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November 2017 • Vol 7 Issue 1 • Split Cast Mounting: Review and New Technique • Occupational Concerns Associated with Regular Use of Microscope • Ceramic Veneers With Minimal Preparation • Mastication Improvement After Partial Implant-supported Prosthesis Use • Tax Season Opened on 1 July: Here’s What You Need To Know, And Do

SADTJ

ISSN 2077-2793

The Southern African Dental Technology Journal

9.9


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you off, you will receive constructive criticism and suggestions on how to improve your writing, should your article not be published the first time round.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: • • • •

• • • • •

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 7 Issue 1


In This Issue SADTJ Vol 7 Issue 1 November 2017

Editor

Axel Grabowski

Managing Editor Mariaan Roets

Split Cast Mounting: Review and New Technique

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PUBLISHED BY

The Dental Technicians Association of South Africa

LAYOUT AND DESIGN Nicola van Rensburg

Occupational Concerns Associated with Regular Use of Microscope

ADVERTISING ENQUIRIES

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m.roets@dentiworks.com

ADDRESS CHANGES

Elize Morris: dentasa@absamail.co.za

Ceramic Veneers With Minimal Preparation

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

Mastication Improvement After Partial Implant-supported Prosthesis Use

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DENTASA

PO Box 95340, Waterkloof, 0145 Tel: 012 460 1155 Fax: 086 233 7122 dentasa@absamail.co.za www.dentasa.org.za

Tax Season Opened on 1 July: Here’s What You Need To Know, And Do

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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.

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Editor’s Page The DENTASA Summit and AGM has come and gone. Well done to Melanie and her team, you did this profession proud. Not only was it successful in the sense of a well-run two days, but the lectures were well presented and covered a wide range of topics. The vast majority of lecturers were home bred, and proved again, that we do not have to stand back for anybody. The office is already busy with finalising a venue for 2018. The DENTASA Summit and AGM will be held on the 20th and 21st July 2018. This will be very different from all the previous Summits, as we are planning a family orientated weekend with lots of fun included. The weekend will not only focus on CPD as in the past. Once we have finalised the venue we will go flat out to make this upcoming event something memorable. The venue lies in the cradle of mankind, nestled in the foothills of the Swartkop mountains. The Misty Hills Hotel offers a great variety of interesting restaurants that are unique to Africa. I trust that you will find this edition of the SADTJ informative and interesting as always. We will publish one more journal towards the end of the year. Happy reading, Editorially yours, Axel

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IMPORTANT INFORMATION REGARDING CPD How are the CEUs calculated for the Journal? The Journal falls under Category B: (Measurable) Training and Publications: Dental Technology and related fields, sub-category B8. A maximum of 20 of the required CEUs may be obtained/claimed from this category but not more than 10 from any sub-category, with the exception of B4 which may not exceed 20 CEU’s Answer/complete multiple-choice questionnaires (MCQ) in journals, including electronic journals and or professional association News Letters with required pass mark. 70% is needed to pass and 0.2 CEU per standard page of prescribed reading and 0.2 CEU per question is awarded.

CPD via the SADTJ – Request to Council The DENTASA office has been inundated with phone calls and request from all dental technicians to be allowed to do older SADTJ issues to be able to acquire the additional CPD credits as stipulated by letters received by Council. We have sent a formal request to Council regarding the abovementioned and our correspondence was tabled at the CPD Committee meeting of the SADTC. We in addition tabled a request for Council to remove the maximum CEUs per category limitation to ensure that CPD becomes achievable and accessible to all in the profession. We are now awaiting a response from Council. We will inform you as soon as we receive an answer. Regards,

Elize Morris DENTASA Secretary The Dental Technology Association of South Africa Tel: 012-460 1155 www.dentasa.org.za SADTJ Vol 7 Issue 1

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CPD: The waiting game It is generally accepted that CPD requirements must be: • • • • • •

reasonable, achievable, fair, accessible to all (cost-effective), transparent, flexible, and

inclusive.

