re-writing of our very out dated Act. The SADTC task team, which consists of the following members, must be congratulated for their hard work and effort. Mr. Louis Steyn –Chairman, Mrs. Catherine Makwakwa, Mr. David van Eck, Mr. A. Grabowski (DENTASA) Mrs. P. Nkuna and Mr. T. Modiba, Dr J. Smit. The Act is now with Adv. Leon Kellermann, appointed by Council to get it ready for parliament. I unfortunately have to inform you that our Managing Editor, Naomi Fourie had to resign due to unfortunate and unforeseen circumstances. We at the SADTJ wish her well for the future, and thank her for her input. Mrs. Mariaan Roets has been appointed in her position, and I wish you a successful time with the SADTJ. I sincerely hope you find this Edition of great value and interest. Editorially yours, Axel

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Obstructive Sleep Apnea and Mandibular Advancement Splints: Occlusal Effects and Progression of Changes Obstructive Sleep Apnea Advancement Splints: Associated withand a Mandibular Decade of Treatment

3.4

pii: jc-00046-14 http://dx.doi.org/10.5664/jcsm.4278 pii: jc-00046-14 http://dx.doi.org/10.5664/jcsm.4278

Occlusal Effects Progression of Changes Associated with Obstructive Sleepand Apnea and Mandibular Advancement Splints: Decade of Treatment Occlusal Effects anda Progression of Changes Associated with Benjamin T. Pliska, D.D.S., M.Sc.; Hyejin Nam; Hui Chen, D.M.D., Ph.D.; Alan A. Lowe, D.M.D., Ph.D.; a Decade of Treatment Fernanda R. Almeida, D.D.S., Ph.D. Benjamin T. Pliska, M.Sc.; Hyejin Hui Chen, D.M.D., A. Lowe, D.M.D., Ph.D.; Department of Oral HealthD.D.S., Sciences, Faculty of Nam; Dentistry, University of Ph.D.; BritishAlan Columbia, Vancouver, BC, Canada Fernanda R. Almeida, D.D.S., Ph.D.

S C I SE CN ITEI NF TI CI F II NC V IENSVTEI SG TAITGI A O TNISO N S

ThisofisDentistry, an open access article Department of Oral Health Sciences, Faculty University of British Columbia, Vancouver, BC, Canada

O O

Study Objectives: To evaluate the magnitude and progression of dental changes associated with long-term mandibular Study Objectives: evaluatetreatment the magnitude and progression advancement splintTo(MAS) of obstructive sleep of dental changes associated with long-term mandibular apnea (OSA). advancement splint (MAS) treatment obstructive sleep Methods: Retrospective study of adultsoftreated for primary apnea snoring(OSA). or mild to severe OSA with MAS for a minimum of 8 Methods: study of of adults treated primary years. The Retrospective series of dental casts patients wereforanalyzed snoring or mild to severe OSA with MAS for a minimum of 8 with a digital caliper for changes in overbite, overjet, dental years. The series of dental casts of patients were analyzed arch crowding and width, and inter-arch relationships. The with a digitalofcaliper for changes overbite, overjet, dental progression these changes overintime was determined and arch anddental width,characteristics and inter-archwere relationships. initial crowding patient and evaluatedThe as progressionof of changes over time was of determined predictors thethese observed dental side effects treatment.and initial patient and ofdental characteristics were Results: A total 77 patients (average ageevaluated at start as of predictors of47.5 the observed dental side treatment. treatment: ± 10.2 years, 62 effects males) ofwere included Results: A total 77 patients (average of in this study. The of average treatment length age was at 11.1start ± 2.8 treatment: ± 10.2 years,interval 62 males) werethere included years. Over47.5 the total treatment evaluated was this study. average treatment length was 11.1 ain signifi cant (pThe < 0.001) reduction in the overbite (2.3 ± 2.8 1.6 years. Over the treatment interval evaluated there was mm), overjet (1.9total ± 1.9 mm), and mandibular crowding (1.3 cantA(pcorresponding < 0.001) reduction in the(poverbite ± 1.6 ±a signifi 1.8 mm). significant < 0.001)(2.3 increase mm), overjet (1.9 ± 1.9 mm), crowding (1.3 of mandibular intercanine (0.7 and ± 1.5mandibular mm) and intermolar (1.1 ± 1.8 mm). A corresponding significant (p < 0.001) increase of mandibular intercanine (0.7 ± 1.5 mm) and intermolar (1.1

± 1.4 mm) width as well as incidence of anterior crossbite and posterior open bite was observed. Overbite and mandibular ±intermolar 1.4 mm) distance width as well incidence anterior less crossbite and wereasobserved to of decrease with time, posterior openmandibular bite was observed. while overjet, intercanineOverbite distance,and andmandibular lower arch intermolar werecontinuously observed toatdecrease less with time, crowding alldistance decreased a constant rate. while overjet, mandibular intercanine distance, and lower arch Conclusions: After an average observation period of over 11 crowding all decreased continuously a constant rate. years, clinically significant changes in at occlusion were observed Conclusions: After an average observation periodreaching of over 11 and were progressive in nature. Rather than a years, clinically signifi cant changes in occlusion were discernible end-point, the dental side effects of MASobserved therapy and werewith progressive in nature. continue ongoing MAS use. Rather than reaching a discernible end-point, the dental MAS therapy Commentary: A commentary onside this effects article of appears in this continue with ongoing issue on page 1293. MAS use. Commentary: A commentary this article in this Keywords: obstructive sleep on apnea, sleep appears apnea therapy, issue on pagecomplications, 1293. sleep apnea removable orthodontic appliances, Keywords: obstructiveadverse sleep effects, apnea, time sleepfactors, apneatreatment therapy, orthodontic appliances sleep apnea complications, removable orthodontic appliances, outcome orthodonticPliska appliances adverse effects, time factors, treatment Citation: BT, Nam H, Chen H, Lowe AA, Almeida FR. outcome Obstructive sleep apnea and mandibular advancement splints: Citation: Pliska and BT, progression Nam H, Chen H, Loweassociated AA, Almeida occlusal effects of changes withFR. a Obstructive sleep apnea and mandibular advancement splints: decade of treatment. J Clin Sleep Med 2014;10(12):1285-1291. occlusal effects and progression of changes associated with a decade of treatment. J Clin Sleep Med 2014;10(12):1285-1291.

bstructive sleep apnea (OSA) often leads to poor sleep BRIEF SUMMARY quality, daytime sleepiness, and an increased risk of motor 1 Current Knowledge/Study Rationale: Mandibular advancement splints bstructive sleep apnea (OSA) often leads to poor sleep vehicle accidents, hypertension, and stroke. Oral appliances, are an effective treatment option for OSA patients, with changes to the BRIEF SUMMARY quality, daytime sleepiness, and an increased risk of motor which function to hold the mandible in a forward position and dental occlusion as a common side effect. Due to theadvancement indefinite nature of 1 Current Knowledge/Study Rationale: Mandibular splints vehicle Oral enlarge accidents, the airwayhypertension, during sleep,and arestroke. indicated as appliances, a primary OSA clear understanding of thepatients, magnitude progression are antreatment effectiveatreatment option for OSA withand changes to the which function hold the mandible forward position and treatment optiontofor snoring and mildintoamoderate OSA. These of long-term occlusal needed. dental occlusion as a changes common is side effect. Due to the indefinite nature of enlarge the airway during sleep, are indicated as a primary Study Impact: aWith longest observation period yetand to be reported, appliances are also being implemented as a alternative for paOSA treatment clearthe understanding of the magnitude progression the results from this study confi rm that long-term MAS treatment leads treatment option for snoring and mild to moderate OSA. These of long-term occlusal changes is needed. tients with severe OSA who are unwilling or unable to tolerto signifi cant changes inlongest occlusion for the majority of patients. These Study Impact: With the observation period yet to be reported, appliances are also being implemented as a alternative for paate continuous positive airway pressure for the management of dental changes foundconfi to be in MAS nature, and continue the results from were this study rm progressive that long-term treatment leads 1 tients with severe OSA are unwilling unable to docutolertheir disease. To this endwho a number of recent or studies have with ongoing use. in occlusion for the majority of patients. These to signifi cant MAS changes ate continuous positive airway pressure for the management of mented the efficacy of mandibular advancement splints (MAS) dental changes were found to be progressive in nature, and continue 1 their disease. To this end a number of recent studies have docuin improvements in daytime sleepiness, AHI, and mean arterial with ongoing MAS use. mentedpressure the efficacy ofcardiovascular mandibular advancement blood and/or health.2-10 splints (MAS) However, some of these studies are limited by a relatively short in The improvements in main daytime AHI, andcurrently mean arterial MAS is the typesleepiness, of oral appliance used, observation period, considering that MAS treatment may con2-10 blood pressure and/or cardiovascular health. However, these studies are limited by a relatively short and though well tolerated, has identified short-term and longtinue indefisome nitelyofthrough a patient’s lifetime. The MAS is the main type of oral appliance currently used, observation period, considering that MAS conterm side effects. Initial transient effects may include excess Previous studies examining effects overtreatment at least may a 5-year and though well tolerated, has identifi ed short-term and longtinue indefi nitely through a patient’s lifetime. salivation or mouth dryness, temporomandibular joint and dentreatment period have shown significant decreases in overbite 11 term side effects. transient effectstissues. may include excess Previous vertical studies examining over atteeth, leastand a 5-year tal discomfort and Initial irritation of intra-oral The skeletal (OB)—the overlap of effects the anterior oversalivation or mouth dryness, temporomandibular joint and dentreatment period have shown signifi cant decreases in overbite and dental changes that occur after prolonged MAS treatment jet (OJ)—the horizontal overlap of the anterior teeth, rang11 tal discomfort and irritation of intra-oral The skeletal (OB)—the verticalmm overlap of the anterior teeth, and overhave been previously described in termstissues. of appliance design, ing from 0.6-1.91 and 0.6-1.24 mm, respectively, after 12-15 16-18 and dental changes that occur after prolonged MAS treatment jet (OJ)—the horizontal overlap of the anterior teeth, rangamount of mandibular protrusion, and duration of wear. long-term appliance use. These studies also report various have been previously described in terms of appliance design, ing from 0.6-1.91 mm and 0.6-1.24 mm, respectively, after 16-18 Sleep Medicine, Vol. 10, No. 12, 2014 Journal of use. Clinical amount of mandibular protrusion, and duration of wear.12-15 1285 long-term appliance These studies also report various 1285

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MAS Treatment

Table 1—Baseline patient characteristics. N Males Age (years) Years in treatment BMI AHI (N = 54)

77 62 47.5 ± 10.2 (26–70) 11.1 ± 2.8 (8.0–19.3) 29.4 ± 7.2 (18.7–63.6) 29.8 ± 16.9 (2.4–77.4)

Values presented as mean ± standard deviation (range).

degrees of changes in mandibular crowding, posterior occlusal contacts and in mandibular arch width. The progression at which these changes occur is still unclear. It has been proposed that dental changes may decrease with time,16,19 while others20 have found that changes tend to be progressive in nature. Interestingly, Battagel, in a study of 30 patients averaging 3.64 years of MAS use, found no statistically significant correlation between the duration of MAS wear and the change in OB and OJ.15 However these previous attempts to classify the time course of occlusal changes with MAS use may have been over too short an observation period to appreciate their progression. Though MAS adherence rates vary, potential reasons for discontinuing treatment are occlusal side effects and complications.21 It is hoped that an improved understanding of the progression of these dental changes may help in designing optimal treatment protocols that allow for maximum adherence to prescribed MAS treatment. The present study characterizes the dental changes associated with MAS therapy over the longest observation period published to date, as well as an examination of the progression of these side effects over time. The specific aims of this study are to report on the magnitude and progression of dental changes associated with longterm MAS treatment, as well as to investigate the relationship between the observed changes, the initial occlusion, and the BMI.

METHODS

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Data Collection and Statistical Analysis

The dental study casts were measured with a digital caliper with a resolution of 0.1 mm by a single investigator. Characteristics assessed included OJ and OB (mean values for the central incisors were used), dental crowding, intermolar and intercanine distances, as well as the number of posterior teeth with open occlusal contacts and anterior teeth in crossbite.18 Fifteen sets of models were measured a second time after a 2-week interval to assess method error. Descriptive measures and paired t-tests were used to report changes over the entire observation period (final – initial records), while method errors were calculated using Dahlberg’s formula. Spearman and Pearson correlation coefficients were used to determine the influence of initial patient characteristics on the magnitude of occlusal changes. In an examination of all available data points, a mixed-effect polynomial regression analysis was used to analyze the data for the rate at which changes occur over the course of treatment. To determine the influence of initial occlusion on the rate of change, patients were also further subdivided into groups of normal or excessive initial OJ and OB for this analysis. Statistical significance was determined at p < 0.05.

RESULTS

De-identified demographic data and dental study casts of patients (Table 1) who were treated a minimum of 8 years with a MAS for snoring or OSA were retrieved from the Sleep Apnea Dental Clinic at the University of British Columbia and the private practice of a co-author. In these clinics it is typical protocol to produce dental casts for any follow-up appointment requiring major repair or replacement of the MAS. Thus patients had a variable number of intermediate records available; however, all had ≥ 8 years between their initial and most recent set of records. Patients were excluded if they had missing dental study casts from either their initial or most recent set of records, and most patients reported wearing the appliance nightly. The total period of MAS use was calculated as the interval between initial appliance placement and the date of the most recent study casts. Initial severity of OSA for treated patients ranged from primary snoring to severe OSA. The Clinical Research Ethics Board of the University of British Columbia approved this study. Journal of Clinical Sleep Medicine, Vol. 10, No. 12, 2014

All patients were treated with a custom made, titratable, biblock mandibular advancement appliance (Klearway; Space Maintainers Laboratories Canada Ltd., Calgary, Canada), made of thermoplastic material with embedded metal clasps. The upper and lower members of the appliance are connected via an adjustable screw assembly, which fits in the area of the palatal vault and allows for titration in 0.25-mm increments. The initial mandibular advancement was set at two-thirds of maximum mandibular protrusion, and then further advancements were prescribed by 0.25-mm increments until self-reported resolution of snoring and daytime sleepiness symptoms, or until uncomfortable for the patient. Improvement in OSA was then often verified by a follow-up overnight sleep study with the appliance in place.

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Overall Occlusal Changes

The records of a total of 77 patients with an average treatment time of 11.1 years were included for analysis in this study. Twenty-six patients presented with mild and moderate OSA, while 28 had severe OSA prior to initiation of treatment. The remaining 23 patients were either snorers or had only baseline oximetry performed. They were predominantly male and mildly obese (mean BMI 29 kg/m2). Further description of the patient’s baseline characteristics can be seen in Table 1. The assessed method error for the dental measurements ranged from 0.13 to 0.64 mm. Over the total treatment interval evaluated there was a significant change in the relationship between the upper and lower arches where a decrease in the OJ and OB was observed. Additionally the lower arch was found to have expanded significantly, as measured by increases in mandibular intercanine and intermolar distances, as well as a decrease in mandibular arch


Long-Term Occlusal Effects of Mandibular Advancement Splints

Table 2—Overall occlusal changes during treatment (n = 77). Overbite (mm) Overjet (mm) Mandibular crowding (mm) * Maxillary crowding (mm) Mandibular intercanine width (mm) Maxillary intercanine width (mm) Mandibular intermolar width (mm) Maxillary intermolar width (mm) Mandibular posterior teeth out of occlusion

Initial 3.4 ± 2.3 3.3 ± 1.7 0.6 ± 2.5 2.0 ± 2.9 26.2 ± 2.3 34.6 ± 2.8 34.8 ± 3.5 39.5 ± 4.0 0.7 ± 2.0

Final 1.1 ± 2.1 1.4 ± 2.1 -0.6 ± 2.7 1.8 ± 2.9 26.9 ± 2.2 34.4 ± 2.9 35.9 ± 3.6 39.8 ± 4.4 2.6 ± 2.6

Final – Initial -2.3 ± 1.6 -1.9 ± 1.9 -1.3 ± 1.8 +0.2 ± 1.3 +0.7 ± 1.5 -0.2 ± 1.2 +1.1 ± 1.4 +0.4 ± 1.4 +1.9 ± 2.1

p value < 0.001 < 0.001 < 0.001 0.31 < 0.001 0.11 < 0.001 0.02 < 0.001

Values presented as mean ± standard deviation. * A negative number denotes spacing.

Figure 1—All data points for the entire sample population for overbite (A) and overjet (B) in millimeters, as a function of number of years in treatment.

A

B

The data for each individual patient is connected by a gray line. The overall relationship of all data is represented by the black line, demonstrating the decreasing but leveling off, and linear rate of changes for overbite and overjet respectively.

crowding (Table 2). No significant changes were observed in maxillary variables. Two important characteristics that anecdotally weigh heavily in a patient’s perception of the quality of occlusion, posterior openbite and anterior crossbite, both demonstrated significant changes in the sample population. A posterior openbite, which for the purposes of this study is defined by the loss of occlusal contact on at least 2 posterior teeth, developed in 51% (39/77) of the sample. Similarly 62% (48/77) of the sample developed an anterior crossbite of at least one tooth—defined as a lack of positive horizontal overlap of the upper anterior teeth over the lower anterior teeth. However of those patients that developed a crossbite, an average of 4 teeth were involved.

Progression of Occlusal Changes

Of the occlusal parameters that changed significantly during treatment (p < 0.001), additional analysis was performed to 1287

characterize how these changes progressed with time. Mixed effects polynomial regression analyses were performed to determine the relationship of these variables to time in treatment. The scope of the population data for both OJ and OB are illustrated in Figure 1. Once this relationship was established the rate of change per year could be calculated, demonstrating significant differences in how these changes progressed over time. Looking at the entire sample population, OB was observed to decrease less with time, while OJ decreased continuously at a constant rate. The progression in OB and OJ changes were further examined in terms of initial occlusal characteristics (Figures 2 and 3, respectively), which revealed that the initial amount of OJ had no effect on the progression of change. However the initial amount of OB did alter the pattern of future changes, as patients with a small initial OB were found to have the rate of change first decrease, and then later increase in magnitude as treatment time was extended beyond 9 years. Conversely, patients with Journal of Clinical Sleep Medicine, Vol. 10, No. 12, 2014 SADTJ Vol 6 Issue 1

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Figure 2—Rate of change in overbite based on baseline bite characteristic of deep (N = 48) or normal (N = 26).

Figure 3—Rate of change in overjet based on baseline bite characteristic of excess (N = 39) or normal (N = 38) horizontal overlap of the anterior teeth.

Patients with no initial vertical overlap (N = 3) were excluded from the analysis.

Figure 5—Rate of change in mandibular intermolar distance. Figure 4—Rate of change in mandibular intercanine distance.

mandibular arch crowding decreases appears to be more complex, with early rapid decrease followed by small changes until after 12 years of treatment when the rate rises again (Figure 6).

Figure 6—Rate of change in mandibular arch crowding.

Patient Characteristics as Predictors of Occlusal Changes

deep bite at pre-treatment saw the rate at which their overbite lessened, gradually decrease with time. Examining the mandibular arch characteristics, we found significant change over time in the intercanine width, which continuously increased at a constant rate, while mandibular intermolar distance was found to increase most rapidly initially and then taper off with small increases occurring after 12 years of treatment time (Figures 4 and 5) The changes in the rate at which Journal of Clinical Sleep Medicine, Vol. 10, No. 12, 2014

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In assessing initial patient characteristics for predictors of occlusal changes, we found that patient age, sex, and pretreatment BMI were unrelated to the amount of both OJ and OB reduction, as well as the occurrence of anterior crossbite or posterior openbite. The amount of total change in overjet was significantly correlated to initial AHI (r = 0.28), though no other relationships with occlusal variables were found. Initial OJ was not significantly related to the occurrence of anterior crossbite or posterior openbite. Initial OJ was positively correlated to the total observed change in both OB (r = 0.28) and OJ (r = 0.33). Initial overbite was significantly negatively correlated (r = -0.37) to anterior crossbite and positively correlated (r = 0.44) to total observed change in overbite caused by MAS treatment.