Measured against these categories the SADTC’s CPD requirements falls far short as the rules are draconian and very user-unfriendly towards the profession. The maximum threshold for CEUs in certain categories is a case in point. When bench marking against other councils like the Pharmacy Council, The South African Council for Social Service Professions, The South African Institute for Professional Accountants , The Actuarial Society and most importantly the HPCSA with its TWELVE professional boards, none of them have a maximum threshold for CEUs in a category. By removing the maximum CEUs per category and making it possible to obtain all the CEUs from the Journal the SADTC will go a long way in making CPD achievable and accessible to all in the profession. DENTASA also requested the SADTC to allow the technicians to complete the SADTJ questionnaires of the 2014/2015 period to make up their CEU short fall, this will also be discussed at the planned workshop. In light of the above DENTASA requested that Mariaan Roets be allowed to attend and give her valued input at their proposed workshop which was supposed to have been held in March. It is now the middle May and we are still waiting for any feedback from Council, seven months after our initial letters. Our request to publish the SADTC newsletters and annual report in order for technicians to gain Ethic and Business points by completing the questionnaires was prohibited. We regret this decision as it would have made it possible for technicians in the rural areas to earn their Ethics and Business CEUs much easier and cheaper. Half of this year is almost gone, we need clarity on the above issues, the CPD compliance rate is abysmal, let’s make it reasonable, achievable, fair, accessible, transparent, flexible and inclusive. It is possible. Ms. Roets attended the CPD workshop representing DENTASA. We suggested the following to make it easier for technicians to comply, for service providers to apply and for the Council to administer: 1. Abolish maximum threshold per category 2. Make Ethics and Business CEUs available in accredited publications and other media 3. Simplify accreditation process 4. That technicians be given a chance to get the required CEU’s for 2014/2015 by completing the 2014/2015 questionnaires in the SADTJ. The CPD Committee discussed the requests after the workshop in their meeting and will make recommendations to the Council. The next SADTC meeting is 15 July.

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J Indian Prosthodont Soc (December 2014) 14(Suppl. 1):S345–S347 DOI 10.1007/s13191-014-0380-0

SPLIT CAST MOUNTING: REVIEW AND NEW TECHNIQUE

CLINICAL TIPS

‘‘Split Cast Mounting: Review and New Technique’’ S. M. Gundawar • Neelam A. Pande Priti Jaiswal • U. M. Radke

Received: 20 November 2013 / Accepted: 22 June 2014 / Published online: 29 July 2014  Indian Prosthodontic Society 2014

Abstract For the fabrication of a prosthesis, the Prosthodontist meticulously performs all the steps. The laboratory technician then make every effort/strives to perform the remaining lab procedures. However when the processed dentures are remounted on the articulator, some changes are seen. These changes may be divided into two categories: Pre-insertion and post-insertion changes, which deal with the physical properties of the materials involved (Parker, J Prosthet Dent 31:335–342, 1974). Split cast mounting is the method of mounting casts on the articulator. It is essentially a maxillary cast constructed in two parts with a horizontal division. The procedure allows for the verification of the accuracy of the initial mounting and the ease of removal and replacement of the cast. This provides a precise means of correcting the changes in occlusion occurring as a result of the processing technique (Nogueira et al., J Prosthet Dent 91:386–388, 2004). Instability of the split mounting has always been a problem to the Prosthodontist thereby limiting its use. There are various materials mentioned in the literature. The new technique by using Dowel pins and twill thread is very easy, cheaper and simple way to stabilize the split mounting. It is useful and easy in day to day laboratory procedures. The article presents different methods of split cast mounting and the new procedure using easily available materials in prosthetic laboratory. Keywords Split mounting  Stability  Technical procedure

S. M. Gundawar  N. A. Pande (&)  P. Jaiswal  U. M. Radke VSPM’s Dental College & Hospital, Nagpur, Maharashtra, India e-mail: abhay.angp@gmail.com

Introduction The first mention of ‘‘split casts’’ was by J.W. Needles in 1923. Properly constructed split casts provide a simple and reliable means of obtaining a high degree of accuracy in articulator mounting and verification of articulator settings from occlusal records. The ‘‘split cast’’ is essentially a maxillary cast constructed in two parts with a horizontal division. The first part of the split maxillary master cast with index grooves, is known as primary base. The design, number, and position of the index grooves are determined on the basis of the height of the palatal vault depth of the sulcus the personal preference of the clinician. The second part, which is fitted to the master cast and is attached to the upper member of the articulator is referred to as secondary base or sandwich. The perfect fit of the master cast, sandwich and upper member of the articulator verifies the correct centric relation record. If gap is present between the master cast and sandwich or sandwich and upper member of the articulator that determines the previous recording of centric relation is incorrect [3]. The sandwich should have a contrasting color for easy detection and should also have index grooves. The splitcast mounting procedure allows for: (i) (ii) (iii) (iv)

Ease of removal and replacement of the casts. To program the articulator by means of eccentric records. Verification of centric jaw relation records. For correcting occlusal errors as a result of the processing technique.

The literature shows [4–6], use of following materials for split cast mounting: plaster, sticky wax, masking tape and elastic adhesive bandage (Figs. 1, 2, 3, 4).

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Fig. 5 Pouring of cast using dowel pins Fig. 1 Split mounting using plaster

Fig. 2 Split mounting using sticky wax

Fig. 6 Metal plates, dowel pins and ligature wire

(iii)

Fig. 3 Split mounting using masking tape

(iv) (v)

(vi)

(vii)

Fig. 4 Split mounting using elastic adhesive bandage

Another new technique is described here using metal plates, dowel pins and ligature wire assembly.

Technique (i)

(ii)

After completion of the final impression, beading and boxing is completed, for pouring the base of the cast. Two dowel pins with plastic/metal sleeves, are then inserted in the boxing wax, with a gap of 2–3 mm on right and left side.

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Dental stone is then poured in the boxed impression. Once the stone sets hard, finishing of the master cast is done on trimmer, by removing the dowel pins from their sleeves. After finishing of the cast, the dowel pins are reinserted in their sleeves (Fig. 5). Base of master cast is sharply grooved. For this master cast, using die stone, sandwich or secondary base is made having thickness of 3–4 mm. On this base also index grooves are cut. Using face bow, the combined primary and secondary base cast are mounted on the upper member of the articulator. Two metal plates with serrations on one end (routinely available forks) are cut in required length. The other end is also slightly notched, for encircling the ligature wire. During mounting, before plaster sets hard, these plates with serrated end, are inserted into plaster on right and left side (Fig. 6). Once the plaster sets hard, the ligature wire is moved around the two dowel pins which is attached to the master cast. It is encircled over the notched surface of the metal plate, tightened to stabilize the upper mounting (Fig. 7).

Advantage: Damage to cast is minimum. Mounting is stable. Easy to use. Easy removal and reattachment of maxillary cast to the articulator. Disadvantage: Extra time is required in attaching the dowel pins to the cast.


J Indian Prosthodont Soc (December 2014) 14(Suppl. 1):S345–S347

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Fig. 7 Split mounting using metal plates, dowel pins and ligature wire

Summary

References

Instability of the split mounting has always been a problem to the Prosthodontist thereby limiting its use. Sticky wax is the most popularly used material, plaster is the second most popularly used material another method is the use of elastic adhesive bandage, which provides easier and hygienic method to secure the master cast to the sandwich and the upper member of the articulator. The use of routinely available dowel pins and serrated metal plates is new technique. This is also very easy, cheaper and simple technique to stabilize the split mounting. The technique is useful and easy in day to day laboratory procedures.