DISCUSSION The present results demonstrate the dental changes associated with MAS treatment of OSA over the longest observation


Long-Term Occlusal Effects of Mandibular Advancement Splints

period published to date. After an average of over 11 years of treatment, clinically significant reductions of 2.3 mm and 1.9 mm in OB and OJ, respectively, are seen. Also, it is clear that the changes in occlusion are progressive in nature. Rather than reaching a discernible end-point, the reductions in OB and OJ and widening of the lower dental arch continue with ongoing MAS use. The magnitude of the changes presently reported are slightly greater than those previously described for long-term (> 5 years) studies. Martinez et al. found a mean OB reduction of 0.81 mm and OJ reduction of 1.1 mm from 15 OSA patients with 4.8 years of MAS use.16 Similarly, Marklund found reductions in both OB and OJ of 0.6 mm from a 5-year follow-up of 187 OSA patients.18 Almeida and colleagues18 in an examination of 70 patients over a 7-year period recorded reductions of 1.91 mm and 1.24 mm in overbite and overjet, respectively. These minor differences may be due in part to varying observation periods and smaller sample sizes. The smaller amounts of change reported by Marklund17 maybe further influenced by her use of monoblock, non-adjustable appliances. Importantly, the dental changes occurring from MAS use are not limited to decreases in OB and OJ, but rather include a number of parameters of the dentition (Table 2). Mandibular crowding decreases, just as mandibular intercanine and intermolar width increase over the course of treatment. We also found on average that an openbite developed on more than two lower posterior teeth. These findings are in line with those previously reported by other long-term studies.16,18,22 The physiology of biologic tooth movement has been well characterized,23 and it is understood that even very low applied forces, if applied for a sustained amount of time (such as for several hours during nighttime wear of an appliance) will result in tooth movement. All MAS appliances position the mandible forward and retain it in place by contacting the dentition. The force required to suspended the mandible and associated soft tissues thus is transmitted to the dental arches and likely results in the occlusal changes reported.24 It should be understood then that the dental side effects of MAS treatment are a product of protruding the mandible to achieve a therapeutic effect rather than specific appliance design.25 This is likely why studies examining side effects comparing different appliance designs have found very little difference in terms of magnitude of these secondary effects of dental movement.12,13 Indeed, by extension into the orthodontic literature, one can see that attempts to provide more or less tooth-appliance contact or even rigidly splinting the mandibular teeth together with a cast metal framework does little to mitigate the dental movement.26 All but one of the 77 patients examined experienced greater than 0.2 mm of occlusal change in terms of overjet and overbite, which speaks to the confidence at which one can expect to see dental movement with this type of therapy. The development of posterior open bite and anterior teeth in crossbite were also common among the patients of this study. A posterior openbite may occur as the lower arch, and in particular the lower incisors are protruded forward as a result of prolonged MAS treatment. Commonly observed in the orthodontic treatment of retrognathic malocclusions with functional appliances,27 this type of tooth movement causes an occlusal interference as the patient is now unable to close the posterior teeth

down together completely due to the premature contact of the anterior teeth. Similarly, crossbites of anterior teeth will occur as the lower arch moves forward and the overjet and overbite are reduced to the point where the lower teeth protrude beyond the upper anterior teeth. These two facets of occlusion have also been previously reported in the literature. Vezina et al. reported both anterior and posterior openbite in a small proportion of patients who had been treated with MAS for an average of over 3.5 years, though no openbites were found in patients treated for 6 months or less.12 Rose and colleagues, after a treatment period of at least two years in 34 patients, found a posterior openbite had developed in 26% of the patients studied.25 Upon examining the time frame at which occlusal changes occur with MAS treatment, we found that the reduction in overjet is progressive and continues at a constant rate so as long as the MAS treatment continues. This is a logical finding considering that the main mechanism of action with a MAS appears to be the protrusion of the mandible and associated soft tissues, improving the caliber of the upper airway.28 As long as this continues to occur, forces will also continue to be applied to the teeth resulting in tooth movement. Overbite however was found to decrease less with time in our sample population. This may be explained by the inseparable relationship of overjet and overbite. As the mandible and lower arch are protruded forward, the overbite will decrease less and less until eventually there is no longer any further vertical overlap of the anterior teeth. At this point the lower arch can continue to be protruded forward without any further interference from the upper anterior teeth. Our results align with those of Marklund, who reported on the progression of occlusal changes in a subset of 51 patients treated for at least 5 years with a mono-block style of MAS.17 Marklund found overall that dental side effects increased with treatment time as well as more frequent use of the device. She also stated that overjet decreased continuously during the observed 5-year treatment period, whereas overbite changes diminished with time in the sample population studied. Conflicting results were previously reported by Pantin et al. in a retrospective survey of 106 patients recalled and examined following an average duration of MAS treatment of 31 Âą 18 months.19 They found that the proportion of patients with occlusal change increased with length of use of the mandibular advancement splint up to 2 years. Beyond 2 years, the proportion remained relatively constant. The authors further stated that this implies that a patientâ&#x20AC;&#x2122;s period of greatest vulnerability to these complications is within the first 2 years of treatment. This key difference with the present study may be partially explained by differences in study design. Unlike our longitudinal examination of patients, Pantin et al. performed a cross-sectional analysis, where patients were examined only once at a particular point in time. Additionally very few (n = 27) of these patients were in MAS treatment longer than 48 months. Pre-treatment BMI was found to be unrelated to any observed occlusal changes. This may not be surprising considering the extended observation period, throughout which patients may see their BMI vary widely, masking any direct relationship that may exist between these variables. We found that the initial AHI was positively related to the magnitude of observed reduction in overjet. The influence of AHI on change in overjet may be explained by the fact that patients with more severe OSA

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could be more likely to have their mandibles advanced a greater amount to see a relief in symptoms compared to patients with a milder degree of the disease.29 It has been previously shown that the relationship between the force applied to the arches and amount of mandibular advancement is almost linear, with the force increasing with increasing mandibular advancement.24 In the present study, patients with a greater amount of initial overjet tended to see larger total reductions to both overjet and overbite. This may be due to the greater amount of clearance for the forward movement of the lower dentition that occurs in these patients, before the lower anterior teeth would contact the corresponding upper anterior teeth. We also found that patients with minimal amounts of initial overbite were more likely to experience crossbite of the anterior teeth with prolonged MAS treatment, while those with greater amounts of initial overbite saw greater amounts of overbite reduction as the result of treatment. These results lead to the notion that the specific expected occlusal changes associated with MAS treatment may be predicated on the presentation of patient’s dentition, with the vast majority seeing marked reductions in both overbite and overjet. This study has some limitations, including that only one particular MAS was investigated and the risk of selection bias due to the retrospective study design. While great care was used to include all available records that met the treatment time (> 8 years) criteria, the patients who discontinued treatment for any reason over this period were not included in the analysis. Also, the compliance and reporting of the exact amount of time the appliance was used was subjective and based on patient selfreporting to routine follow-up questions. However the majority of patients in this study all were successfully treated with their MAS appliance based on follow-up PSG, and over the course of the observation period most had their MAS remade or replaced at their own cost—an unlikely occurrence if the appliance was rarely used. Future studies involving multiple appliance designs and incorporating newly developed compliance monitors embedded within the MAS should help determine a minimum threshold of use that will result in the dental changes reported here. The strength of this study is the observed period of MAS treatment at 11.1 years, which is the longest to date, described in the literature. This long-term treatment with several intervening data time points allowed for the novel reporting of a longitudinal analysis of the progression of occlusal changes associated with MAS treatment. Mandibular advancement splints are an effective, noninvasive treatment option for snoring and obstructive sleep apnea. The present findings make it clear that many of the significant dental changes that occur will continue to progress over the duration of treatment, and as MAS treatment of OSA will continue indefinitely, the prudent clinician will be aware of these changes and discuss them openly with patients in their care.

REFERENCES 1. Kushida CA, Morgenthaler TI, Littner MR, et al. Practice parameters for the treatment of snoring and obstructive sleep apnea with oral appliances: an update for 2005. Sleep 2006;29:240-3. 2. Holley AB, Lettieri CJ, Shah AA. Efficacy of an adjustable oral appliance and comparison with continuous positive airway pressure for the treatment of obstructive sleep apnea syndrome. Chest 2011;140:1511-6.

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3. Gotsopoulos H, Kelly JJ, Cistulli PA. Oral appliance therapy reduces blood pressure in obstructive sleep apnea: a randomized, controlled trial. Sleep 2004;27:934-41. 4. Barnes M, McEvoy RD, Banks S, et al. Efficacy of positive airway pressure and oral appliance in mild to moderate obstructive sleep apnea. Am J Respir Crit Care Med 2004;170:656-64. 5. Aarab G, Lobbezoo F, Heymans MW, Hamburger HL, Naeije M. Long-term follow-up of a randomized controlled trial of oral appliance therapy in obstructive sleep apnea. Respiration 2011;82:162-8. 6. Gagnadoux F, Fleury B, Vielle B, et al. Titrated mandibular advancement versus positive airway pressure for sleep apnoea. Eur Respir J 2009;34:914-20. 7. Hoekema A, Stegenga B, Bakker M, et al. Simulated driving in obstructive sleep apnoea-hypopnoea; effects of oral appliances and continuous positive airway pressure. Sleep Breath 2007;11:129-38. 8. Aarab G, Lobbezoo F, Hamburger HL, Naeije M. Oral appliance therapy versus nasal continuous positive airway pressure in obstructive sleep apnea: a randomized, placebo-controlled trial. Respiration 2011;81:411-9. 9. Andrén A, Hedberg P, Walker-Engström ML, Wahlén P, Tegelberg Å. Effects of treatment with oral appliance on 24-h blood pressure in patients with obstructive sleep apnea and hypertension: a randomized clinical trial. Sleep Breath 2013;17:705-12. 10. Dieltjens M, Vanderveken OM, Hamans E, et al. Treatment of obstructive sleep apnea using a custom-made titratable duobloc oral appliance: a prospective clinical study. Sleep Breath 2013;17:565-72. 11. Chan AS, Cistulli PA. Oral appliance treatment of obstructive sleep apnea: an update. Curr Opin Pulm Med 2009;15:591-6. 12. Vezina JP, Blumen MB, Buchet I, Hausser-Hauw C, Chabolle F. Does propulsion mechanism influence the long-term side effects of oral appliances in the treatment of sleep-disordered breathing? Chest 2011;140:1184-91. 13. Lawton HM. A comparison of the Twin Block and Herbst mandibular advancement splints in the treatment of patients with obstructive sleep apnoea: a prospective study. Eur J Orthod 2005;27:82-90. 14. Doff MHJ, Finnema KJ, Hoekema A, Wijkstra PJ, de Bont LGM, Stegenga B. Long-term oral appliance therapy in obstructive sleep apnea syndrome: a controlled study on dental side effects. Clin Oral Investig 2013;17:475-82. 15. Battagel JM, Kotecha B. Dental side-effects of mandibular advancement splint wear in patients who snore. Clin Otolaryngol 2005;30:149-56. 16. Martínez-Gomis J, Willaert E, Nogues L, Pascual M, Somoza M, Monasterio C. Five years of sleep apnea treatment with a mandibular advancement device. Side effects and technical complications. Angle Orthod 2010;80:30-36. 17. Marklund M. Predictors of long-term orthodontic side effects from mandibular advancement devices in patients with snoring and obstructive sleep apnea. Am J Orthod Dentofacial Orthop 2006;129:214-21. 18. Almeida FR de, Lowe AA, Otsuka R, Fastlicht S, Farbood M, Tsuiki S. Long-term sequellae of oral appliance therapy in obstructive sleep apnea patients: Part 2. Study-model analysis. Am J Orthod Dentofacial Orthop 2006;129:205-13. 19. Pantin CC, Hillman DR, Tennant M. Dental side effects of an oral device to treat snoring and obstructive sleep apnea. Sleep 1999;22:237-40. 20. Robertson C, Herbison P, Harkness M. Dental and occlusal changes during mandibular advancement splint therapy in sleep disordered patients. Eur J Orthod 2003;25:371-6. 21. Ferguson KA, Cartwright R, Rogers R, Schmidt-Nowara W. Oral appliances for snoring and obstructive sleep apnea: a review. Sleep 2006;29:244-62. 22. Ueda H, Almeida FR, Lowe AA, Ruse ND. Changes in occlusal contact area during oral appliance therapy assessed on study models. Angle Orthod 2008;78:866-72. 23. Proffit WR, Fields HW Jr, Sarver DM. Contemporary orthodontics. 5 ed. St. Louis: Elsevier, 2013. 24. Cohen-Levy J, Petelle B, Pinguet J, Limerat E, Fleury B. Forces created by mandibular advancement devices in OSAS patients. Sleep Breath 2012;17:781-9. 25. Rose EC, Staats R, Virchow C, Jonas IE. Occlusal and skeletal effects of an oral appliance in the treatment of obstructive sleep apnea. Chest 2002;122:871-7. 26. Weschler D, Pancherz H. Efficiency of three mandibular anchorage forms in Herbst treatment: a cephalometric investigation. Angle Orthod 2005;75:23-7. 27. DeVincenzo JP. Changes in mandibular length before, during, and after successful orthopedic correction of Class II malocclusions, using a functional appliance. Am J Orthod Dentofacial Orthop 1991;99:241-57. 28. Chan ASL, Sutherland K, Schwab RJ, et al. The effect of mandibular advancement on upper airway structure in obstructive sleep apnoea. Thorax 2010;65:726-32. 29. Marklund M, Franklin KA, Sahlin C, Lundgren R. The effect of a mandibular advancement device on apneas and sleep in patients with obstructive sleep apnea. Chest 1998;113:707-13.


Long-Term Occlusal Effects of Mandibular Advancement Splints

SUBMISSION & CORRESPONDENCE INFORMATION

DISCLOSURE STATEMENT

Submitted for publication February, 2014 Submitted in final revised form July, 2014 Accepted for publication July, 2014 Address correspondence to: Dr. Benjamin T. Pliska D.D.S., M.Sc., FRCD(C), Department of Oral Health Sciences, Faculty of Dentistry, University of British Columbia, 2199 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3; Tel (604) 8227237; Fax: 604-822-3562; E-mail: pliska@dentistry.ubc.ca

This was not an industry supported study. Support was provided by oral appliance royalties paid to the University of British Columbia and an UBC Undergraduate Student Summer Research Award. The authors have indicated no financial conflicts of interest. The work was performed at the Department of Oral Health Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada.

Obstructive Sleep Apnea and Mandibular Advancement Splints: Occlusal Effects and Progression of Changes Associated with a Decade of Treatment Question 1

To Evaluate long-term dental changes when using mandibular advancement splints

True or False Question 2

Changes measured in this study included:

A Overbite B Overjet C Dental arch crowding D Inter arch relationship E All of the above Question 3

Obstructive sleep apnea can lead to heart diseases

True or False Question 4

Mandibular advancement splints are mainly used in treatment for snoring and mild to moderate obstructive sleep apnea

True or False Question 5 A B C D

Side effects of mandibular advancement splints may include:

Excessive salivation or mouth dryness Temporomandibular joint and dental discomfort Irritation of intra oral tissue All of above

Question 6

All splints were made of gum guard material

True of False Question 7 A B C

All patients have to have dental casts that were:

More than 2 years Less than 8 years More than 8 years 1291

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Question 8 A B C D

Which of the following statements are correct?

Overjet increased continuously at the linear rate while the overbite decreased but eventually started to level off Overjet decreased continuously at the linear rate while the overbite increased but eventually started to level off Overjet increased continuously at the linear rate while the overbite increased but eventually started to level off Overjet decreased continuously at the linear rate while the overbite decreased but eventually started to level off

Question 9 The patientâ&#x20AC;&#x2122;s overall weight had a direct relationship to the amount of both overjet and overbite reduction. True or False Question 10 Patients with a greater amount of initial overjet tended to see larger total reductions to both overbite and overjet. True of False Question 11 Changes in occlusion were progressive in nature and continued with ongoing use of man- dibular advancement splints. True of False

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Case report Case report

Safe Safe approach approach in in “All-on-four” “All-on-four” technique: technique: a Safereport Approach in “All-on-four” technique: a case case report

2.8

A Case Report

Marouene Ben Hadj Hassine, DDS1 2 Marouene Ben Hadj Hassine, DDS1 Paolo Bucci, MD, DDS 2 Paolo Bucci, MD, DDS Roberta Gasparro, DDS, PhD2 Roberta Gasparro, DDS, PhD2 DDS2 Alessandro Espedito Di Lauro, 2 Alessandro Espedito Di Lauro, Gilberto Sammartino, MD, DDS DDS Gilberto Sammartino, MD, DDS Department of Oral Medicine and Oral Surgery, UniDepartment of Oral Medicine and Oral Surgery, University of Dental Medicine, Monastir, Tunisia 2 University versity of Dental Medicine, Monastir, Tunisia of Naples Federico II, Italy 2 University of Naples Federico II, Italy 1 1

Corresponding author: Corresponding author: Gilberto Sammartino, MD, DDS Gilberto FedericoSammartino, II University MD, DDS Federico II University Via Pausini, 5 Via Pausini, 5 Italy 80131 Napoli, 80131 Napoli, Italy E-mail: gilberto.sammartino@unima.it E-mail: gilberto.sammartino@unima.it This is an open access article

Summary Summary

The “All-on-Four” concept is based on the placeThe concept is anterior based on theofplacement“All-on-Four” of four implants in the part fully ment of fourjaws implants in the a anterior part offixed, fully edentulous to support provisional, edentulous jaws toloaded support a provisional, fixed, and immediately full-arch prosthesis. and immediately loaded full-arch prosthesis. Combining tilted and straight implants for supCombining tilted and straight implants for supporting fixed prostheses can be considered a viporting fixed prostheses can be considered viable treatment modality resulting in a more asimable treatment modality resulting in a more simple and less time consuming procedure, in signifiple andless lessmorbidity, time consuming procedure, in significantly in decreased financial costs cantly in decreased financial costs and a less moremorbidity, comfortable postsurgical period for and a more comfortable period for the patients. The authorspostsurgical present a case report the Theatrophy authors present a case report withpatients. mandibular and left mental foramina with mandibular left mental foramina on the top of the atrophy residual and crest. on the top of the residual crest. Key words: edentulous jaw, dental implants, imKey edentulous jaw, dental implants, implantwords: placement. plant placement.

Introduction Introduction

Current standards in implant dentistry are intended to Current prosthetic standards restorations in implant dentistry intended to provide with theare finest esthetic provide prosthetic restorations with the finest esthetic and functional outcomes. Several parameters have been and functional outcomes. Several parameters been suggested to achieve gold standard results:have adequate suggested to achieve gold standard results: adequate bone height, width and sagittal projection, adequate soft bone width sagittal projection, soft tissueheight, quantity and and quality, preservation of adequate buccal sulcus tissue quantitypapillae and quality, preservation of buccal and adequate and gingival contour (1) . sulcus and adequate papillae andridge gingival contour (1) . the use Solutions to inadequate height include Solutions to inadequate ridgeridge height include the prouse of short implants (2) , vertical augmentation of short implants , verticalprostheses ridge augmentation procedures (3, 4), or(2) cantilever (5). Although cedures 4), or cantilever prostheses Although having a(3, comparable short-term survival(5). rate, some having a comparable short-term survival rate, some

142 142

authors state that the long-term performance of short authors that the long-term performance short implantsstate is less understood, especially in the of posteriimplants is less understood, especially in the posterior maxilla with lower bone density (6). Vertical augor maxilla procedures with lower bone density (6). morbidity Vertical augmentation increase patient and mentation procedures increase patient and the outcome is less predictable, mainly morbidity in the posterithe outcome is less predictable, mainly in incur the posterior mandible. Cantilever prostheses might higher or mandible. Cantilever prosthesessuch mightas incur higher rates of prosthetic complications abutment rates of prosthetic complications suchfailure. as abutment loosening, denture fracture and implant loosening, fracture and implant failure. assoDue to the denture less predictable long-term prognosis Due to the less predictable long-term prognosis ciated with the above mentioned procedures, theasso“Allciated withtechnique the abovewas mentioned procedures, the “Allon-Four” proposed for the rehabilitaon-Four” techniquejaws. was proposed for the concept rehabilitation in edentulous The“All-on-Four” is tion in on edentulous jaws. The“All-on-Four” is based the placement off our implants concept (two axial based ontilted the placement offthe ouranterior implantspart (two and two implants) in of axial fully and two tilted implants) in the anterior part of fully edentulous jaws to support a provisional, fixed, and edentulous to full-arch support prosthesis. a provisional, fixed, and immediatelyjaws loaded immediately loaded Combining tilted andfull-arch straightprosthesis. implants for supporting Combining tilted and straight implants aforviable supporting fixed prostheses can be considered treatfixed prostheses can be considered a viable ment modality (7) resulting in a more simple andtreatless ment modality (7)procedure, resulting inina significantly more simpleless and morless time consuming time procedure, significantly less commorbidity,consuming in decreased financialincosts and a more bidity, decreased financial and a more fortableinpostsurgical period forcosts the patients (8). comfortable postsurgical period for the patients (8).