1. Parker HM (1974) Effective management of laboratory procedures and use of split-cast technique. J Prosthet Dent 31:335–342 2. Nogueira SS et al (2004) A variation on split-cast mounting for complete denture construction. J Prosthet Dent 91:386–388 3. Lauritzen AG, Wolford LW (1964) Occlusal relationships: the split-cast method for articulator techniques. J Prosthet Dent 14:256–265 4. Barrett GD (1985) Reproducible split-cast procedure for remounting the complete denture master cast. J Prosthet Dent 54:737–740 5. Liu F-C, Luk K-C, Suen P-C, Tsai T, Ku Y-C (2010) Modified split-cast technique: a new, time saving clinical remount technique. J Prosthodont 19:502–506 6. Gundawar SM, Radke UM (2013) Elastic adhesive bandage ‘‘In Prosthodontics’’. J Indian Prosthodont Soc Supplementary:62–64

DENTASA SUMMIT 2018 20 & 21 JULY

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ORIGINAL PAPER International Journal of Occupational Medicine and Environmental Health 2014;27(4):591 – 598 http://dx.doi.org/10.2478/s13382-014-0288-2

OCCUPATIONAL CONCERNS ASSOCIATED WITH REGULAR USE OF MICROSCOPE GARIMA JAIN and PUSHPARAJA SHETTY A.B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore, India Department of Oral Pathology and Microbiology Abstract Objectives: Microscope work can be strenuous both to the visual system and the musculoskeletal system. Lack of awareness or indifference towards health issues may result in microscope users becoming victim to many occupational hazards. Our objective was to understand the occupational problems associated with regular use of microscope, awareness regarding the hazards, attitude and practice of microscope users towards the problems and preventive strategies. Material and Methods: a questionnaire based survey done on 50 professionals and technicians who used microscope regularly in pathology, microbiology, hematology and cytology laboratories. Results: Sixty two percent of subjects declared that they were suffering from musculoskeletal problems, most common locations being neck and back. Maximum prevalence of musculoskeletal problems was noted in those using microscope for 11–15 years and for more than 30 h/week. Sixty two percent of subjects were aware of workplace ergonomics. Fifty six percent of microscope users took regular short breaks for stretching exercises and 58% took visual breaks every 15–30 min in between microscope use sessions. As many as 94% subjects reported some form of visual problem. Fourty four percent of microscope users felt stressed with long working hours on microscope. Conclusions: The most common occupational concerns of microscope users were musculoskeletal problems of neck and back regions, eye fatigue, aggravation of ametropia, headache, stress due to long working hours and anxiety during or after microscope use. There is an immediate need for increasing awareness about the various occupational hazards and their irreversible effects to prevent them. Key words: Occupational hazards, Microscope use, Ergonomics, Musculoskeletal problems

INTRODUCTION Occupations in any field may use up all the energy, health and patience of an individual, and occupational problems may take their toll on the well-being and feeling of satisfaction in the employee [1]. Oxford English Dictionary defines an occupational hazard as “a risk accepted as a consequence of a particular occupation” [2]. The development and implementation of some rules and regulations by concerned administrative bodies for every profession may help reduce these unpleasant experiences.

A number of highly trained medical professionals and technicians may help doctors to make decisions and save lives [3]. One such group comprises those who use microscope as a tool of investigation [3]. Microscope users may be unaware or may neglect the health risks associated with their work and fall prey to a number of occupational problems [3]. The association of prolonged microscope use with the development of chronic pain syndromes and visual problems has been recognized for decades, yet awareness about these occupational hazards comes only when a person becomes victim to these hazards [4].

Received: December 16, 2013. Accepted: April 14, 2014. Corresponding author: G. Jain, Department of Oral Pathology and Microbiology, A.B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore (e-mail: drgarimajain7@gmail.com).