Case presentation Case presentation

A 58-year-old man, edentulous for a long period of A 58-year-old man, edentulous long period of time due to periodontal disease, for wasa referred to the time due to periodontal disease, was referred to the Department of Oral Surgery-University of Naples Department of Oral Surgery-University of rehabiliNaples Federico II, Italy, requiring a fixed prosthetic Federico II, Italy, fixedmedical prosthetic rehabilitation in the lowerrequiring jaw. Hisapast history was tation in the lower uneventful (Fig. 1). jaw. His past medical history was uneventful (Fig. 1). The panoramic radiograph revealed an advanced The panoramic radiograph revealedin an alveolar bone resorption, particularly theadvanced mandible alveolar resorption, particularly in the mandible (Fig. 2). bone The Ct scan confirmed the mandibular atro(Fig.and 2). The Ct scan confirmed mandibular phy showed the left mental the foramina on theatrotop phytheand showed the(Fig. left 3). mental foramina on the top of residual crest of the“All-on-Four” residual cresttechnique (Fig. 3). was scheduled to rehaThe The “All-on-Four” technique was scheduled to rehabilitate the lower jaw. bilitate the lower jaw. Under local anesthesia, a full thickness crestal inciUnder local anesthesia, full thickness crestal incision was performed from athe right first molar region to sion was performed right first molar region to the left first premolarfrom one.the A midline releasing incision the left first premolar one. Aflap midline releasing incision was carried out to facilitate reflection and to idenwasthe carried out to facilitate flap reflection and identify left mental nerve emergence (Fig. 4).toThe 2 tify the left mental nerve emergence (Fig. 4). The 2 mm osteotomy was made in the midline position and mm osteotomy was made theThe midline position the guide was placed (Fig.in 5). vertical linesand on the guide was placed (Fig. 5). The vertical lines on the guide were used as a reference to prepare the the guide were usedcorrect as a reference to prepare the implant sites in the position, with an angulaimplant sites in the position, angulation which should notcorrect exceed 45°. Allwith sitesan were pretion which not exceed 45°. All sites (Tekka were prepared usingshould the manufacturer’s guidelines Inpared using thecopious manufacturer’s guidelines (Tekka Inkone®), under sterile saline irrigation. A conkone®), copious sterile salinebetween irrigation.implant A control of a under possible communication trol ofwas a possible communication between implant sites done before implant placement. sites was done before implant placement. Annali di Stomatologia 2014; V (4): 142-145 Annali di Stomatologia 2014; V (4): 142-145

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Safe approach in “All-on-four” technique: a case report The two anterior implants (Tekka In-kone®) were placed in the incisive area, whereas the two posterior implants were placed, following the diagonal of the rectangle (Fig. 6), at an angle of 30° mesially to the mental foramina. After soft tissue management and closure, straight and angulated abutments were placed onto the implants (Fig. 7) and the multiunit impression copings were attached to the prosthetic abutments and splinted using wire-bars and low shrinkage autopolymerizing resin (Fig. 8) to ensure an accurate transfer with-

Figure 1. Preoperative clinical view.

out accidental displacement, when an alginate impression was taken. The polyvinylsiloxane impression of the complete removable prosthesis was made to detect the position of implants and soft tissue. The definitive, immediate loaded prosthesis was given to the patient after 24 hours (Fig. 9). The panoramic radiograph at 1-year-follow up revealed a good bone healing and no sign of bone resorption around implant shoulders (Fig. 10).

Figure 2. Preoperative panoramic radiograph.

Figure 3. CT Scan showing the crestal position of the left mental nerve.

Figure 4. Identification of the mental nerve: (left side).

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Figure 5. Identification of the mental nerve: (right side).

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M.B. Hadj Hassine et al.

Figure 10. Panoramic radiograph after 1-year-follow-up. Figure 6. Placement of the mandibular guide.

Figure 7. Preparation of the distal implant site.

Figure 8. Placement of straight and angulated abutments.

Figure 9. The definitive prosthesis.

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Discussion A recent shift in practice paradigm has been to minimize treatment costs and patient morbidity while providing the most satisfying patient-centered treatment outcomes according to the state of the art of dental practice. The “Allon-Four” treatment concept is an attempt to reach these objectives by providing relatively straight forward, predictable treatment option to rehabilitate edentulous patients with a high outcome of quality of life (9). In this technique, the placement of the two posterior implants in front of mental foramina and tilted with a distal direction avoids to injure the inferior alveolar nerve and decreases the cantilevers, allowing the increase of the polygonal area for a full fixed prosthesis and providing satisfactory molar support (10, 11). According to Krekmanov et al., the gained mean distance of prosthesis support in the mandible is 6,5 mm while it is 9,3 mm in the maxilla (12). The “All-onFour” procedure also improves cortical anchorage and primary stability, allowing the use of longer implants. In a three-dimensional finite element analysis about load transmission using different implant inclinations and cantilever lengths, Bevilacqua et al. reported a reduction of stress around anterior implants in a full fixed prosthesis design, when tilted implants were compared to straight implants (13). Furthermore there are no significant differences between axial and tilted implants in terms of success rates and marginal bone loss (14). In the present case report, the crestal position of the mental nerve requested to change the flap design with respect to the surgical protocol, which consists of a linear incision performed from the first molar to the contralateral one, with or without two vertical distal incisions. The midline releasing incision allowed an easier reflection of the flap, a less difficult implant placement and nerve injury preservation. The bone growth around the implant shoulders might be justified by the subcrestal position and the implant characteristics, such as platform switching and a morse taper connection. Moreover, the microstructured surface texture extended onto the implant shoulder seems to play a role in minimizing the marginal bone loss (0.11 mm, 0.08 mm) and in promoting bone formation on the implant platform, even when using tilted implants (15, 16). Annali di Stomatologia 2014; V (4): 142-145

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Safe approach in “All-on-four” technique: a case report

Conclusion The “All-on-4” treatment concept seems to be an alternative option for rehabilitating edentulous jaws compared with advanced surgical approaches without using removable prostheses. It is a cost-effective procedure, decreasing the treatment times, the morbidity and allowing a higher patient quality of life. Marginal bone loss around splinted tilted implants to support full-arch fixed prosthesis doesn’t significantly differ from straight implants in short and mediumterm. Nevertheless, long-term results are required to verify this finding. Furthermore, platform switching, morse taper connection and microstructured surface texture extended onto the implant shoulder seem to play a role in stabilizing the peri-implant bone, also when tilted implants are used.

6. 7. 8.

9. 10.

11.

References 1. Guerrero C, Lopez P, Figueroa F, et al. Three-dimensional alveolar distraction osteogenesis. In: Bell W, Guerrero C, editors. Distraction osteogenesis of the facial skeleton. 1st edition. Hamilton (Canada): BC Decker, 2007; 457-93. 2. Esposito M, Grusovin MG, Coulthard P, Worthington HV. The efficacy of various bone augmentation procedures for dental implants. A Cochrane systematic review of randomized controlled clinical trials. Int J oral Maxillofac Implants. 2006;21:696-710. 3. Sorní M, Guarinós J, García O, Peñarrocha M. Implant rehabilitation of the atrophic upper jaw: a review of the literature since 1999. Med Oral Patol Oral Cir Bucal. 2005;10 Suppl 1:E45-56. 4. Maestre-Ferrín L, Boronat-Lopez A, Penarrocha-Diago M, et al. Augmentation procedures for deficient edentulous ridges, using on lay autologous grafts: An update. Med Oral Patol Oral Cir Bucal. 2009;14:402. 5. Chaushu G, Mardinger O, Peleg M, et al. Analysis of com-

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15.

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plications following augmentation with cancellous block allografts. J Periodontol. 2010;81:1759. Hashemi HM. Neurosensory function following mandibular nerve lateralization for placement of implants. Int J Oral Maxillofac Surg. 2010; 39:452. Vega LG, Bilbao A. Alveolar distraction osteogenesis for dental implant preparation: An update. Oral Maxillofac Surg Clin North Am. 2010;22:369. Peñarrocha Diago M, Maestre Ferrín L, Peñarrocha Oltra D, Canullo L, Calvo Guirado JL, Peñarrocha Diago M. Tilted implants for the restoration of posterior mandibles with horizontal atrophy. An alternative treatment. J oral Maxillofac Surg. 2013;71.856-864. Rangert B, Jemt T, Jörneus L. Forces and moments on Brånemark implants. Int J Oral Maxillofac Implants. 1989;4:241-247. Sertgöz A, Güvener S. Finite element analysis of the effect of cantilever and implant length on stress distribution in an implant-supported fixed prosthesis. J Prosthet Dent. 1996;76:165-169. Butura CC, Galindo DF, Jensen OT. Mandibular all-on-four therapy using angled implants: a three-year clinical study of 857 implants in 219 jaws. Oral Maxillofac Surg Clin North Am. 2011 May;23(2):289-300. Malo P, Rangert B, Nobre M. ‘‘All-on-four’’ immediate-function concept with Branemark system implants for completely edentulous mandible: A retrospective clinical study. Clin Implant Dent Relat Res. 2003;5:2. De Vico G, Bonino M, Spinelli D, Schiavetti R, Sannino G, Pozzi A, Ottria L. Rationale for tilted implants: FEA considerations and clinical reports. Oral Implantol (Rome). 2011 Jul;4(3-4):23-33. Krekmanov L, Kahn M, Rangert B, Lindstrom H. Tilting of posterior mandibular and maxillary implants of improved prosthesis support. Int J Oral Maxillofac Implants. 2000;15:405414. Bevilacqua M, Tealdo T, Pera F, et al. Three-dimensional finite element analysis of load transmission using different implant inclinations and cantilever lengths. Int J Prosthodont. 2008; 21:539-542. Gowgiel JM. The position and course of the mandibular canal. J Oral Implantol. 1992;18:383.

Safe approach in “All-on-four” technique: a case report QUESTION 12 True or false: The “All-in-four” concept is based on the placement of four implants in the posterior part of the fully edentulous jaws to support a provisional, fixed and immediately loaded full-arch prosthesis. QUESTION 13 After 1 year, was there resorption around the implant shoulders? YES or NO QUESTION 14 The CT scan confirmed the mandibular atrophy and showed the left mental foramina of the residual crest on the: a) Top b) Middle c) Bottom

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QUESTION 15 True or false: The bone growth around the implant shoulders might be justified by the subcrestal position and the implant characteristics, such as platform switching and a morse taper connection. QUESTION 16 What guideline was used to prepare the implant sites? a) Tekka Inkone b) Gilberto Sammartino c) Maestre-Ferrin QUESTION 17 Select one of the parameters that have been suggested to achieve gold standard results. a) b) c) d)

Bone contour Adequate gingival height Preservation of buccal sulcus Lingual sulcus

QUESTION 18 Immediate loading of the prosthesis was given to the patients after: a) b) c)

48 hours 24 hours 72 hours

QUESTION 19 True or false: The patient had good periodontal health. QUESTION 20 According to Krekmanov et al, the gained mean distance of prosthesis supporting the mandible is: a) 9.3mm b) 6.5mm QUESTION 21 Is the â&#x20AC;&#x153;All-on-fourâ&#x20AC;? procedure cost effective for the patient, YES or NO?

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The Saudi Dental Journal (2015) 27, 149–154 The Saudi Dental Journal (2015) 27, 149–154

King Saud University

2.6

Saud University The Saudi King Dental Journal

The Saudi Dental Journal www.ksu.edu.sa www.sciencedirect.com www.ksu.edu.sa www.sciencedirect.com

Fit Accuracy of Metal Partial Removable Dental ORIGINAL ARTICLE Prosthesis Frameworks Fabricated by Traditional ORIGINAL ARTICLE Fit accuracy of metal Modeling partial removable dental or Light Curing Material Technique: Fit accuracy of metal partial removable dental

prosthesis frameworks fabricated by traditional or In Vitro Study prosthesis frameworks fabricated by traditional or lightAn curing modeling material technique: An lightstudy curing modeling material technique: An in vitro in vitro study Original Article Mohammad Tarek M. Anan 1, Mohannad H. Al-Saadi * Mohammad Tarek M. Anan 1, Mohannad H. Al-Saadi

*

Department of Removable Prosthodontics, Faculty of Dentistry, Damascus University, Damascus, Syria Department of Removable Prosthodontics, Faculty of Dentistry, Damascus University, Damascus, Syria Received 24 July 2013; revised 17 August 2014; accepted 19 November 2014 Available online 24 April 2015 Received 24 July 2013; revised 17 August 2014; accepted 19 November 2014 Available online 24 April 2015 KEYWORDS

Abstract Objective: The aim of this study was to compare the fit accuracies of metal partial removable dental prosthesis (PRDP) frameworks fabricated by the traditional technique (TT) or Accuracy; KEYWORDS Abstract Objective: Thetechnique aim of this study was to compare the fit accuracies of metal partial the light-curing modeling material (LCMT). Chrome cast framework; removable dental prosthesis (PRDP) frameworks by the 1traditional technique Materials and methods: A metal model of a Kennedy classfabricated III modification mandibular dental (TT) or Accuracy; Partial denture fit; material technique (LCMT). Chrome castmateframework; arch with the twolight-curing edentulous modeling spaces of different spans, short and long, was used for the study. Thirty Light curing modeling Materials methods: metal model of a Kennedy classeach III modification 1 mandibular dental Partial denture fit; rial technique; identical working castsand were used toAproduce 15 PRDP frameworks by TT and by LCMT. arch with two edentulous spaces of different spans, short and long, was used for the study. Thirty Light curing modeling mateGap measurement; Every framework was transferred to a metal master cast to measure the gap between the metal base rial technique; Cobalt–chromium identicaland working casts werealveolar used toridge produce PRDP eachatbythree TT points and by LCMT. of the framework the crest of the of the15cast. Gapsframeworks were measured Gap measurement; Every framework was transferred to a metal master cast to measure the gap between on each side by a USB digital intraoral camera at ·16.5 magnification. Images were transferred the to ametal base Cobalt–chromium of the framework theexaminer crest of the alveolar all ridge of the cast. Gaps were measured three points graphics editing program. Aand single performed measurements. The two-tailed t-testat was sidesignificance by a USB digital performedon ateach the 5% level. intraoral camera at ·16.5 magnification. Images were transferred to a editing single examiner performed all measurements. The two-tailed Results:graphics The mean gap program. value wasAsignificantly smaller in the LCMT group compared to the TT t-test was performed at the 5% significance level. group. The mean value of the short edentulous span was significantly smaller than that of the long Results: meangroup, gap value was significantly in the LCMTingroup compared edentulous span in theThe LCMT whereas the oppositesmaller result was obtained the TT group. to the TT group. The mean value of the short edentulous span was significantly smaller than that of the long edentulous span in the LCMT group, whereas the opposite result was obtained in the TT group.

* Corresponding author at: P.O. Box 4926, Damascus, Syria. Tel.: +963 932844346; fax: +963 112124757. * Corresponding author at: P.O. Box 4926, Damascus, E-mail addresses: dr.tarekanan@googlemail.com (M.T.M. Anan),Syria. Tel.: +963 932844346; +963 112124757. malssadi@gmail.com (M.H. fax: Al-Saadi). 1 Tel.: +963 944386529; fax: dr.tarekanan@googlemail.com +963 112124757. E-mail addresses: (M.T.M. Anan), Peer reviewmalssadi@gmail.com under responsibility (M.H. of KingAl-Saadi). Saud University. 1 Tel.: +963 944386529; fax: +963 112124757. Peer review under responsibility of King Saud University.

Production and hosting by Elsevier Production and hosting by Elsevier http://dx.doi.org/10.1016/j.sdentj.2014.11.013 1013-9052 ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). http://dx.doi.org/10.1016/j.sdentj.2014.11.013 1013-9052 ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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M.T.M. Anan, M.H. Al-Saadi Conclusion: Within the limitations of this study, it can be concluded that the fit of the LCMTfabricated frameworks was better than the fit of the TT-fabricated frameworks. The framework fit can differ according to the span of the edentate ridge and the fabrication technique for the metal framework. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction Use of wax in dentistry dates back 200 years to the use of beeswax to take impressions of teeth. Resins have been used as patterns for dental restorations. Resins offer higher strength and lower flow than pattern waxes and non-residue burnout. Light-cured resins offer a greater working time to build the pattern compared to chemically cured resins (Craig and Wataha, 2004). The newer light-polymerized, dimethacrylate modeling resins can be manipulated with increased precision and stability after light polymerization. Advantages of these resins include low polymerization shrinkage, good dimensional stability, ease of use, less chair time, and absence of residue after burnout (Derleth et al., 1987). Unlike wax, curing the plastic pattern allows for removal of the framework from the master cast without distortion for subsequent casting procedures Potential causes of ill-fitting for cast frameworks may include dimensional changes in the investment materials, solidification shrinkage, and distortion of the wax pattern (Fenlon et al., 1993). As much as 75% of removable partial dentures does not fit the mouth on the day of insertion. Improper fit may contribute to movement of the associated teeth and discomfort. Improper fit also may be the primary reason that many removable partial dentures are not worn (Phoenix et al., 2003). An ill-fitting prosthesis can exaggerate other problems caused by the prosthesis. Harmful effects, such as caries (especially root caries), periodontitis, oral candidiasis, denture stomatitis, and halitosis, can arise from the plaque that accumulates around a partial prosthesis. Plaque may serve as a reservoir for pathogens that cause pneumonia and other systemic diseases (Yang et al., 2014). In one study, the authors compared the fit of a clasp assembly fabricated by the standardized conventional refractory wax up method or by a light-cured pattern. The clasp assembly fabricated by the light-cured pattern had better fit than the assembly fabricated by the conventional refractory wax up (Kumar et al., 2010). Another study described a new technique for fabricating a cast framework by using a light-polymerizing plastic pattern. This technique was proposed to minimize laboratory cost and time for partial denture construction. Although the accuracy of the framework was clinically acceptable, the dimensional stability of the denture required further assessment (Takaichi et al., 2011). The influence of the pattern material of conventional wax and light-polymerized patterns on the initial surface roughness and internal porosity of cobalt–chromium castings of partial removable dental prostheses (PRDPs) was investigated, but revealed no significant differences between the two pattern materials (Swelem et al., 2014). The aim of this study was to compare the fit accuracies of metal PRDP frameworks fabricated by the traditional technique (TT) or the light-curing modeling material technique

(LCMT). The null hypotheses were as follows: (a) There is no significant difference in accuracy between the TT- and LCMT-fabricated frameworks, and (b) The edentulous span has no effect on the framework fit for either technique. 2. Materials and methods The research protocol was approved by the Ethics Committee of the Faculty of Dentistry of the Damascus University. 2.1. Preparation of the metal master cast A typodont model of the mandibular arch was prepared with the following specifications, and then duplicated into an aluminum metal master cast. Missing teeth were the second premolar and first molar on both sides and the second molar on the right side. Four rest seats were prepared adjacent to the edentulous spaces. The model was surveyed to ensure parallel guiding planes. The model was provided with a blockout relief, creating a ledge of 0.25-mm undercut gauge on the abutments, to delineate the positions of the retentive clasp tips. The alveolar ridges were smoothly planed. Three notches, serving as landmarks for measurement, were prepared on each side buccal to the alveolar ridge (Fig. 1). 2.2. Preparation of the stone casts The metal master cast was duplicated by using additional silicone impression material (Ormaduplo 22, Major Prodotti Dentari S.P.A. Italy) and type IV stone (BegoStone Plus, BEGO Bremer Goldschlagerei Wilh. Herbst GmbH & Co., Germany) to make 30 stone master casts. The sample size was determined by using G*Power 3.1.7 (Franz Faul, Universitat Kiel, Germany). According to the calculations, the actual power of the study was 0.996 with 15 samples per group. 2.3. Selection of the framework design The design selected for both techniques consisted of a lingual bar major connector, four simple circumferential clasps placed on the prepared abutments, metal bases fitted directly on the cast, and minor connectors joining the major connector to the other framework components. The design was standardized for all frameworks in both groups. 2.4. Preparation of the PRDP frameworks by the TT Fifteen metal frameworks were fabricated by following the traditional steps of PRDP metal framework fabrication: duplication of the master cast, hardening of the refractory cast,

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Comparison of fit accuracies of metal partial removable dental prosthesis (PRDP) frameworks

Figure 1

151

The metal master cast. Figure 2

A TT framework on its corresponding stone cast.

beeswax dipping, adaptation of the prefabricated wax patterns (BEGO Bremer Goldschlagerei Wilh. Herbst GmbH & Co.), spruing, investing with phosphate-bonded refractory material (Cobavest, YETI Dentalprodukte, Germany), burnout, casting the cobalt–chromium alloy (Wironit, BEGO Bremer Goldschlagerei Wilh. Herbst GmbH & Co.) in a casting machine (Degussa TS-1, Degussa-Hu¨ls, Germany), casting recovery, and fitting the framework to the stone cast by removing any metal nodule that may prevent fitting (Fig. 2). All the steps were standardized in all frameworks. 2.5. Preparation of the PRDP frameworks by the LCMT LiWa� light-curing modeling material (LiWa; Willmann & Pein GmbH, Germany) was used for the LCMT. Fifteen metal frameworks were fabricated by following the steps of PRDP metal framework fabrication. A stone master cast was isolated by using LiWa Iso Step I + II. LiWa light-polymerizing plastic patterns were modeled directly on the master cast. Modeling of the light-curing material involves cold and hot modeling. In cold contouring, LiWa is shaped by kneading and contouring with the fingers in wet protective gloves or by using metal or rubber instruments. In hot contouring, the pattern can be built up gradually by using an electric wax knife (Liwaxer; Willmann & Pein GmbH). The pattern was sprayed with a cold spray to alter the consistency of LiWa from slightly viscous to sculptable. Plastic patterns were supported with 0.9mm clasp wires connecting the right and left sides to minimize potential distortion of the plastic frameworks (Fig. 3). Lightcuring was achieved by using a LaWa UV light-curing unit for 6 min. A LiWa finish varnish was used for conditioning the pattern surface, and then light-curing was repeated for 2 min. Spruing, investment, burnout, casting, and fitting the framework were performed similar to the TT procedures without using a refractory cast. All the steps were standardized in all frameworks. 2.6. Measurement of fit accuracy Each framework was transferred to the metal master cast and stabilized with a simple clamp. The gap between the metal

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Figure 3 wire.