Nofer Institute of Occupational Medicine, Łódź, Poland

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Work related Musculoskeletal disorders (MSDs), also known as cumulative trauma disorder, occur in microscope users due to excessive force, repetitive movement, awkward posture, prolonged static posture or vibration [4]. According to statistics of National Safety Council 2006 and Straker et al. (2004), out of all injuries which prevent an employee from attending work, MSDs are the reason in approximately one third cases [5]. Ergonomics is identified as an emerging area of practice. As told by OSHA, it deals with fitting a job to a person that helps lessen muscle fatigue, increases productivity and reduces the number and severity of work-related MSDs [6]. In microscope users, repetitive eye movements while screening slides, difficulty in accommodation and convergence of eye can result in fatigue, eye strain, and visual discomfort. These problems can also be linked to monotony and prolonged working time without a break [7,8]. The more unexplored areas of occupational hazards with regular microscope use are stress, burnout, depression and anxiety among such personnel. In the present questionnaire based study, an effort has been made to understand the occupational concerns in the population of microscope users as well as their knowledge, awareness and attitude about occupational problems like musculoskeletal disorders, visual problems and stress. The opinion of the subjects included in study about their working environment and comfort levels have also been voiced.

MATERIAL AND METHODS This study is based on a questionnaire comprising 40 questions. It aimed to include all professionals who used microscope regularly, like pathologists, microbiologists, oral pathologists, post-graduate students and technicians in pathology, microbiology, hematology and cytology laboratories. The questionnaires were given in person, explaining the objective of the study. Every questionnaire had an informed consent form attached to it. Filled questionnaires 592

with informed consent form duly signed, were later collected. Fifty microscope users answered the questionnaire. Statistical analysis Data collected was subjected to statistical analysis including frequency analyses, Chi2 test and Fisher’s exact tests.

RESULTS Participation Thirty three females and 17 males (total: 50) with an age range of 23–70 years (mean: 33.62 years) participated in the study. Twenty four participants were below 30 years, 17 between 31–40 years and 9 were above 40 years. Out of the 50 subjects, 13 were pathologists, 6 microbiologists, 8 oral pathologists, 13 postgraduate students and 10 technicians in pathology, hematology and microbiology laboratories. The questionnaire survey has been summarized in Table 1 and work place specifications as asked in the questionnaire have been briefed in Table 2. Questionnaire Musculoskeletal disorders Sixty two percent of the microscope users in this study declared that they were suffering from musculoskeletal problems and 58% of them faced it repetitively. The most common locations were neck and back (Figure 1). Other problematic areas included shoulder, wrist and hand. There was a statistically significant difference in overall prevalence of musculoskeletal problems with maximum in those using microscope for 11–15 years (p = 0.029) and, surprisingly, less subjects in the groups using microscope for more than 15 years reported musculoskeletal problems. All the subjects who used microscope for more than 30 h per week said that they were victims of musculoskeletal problems, followed by 60% (21–30 h/week), 52.4% (1–10 h/week) and 44.4% (11–20 h/week).

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ORIGINAL PAPER

Table 1. Questionnaire survey summary Respondents (N = 50)* (%)

Characteristic yes Ever experienced work-related musculoskeletal problems Repetitive attacks of musculoskeletal problems Taken sick leave due to musculoskeletal problem Taken any form of treatment/hospitalization for musculoskeletal problems Take regular short breaks for stretching exercises Aware of work place ergonomics Suffering from any known ametropia Aggravation of ametropia during working years on microscope Experiencing eye fatigue during microscope use Experiencing headache during microscope use Taking visual breaks every 15–30 min in between microscope use Getting regular ophthalmic check up done Difficulty in viewing the microscope with spectacles Signed off from work due to visual problems Stressed due to long hours spent on microscope Find reporting of microscopic findings and final diagnosis stressful Feel anxious/irritated while or after using microscope Feel depression or burnout due to regular microscope use Aware of CDC guidelines for microscope use Satisfied with comfort levels of workplace/microscope

no

31 (62.00) 18 (58.06)* 2 (6.45)* 7 (22.60)* 28 (56.00) 31 (62.00) 30 (60.00) 18 (36.00) 28 (56.00) 24 (48.00) 29 (58.00) 23 (46.00) 9 (18.00) 4 (8.00) 22 (44.00) 13 (26.00) 14 (28.00) 13 (26.00) 18 (36.00) 37 (74.00)

19 (38.00) 13 (41.93)* 29 (93.55)* 24 (77.42)* 22 (44.00) 19 (38.00) 20 (40.00) 32 (64.00) 22(44.00) 26 (52.00) 21 (42.00) 27 (54.00) 41 (82.00) 46 (92.00) 28 (56.00) 37 (74.00) 36 (72.00) 37 (74.00) 32 (64.00) 13 (26.00)

CDC – Centres for Disease Control and Prevention. * Except for marked values, where N = 31 (values and % are out of 31).