The plastic pattern supported using a 0.9 mm clasp

saddle of the framework and the crest of the alveolar ridge of the metal cast was measured at three points on each side (Fig. 4). A USB digital intraoral camera (WTH, VIMICRO, China(with 480 k pixel resolution and a focus rate of 8– 12 mm was used to capture images at ·16.5 magnification. A single examiner captured all images. While capturing the images, a determinant with two prominences specifically designed for this study was fixed to the camera by using a cyanoacrylate adhesive to secure a perpendicular fixed distance of 9.1 mm between the camera and the measured gap (Fig. 5). Images were transferred to a graphics editing program (Adobe Photoshop CS5 ME version 12.0, Adobe Systems Inc., San Jose, CA, USA(and enlarged by 200%. The gap distance was measured by using the Marquee tool through the ‘‘Info’’ window (Fig. 6). A millimetric ruler with vertical and horizontal calibrations was positioned above the cast during capturing to be included in the image and used to detect the accuracy of the measurements. Each gap was measured only once at three points per side. A single investigator performed all measurements.


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M.T.M. Anan, M.H. Al-Saadi

Figure 4

Figure 5

Framework on the metal cast with the three gap measurement sites at each side (arrows).

Special determinant secured to the camera to standardize the distance between the camera and measured gaps.

2.7. Statistical analysis A total of 180 gap measurements were made, including 90 measurements of the short and long edentulous spans in the TT group (TT-S and TT-L) and 90 measurements of the short and long edentulous spans in the LCMT group (LCMT-S and LCMT-L). Means and standard deviations (SDs) of gap measurements were calculated for each group, as well as for the long and short edentulous spans within each group. A two-tailed t-test was conducted to compare between the two groups as a whole (TT and LCMT) and between the short and long edentulous spans within each group (TT-L and TT-S; LCMT-L and LCMT-S). All tests were performed by using SPSS version 12 (SPSS, Chicago, IL) at a significance level of 5%. 3. Results Means and SDs of the measured gaps of TT and LCMT are presented in Table 1. The mean gap value was smaller in the LCMT group compared to the TT group (p = 0.02). Table 2 shows the means and SDs of

the measured gaps of the short and long edentulous spans for the TT and LCMT frameworks. The mean gap value was smaller for LCMT-S compared to LCMT-L (p = 0.01), and for TT-L compared to TT-S (p = 0.003).

4. Discussion According to the results of the present study, both null hypotheses were rejected. LCMT-fabricated frameworks fit better than TT-fabricated frameworks, and the framework fit differed depending on the edentulous span. A misfit in the saddle area was considered to be representative of misfit for the whole framework. Metal denture bases are well suited for attaining healed and ideally contoured residual edentulous ridges (Phoenix et al., 2003). Gaps between the metal saddle and the crest of the alveolar ridge of the metal cast were measured to determine the fit accuracy of the metal PRDP frameworks. Neither technique was able to achieve an optimal fit. One reason for the lack of fit is the high linear

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Comparison of fit accuracies of metal partial removable dental prosthesis (PRDP) frameworks

Figure 6

A Photoshop screen image showing the width of the measured gap (arrow); using the marquee tool and ‘‘info’’ window.

Table 1 Means, standard deviations, minimum and maximum values (micrometer) of measured gaps of TT and LCMT frameworks. Group

Number of measured gaps

Mean

SD

Minimum

Maximum

TT LCMT

90 90

159.59 135.47

69.4 68.96

32 32

393 300

Table 2 Means, standard deviations, minimum and maximum values (by micrometer) of measured gaps of short (S) and long (L) edentulous spans of TT and LCMT frameworks. Subgroup

Number of measured gaps

Mean

SD

Minimum

Maximum

TT-S TT-L LCMT-S LCMT-L

45 45 45 45

181.11 138.07 117.02 153.91

71.9 60.3 64.35 69.15

32 32 32 48

393 270 276 300

solidification shrinkage of cobalt–chromium-based alloys (2.3%) (Anusavice et al., 2012). Moreover, the PRDP framework is a complex casting because it is usually fabricated from a high-fusing base metal alloy, which results in higher shrinkage than gold alloys (Gowri et al., 2010; Kumar et al., 2010). Hence, it is not surprising that we had difficulty achieving the desired fit. Gowri et al. (2010) studied the effect of anchorage on the accuracy of the palatal major connector of PRDP frameworks. Gap values between the major connector and metal cast were significantly different between the experimental group

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(0.16–0.43 mm) and the control group (0.44–0.65 mm). These authors did not discuss the clinical consequences of these high palatal gap values, but concluded that precision of fit of dental castings may be difficult to achieve. Gebelein et al. (2003) studied the dimensional changes of one-piece frameworks supported on telescopic crowns. The metal frameworks underwent significant dimensional changes during fabrication and tended to contract toward the geometric center. The resulting geometric contraction between the telescopic crowns would appear to exceed the physiological tooth mobility and, therefore, affect the desired passive fit outcomes. The fit of the cobalt–chromium PRDP may be compromised by errors in wax blocking out and duplication, variability in expansion of the refractory material, and the techniques used for fitting and polishing the metal frameworks (Brudvik and Reimers, 1992). In the TT, the agar impression material that is normally used for the duplication process undergoes dimensional changes of syneresis and imbibition, which may eventually adversely affect the reproduction of the refractory cast (Kumar et al., 2010). Therefore, it is reasonable to have a more accurate fit with LCMT because there is no duplication of the master cast, and the light-curing modeling material is adapted directly to the desired position on the master cast. Kumar et al. (2010) studied the accuracy of fit of cast clasps designed with conventional wax and light-cured patterns. Castings made by the light-cured patterns had significantly better fits compared to the castings made by the conventional wax patterns. Although our findings could not be compared directly with this study due to the different specimen designs, the results are in general agreement. In the LCMT group, the fit of the short edentulous span was better than the fit of the long edentulous span (p = 0.01). This result can be explained by the proportional casting distortion of the metal geometry (Gebelein et al.,


154 2003). However, the fit of the short edentulous span in the TT group was worse than that of the long edentulous span (p = 0.003). Akeel (2009) fabricated PRDP frameworks by the TT and studied the effect of the edentulous span on the fit of occlusal rests to the working cast. The fit of the bounded saddle PRDP framework occlusal rests was worse on abutments adjacent to long edentate ridges compared to those adjacent to short edentate ridges. Moreover, approximately onefifth of all rests did not contact the rest seat at any point. The disagreement of our results with those of Akeel could be due to the difference in the position of measuring misfit. No contact or poor fit between rests and rest seats does not necessarily mean misfit at the adjacent metal base. Phillips (1991) suggested that dimensional changes of castings may vary between different areas of the casting, and that these changes occur more often vertically than horizontally. Another study found that spaces were significantly greater between palatal aspects of abutment teeth and palatal reciprocal arms, and between buccal aspects of occlusal rests and rest seats. Excessive contraction toward the palate center was found. Expansion of the refractory investment may not have compensated adequately for solidification and cooling contraction of the cobalt–chromium alloy. Although dimensional changes in investment and casting are by volume, no evidence of anisotropic expansion of castings in a vertical direction was found (Fenlon et al., 1993). The abovementioned studies can explain the difference between the results of the present study and those of Akeel. Despite careful attention during the laboratory phases of the PRDP service, some discrepancies in the fit of the framework will occur. Improvements in materials and techniques have reduced the number and size of these discrepancies, but have not eliminated them. It is hoped that discrepancies can be kept to a minimum, but these discrepancies must be corrected if the practitioner is to provide the patient with appropriate care (Phoenix et al., 2003). Laboratory and chair-side fittings of the framework are vital steps for achieving an acceptable clinical fit. One limitation of this study was that we evaluated fit accuracy through metal base adaptation. Further investigation is needed to study the fit accuracy of all framework components to detect the exact position of the interference. In addition, an in vivo study of the ‘‘gaps’’ should be made, to detect whether these gaps were in the clinically acceptable range. 5. Conclusions Within the limitations of this study, it can be concluded that the fit of the LCMT-fabricated frameworks was better than that of the TT-fabricated frameworks. Framework fit can differ according to the span of the edentate ridge and the fabrication technique of the framework.

M.T.M. Anan, M.H. Al-Saadi Conflict of interest The authors have no known conflicts of interest associated with the products used in this study and there has been no financial support for this work that could have influenced its outcome. References Akeel, R., 2009. Effect of edentate ridge length on the fit of occlusal rests of a partial denture metal framework. Pak. Oral. Dent. J. 29, 376–391. Anusavice, K.J., Shen, C., Rawls, H.R., 2012. Phillips’ Science of Dental Materials, 12th ed. Elsevier Saunders Inc., pp. 199–386. Brudvik, J.S., Reimers, D., 1992. The tooth-removable partial denture interface. J. Prosthet. Dent. 68, 924–927. Craig, R.G., Powers, J.M., Wataha, J.C., 2004. Dental Ma: Properties and Manipulation, 8th ed. Mosby, St Louis, pp. 221–230. Derleth, R., Krober, R., Nowak, J., Palacit, G. LC., 1987. The first light curing modeling material. Dent. Labor. March: 1–7. Fenlon, M.R., Juszczyk, A.S., Hughes, R.J., Walter, J.D., Sherriff, M., 1993. Accuracy of fit of cobalt–chromium removable partial denture frameworks on master casts. Eur. J. Prosthodont. Restor. Dent. 1, 127–130. Gebelein, M., Richter, G., Range, U., Reitemeier, B., 2003. Dimensional changes of one-piece frameworks cast from titanium, base metal, or noble metal alloys and supported on telescopic crowns. J. Prosthet. Dent. 89, 193–200. Gowri, V., Patil, N.P., Nadiger, R.K., Guttal, S.S., 2010. Effect of anchorage on the accuracy of fit in removable partial denture framework. J. Prosthodont. 19, 387–390. Kumar, M.V., Murugesan, K., Bhagath, S.N., 2010. The accuracy of fit of cast clasps designed with conventional wax pattern and light cured patterns: a comparative in vitro study. SRM Univ. J. Dent. Sci. 1, 10–13. Phillips, R.W., 1991. Skinner’s Science of Dental Materials. WB Saunders Co., Philadelphia, pp. 385–392. Phoenix, R.D., Cagna, D.R., DeFreest, C.F., 2003. Stewart’s Clinical Removable Partial Prosthodontics, third ed. Quintessence publishing Co., China, pp. 95–337. Swelem, A.A., Abdelnabi, M.H., Al-Dharrab, A.A., AbdelMaguid, H.F., 2014. Surface roughness and internal porosity of partial removable dental prosthesis frameworks fabricated from conventional wax and light-polymerized patterns: a comparative study. J. Prosthet. Dent. 111, 335–341. Takaichi, A., Wakabayashi, N., Igarashi, Y., 2011. Prefabricated lightpolymerizing plastic pattern for partial denture framework. Contemp. Clin. Dent. 2, 402–404. Yang, Y., Zhang, H., Chai, Z., Chen, J., Zhang, S., 2014. Multiple logistic regression analysis of risk factors associated with denture plaque and staining in Chinese removable denture wearers over 40 years old in Xi’an–a cross-sectional study. PLoS One 9 (2), e87749. http://dx.doi.org/10.1371/journal.pone.0087749.

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Fit accuracy of metal partial removable dental prosthesis frameworks fabricated by traditional or light curing modeling material technique: An in vitro study Question 22 When comparing resins with waxes, it seems that resins offer: A B C D

Lower flow Higher strength Non-residue burn-out All of the above

Question 23 The metal master model had planned alveolar ridge, with 3 notches. What was the purpose of these notches? A B C D

Retention of appliance Landmarks for Measurement Model identification Rest seats

Question 24 In the null hypothesis was assumed that both techniques given similar results in relations to fit accuracy, yet it was found that the null hypotheses wereâ&#x20AC;Ś A exactly the same as expected B accepted C different D rejected Question 25 Neither techniques used were able to achieve an optimal fit True or False Question 26 Framework fit can differ, according to the author, which 2 of the following have an influence on the framework fit? A B C D

24

The span of the major connector and materials used Materials used and fabrication technique The span of the edentulous ridge and fabrication technique Fabrication technique and human error

SADTJ Vol 6 Issue 1


Influence of bruxism on survival of porcelain laminate veneers

2.6 Maria Granell-Ruíz 1, Rubén Agustín-Panadero 1, Antonio Fons-Font 2 , Juan-Luis Román-Rodríguez 1, Bruxism and porcelain laminate veneers María-Fernanda Solá-Ruíz

Med Oral Patol Oral Cir Bucal. 2014 Sep 1;19 (5):e426-32. 3

Influence of Bruxism On Survival of Porcelain Laminate Veneers

Journal section: Clinical and Experimental Dentistry 1

doi:10.4317/medoral.19097

DDS,PhD. Associate Profesor, Oclusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, http://dx.doi.org/doi:10.4317/medoral.19097 Spain 2 DDS,PhD,MD. Professor of Oclusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Spain 3 MF,DDS,PhD,MD. Adjunctof Lecturer, Department Stomatology,of University of Valencia, Valencia, veneers Spain Influence bruxism on ofsurvival porcelain laminate Publication Types: Research

This is an open access article Correspondence: 1 Unidad Prostodoncia y Oclusión MariadeGranell-Ruíz , Rubén Edificio Clínica Odontológica María-Fernanda Solá-Ruíz 3 C\ Gascó Oliag, Nº 1 46010 Valencia Spain maria.granell@uv.es

Agustín-Panadero 1, Antonio Fons-Font 2 , Juan-Luis Román-Rodríguez 1, Granell-Ruíz M, Agustín-Panadero R, Fons-Font A, Román-Rodríguez JL, Solá-Ruíz MF. Influence of bruxism on survival of porcelain laminate veneers. Med Oral Patol Oral Cir Bucal. 2014 Sep 1;19 (5):e426-32. http://www.medicinaoral.com/medoralfree01/v19i5/medoralv19i5p426.pdf

DDS,PhD. Associate Profesor, Oclusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Article Number: 19097 http://www.medicinaoral.com/ Spain © Medicina Oral S. L. C.I.F. B 96689336 - pISSN 1698-4447 - eISSN: 1698-6946 2 eMail: medicina@medicinaoral.com DDS,PhD,MD. Professor of Oclusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Received: 31/01/2013 Indexed in: Accepted: 19/05/2013 Spain Science Citation Index Expanded 3 Journal Citation Reports of Valencia, Valencia, Spain MF,DDS,PhD,MD. Adjunct Lecturer, Department of Stomatology, University 1

Index Medicus, MEDLINE, PubMed Scopus, Embase and Emcare Indice Médico Español

Correspondence: Unidad de Prostodoncia y Oclusión Abstract Edificio Clínica Odontológica Objectives: This study aims to determine whether bruxism and the use of occlusalR,splints affect the survival of Granell-Ruíz M, Agustín-Panadero Fons-Font A, Román-Rodríguez C\ Gascó Oliag, Nº 1 porcelain laminate veneers in patients treated with this technique. JL, Solá-Ruíz MF. Influence of bruxism on survival of porcelain laminate 46010 Valencia Spain veneers. Med Oral Patol Oral Cir Bucal. 2014 Sep 1;19 (5):e426-32. Material and Methods: Restorations were made in 70 patients, including 30 patients with some type of parafuncmaria.granell@uv.es http://www.medicinaoral.com/medoralfree01/v19i5/medoralv19i5p426.pdf

tional habit. A total of 323 veneers were placed, 170 in patients with bruxism activity, and the remaining 153 in Article Number: 19097 patients without it. A clinical examination determined the presence orhttp://www.medicinaoral.com/ absence of ceramic failure (cracks, frac© Medicina Oral S. L. C.I.F. B 96689336 - pISSN 1698-4447 - eISSN: 1698-6946 eMail: were medicina@medicinaoral.com tures31/01/2013 and debonding) of the restorations; these incidents analyzed for association with bruxism and the use Received: Indexed in: Accepted: 19/05/2013 of splints. Science Citation Index Expanded Journal Reports and 29 debonding that were present in our Results: Analysis of the ceramic failures showed that of the 13Citation fractures Index Medicus, MEDLINE, PubMed Embaseof and bruxism. Emcare study, 8 fractures and 22 debonding were related to the Scopus, presence Indice Médico Español Conclusions: Porcelain laminate veneers are a predictable treatment option that provides excellent results, recognizing a higher risk of failure in patients with bruxism activity. The use of occlusal splints reduces the risk of Abstract fractures. Objectives: This study aims to determine whether bruxism and the use of occlusal splints affect the survival of porcelain laminate indebonding, patients treated with occlusal this technique. Key words: Veneer,veneers fracture, bruxism, splint. Material and Methods: Restorations were made in 70 patients, including 30 patients with some type of parafunctional habit. A total of 323 veneers were placed, 170 in patients with bruxism activity, and the remaining 153 in patients without it. A clinical examination determined the presence or absence of ceramic failure (cracks, fracIntroduction Introduction have proven to be one of the most successful techniques tures and debonding) the restorations; these incidents analyzed for association with bruxism and the use The veneer restoration of technique was developed in the were used in Restorative Dentistry (1). of splints. mid nineteen-eighties in the United States, and later Porcelain laminate veneers represent a predictable reResults: Analysis the of the ceramic failures showed fractures and 29 debonding that were present in our spread throughout world. Bonding these fragilethat por-of the 13 storative solution for anterior teeth due to their excellent study,laminae 8 fractures and 22 debonding to the presence of bruxism. celain securely to natural teethwere has related been a chalaesthetics as well as their durability and biocompatibiConclusions: Porcelain Fortunately, laminate veneers a predictable treatment option that provides excellent results, reclenge for our profession. these are restorations lity (2). These restorations constitute an alternative to ognizing a higher risk of failure in patients with bruxism activity. The use of occlusal splints reduces the risk of fractures. e426

Key words: Veneer, fracture, debonding, bruxism, occlusal splint.

Introduction

have proven to be one of the most successful techniques used in Restorative Dentistry (1). Porcelain laminate veneers represent a predictable restorative solution for anterior teeth due to their excellent aesthetics as well as their durability and biocompatibility (2). These restorations constitute an alternative to

The veneer restoration technique was developed in the mid nineteen-eighties in the United States, and later spread throughout the world. Bonding these fragile porcelain laminae securely to natural teeth has been a challenge for our profession. Fortunately, these restorations

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full-coverage restorations since they require minimal tooth preparation, there by maintaining the dental structure. Currently, porcelain laminate veneers are indicated for a wide range of situations and can be used to correct the shape and position of teeth, close diastema, replace old composite restorations, mask tooth discoloration (3), and to restore teeth following incisal abrasion and dental erosion. Some authors (4,5) suggest that bruxism constitutes a contraindication to these bonded restorations. Bruxism is generally recognized as non-functional jaw movements, and is defined as a forcible clenching or grinding of the teeth, or a combination of both, and has long been regarded as a disorder requiring treatment (6). According to the American Academy of Orofacial Pain, bruxism is a diurnal or nocturnal parafunctional activity which includes clenching, bracing, gnashing and grinding of the teeth (7). Magne et al. report that the success rate for the veneer is reduced to 60% in patients with bruxism activity (8). This percentage is very similar to that obtained for metal-ceramic restorations in the same situation. The success rates may be increased if bruxism iscontrolled; therefore, a nocturnal and / or diurnal splint is recommended as a preventive measure to reduce the risk of failure, especially in these patients (4,9). The occlusal splint is generally used to treat muscle hyperactivity. Studies carried out by various authors (1013) show that these splints decrease bruxism activity generated during periods of stress; it is therefore advisable to use these devices in patients with suspected bruxism following prosthodontic treatment with either full coverage crowns or with laminate veneers. Restorations placed in patients presenting some type of bruxism activity should have a functional design, especially in situations where the patient has already lost some tooth structure and where these restorations provide the patient with a correct anterior and canine guidance (14). As with any technique, the use of porcelain veneers requires medium and long term studies to confirm their indications (4,9,15-20). These techniques have been used since 1985 at the Prosthodontics and Oclussion Teaching Unit of the University of Valencia, School of Medicine and Dentistry, where to date a large number of patients have been treated with porcelain laminate veneers in response to aesthetic demands. We conducted a retrospective clinical study to review patients wearing porcelain laminate veneers. We analyzed whether the presence of bruxims activity and the use of occlusal splints in our patients, affected the medium and long term survival of these treatments. To this end we developed a data collection methodology to provide reliable results able to withstand the usual sta-

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tistical tests for these sample types and to be compared with results of other authors.

Material Methods Material andand Methods

Three hundred twenty-three porcelain laminate veneers were placed during a period of eight years, all fabricated with IPS-Empress ceramic (Ivoclar®, Schaan, Liechtenstein) in order to standardize the results and eliminate any variables that could arise from the use of different ceramics. At the time of the study, the 323 restorations studied had been placed in 70 patients with a duration ranging from 3 to 11 years. Of the patients studied, 24.3% (17) were male and 75.7% (53) were female, with a mean age of 46 years (range 18 to 74). Thirty of the 70 patients presented bruxism activity, all patients with it, had to use occlusal splints (Hard acrylic), 15 complied with this requirement and 15 did not. The clinical diagnosis was made by clinical inspection of teeth of the consequences of clenching or grinding activities were visible in the dentition and consistent with a bruxing habit. Of the 323 veneers, 124 (38.4%) were of simple design or window preparation, covering only the buccal surface (B) and 199 (61.6%) corresponded to those denominated ‘functional’ (with incisal overlap), covering the incisal edge and part of the palatal/lingual tooth surface (F). Regarding location, 238 were placed in the maxillary arch and 85 in the mandibular arch. Of the maxillary restorations, 97 were on central incisors, 82 on lateral incisors, 49 on canines and 10 on premolars. Of the mandibular restorations, 31 were located on central incisors, 31 on lateral incisors, 19 on canines and 4 on premolars. One hundred seventy veneers were bonded in patients with bruxism activity and 153 in patients without it. This study focussed on the relationship between the different ceramic failures and bruxism; therefore information was collected on the presence or absence of bruxism activity and whether or not these patients had to use splints. These criteria provided us with 3 patients groups for the study: A- Patients without bruxism. This group included 40 patients, representing 57.1% of the total. These patients were restored with 153 veneers (65 conventional design and 88 functional). B- Patients with bruxism activity using splints properly. This group included 15 patients (21.4%) with 89 veneers (31 conventional and 58 functional). C- Patients with bruxism activity not using splints (they have it but they don´t use it). This group included 15 patients (21.4%) with 81 veneers (28 conventional and 53 functional). Therefore, after placing the ceramic restorations, we checked occlusion properly, during maximum intercuspation and during mandibular excursive movements. e427


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Patients who were bruxers were provided with hard acrylic resin occlusal guards to protect the definitive restorations during bruxing episodes. All of the patients were treated at the Prosthodontics and Occlusion Teaching Unit of the University of Valencia School of Medicine and Dentistry by a team that had followed the same method when placing the veneers. The statistical analysis focused on: An initial descriptive analysis containing the frequencies and percentages for the categorical variables in the study. A bivariate analysis, covering all the statistical comparisons necessary to assess the relationship between fractures and debonding in patients with bruxism activity, and the use of a splint by these patients. These analyses were performed using nonparametric statistical tests given the categorical nature of the variables. The Pearson c2 test was used to test the association or dependence between two categorical variables, always provided that more than 5 cases were present in the contingency tables. Otherwise, and only for dichotomous variables, the Fisherâ&#x20AC;&#x2122;s exact test was used. A Kaplan-Meier Survival Analysis was used to study survival. As a comparative test the log-rank test was used (Kaplan-Meier, 1958).

Debonding: A total of 29 debonded restorations were observed, corresponding to 9% of the sample. Twentytwo were found in patients with bruxism, and the remaining 7 in patients without it. By statistically relating ceramic failures with bruxism, a clear link can be seen. On one hand we can see that fractures, although more frequent in the presence of bruxism, are not statistically significant, given that 5 fractures appeared in patients without bruxism versus 8 fractures that occurred in patients with it (p = 0.511) (Chi2); in contrast, statistically significant differences were found when examining the correct use of splints in patients with bruxism, since of these 8 fractures, 1 occurred in a patient who did use a splint, and 7 in patients who did not (p = 0.023) (Fisher). The figure below shows that a higher proportion of fractures were observed in patients with bruxism activity who did not use a splint (9%) than in those who used a splint properly (1%) (Fig. 1). Regarding debonding, this was observed to be more frequent in patients with bruxism. Of the 29 debonded veneers, 22 were produced in these patients (p = 0.009) (Chi2), a clear statistically significant difference can be seen between the two groups of patients (with and without bruxism activity). The figure below illustrates the higher proportion of debonding in patients with bruxism versus those without it (Fig.. 2). Of the 22 debonded restorations in patients with bruxism, 12 appeared in patients using a splint and 10 in patients where splints were not used, without statistically significant differences (p = 0.825) (Chi2). Regarding design, there were no significant differences between the type of restoration used (conventional or functional) and the presence of bruxism activity (p = 0.151) (Chi2); although, in this study most patients with bruxism were fitted with functional restorations (F). The Kaplan-Meier curves (Kaplan-Meier, 1958) clearly show the survival of the restorations, indicating the probability that a restoration will remain in good condition over time. This analysis considered the time in years during which the restoration remained in good condition or the time until deterioration. Two types of deterioration were considered: debonding and fracture, in addition this deterioration was related to the presence or absence of bruxism. Fractures: The estimated survival table showed that the mean survival times were similar between patients with and without bruxism. Furthermore, the log-rank test confirmed that the survival curves were statistically equal (p = 0.519) (Fig. 3). Debonding: Although the estimated survival table indicated that the mean survival times were similar between patients with and without bruxism, the log-rank test confirmed statistically significant differences in the survival curves (p = 0.008) (Fig. 4).

Results Results

During the evaluation period, the results were: Ceramic failures: The survival of restorations in terms of their structural integrity is the most important factor for both patients and professionals when deciding on this treatment option. Therefore, the analysis was made in terms of the presence or absence of the three most important aspects: cracks, fractures and debonding (Table 1). Cracks: At the time of the review no cracks were observed. This does not mean that some of the fractures found had not initiated as a crack, which over time had developed into a fracture. Fractures: A total of 13 fractures were observed (4%). Eight appeared in patients with bruxism, and the remaining 5 in patients without it.

Table 1. Distribution of veneers restorations. Frequency of fractures and debonding.

Presence of

NÂş

Bruxism

patients

NÂş veneers

Fractures Debonding

No

40

153 (65C-88F)

5

7

Yes (with splint)

15

89 (31C-58F)

1

12

Yes (without splint)

15

81 (28C-53F)

7

10

Total

70

323

13

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Fig. 1. Percentage of veneers fractures and use of splint.

Fig. 2. Percentage of veneers debonding and patients with bruxism.

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Fig. 3. Survival estimates according veneers debonding.

Fig. 4. Survival estimates according veneers fractures.

Discussion Discussion

given that certain intraoral conditions cannot be duplicated in the laboratory. These situations include the application of multiple, intermittent and cyclical forces on biting, chewing or grinding; the constant exposure to a moist, bacteria-rich environment; the consumption of

To date many longitudinal clinical studies have investigated the performance of porcelain veneers (4,9,15-20). It has been shown that clinical studies are needed in order to evaluate the performance of restorative materials, e430

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hot and cold liquids, as well as vigorous brushing. In vivo studies are therefore necessary to verify the acceptability of a laminate veneer as a definitive restorative treatment. Retrospective studies can provide a reliable picture of the clinical performance of materials and techniques. While numerous in vitro studies exist (21,22), these do not offer the same prognostic value or long-term predictability of this treatment as studies in vivo. Although longitudinal clinical studies of longer than 5 years certainly provide useful scientific data, they can sometimes become out of date due to the rapid and constant change in technology and materials. Thus, in vitro studies may have more impact, but have no greater utility. Discussion of results With respect to ceramic failures, in the present study there were 13 fractures (4.0%), 29 debondings (9.0%) and no cracks. Cracks: The fact that in this study no cracks appeared in the restorations may be due to the use of high-strength porcelain (IPS-Empress). Magne et al. (8) in a clinical study used conventional feldspathic porcelain for the fabrication of the restorations; the authors observed 12% cracks, thus justifying the use of stronger porcelain. The majority of authors do not consider small cracks in restorations as failures (5,23). Fractures: We found 4% of fractures, data similar to those of Jordan et al. (15) and Calamia (24) with 3%, and Nordbø et al. (17) with 5%. The majority of clinical studies reviewed report a low incidence of fractures, for example Kinh et al. (23) 0%; and Peumans et al. (5) 1%. However, other authors indicate a much higher rate of fractures, Christensen et al. (9) reported 13% at 3 years and Walls (4) 14% at 5 years, arguing that the majority of their patients had a history of bruxism, and that they had used conventional feldspathic porcelain, which has a lower fracture strength than high-strength feldspathic restorations. In the present study it was observed that fractures occurred more frequently in patients with bruxism, and that not using a splint when required constitutes a risk factor for the presence of fractures. Debonding: there was a notably high percentage of debonding in this study (9%), a high proportion of which occurred in patients with bruxism. It was found that of the 22 debonded veneers in patients with bruxism, 12 were related to patients who used an occlusal splint, while the remaining 10 were related to patients who did not use a splint; we therefore consider that the debonding was not so much related to the use or otherwise of a splint, but more to the existence of a history of bruxism, taking into account that these patients generally wear the splint only at night, and it has been found that bruxism may be both diurnal and nocturnal (25). Some authors (16,18) with in vivo studies report high

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Bruxism and porcelain laminate veneers

rates of debonding in restorations due to the presence of composite reconstructions in teeth supporting this type of restoration. In these cases the adhesion is between resin and resin, which reduces the bond strength between the porcelain veneer-tooth complexes. Some authors do not consider debonding as a failure, since the restoration is simply replaced. Fradeani et al. (19), report three cases of debonding in one of their studies, with no signs of internal damage or fracture; these were replaced, commenting that the debonding was most certainly due to an inappropriate adhesive technique.

Conclusions Conclusions

1. In this study, the presence of fractures and debonding in porcelain laminate veneers increases considerably in patients with bruxism. The probability of debonding is almost 3 times higher in patients with it. 2. It was found that, the use of splints reduces the failure rate of porcelain laminate veneers in patients with bruxism activity; the probability of fracture being 8 times greater in patients who are required to use a splint but do not. 3. Longitudinal in vivo clinical studies are needed to evaluate the performance and predictability of restorative materials, since certain intraoral conditions cannot be reproduced in the laboratory.

References References

1. Chen W, Raigrodski AJ. A conservative approach for treating young adult patients with porcelain laminate veneers. J Esthet Restor Dent. 2008;20:223-238. 2. Fons-Font A, Solá-Ruiz MF, Granell-Ruiz M, Labaig-Rueda C, Martínez-González A. A choice of ceramic for use in treatments with porcelain laminate veneers. Med Oral Patol Oral Cir Bucal. 2006;11:e297-302. 3. Freire A, Archegas LR. Porcelain laminate veneer on a highly discoloured tooth: a case report. J Can Dent Assoc. 2010;76:a126. 4. Walls AWG. The use of adhesively retained all-porcelain veneers during the management of fractured and worn anterior teeth: Part 2. Clinical result after five years follow-up. Br Dent J. 1995;178:337340. 5. Peumans M, Van Meerbeeck B, Yoshida Y, Lambrechts P, Vanherle G. Five-year clinical performance of porcelain veneers. Quintessence Int. 1998;29:211-221. 6. Attanasio R. Intraoral orthotic Therapy. Dent Clin North Am. 1997;41:309-324. 7. American Academy of Orofacial Pain. Okeson JP, ed. Orofacial Pain. Guidelines for assessment, diagnosis, and management. Chicago: Quintessence Publish Co; 1996. p. 49-73. 8. Magne P, Perroud R, Hodges JS, Belser UC. Clinical performance of novel-design porcelain veneers for the recovery of coronal volume and length. Int J Periodontics Restorative Dent. 2000;20:440-57. 9. Christensen GJ, Christensen RP. Clinical observations of porcelain veneers: a three-year report. J Esthet Dent. 1991;3:174-9. 10. Solberg WK, Clark GT, Rugh JD. Nocturnal electromyographic evaluation of bruxism patients undergoing short term splint therapy. J Oral Rehabil. 1975;2:215-23. 11. Van Der Zaag J, Lobbezoo F, Wicks DJ, Visscher CM, Hamburger HL, Naeije M. Controlled assessment of the efficacy of occlusal stabilization splints on sleep bruxism. J Orofac Pain. 2005;19:151-158.

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of 6.5 years. J Oral Rehabil. 1997;24:553-9. Bruxism and porcelain laminate veneers 19. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6-to 12 year clinic evaluation- a restorative study. Int J Periodontics Restorative Dent. 2005;25:9-17. 20. Granell-Ruiz M, Fons-Font A, Labaig-Rueda C, MartínezGonzález A, Román-Rodríguez JL, Solá-Ruiz MF. A clinical longitudinal study 323 porcelain laminate veneers. Period of study from 3 to 11 years. Med Oral Patol Oral Cir Bucal. 2010;15:e531-7. 21. Magne P, Kwon KR, Belser UC, Hodges JS, Douglas WH. Crack propensity of porcelain laminate veneers: A simulated operatory evaluation. J Prosthet Dent. 1999;81:327-34. 22. Castelnuovo J, Tjan AH, Phillips K, Nicholls JI, Kois JC. Fracture load and mode of failure of ceramic veneers with different preparations. J Prosthet Dent. 2000;83:171-80. 23. Kihn PW, Barnes DM. The clinical longevity of porcelain veneers: A 48-month clinical evaluation. Jada. 1998;129:747-752. 24. Calamia JR. Clinical evaluation of etched porcelain veneers. Am J Dent. 1989;2:9-15. 25. Beier US, Kapferer I, Burtscher D. Clinical performance of porcelain laminate veneers for up to 20 years. Int J Prosthodont. 2012;25:79-85.

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12. Koyano K, Tsukiyama Y, Ichiki R, Kuwata T. Assessment of bruxism in clinic. J Oral Reabil. 2008;35:495-508. 13. Lobbezoo F, van Der Zaag J, van Selms MKA, Hamburger HL. Principles for management of bruxism. J Oral Reabil. 2008;35:509523. 14. Highton R, Caputo AA, Mátyás J. A photoelastic study of stresses on porcelain laminate preparations. J Prosthet Dent. 1987;58:157-61. 15. Jordan RE, Suzuki M, Senda A. Four year recall evaluation of labial porcelain veneer restoration. J Dent Res. 1989;68Special:544. 16. Dunne SM, Millar BJ. A longitudinal study of the clinical performance of porcelain veneers. Br Dent J. 1993;175:317-21. 17. Nordbø H, Rygh-Thoresen N, Henaug T. Clinical performance of porcelain laminate veneers without incisal overlapping: 3-year results. J Dent. 1994;22:342-5. 18. Shaini FJ, Shortall AC, Marquis PM. Clinical performance of porcelain laminate veneers. A retrospective evaluation over a period of 6.5 years. J Oral Rehabil. 1997;24:553-9. 19. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6-to 12 year clinic evaluation- a restorative study. Int J Periodontics Restorative Dent. 2005;25:9-17. 20. Granell-Ruiz M, Fons-Font A, Labaig-Rueda C, MartínezGonzález A, Román-Rodríguez JL, Solá-Ruiz MF. A clinical longitudinal study 323 porcelain laminate veneers. Period of study from 3 to 11 years. Med Oral Patol Oral Cir Bucal. 2010;15:e531-7. 21. Magne P, Kwon KR, Belser UC, Hodges JS, Douglas WH. Crack Question propensity 27 of porcelain laminate veneers: A simulated operatory The veneerJ restoration technique was developed in the mid eighteen-eighties in the US, and later spread evaluation. Prosthet Dent. 1999;81:327-34. 22. Castelnuovo AH, Phillips K, Nicholls JI, Kois JC. Fracture throughout theJ, Tjan world. load and mode of failure of ceramic veneers with different preparations. J Prosthet Dent. 2000;83:171-80. True or False 23. Kihn PW, Barnes DM. The clinical longevity of porcelain veneers: A 48-month clinical evaluation. Jada. 1998;129:747-752. 24. Calamia28 JR. Clinical evaluation of etched porcelain veneers. Am Question J Dent. 1989;2:9-15. According to the American Academy of Orofacial Pain, bruxism is a diurnal or nocturnal parafunction activi25. Beier US, Kapferer I, Burtscher D. Clinical performance of typorcelain which includes the following: laminate veneers for up to 20 years. Int J Prosthodont. 1) Clenching 2012;25:79-85.

Influence of bruxism on survival of porcelain laminate veneers

2) Bracing 3) Gnashing and, 4) Grinding of teeth True or False

Question 29 Magne et al. report that the success rate for the veneer is reduced to 60% in patients with bruxism activity. This percentage is very similar to that obtained for metal-ceramic restorations in the same situation. The success rate may be increased if bruxism is controlled, therefore a nocturnal and / or diurnal splint is recommended as a preventive measure to reduce the risk of failure, especially in these patients. e432

True or False

Question 30 Patients with bruxism activity who are not using a splint recorded a higher proportion of fractures than those using a splint properly. True or False Question 31 In conclusion, the probability of de-bonding of porcelain veneers is almost 3 times higher in patients with bruxism. The use of splints therefore reduces the failure rate of veneers in patients with bruxism, with the probability of fractures being 8 times greater in these patients when required to use splints but do not make use of them. True or False e432 SADTJ Vol 6 Issue 1

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DOI: 10.7860/JCDR/2015/12207.6089 DOI: 10.7860/JCDR/2015/12207.6089

Dentistry DentistrySection Section

2.4

Original Original Article Article

A Comparison of Masticatory Performance and Efficiency of Complete Dentures Made with High Impact and Flexible Resins: A Pilot Study This is an open access article

1 2 3 4 5 Puja Puja Hazari Hazari1,, anjali anjali BHoyar BHoyar2,, Sunil Sunil Kumar Kumar miSHra miSHra3,, naveen naveen S. S. yaDav yaDav4,, HarSH HarSH maHajan maHajan5

ABStrAct ABStrAct

Background: Background: In In patients patients with with extensive extensive tooth tooth loss, loss, restoration restoration of of masticatory masticatory function function and and aesthetics aesthetics is is main main concern concern for for a a prosthodontist. prosthodontist. Aim Aim of of Study: Study: This This study study aimed aimed to to evaluate evaluate and and compare compare differences differences in in masticatory masticatory efficiency efficiency of of patients patients treated treated with with complete complete dentures dentures made made with with either either high high impact impact or or flexible flexible resins. resins. Setting Setting and and design: design: The The sample sample size size consisted consisted of of 10 10 study study sub subjects. jects. Two Two sets sets of of dentures dentures first first conventional conventional followed followed by by flexible flexible dentures dentures were were fabricated fabricated for for each each subject subject and and both both the the sets sets of of dentures dentures were were accessed for masticatory performance and efficiency. accessed for masticatory performance and efficiency. Materials Materials and and Methods: Methods: This This study study compared compared the the masticatory masticatory performance and efficiency of dentures by means performance and efficiency of dentures by means of of standardized standardized mesh mesh sieves. sieves. Masticatory Masticatory efficiency efficiency was was calculated calculated by by recording recording the the total number of chewing cycles and time required to total number of chewing cycles and time required to completely completely

swallow swallow a a standardized standardized food food item. item. A A patient patient satisfaction satisfaction questionquestionnaire was given and evaluated. naire was given and evaluated. Statistical Statistical Analysis Analysis used: used: The The statistical statistical analyses analyses were were perperformed formed using using Z-test Z-test of of Proportion Proportion and and Paired Paired t-test. t-test. results: results: The The masticatory masticatory performance performance ratio ratio was was found found to to be be more for for hard more hard food food in in conventional conventional dentures. dentures. The The values values of of masticatory masticatory performance performance ratios ratios for for soft soft food, food, time time and and number number of of masticatory masticatory strokes strokes were were indicating indicating better better masticatory masticatory efficiency efficiency of of conventional conventional dentures. dentures. conclusion: conclusion: Though Though masticatory masticatory efficiency efficiency and and performance performance were were found to be better for patient’s dentures made found to be better for patient’s dentures made with with Polymethyl Polymethyl methacrylate methacrylate (PMMA), (PMMA), a a statistically statistically significant significant number number of of patients patients reported that that the the flexible flexible dentures dentures were were more more satisfying satisfying than than the the reported conventional conventional dentures. dentures.