Table 2. Workplace specifications Respondents (N = 50) (%)

Office At least one window Air conditioning Shared with colleagues Microscopes very closely placed Microscope tube adjustable in height allows horizontal line of sight ergonomically optimized chairs regularly serviced

yes 40 (80.0) 21 (42.0) 50 (100.0) 21 (42.0)

no 10 (20.0) 29 (58.0) 0 (0.0) 29 (58.0)

13 (26.0) 19 (38.0) 31 (62.0) 35 (70.0)

37 (74.0) 31 (62.0) 19 (38.0) 15 (30.0) IJOMEH 2014;27(4)

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G. JAIN AND P. SHETTY

Fig. 1. Location of musculosceletal problems in microscope users

Sixty two percent of subjects were aware of workplace ergonomics but awareness about the Centres for Disease Control and Prevention (CDC) guidelines for microscope use was as low as 36%. Only 6% of those suffering took 1–2 days of sick leave during the past year. Those who took sick leave were all males who belonged to the age group of more than 40 years and who spent more than 30 h/week using microscope for more than 15 years. Twenty three percent of those suffering had to take some form of treatment or hospitalization. Fifty six percentage microscope users in our survey took regular short breaks for stretching exercises and 58% took visual breaks every 15–30 min in between microscope use. Only 62% subjects enjoyed the luxury of ergonomically optimized chairs. There was no statistically significant association between overall prevalence of musculoskeletal problems or their repetitive nature, and factors like the habit of taking regular short breaks for stretching exercises, adjustable and ergonomically optimized chairs, adjustability of microscope tube or microscope allowing horizontal line of sight, awareness about work place ergonomics and CDC guidelines for microscope use. We also did not find any significant association between age, gender and profession with musculoskeletal problems or their repetitive attacks. 594

Visual problems In our study group, 60% subjects claimed to suffer from refractive errors. Sixty percent ametropic microscope users reported an aggravation of ametropia during their working years, out of which 33.3% believed that microscope use was the sole reason for this aggravation. Thirty two percent of microscope users experienced both visual and musculoskeletal problems simultaneously. As many as 94% subjects mentioned some form of visual problem or a combination, ranging from eye discomfort (38.3%), headache (51.1%), dry eye (12.8%) with maximum subjects complaining of eye fatigue (59.6%) during microscope use (Figure 2).

Fig. 2. Different visual problems among microscope users

None of the factors like habit of taking visual breaks every 15–30 min in between microscope use, number of years of microscope use, weekly working hours, or whether they used spectacles while looking into the microscope or not made a statistically significant difference in aggravation of ametropia. Stress Fourty four per cent of microscope users felt stressed with long working hours on microscope, out of which 26% considered it due to physical fatigue only. Twenty six percentage found the reporting of microscopic findings and final diagnosis as a cause of stress while 52% found the lack of

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achievement of final diagnosis to be stressful. According to the information disclosed in the questionnaire, males experienced significantly higher stress than females (p = 0.007). Eight per cent of microscope users always felt anxious and irritated during or after using microscope while 20% felt the similar way only a few times. Twenty six percent felt depressed and burnout after using microscope. There was a statistically significant association between no. of hours of microscope use per week and stress, with complaint of feeling anxious/irritated during or after microscope use and feeling depressed/burnout recorded among maximum subjects belonging to the group using microscope for more than 30 h/week. Factors like age, number of years of microscope use, talking to colleagues while reporting, (whether subject matters or otherwise) did not seem to have an influence on work related stress. Satisfaction with workplace Eighty percent of subjects had at least one window in their microscope room, while 42% enjoyed air conditioned microscope rooms. All the subjects shared the microscope use area with their colleagues. Forty two percent of microscope users reported that their microscopes were very closely placed. In spite of these conditions, only 18% of them thought that they did not have enough place to sit comfortably. Seventy percentage informed that their microscopes were serviced regularly. Only 62% subjects enjoyed the luxury of adjustable and ergonomically optimized chairs. Seventy four percent of subjects were satisfied with the comfort levels of their workplace with statistically significant association with those having at least one window in their microscope room or air conditioned rooms, enough place to sit comfortably, adjustable chairs and those provided the privilege of regular servicing of microscopes. Eighty two percent of subjects were satisfied with their working environment.