Keywords: Keywords: Conventional Conventional dentures, dentures, Thermoplastic Thermoplastic flexible flexible dentures, dentures, Polymethyl Polymethyl methacrylate methacrylate

IntrOductIOn IntrOductIOn

The The restoration restoration of of masticatory masticatory function function and and aesthetics aesthetics is is an an important aim important aim in in dentistry dentistry mainly mainly when when patients patients present present with with extensive extensive tooth tooth loss. loss. The The loss loss of of tooth tooth in in elderly elderly patients patients not not only only impairs the stomatognathic system but also their psychological impairs the stomatognathic system but also their psychological status status and and quality quality of of life life [1,2]. [1,2]. The The important important criteria’s criteria’s for for the the success of of dentures dentures are are patient’s patient’s expectations expectations and and the the ability ability of of success the the denture denture to to replace replace the the lost lost masticatory masticatory efficiency. efficiency. For For long long polymethyl polymethyl methacrylate methacrylate (PMMA) (PMMA) has has dominated dominated the the field field of of denture denture base materials but today flexible dentures have emerged as base materials but today flexible dentures have emerged as a a major major competitor to PMMA dentures. Flexible dentures, also known competitor to PMMA dentures. Flexible dentures, also known as as nylon dentures, dentures, are are considered considered perfect perfect alternatives alternatives to to conventional conventional nylon and and partial partial acrylic acrylic dentures. dentures. Flexible Flexible dentures dentures made made of of thermoplastic thermoplastic material, are resistant to breakage and very comfortable material, are resistant to breakage and very comfortable for for the the edentulous patients. These dentures are easy to wear and edentulous patients. These dentures are easy to wear and very very pleasant for for patients patients as as they they are are much much thinner, thinner, stay stay firmly firmly in in place place pleasant and and more more retentive retentive when when compared compared to to conventional conventional dentures. dentures. They They do do not not cause cause any any allergic allergic reactions, reactions, are are light light in in weight weight and and take take minimum minimum space space in in the the oral oral cavity. cavity. Further Further studies studies have have proved proved that that these flexible flexible dentures dentures have have less less solubility solubility and and sorption sorption values values than than these heat heat cure cure PMMA PMMA [3,4]. [3,4]. Though Though widely widely used used for for partial partial dentures dentures the the flexible flexible material material is is not not usually used used for usually for complete complete dentures. dentures. The The criteria criteria of of better better masticatory masticatory performance performance and and masticatory masticatory efficiency efficiency of of dentures dentures may may change change the the future prospective of denture base materials. Thus, it is future prospective of denture base materials. Thus, it is of of utmost utmost importance importance to to study study the the masticatory masticatory performance performance and and masticatory masticatory efficiency in cases of rehabilitation with the flexible efficiency in cases of rehabilitation with the flexible dentures dentures for for elderly individual individual for for detailed detailed diagnosis diagnosis and and prognosis, prognosis, which which will will elderly improve improve their their quality quality of of life. life. Journal Journal of of Clinical Clinical and and Diagnostic Diagnostic Research. Research. 2015 2015 Jun, Jun, Vol-9(6): Vol-9(6): ZC29-ZC34 ZC29-ZC34

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The The null null hypothesis hypothesis to to be be tested tested in in this this study study was was that that there there was was no no difference difference in in masticatory masticatory performance performance and and masticatory masticatory efficiency efficiency of of patients patients treated treated with with complete complete dentures dentures made made with with high high impact impact PMMA resins and flexible thermoplastic material. PMMA resins and flexible thermoplastic material.

AIM AIM Of Of Study Study

This This study study aimed aimed to to evaluate evaluate and and compare compare differences differences in in masticatory masticatory efficiency of patients treated with complete dentures made efficiency of patients treated with complete dentures made with with high high impact resins and flexible resins. impact resins and flexible resins.

MAterIAlS MAterIAlS And And MethOdS MethOdS

This This cross-sectional, cross-sectional, prospective prospective study study was was conducted conducted at at Peoples Peoples College of Dental Sciences and Research Centre, Bhopal College of Dental Sciences and Research Centre, Bhopal in in 2013. 2013. The The study study group group comprised comprised of of randomly randomly selected selected 10 10 completely completely edentulous patients patients (6 (6 males males & & 4 4 females) females) reported edentulous reported to to the the Department Department of of Prosthodontics. Prosthodontics. The The inclusion inclusion and and exclusion exclusion criteria’s criteria’s were were as as follows: follows:

Inclusion Inclusion criteria criteria

Only Only healthy healthy edentulous edentulous patients patients and and denture denture wearers wearers for for the the first first time were included in the study. Patient’s ages were between time were included in the study. Patient’s ages were between 454565 65 years. years. Patients Patients were were advised advised orthopantomographs orthopantomographs to to rule rule out out hard tissue tissue abnormalities abnormalities and hard and Temporomandibular Temporomandibular Joint Joint (TMJ) (TMJ) dysfunctions. dysfunctions. The The nature nature of of the the study study was was explained explained and and an an informed informed consent was taken from the patient. consent was taken from the patient.

exclusion exclusion criteria criteria

Patients Patients with with history history of of temporomandibular temporomandibular disorders disorders such such as as Myofacial Pain Dysfunction Syndrome (MPDS), trismus, Myofacial Pain Dysfunction Syndrome (MPDS), trismus, trauma, trauma, dislocation, dislocation, ankylosis ankylosis and and with with poor poor control control of of systemic systemic diseases diseases 29 29


Puja Hazari et al., A Comparison of Masticatory Performance and Efficiency of Complete Dentures made with High Impact and Flexible Resins

such as haematological, cardiovascular and renal disorders, autoimmune/endocrinological disorders, compromised oral conditions, local lesions, resorbed or flabby ridges and edentulous period less than three months. Selection bias was removed by selecting various subjects randomly who fulfilled the inclusion and exclusion criteria’s and with same systemic conditions. After consultation from statistician the sample size was taken as ten subjects for the pilot study. The informed consent was obtained from the subjects participating in the study, and ethical clearance was obtained from Institutional Ethical Committee to carry out the study. The study was carried over a period of eight months. For each patient two sets of complete denture were fabricated. Initially all the subjects were given Conventional High Impact dentures (Group-1) for three months and there masticatory performance was evaluated. Later the conventional high impact dentures were withdrawn and all the subjects were given Flexible denture (Group-2) for three months and there masticatory performance was again evaluated. The first set of denture was made by conventional method following the standardized denture fabrication protocol. The second set of denture was made by duplication of master cast and jaw relation as follows. Using condensation silicone of putty consistency (Zermack putty, Zetaplus, Badia Polesine, Rovigo, Italy) and Hanau flasks the master casts of each patient were duplicated, and poured in Type III Dental stone (Gyprock, Rajkot, India).Face bow transfer was made using Hanau Springbow and jaw relations were recorded. Extra oral tracing was done to verify the tentative centric jaw relation. Interocclusal plaster records, for centric and protrusive relation were made for programming the articulator (Hanau H2). With the help of putty indexes and plaster indexes the duplicated casts and occlusal rims were mounted in the same spatial relationship as they were mounted on the articulator after gothic arch tracing for the first set of denture. Three putty indexes were made. First and second indexes were made for the duplication of the maxillary and mandibular occlusal rims and third index for the entire frontal surface of the maxillary and mandibular occlusal rims to duplicate the over jet and overbite relation. Next, using mounting jig of the articulator two plaster indexes were made with three acrylic stops [Table/Fig-1] to mount the duplicated maxillary and mandibular cast in the same spatial relationship as the original maxillary and mandibular casts were mounted. Teeth arrangement for both the set of dentures was done using Acry Rock teeth sets (Ruthinium Dental Products (P)

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Ltd, Italy) in balanced occlusion. Try in of the waxed up dentures was done. High Impact Polymethyl Methacrylate resin (Trevalon Hi, Dentsply India Pvt. Ltd Haryana, India) was used to fabricate the conventional dentures using conventional flasking and compression molding technique. Denture insertion of the conventional denture was done. First patient recall was done after 24 hours. Patients were recalled after three months for masticatory efficiency estimation. After withdrawal of conventional dentures, the second set of flexible dentures were fabricated using co-polyamide nylon resin (Lucitone FRS Dental Resin, Dentsply India Pvt. Ltd, Haryana, India) using success injection molding system (Dentsply, Milford, USA) and given to patients after one week and patient was recalled after three months for masticatory efficiency estimation. The objective and subjective evaluation of masticatory function was done by chewing tests and questionnaire [Table/Fig-2] respectively. In order to eliminate experimental bias stratified randomization was carried out. In order to avoid inter examiner variability data were collected by a single examiner who participated in the calibration process, which was done by theoretical discussions and practical activities. For chewing tests, each subject were instructed to chew the portion of test food, twenty strokes for peanuts and forty strokes for raw carrots [5]. For estimating the masticatory performance three grams of nuts and five grams of carrots were used. After the specified number of chewing strokes, the chewed food was collected in a disposable cup. The subjects were instructed to rinse their mouth twice and the rinse obtained was also added to the same disposable cup. After stirring the chewed food with a glass rod it was poured on a brass sieve. To measure the swallowing threshold, each subject was instructed to chew a test portion of food (3gms of peanuts) until it was ready for swallowing, without specifying side or number of chewing strokes. When the subject considered the food sufficiently chewed for swallowing, the food was expectorated into a cup and the mouth rinsed twice with water to recover the entire test sample. The recovered chewed food was subjected to the sieve analysis described above, and masticatory performance ratios were calculated. This test helps to determine the qualitative estimation of the chewed food before swallowing. The filtered food particles on the filter paper and on the sieve were collected in borosilicate glass test tubes (Borosil, Mumbai, India) [Table/Fig- 3] and the tubes were centrifuged (Centrifuge-5804-R, Eppendorf, Germany) for 3 minutes at 1,500 rpm [Table/Fig-4]. The weight Grading Criteria for denture satisfaction- 1 to 3 (1-Poor , 2-average, 3 –Good) assessment by the Doctor: Question

Group1

Group2

Group1

Group2

Esthetics Retention of maxillary dentures Retention of mandibular dentures Speech assessment by the Patient: Question Esthetics Retention of maxillary dentures Retention of mandibular dentures Speech Chewing efficiency with soft food Chewing efficiency with medium food Chewing efficiency with hard food Comfort of maxillary denture Comfort of mandibular denture Overall satisfaction [table/fig-1]: First mounting jig with three acrylic stops for duplication of orientation jaw relation

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[table/fig-2]: Patient’s satisfaction Questionaire. Group 1-Polymethyl Methacrylate Dentures, Group 2- Flexible Dentures Journal of Clinical and Diagnostic Research. 2015 Jun, Vol-9(6): ZC29-ZC34

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Puja Hazari et al., A Comparison of Masticatory Performance and Efficiency of Complete Dentures made with High Impact and Flexible Resins

[table/fig-3]: Test tubes with test specimen

[table/fig-5]: Vacuum concentrator (Dessicator)

[table/fig-4]: Centrifugal machine

of the test material (sediment) in each tube was recorded using digital weighing machine (Axis, AGN 204-PO, Max-200g, d-0.0001g, India). Masticatory performance in this study has been quantitated in the method suggested by Yurkstas and Manly [6]. Performance was evaluated for any particle size (sieve size) by dividing the weight of test food passing through a sieve (of a given mesh) by the total weight of test food recovered. This fraction was then expressed as percent. First wet weight was calculated. The test specimens were placed in a desiccator (Concentrator Plus, Eppendorf, Germany) for 2 hours [Table/Fig- 5] and again the dry weights were measured. This test was carried out for both the sets of denture after an adjustment period of three month [Table/ Fig-6]. To compare the masticatory efficiency of both the sets of dentures the time and number of masticatory strokes were calculated. The set of denture requiring less time and less number of masticatory strokes for complete mastication of food had a better masticatory efficiency. The patientâ&#x20AC;&#x2122;s satisfaction such as retention, stability, comfort, and aesthetics were assessed by means of a questionnaire. Journal of Clinical and Diagnostic Research. 2015 Jun, Vol-9(6): ZC29-ZC34

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[table/fig-6]: Conventional and flexible dentures of a patient

StAtIStIcAl AnAlySIS Data were analysed using a statistical package program, SPSS version 18.0 (IBM, India, trial version). The statistical analyses were performed using Z-test of Proportion to find out patient satisfaction with both group of dentures and Paired t-Test to determine the differences between the mean values of both the groups of dentures. Chewing efficiency using carrots and peanuts can be calculated from the formula

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Puja Hazari et al., A Comparison of Masticatory Performance and Efficiency of Complete Dentures made with High Impact and Flexible Resins

Where P is performance ratio, 103 is constant, and 1.2 the slope of the norm. The chewing efficiencies for various performance ratios for peanuts, was read directly from table by Manley RS [6].

reSultS According to the results of our study [Table/Fig-7], the mean values of wet weights for soft food, for conventional dentures was 0.39842 and for flexible dentures was 0.37559.The t-value was 1.1705 and p-value was 0.2719. There was no significant difference between both groups at 5% level of significance. Mean values for masticatory performance of wet weights for hard food, for conventional dentures was 0.47661 and for flexible dentures was 0.36345.The t-value was 3.17 and p-value was 0.0112. There was significant difference between both groups at 5% level of significance. Mean values of dry weights for soft food for conventional dentures were 0.36389 and for flexible dentures were 0.35021.The t-value was 0.6669 and p-value was 0.5216. There was no significant difference between both groups at 5% level of significance. The mean values of dry weights for hard food for conventional dentures were 0.43789 and for flexible dentures were 0.32453.The t-value was 2.5610 and p-value was 0.0306. There was significant difference between both groups at 5% level

Component Masticatory performance [wet weight]

n

0.39842±0.108021

10

Group-2 Peanuts

0.37559±0.071501

10

*Group-1 Carrots

0.47661±0.10911

10

Group-2 Carrots

0.36345±0.11708

10

*Group-1 Peanuts

0.67738±0.124438

10

Group-2 Peanuts

0.66472±0.127126

10

*Group-1 Peanuts

0.36389±0.10030

10

Group-2 Peanuts

0.35021±0.07785

10

*Group-1 Carrots

0.43789±0.12623

10

Group-2 Carrots

0.32453±0.11239

10

*Group-1 Peanuts

0.66214±0.13257

10

Group-2 Peanuts

0.63659±0.10326

10

63.4±11.98

10

Masticatory performance [dry weight]

Swallowing threshold [dry weight]

Time in seconds for complete mastication of test food[3gms of peanuts] No of masticatory strokes for complete mastication of test food[3gms of peanuts] Rate of masticatory cycles for complete mastication of test food[3gms of peanuts]

As there was a statistically significant difference in masticatory performance for hard food between the two groups the null hypothesis was rejected.

mean±Standard Deviation

Swallowing threshold [wet weight]

of significance. The test group showed no statistically significant difference for masticatory performance calculated by swallowing threshold of peanuts between the two groups in wet weight (t-value0.3709, p-value 0.7193) and dry weight (t-value 0.5533, p-value 0.5936).Further the test groups showed no statistically significant difference in time, total number of masticatory strokes and the rate of masticatory cycles. Following the denture and dentition norms, for peanuts, the line diagrams showed a trend towards higher masticatory efficiency for conventional high impact dentures [Table/Fig-8,9]. According to denture norms for carrots, the line diagram showed a higher masticatory efficiency values for conventional high impact dentures [Table/Fig-10]. The questionnaire was analysed using the z-test of proportion. It was found that the aesthetics and retention of the mandibular dentures was significantly more for the flexible dentures. Patient experienced aesthetics, comfort, retention of mandibular dentures and overall satisfaction with the dentures more for flexible dentures. Factor such as chewing efficiency with hard food was more for conventional denture [Table/Fig-11].

*Group-1 Peanuts †

*Group-1 †

Group-2

*Group-1 Group-2

* Group-1 Group-2

¦

66.2±13.55

10

70.7±13.86

10

76.3±17

10

0.90±0.126068

10

0.87±0.093044

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Confidence interval (95% level)

t –value

df**

p- value (5% level)

1.1705

9

0.2719 §

-0.0212 to 0.0669

3.1774

9

0.0112 ‡

0.0325 to 0.1937

0.3709

9

0.7193 §

-0.0645 to 0.0898

0.6669

9

0.5216 §

-0.0327 to 0.0600

2.5610

9

0.0306 ‡

0.5533

9

0.5936 §

-0.0789 to 0.1300

0.6347

9

0.5414 §

-12.78 to 7.18

1.8196

9

0.1022 §

12.56 to 1.36

0.9329

9

0.3752 §

-0.0457 to 0.1100

10

0.0132 to 0.2134

[table/fig-7]: Student’s paired t-test p>0.05 there was no significant difference between groups § p<0.05 there was significant difference between groups

* Group1- Conventional High Impact Polymethyl Methacrylate dentures; †Group2-Flexible dentures; ‡Significant difference;

§

No significant difference; ¦ Number of patients;

degree of freedom

**

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Puja Hazari et al., A Comparison of Masticatory Performance and Efficiency of Complete Dentures made with High Impact and Flexible Resins Satisfaction response as poor by number of subjects

Satisfaction response as average by number of subjects

Satisfaction response as Good by number of subjects

Group-1

3

5*

2

Satisfaction Factors Esthetics

[table/fig-8]: Masticatory efficiency according to dentition norms for wet peanuts

Group

Group-2

0

3

7*

Retention of maxillary dentures

Group-1

0

3

7*

Group-2

0

1

9*

Retention of mandibular dentures

Group-1

3

4

3

Group-2

1

3

6*

Speech

Group-1

0

9*

1

Group-2

0

7*

3

Chewing efficiency with soft food

Group-1

0

2

8*

Group-2

0

4

6*

Chewing efficiency with medium food

Group-1

1

4

5

Group-2

3

4

3

Chewing efficiency with hard food

Group-1

1

3

6*

Group-2

3

5*

2

Comfort of maxillary denture

Group-1

0

4

6*

Group-2

0

1

9*

Comfort of mandibular denture

Group-1

0

7*

3

Group-2

0

2

8*

Overall satisfaction

Group-1

0

6*

4

Group-2

0

3

7*

[table/fig-11]: Z-test of proportion for patient satisfaction (subjective evaluation). Group-1= Conventional High Impact dentures; Group-2= Flexible denture *Indicates higher response by subjects in that group

dIScuSSIOn

[table/fig-9]: Masticatory efficiency according to denture norms for wet peanuts

The majority of the tests developed so far for measuring masticatory performance and efficiency of dentures depend on the fractional sieving of the chewed food [7,8]. In our study we have also used the single volumetric sieving method. Single sieve method is certainly a convenient and reliable method to be used clinically. For the estimation of chewing performance with peanuts (soft food) a mesh sieve of 10 numbers (U.S. standard sieves) and for carrots (hard food) 5 number mesh sieve was used [9-11]. The better the food chewed before swallowing more will be the filtered particles, and more will be the masticatory efficiency [12-14]. There was no distinction of sex in our study, as studies prove that no gender differences in bite force and masticatory performance were found among complete denture wearers [1]. In this study the adjustment period for each denture were taken as three months. This time period is considered sufficient for denture adaptation by the patient [15]. A statistically significant number of patients found the flexible dentures to be more satisfying and comfortable than the conventional dentures. These results were in accordance with the study conducted by Dhiman RK [16]. These findings may again be attributed to the basic nature of the denture base materials. The same was suggested by Marcelo Coelho Goiato et al., in their study [17].

[table/fig-10]: Masticatory efficiency according to denture norms for wet carrots

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Al-Jammali ZMJ [18] in their study found that the flexible partial denture provide better chewing efficiency than heat cure acrylic partial denture, the masticatory performance was higher for flexible partial denture than heat cure acrylic partial denture but contradictory to the above study the results of our study showed that conventional dentures were more efficient for mastication with hard test food in comparison to the flexible dentures. These results can be attributed to the basic nature of the two denture base materials. The conventional dentures provide a firm denture base, deform and flex minimum during function and provide hard surfaces for the grinding of food [19,20]. The result was in accordance with study by Shah J et al., [4] were flexible resin demonstrated lower hardness values and also possessed lower amounts of cross-linking agents, which 33


Puja Hazari et al., A Comparison of Masticatory Performance and Efficiency of Complete Dentures made with High Impact and Flexible Resins

may affect surface hardness. As there was no statistically significant difference for masticatory performance of soft food between the conventional and flexible dentures, these flexible dentures with diet modification can be a better alternative to conventional dentures in patients with repeated midline fracture of denture, allergic to PMMA and denture sore mouth [3,16].

[5]

clInIcAl IMplIcAtIOnS

[9]

The flexible dentures are much thinner than conventional dentures, are more aesthetically pleasing and easily acceptable to the patient. They can be given as a substitute to patients allergic to PMMA. As they are lightweight and flexible they can be successfully given to patients with bony undercuts. The flexibility of the material provided a certain degree of stress-breaking effect and there was no denture sore-mouth [21-23].

cOncluSIOn Based on the study conducted it may be concluded that there was statistically significant difference for masticatory performance in wet and dry weight values of hard food, but there was no statistically significant difference for masticatory performance in wet and dry weight values of soft food between the conventional and flexible dentures. The subjective evaluation pointed towards better aesthetics, comfort, retention and overall satisfaction for flexible dentures.

referenceS

[1] Soboleva U, Laurina L, Slaidina A. The masticatory system-an overview. Stomatologija Baltic Dental and Maxillofacial Journal. 2005;7:77-80. [2] Zmudzki J, Chladek G, et al. The stimulation of mastication efficiency of the mucous-borne complete dentures. Achievements in Materials and Engineering. 2013;63:75-86. [3] Pusz A, Szymiczek M, Michalik K. Ageing process influence on mechanical properties of polyamide - glass composites applied in dentistry. Journal of Achievements in Materials and Manufacturing Engineering. 2010;38:49-55. [4] Shah J, Bulbule N, et al. Comparative Evaluation of Sorption, Solubility and Microhardness of heat cure polymethylmethacrylate denture base resins &flexible denture base material. J Clin Diagn Res. 2014;8: ZF01-ZF04.

[6] [7] [8]

[10] [11] [12] [13]

[14] [15]

[16] [17] [18]

[19] [20] [21] [22] [23]

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Kapur KK, Soman S. Masticatory performance and efficiency in denture wearers. J Prosthet Dent. 2004;92:107-11. Manley RS.Factors affecting masticatory performance and efficiency among young adults. J Dent Res. 1951;30:874. Bascom PW. Masticatory efficiency of completed dentures. J Prosthet Dent. 1962;12:453-59. Kapur KK, Soman S, Katherine S. The effect of denture factors on masticatory performance. Part I: Influence of Denture Base Extension. J Prosthet Dent. 1965;15:54-64. Kapur KK, Soman S. The effect of denture factors on masticatory performance Part II: Influence of the Polished Surface Contour of Denture Base. J Prosthet Dent. 1965;15:231-40. Manly RS, Vinton P. A survey of the chewing ability of denture wearer. J Dent Res. 1951;30:314-21. Akeel RF. Masticatory efficiency, a literature review. The Saud Dent Journal. 1992;4:63-69. Goiato MC, Ribeiro Pdo P, Garcia AR, Dos Santos MD. Complete denture masticatory efficiency: A literature review. J Calif Dent Association. 2008;36: 683-86. Mahmood WA, Watson CJ, Ogden AR, Hawkins RV. Use of image analysis in determining masticatory efficiency in patients presenting for immediate dentures. Int J Prosthodont. 1992;5:359-66. Al-Ali F, Heath MR, Wright PS. Simplified method of estimating masticatory performance. J Oral Rehabil. 1999;26:678-83. Neto AF, Junior WM, Carreiro AFP. Masticatory efficiency in denture wearers with bilateral balanced occlusion and canine guidance. Braz Dent J. 2010;20:16559. Dhiman RK, Chowdhury SKR. Midline fractures in single maxillary complete acrylic vs flexible dentures. MJAFI. 2009;65:141-45. Goiato MC, et al. Effect of accelerated aging on the microhardness and color stability of flexible resins for dentures. Braz Oral Res. 2010;24:114-19. Al-Jammali ZMJ, Al Nakkash WAH. Clinical evaluations for the masticatory efficiency of heat cure resin and flexible types of denture base materials. J Bagh College Dentistry. 2013;25(3):57-61. Regli CP, Kydd WI. A preliminary study of the lateral deformation of metal base dentures in relation to plastic base dentures. J Prosthet Dent. 1953;3:326-31. Regli CP, Gaskill HL. Denture base deformation during function. J Prosthet Dent. 1954;4:548-54. Kutsch VK, Whitehouse J, Schermerhorn K, Bowers R. The evolution and advancement of Dental Thermoplastics. Dental Town Magazine. 2003;4:52-56. Ahmad SF. An insight into the masticatory performance of complete denture wearer. Annal Dent Univ Malaya. 2006;13:24â&#x20AC;&#x201C;33. Kaira LS, Dabral E. Flexible dentures. Indian J Dent Adv. 2013;5(3):1264-67.

ParTiCularS oF ConTriBuTorS: 1. Senior Lecturer, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India. 2. Professor, Department of Maxillofacial Prosthodontics and Implantology, Peoples College of dental sciences, Bhopal, Madhya Pradesh, India. 3. Reader, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India. 4. Professor, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India. 5. Reader, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India.

A Comparison of Masticatory Performance and Efficiency of Complete Dentures Made with High Impact and Flexible Resins: A Pilot Study name, aDDreSS, e-mail iD oF THe CorreSPonDinG auTHor: Dr. Puja Hazari, Senior Lecturer, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh-462037, India. E-mail: hazaripuja@yahoo.in

Date of Submission: nov 19, 2014 Date of Peer Review: Feb 01, 2015 Date of Acceptance: apr 28, 2015 Date of Publishing: jun 01, 2015

FinanCial or oTHer ComPeTinG inTereSTS: None.

Question 32

Flexible dentures can be successfully given to patients with bony undercuts, as they are light weight and flexible.

True or False Question 33 A B C D

34

The loss of teeth in elderly patients impairs Stomatognathic system Psychological status Quality of life All of the above

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Question 34 In conclusion to the study the patients found the flexible dentures more satisfying

True or False

Question 35 According to the article masticatory performance ratio was less with conventional denture

True or False

Question 36

38

Important criteria for the success of dentures is the patientâ&#x20AC;&#x2122;s expectations and the ability of denture to replace the lost masticatory efficientcy

True or False

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International Journal of Occupational Medicine and Environmental Health 2014;27(5):785 – 796 http://dx.doi.org/10.2478/s13382-014-0301-9

PNEUMOCONIOSIS AND RESPIRATORY PNEUMOCONIOSIS RESPIRATORY PROBLEMS INAND DENTAL LABORATORY PROBLEMS IN DENTAL LABORATORY TECHNICIANS: ANALYSIS OF 893 DENTAL TECHNICIANS: ANALYSIS OF 893 DENTAL TECHNICIANS TECHNICIANS

This is an open access article DILEK ERGÜN1, RECAI ERGÜN2, CENGIZ ÖZDEMIR3, TÜRKAN NADIR ÖZIŞ1, HINÇ YILMAZ4, and İBRAHIM AKKURT5 DILEK ERGÜN1, RECAI ERGÜN2, CENGIZ ÖZDEMIR3, TÜRKAN NADIR ÖZIŞ1, HINÇ YILMAZ4, 1 Ankara Occupational Diseases Hospital, Ankara, Turkey and İBRAHIM AKKURT5 Department of Chest Diseases 1 Ankara Occupational Hospital, Ankara,ofTurkey 2 Ministry of Diseases Health of the Republic Turkey Training and Research Hospital, Ankara, Turkey Department of Chest Diseases Chest Diseases Clinic 2 Ministry3of Health Yedikule of the Republic Turkey Training andSurgery ResearchTraining Hospital,and Ankara, Turkey Istanbul ChestofDiseases and Chest Research Hospital, Istanbul, Turkey Chest Diseases Clinic Chest Diseases Clinic 3 Istanbul 4Yedikule Diseases Diseases and ChestHospital, Surgery Training Research Hospital, Istanbul, Turkey Ankara Chest Occupational Ankara,and Turkey Chest Diseases Clinic of Toxicology Department 4 Ankara Occupational Diseases Hospital, Ankara, Turkey 5 Akay Hospital, Ankara, Turkey Department of Toxicology Chest Diseases Clinic 5 Akay Hospital, Ankara, Turkey Chest Diseases Clinic Abstract Objectives: To explore the rate of pneumoconiosis in dental technicians (DTP) and to evaluate the risk factors. Material and Methods: Data of 893 dental technicians, who were admitted to our hospital in the period January 2007–May 2012, Abstract from 170 dental laboratories were retrospectively examined. Demographic data, respiratory symptoms, smoking status, Objectives: work To explore the rate of pneumoconiosis in dental technicians physical (DTP) and to evaluatefindings, the risk factors. Material pulmonary funcduration, working fields, exposure to sandblasting, examination chest radiographs, and Methods: Data of 893 dental technicians, who were admitted to our hospital in the period January 2007–May 2012, pneumoconiosis tion tests and high-resolution computed tomography results were evaluated. Results: Dental technicians’ from 170 dental laboratories were retrospectively examined. Demographic data, respiratory symptoms, smoking status, rate was 10.1% among 893 cases. The disease was more common among males and in those exposed to sandblasting who work duration, to sandblasting, physical examination findings, pulmonary funchadworking 77-foldfields, higherexposure risk of DTP. The highest profusion subcategory waschest 3/+ radiographs, (according to the International Labour Organition tests and high-resolution computed tomography results were evaluated. Results: Dental technicians’ pneumoconiosis zation (ILO) 2011 standards) and the large opacity rate was 13.3%. Conclusions: To the best of our knowledge, it was the rate was 10.1% among 893case cases. The(N disease was more common among males andHealth in those exposed to sandblasting who regularly for the largest DTP series = 893/90) in the literature in English. screenings should be performed had 77-fold early higherdiagnosis risk of DTP. The highest profusion subcategory was 3/+occupational (according to disease the International Labour Organiof pneumoconiosis, which is an important for dental technicians. zation (ILO) 2011 standards) and the large opacity rate was 13.3%. Conclusions: To the best of our knowledge, it was the largest DTPKey casewords: series (N = 893/90) in the literature in English. Health screenings should be performed regularly for the early diagnosis of pneumoconiosis, which is an important occupational disease for dental technicians. Pneumoconiosis, Dental laboratory technicians, Occupational respiratory disease, Pulmonary function, High-resolution computed tomography Key words: Pneumoconiosis, Dental laboratory technicians, Occupational respiratory disease, Pulmonary function, High-resolution computed tomography

Received: February 4, 2014. Accepted: May 7, 2014. Corresponding author: R. Ergün, Ministry of Health of the Republic of Turkey Training and Research Hospital, Chest Diseases Clinic, İrfan Baştuğ 10, 0 Turkey (e-mail: recaiergun@gmail.com). Received: February 4, 2014. Accepted: May 7, 2014. Corresponding author: R. Ergün, Ministry of Health of the Republic of Turkey Training and Research Hospital, Chest Diseases Clinic, İrfan Baştuğ 10, 06340 Ankara, Turkey (e-mail: recaiergun@gmail.com). Nofer Institute of Occupational Medicin

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INTRODUCTION INTRODUCTION Dental staff is exposed to various physical, chemical and biological harmful conditions in the working environment [1,2]. Defining the working conditions and risks that are likely to be experienced is mandatory in order to take work-related preventive measures. Dental technicians are exposed to numerous potential toxic substances and airborne residuals (including silica, alloys and acrylic-plastics) in the working environment. As a consequence, dental technicians develop occupational lung diseases such as asthma, bronchial cancer, mesothelioma and pneumoconiosis depending inter alia on the duration of exposure [3,4]. Pneumoconiosis is a disease that results from accumulation of inhaled particles in the lungs. Many substances such as asbestos, coal dust, silica, beryllium, cobalt, tungsten carbide, and iron oxide cause pneumoconiosis [5]. Silicosis has been reported as one of the most common pneumoconiosis among dental technicians [6]. Nevertheless, dental technicians’ pneumoconiosis (DTP) is considered as a specific entity and thought to be associated with exposure to cobalt-chromium-molybdenum (CoCrMo) [7]. Pneumoconiosis is an important occupational disease with potential fatal outcomes. Besides, it is also known that the frequency of tuberculosis and cancer is higher in pneumoconiosis cases as compared to the normal population [8–11]. Thus, it is necessary to make an early diagnosis, know the risk factors, and take preventive measures to decrease the mortality and morbidity rates of the disease. Chest radiographs have been used for a number of years for the screening and pre-diagnosis of occupational lung diseases. Nevertheless, it is known that computerized tomography (CT) is more sensitive in detecting pleura-parenchymal abnormalities in pneumoconiosis. Moreover, in order to detect pneumoconiosis lesions, high-resolution CT (HRCT), which is a more sensitive diagnostic tool is used [12–14]. Our hospital is one of the 3 reference centers for the final legal diagnosis of occupational diseases in Turkey. IJOMEH 2014;27(5)

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As in many other developing countries, there are many unlicensed dental prosthesis laboratories. Therefore, the number of dental prosthesis technicians is not exactly known. However, it is estimated there are 2500–3000 dental prosthesis laboratories and nearly 12 000 dental prosthesis technicians. In accordance with the statutes of the Ministry of Health, chest radiographs of these technicians are taken every 2 years for pneumoconiosis screening and sent by mail to 3 reference centers. Our hospital is one of these centers and people with suspicious lesions in chest radiographs are referred to our hospital for further investigations. The aim of the present study was to explore the rate of pneumoconiosis among dental technicians admitted to our hospital for the screening of pneumoconiosis, and to evaluate the results of respiratory function tests, chest radiographs and HRCT, as well as the risk factors that influence the development of pneumoconiosis. MATERIAL AND METHODS MATERIAL AND METHODS Data of 893 dental technicians, who came to the outpatient clinic of Ankara Occupational Diseases Hospital between January 2007 and May 2012, from 170 dental laboratories affiliated to the provincial directory of health, were retrospectively evaluated. The majority of dental technicians were working in small places with inadequate ventilation. They were exposed to a lot of dust as many procedures were carried out simultaneously. Patients with active tuberculosis or a history of the disease were not included in the study. The diagnosis of pneumoconiosis was based on the history of exposure to a mixture of dust and radiological changes consistent with pneumoconiosis. In addition to demographic data, respiratory symptoms, smoking status, total work duration, working fields, exposure to sandblasting, physical examination findings, chest radiographs, and results of pulmonary function tests (PFTs) were recorded on the evaluation form. The


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study was approved by the Human Ethics Committee of the Ministry of Health of the Republic of Turkey Training and Research Hospital, Ankara, Turkey. Working fields were evaluated in 4 groups: – modeling department (modeling, muffle, installation, porcelain, wax studies), – leveling and polishing department (trimming, polishing, sandblasting, prosthesis, casting studies), – plaster and revetment department, – administrative division (courier, director, etc.). Individuals non-smoking for a year or longer were considered as ex-smokers, those smoking 1 or more cigarettes a day for at least one year were considered as smokers, and those smoking less or none were considered as nonsmokers. PFTs were interpreted in accordance with the American Thoracic Society standards [15]. A standard spirometry measurement was done using dry-seal-spirometry (Zan 100, nSpire Health Inc., Oberthulba, Germany). The spirometry device was calibrated by measuring the humidity and temperature of the environment prior to each measurement. A forced vital capacity (FVC) maneuver was performed in each subject according to the standard procedure. Postero-anterior (PA) chest X-rays were taken in the radiology clinic of our hospital. A technique with short exposure time and with high voltage (Trophy UFXRAY, 500 mA, TM) was used. PA chest X-rays were evaluated in accordance with International Labour Organization (ILO) 2011 standards [16] by 3 B readers (2 chest disease specialists and a radiologist) and an A reader, i.e., a general practitioner. If there was any inconsistency between the 4 readers, they re-evaluated the PA chest X-rays. All of the X-rays were quality 1 or 2 according to the ILO classification. Those with ILO category 1/0 and over were considered as pneumoconiosis. After standard radiographs were compared, profusion was assessed and recorded as: 0 (0/–; 0/0; 0/1), 1 (1/0; 1/1; 1/2), 2 (2/1, 2/2, 2/3) or 3 (3/2; 3/3; 3/+).

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The shape and size were evaluated by comparing standard radiographs. The predominant shape and size were expressed as p, q, r, s, t or u. Large opacities and complete classification were noted as size A, B or C [16]. All subjects, whose X-rays were suspicious in terms of DTP, underwent thoracic HRCT. A GE HiSpeed scanner (General Electric Medical Systems, Milwaukee, HI spit NXI, Milwaukee, Wisconsin, USA) was used for the HRCT. Slices in 1 mm size at 1.5 s intervals which increased by 10 mm, image reconstruction with a 512×512 px matrix with the use of a high-resolution algorithm, and 1000 Hounsfield unit (HU) width were used. Data were analyzed using the Statistical Package for the Social Sciences (SPSS Inc., Chicago, IL, USA) version 15.0. Descriptive statistics were presented as cross-tables for categorical variables and as mean, median, standard deviation, minimum and maximum for numerical variables. Independent categorical variables were compared using the Chi2 test. In the case the Chi2 condition was not met, the Monte Carlo Simulation was used for multiple comparisons, and the Fisher’s exact test was used for paired comparisons. In case the normal distribution condition was not met, the MannWhitney U test was used for paired comparison of numerical variables, whereas the Kruskal-Wallis test was used for the comparison of multiple groups. Subgroup comparisons were performed using the Mann-Whitney U test with the Bonferroni correction. In order to determine the risk factors, the Backward-Stepwise method and logistic regression analysis were used for categorical dependent variables and the Enter method and linear regression analysis were used for numerical dependent variables. A p value < 0.05 was considered significant.

RESULTS RESULTS The study comprised 893 dental technicians (726 males, 167 females) with a mean age of 34.7±8.5 years. None of the dental technicians had previous dust exposure in their occupational history. IJOMEH 2014;27(5)

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Pathological signs were detected on the chest X-rays of 90 (10.1%) patients out of 888. Chest X-rays could not be taken in 5 patients due to pregnancy. Pulmonary function test could not be performed in 10 patients due to a compliance problem. Among the 883 patients that underwent PFT, 30 (3.4%) had restrictive and 71 (8%) had obstructive signs, whereas the results of 782 (87.6%) PFTs were unremarkable. Consequently, 10.1% (N = 90) of dental technicians were considered to have pneumoconiosis. We evaluated 171 cases with sandblasting history as a special subgroup. Seventy-nine of these cases (46.1%) had radiological pneumoconiosis findings. The comparison of the characteristics of all dental technicians with or without pneumoconiosis is presented in Table 1. The rate of males was remarkably high and the rate of smokers and the number of consumed cigarettes were significantly high among those with DTP. Overall respiratory tractrelated complaints were more frequent in those with DTP. The rate of exposure to sandblasting was also significantly high in those with DTP. There was no significant difference between groups in terms of overall duration of work, while duration of work in the leveling and polishing department was found to be significantly higher in those with DTP. The rate of impaired PFT (obstructive, restrictive) was significantly higher in those with DTP as compared to those without DTP. The mean results of PFTs, except for FVC and peak expiratory flow (PEF), were significantly lower in those with DTP (Table 2). The profusion category, shape, size, and zone of small opacities on the X-rays, as well as ILO classification of large opacities, are presented in Table 3. Among those with DTP, 40% had category 1, 35.6% had category 2, and 24.4% had category 3 profusion, whereas 48.9% had p, 43.3% had q, 4.4% had r, 1.1% had s, and 2.2% had u opacity. Out of the large opacities, 3.3% was A, 3.3% was B, and 6.7% was C opacity (Photo 1 and 2). While all zones were involved in 56.7% of the subjects, the lesions were located in the upper zone in 35.6%. IJOMEH 2014;27(5)

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Photo 1. Postero-anterior (PA) chest X-ray of a 38-year-old male dental technician, who had been working in a leveling and sandblasting department for 24 years (r/r 3/3+C as in Table 3)

Photo 2. High-resolution computed tomography sections of the patient mentioned in Photo 1 â&#x20AC;&#x201C; large opacities in 2 separate sections

High-resolution CT evaluations revealed that the rates of subjects with hilar lymphadenopathy (LAP), mediastinal LAP, micronodule, reticulonodular infiltration, linear density increment, and interlobular septal thickening were higher among those with DTP (Table 4). The model created by including the age at the start of employment, male gender, total work time, smoking status, duration of work in each department (work experience), and exposure to sandblasting to determine the risk factors


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Table 1. Characteristics of dental technicians and comparison of the characteristics of those with and without dental technicians’ pneumoconiosis Variable Age (years) (M±SD)

All dental technicians (N = 893)

Without DTP (N = 803)

With DTP (N = 90)

p*

34.7±8.5

34.7±8.7

34.9±6.9

0.624

Gender [n (%)]

< 0.001

female

167 (18.7)

166 (20.7)

1 (1.1)

male

726 (81.3)

637 (79.3)

89 (98.9)

Smoking status [n (%)]

0.033

no

321 (36.0)

297 (37.0)

24 (26.7)

yes

459 (51.4)

401 (50.0)

58 (64.4)

quitted

113 (12.7)

105 (13.1)

8 (8.9)

Amount of smoking (pack/year) (M±SD)

7.7±10.2

7.5±10.4

9.3±8.7

Presence of complaints [n (%)]

133 (14.9)

98 (12.2)

35 (38.9)

< 0.001

Cough [n (%)]

65 (7.3)

48 (6.0)

17 (18.9)

< 0.001

Sputum [n (%)]

61 (6.8)

48 (6.0)

13 (14.4)

0.003

Shortness of breath [n (%)]

76 (8.5)

51 (6.4)

25 (27.8)

< 0.001

Chest pain [n (%)]

38 (4.3)

25 (3.1)

13 (14.4)

< 0.001

Palpitation [n (%)]

28 (3.1)

27 (3.4)

1 (1.1)

modeling department [n (%)]

775 (86.8)

714 (88.9)

61 (67.8)

< 0.001

work experience (years) (M±SD)

10.8±7.5

10.8±7.4

11.2±8.5

0.831

leveling and polishing department [n (%)]

566 (63.4)

503 (62.6)

63 (70.0)

0.169

8.4±5.7

8.0±5.6

11.4±6.1

< 0.001

176 (19.7)

174 (21.7)

2 (2.2)

< 0.001

work experience (years) (M±SD)

4.1±3.3

4.1±3.3

4.0±1.4

0.636

administrative department [n (%)]

69 (7.7)

60 (7.5)

work experience (years) (M±SD)

7.7±6.9

8.2±7.2

4.1±2.1

0.139

18.7±5.3

18.7±5.3

18.7±5.9

0.742

16.1±8

16.1±8.1

16.1±6.8

0.631

≥ 15

490 (54.9)

439 (54.7)

51 (56.7)

0.718

≥ 20

286 (32.0)

263 (32.8)

23 (25.6)

0.166

≥ 30

65 (7.3)

62 (7.7)

3 (3.3)

0.129

171 (19.1)

92 (11.5)

79 (87.8)

0.008

0.349

Working field and duration

work experience (years) (M±SD) plaster and revetment department [n (%)]

Age at the beginning of employment (years) (M±SD) Total work experience (years)

Sandblasting [n (%)]

9 (10.0)

0.394

< 0.001

DTP – dental technicians’ pneumoconiosis. M – mean; SD – standard deviation. * Dental technicians – with DTP vs. without DTP.

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Table 2. Results of pulmonary function tests in those with and without dental technicians’ pneumoconiosis Without DTP (N = 796)

Pulmonary function test Normal [n (%)]

With DTP (N = 87)

p

728 (91.5)

54 (62.1)

< 0.001

Obstructive [n (%)]

46 (5.8)

25 (28.7)

Restrictive [n (%)]

22 (2.8)

8 (9.2)

FEV (ml) (M±SD)

3.5±0.7

3.2±0.8

< 0.001

FEV (%) (M±SD)

95.5±13.1

83.1±18.0

< 0.001

FVC (ml) (M±SD)

4.2±0.8

4.1±0.8

FVC (%) (M±SD)

96.7±11.5

89.4±14.7

< 0.001

Ratio (M±SD)

83.2±6.2

78.4±9.8

< 0.001

PEF (ml) (M±SD)

7.5±1.9

7.2±2.2

0.294

PEF (%) (M±SD)

85.9±17.5

78.8±23.3

0.005

MEF 25–75 (ml) (M±SD)

4.3±13.0

3.0±1.2

< 0.001

MEF 25–75 (%) (M±SD)

86.5±23.5

65.8±26.1

< 0.001

MEF 75 (ml) (M±SD)

6.9±1.8

6.0±2.1

< 0.001

MEF 75 (%) (M±SD)

91.6±19.8

77.0±25.9

< 0.001

MEF 50 (ml) (M±SD)

5.3±19.8

3.6±1.5

< 0.001

MEF 50 (%) (M±SD)

93.1±28.2

71.4±29.0

< 0.001

MEF 25 (ml) (M±SD)

1.8±0.8

1.3±0.7

< 0.001

MEF 25 (%) (M±SD)

79.9±29.9

59.9±27.5

< 0.001

0.158

FEV – forced expired volume; FVC – forced vital capacity; PEF – peak expiratory flow; MEF – maximal expiratory flow. Other abbreviations as in Table 1.

Table 3. Evaluation of lung graphs according to the International Labour Organization classification (16) in those with dental technicians’ pneumoconiosis Variable Profusion category 0 1 2 3 Shape and size p q r s u IJOMEH 2014;27(5)

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With DTP (N = 90) [n (%)] 0 (0.0) 36 (40.0) 32 (35.6) 22 (24.4) 44 (48.9) 39 (43.3) 4 (4.4) 1 (1.1) 2 (2.2)


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Table 3. Evaluation of lung graphs according to the International Labour Organization classification (16) in those with dental technicians’ pneumoconiosis – cont. With DTP (N = 90) [n (%)]

Variable Zone upper

32 (35.6)

intermediate

2 (2.2)

lower

3 (3.3)

upper-intermediate

2 (2.2)

all zones

51 (56.7)

Large opacity no

78 (86.7)

A

3 (3.3)

B

3 (3.3)

C

6 (6.7)

DTP – as in Table 1. 0 – no nodules; 1 – a few nodules without vascular blurring; 2 – a large number of nodules with or without vascular blurring; 3 – a large number of nodules with vascular blurring. p – round opacities up to 1.5 mm in diameter; q – round opacities 1.5–3 mm in diameter; r – round opacities 3–10 mm in diameter; s – irregular opacities with widths up to about 1.5 mm; t – irregular opacities with widths exceeding 1.5 mm and up to about 3 mm. A – one large opacity having the longest dimension up to about 50 mm, or several large opacities with the sum of their longest dimensions not exceeding about 50 mm; B – one large opacity having the longest dimension exceeding 50 mm, but not exceeding the equivalent area of the right upper zone, or several large opacities with the sum of their longest dimensions exceeding 50 mm, but not exceeding the equivalent area of the right upper zone; C – one large opacity which exceeds the equivalent area of the right upper zone, or several large opacities which, when combined, exceed the equivalent area of the right upper zone.

Table 4. High-resolution computed tomography findings in those with and without DTP Without DTP (N = 109) [n (%)]

With DTP (N = 90) [n (%)]

p

Ground glass

9 (8.3)

9 (10)

0.670

Hilar LAP

1 (0.9)

18 (20)

< 0.001

Mediastinal LAP

1 (0.9)

29 (32.2)

< 0.001

Micronodular

28 (25.7)

83 (92.2)

< 0.001

Peribronchial thickening

17 (15.6)

8 (8.9)

0.155

5 (4.6)

4 (4.4)

1.000

Emphysema

19 (17.4)

14 (15.6)

0.723

Bronchiectasis

18 (16.5)

11 (12.2)

0.393

Atelectasis

0 (0.0)

2 (2.2)

0.521

Reticulonodular infiltration

5 (4.6)

34 (37.8)

Variable

Air cyst

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Table 4. High-resolution computed tomography findings in those with and without DTP – cont. Variable

Without DTP (N = 109) [n (%)]

Calcified nodule

12 (11)

With DTP (N = 90) [n (%)]

p

13 (14.4)

0.467 0.001

Linear density increment

5 (4.6)

18 (20)

Interlobular septal thickening

6 (5.5)

24 (26.7)

< 0.001

DTP – as in Table 1; LAP – lymphadenopathy.

Table 5. Risk factors for dental technicians’ pneumoconiosis Variable Male gender

p 0.040

Plaster and revetment department

< 0.001

Sandblasting

< 0.001

OR (95% CI) 9.207 (1.112–76.204) 0.337 (0.192–0.591) 77.309 (37.873–157.809)

OR – odds ratio; CI – confidence interval.

for DTP revealed that male gender and exposure to sandblasting were significant risk factors; however, work experience at plaster and revetment departments was a significant preventive factor. Sandblasting was found to be the greatest risk factor, which increased the rate of DTP development by 77-fold (Table 5). DISCUSSION DISCUSSION It is known that pneumoconiosis results from chronic inhalation of substances which one is exposed to. Nevertheless, the fact is that pneumoconiosis does not develop in everybody exposed to the same substances at the same degree, but it develops in some people, which suggests that there is a genetic predisposition [17]. Illumination of the mechanisms and pathogenesis related to the interaction between genetic and environmental factors is of great importance since it can enable determination of high risk groups and prevention of the disease. The prevalence of pneumoconiosis among dental technicians has been reported to vary between 4.5% and 24% [18–26]. Different study populations (including IJOMEH 2014;27(5)

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such as all technicians in the region, only those responding to the questionnaire, only those admitted to hospital), different total and daily working times, and different working environment (it may be considered that large laboratories have better air conditioning and preventive measures) may lead to different prevalence rates for DTP. Choudat et al. [18] evaluated 105 dental technicians. Their X-rays revealed that the prevalence of small opacities (1/0 or greater), according to ILO classification, was 11.8% for a mean duration of exposure of 28.4 years. Froudarakis et al. [19] reported the prevalence of pneumoconiosis to be 9.8% in 51 dental technicians for a mean duration of exposure of 18.6 years. Rom et al. [20] found the prevalence of pneumoconiosis to be 4.5% in 178 dental technicians for mean work experience of 12.8 years. Selden et al. [21] found the prevalence of DTP at the level of 16% in their study group (N = 37). Radi et al. [22] reported the prevalence of small opacities with profusion ≥ 1/0 to be 12.3% in technicians with mean work experience of 16.5 years. Doğan et al. [23] found that prevalence of pneumoconiosis was 13.8% in dental technicians with a work duration of 13.8 years and it was reported that prevalence increased


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to 47% after 7 years of a follow-up [26]. Sherson et al. [24] evaluated 31 technicians and found the prevalence of DTP to be 19.4%. Cimrin et al. [25] detected signs of pneumoconiosis in the X-rays of 23.6% of 140 dental technicians with mean work experience of 12.1±9 years. In the present study, the rate of pneumoconiosis was found to be 10.1% among 893 dental technicians, who were admitted to our hospital in the last 5 years. To the best of our knowledge, the present study had the largest case series reported in dental technicians and evaluated the risk factors through the comparison of the characteristics of the cases with (N = 90) and without (N = 803) DTP. The level of inhalable dust and the concentration of the substances in the dusts show variation among working fields [27]. Therefore, departments in which dental technicians have been working indicate the level of exposure. Radi et al. [22] reported that the most common substances they were exposed to were plaster (93.3%), wax (83.6%), nickel-chromium alloys (82.1%), silica (78.9%) and resin (78.3%). In their study, Cimrin et al. [25] reported that the frequency of pneumoconiosis was higher in metal flattening, sandblasting and casting sections and indicated that it reached 50% in workers with a history of sandblasting during their work experience. In the present study, the highest rate of DTP was found in the subjects working in the leveling and polishing department, whereas the lowest rate was found in the subjects working in the plaster and revetment department. The rate of exposure to sandblasting was found to be significantly higher in those with DTP as compared to that in those without DTP (87.8% vs. 11.5%, p < 0.001). In the analysis of the subgroup with a history of sandblasting, pneumoconiosis was found at the rate of 46.1%. In sandblasting, as the breathable fractions of the particles are separated into even smaller parts with the blast of silica particles after being sprayed with pressured air, their accumulation in the lungs increases as well. The risk of silicosis is high here [28]. As the limit of crystalline silica

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dust is accepted as 0.05 mg/m3 according to NIOSH, it was demonstrated that this level is exceeded by 200–300 fold during sandblasting [29–33]. In the present study, it was demonstrated that sandblasting increases the risk of DTP 77-fold, which indicates that dental technicians are heavily exposed to silica. In view of this information, it should be emphasized that the risk of the development of pneumoconiosis is very high in dental technicians. The relation between the duration of exposure and DTP has been investigated and different results have been reported. Choudat et al. [18] found that the prevalence of DTP was significantly higher (22.2%) in those with exposure lasting ≥ 30 years as compared to those with exposure lasting < 30 years (3.5%, p < 0.004). Cimrin et al. [25] reported no significant relationship between the prevalence of DTP and work experience. Also in the present study no significant relationship was found between those with and without DTP in terms of the total work experience. However, the duration of working in the leveling and polishing department was found to be significantly higher in the group with DTP. The rate of smoking being usually higher among DTP cases makes it difficult to decide how many of the pathological changes result from occupational exposure. Some studies have reported the prevalence of smoking to be higher than 50% among dental technicians [25]. In the present study, the rate of smoking was found to be 51.4% and higher in those with DTP as compared to those without DTP. However, smoking was not found as a significant risk factor in the development of DTP. Karaman et al. [34] reported a DTP case, who had never used tobacco or tobacco products in any period of life and whose history revealed no characteristics likely to cause a tendency towards interstitial lung disease, and concluded that existing pathological findings were associated with occupational exposure. In the present study, 14.9% of dental technicians had respiratory system-related complaints, out of whom 38.9% IJOMEH 2014;27(5)

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had DTP and 12.2% had no DTP. Respiratory system-related symptoms (cough, sputum, dyspnea and wheezing) were also more frequent among cases with DTP as compared to those without. Cimrin et al. [25] found that 46.7% of the cases had at least 1 of the respiratory system-related symptoms (26.6% had cough, 30.4% had sputum, 18.2% had dyspnea, and 15.0% had wheezing). They failed to find a significant correlation between the rate of pneumoconiosis and the presence of the respiratory system symptoms. In their study conducted on dental technicians and ageand-smoking status-matched controls, Doğan et al. [23] found no difference between the groups in terms of respiratory system symptoms (cough, sputum, dyspnea, wheezing) and PFTs, except for FEV1. Radi et al. [22] conducted a study on 134 dental technicians and 131 nonexposed subjects and reported significant risks for cough (day and night) and usual phlegm in dental technicians. Moreover, they found that FVC%, forced mid expiratory flow (FEF25%), and FEF50% values were significantly lower in the dental technicians group as compared to those in the non-exposed group. In the present study, the results of PFTs, except for FVC (ml) and PEF (ml) were significantly lower in those with DTP as compared to those without it. The rate of impaired PFT (obstructive, restrictive) was found to be higher in the subjects with DTP than that in the subjects without DTP. Since exposure to multiple substances occurs in DTP, it can be assumed that there would be a diversity in the radiological findings. In the present study, 40% of DTP cases had profusion category 1 and 48.9% had small p opacity; all zones were involved in 56.7%. Froudarakis et al. [19] found DTP in 5 cases, out of whom 1 had 2/2 ILO profusion and diffuse irregular opacities (sr) and 4 had regular small opacities (pq) localized on the upper lobes. They noted no pleural changes. Radi et al. [22] detected a large opacity in 3.8%. Among the subjects with DTP, 12 (13.3%) had a large opacity; this was also one of the remarkable findings of the present study. IJOMEH 2014;27(5)

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In the silicosis case reported by Boyraz and Akın [35], HRCT revealed high-density millimetric nodules extensive in both lungs, but denser in the upper zones, nodular densities showing conglomeration in the upper zones and consistent with progressive massive fibrosis, mediastinal and hilar multiple lymph nodes enlargements containing remarkable calcifications. In the present study, HRCT examination revealed that the rate of subjects with hilar and mediastinal lymph nodes enlargement, micronodule, reticulonodular infiltration, linear density increment, and interlobular septal thickening was significantly higher in the DTP group. One potential limitation of this study was that the dose and incidence of the occupational exposure were not quantified. Although we used well defined criteria for diagnosis, the study lacks pathological confirmation. Another limitation is that our patient group may not represent the entire population of dental laboratory technicians. However, we believe that we met our aim to define the clinical and the radiological features of pneumoconiosis in dental laboratory technicians. CONCLUSIONS CONCLUSION The rate of DTP was 10.1%, the highest profusion category was 3/+, and the rate of large opacities was 13.3% in the present study. To the best of our knowledge, this is the largest DTP case series (N = 90) in the literature and we noted that the disease was more common among males and especially in those exposed to sandblasting who had a 77-fold higher risk of DTP. Occupational evaluation should be considered as supplementary to the clinical, radiological and pathological evaluation of the patients with suspected pneumoconiosis. Health screenings should be performed regularly for the early diagnosis of pneumoconiosis, which is an important occupational disease for dental technicians. Moreover, dental technicians should be encouraged to use the protecting materials adequately and ought to be regularly trained on this issue.


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PNEUMOCONIOSIS IN DENTAL TECHNICIANS

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33. Sevinc C, Cimrin AH, Manisali M, Yalcin E, Alkan Y. Sandblasting under uncontrolled and primitive conditions in Turkey. J Occup Health. 2003;45(1):66–9, http://dx.doi. org/10.1539/joh.45.66. 34. Karaman EC, Itil O, Gülşen A, Kargı A, Cimrin A. Dental technician’s pneumoconiosis: A case report. Tuberk Toraks. 2008;56:204–9.

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PNEUMOCONIOSIS AND RESPIRATORYPROBLEMS IN DENTAL LABORATORY TECHNICIANS: ANALYSIS OF 893 DENTALTECHNICIANS Question 37 How often were the technicians in Turkey tested for Pneumoconiosis? A Every Year B Every 2 Year C Every 5 Year D Never

This work is available in Open Access model and licensed under a Creative Commons Attribution-NonCommercial 3.0 Poland License – http://creativecommons.org/ licenses/by-nc/3.0/pl/deed.en.

Question 38 The occupational lung diseases, dental technicians can develop is Asthma, Bronchi IJOMEH 2014;27(5) al cancer, mesothelioma and pneumoconiosis True or False

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Question 39 What methods is used to detect pneumoconiosis lessions A B C D

High resolusion CT (HRCT Chest radiographs Computerized tomography (CT) None of above

Question 40 Pneumoconiosis is a disease that results from accumulation of inhaled particles in the lungs True or False Question 41 What is the most common pneumoconiosis found among dental technicians? A Mesothelioma B Asthma C Silicosis D All of above Question 42 Which 2 Diseases occurs more frequently in pneumoconiosis cases? A B C D

Hepotitus B and Hepotitus C Tuberculosis and cancer HIV and yellow fever Alzheimerâ&#x20AC;&#x2122;s and Parkinsonâ&#x20AC;&#x2122;s

Question 43 By how much was the rate of dental technician pneumoconiosis increased when exposed to sandblasting? A 9-fold B 18-fold C 77-fold D Non of above Question 44 The percentage of prevalence of pneumoconiosis among dental technicians has been reported to vary between 4.5% and 24% True or False Question 45 Occupational evaluation should be considered as supplementary to the clinical, radio- logical and pathological evaluation of the patients with suspected pneumoconiosis. True or False Question 46 The age-and-smoking status-matched control conducted on dental technicians, Dogan et al. found no difference between groups in terms of respiratory system symptoms(cough, sputum, dyspnea, wheezing) True or False SADTJ Vol 6 Issue 1

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