ORIGINAL PAPER

DISCUSSION This study indicates that there are various work related problems, lack of awareness and ignorance among microscope users, which, if not dealt suitably with, may make their profession a burden rather than a boon. In the present study, the prevalence of musculoskeletal problems among microscope users was high (62%). A similar study conducted by Fritzsche et al. on pathologists in Switzerland also revealed prevalence of musculoskeletal problems, which was as high as 76% [3]. It is interesting to note that these problems were faced by many young microscope users too, which argues against a mere aging effect of this disorder. Being repetitive in many, it also forced some microscope users to be absent from work for 1–2 days. According to the National Safety Council 2006, musculoskeletal injuries could result in loss of median 10 working days (> 8 median working days lost for all injuries) [5]. The most common locations of musculoskeletal problems in our study were neck and back, similar to a study by Lorusso et al. on musculoskeletal complaints among microscope workers [9]. Other problematic areas included shoulder, wrist and hand. The study by Fritzsche et al. found neck and shoulders to be the most common locations, apart from other locations like hips, face/head, ankles etc. [3]. Other surveys on cytotechnologists reported high prevalence of pain of neck, upper back, lower back, shoulder and upper extremities [10,11]. Kreczy et al. studied the pattern of musculoskeletal disorders in microscope users and found it to be associated with non-ergonomic microscope workstations, which contribute to increased muscle strain (especially in trapezius, T8, L3 and biceps brachii), fatigue, and pain with sustained work [7]. Prevalence of musculoskeletal problems was found in maximum numbers in those using microscope for 11–15 years, while smaller numbers of subjects reported musculoskeletal problems in the groups using microscope for more than 15 years. These findings were not as expected, but IJOMEH 2014;27(4)

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could be due to reduced time taken by these microscope users in diagnosis owing to more than 15 years of experience. Flavin et al. in a similar study found a lack of association between the number of working years and musculoskeletal problems, but they also reported a higher incidence of musculoskeletal problems in those who worked for less than 15 years [12]. In the present study, increased working hours were associated with musculoskeletal problems with all subjects of the group using microscope for more than 30 h/week complaining of some or the other form of musculoskeletal problem. This was probably due to prolonged static load, repetitive movements and awkward postures. Falla proved by surface electromyography that neck and back muscles were constantly working when one sits down to view slides at microscope [13]. Centre for disease control and prevention (CDC) guidelines for microscope use do not allow the microscope users to work for more than 5 h per day [4]. It also advises to take frequent short breaks from microscopy work [4]. In the present study, the habit of taking regular short breaks did not show significant association with lower levels of musculoskeletal complaints. The explanation for this finding could be the development of habit of regular breaks only after the problem started, incorrect technique of doing it or not providing accurate information in the questionnaire. We found a lack of association of an ergonomic workplace setting with lower prevalence of musculoskeletal problems, the results being similar to the study by Lorusso et al. [9]. This could probably be due to procurement of ergonomic equipment after developing musculoskeletal disorders, adaptation and continuation of using wrong postures in the ergonomic work settings or lack of awareness despite the equipment. In contrast to our findings, Thompson et al. adjudged that basic ergonomic training and use of ergonomic aids could substantially decrease musculoskeletal problems [11]. 596

On assessment of awareness levels among subjects, 38% were ignorant about work place ergonomics and 64% did not have the slightest clue about CDC guidelines for microscope use. Darragh et al. evaluated the effect of occupational therapy ergonomics intervention on the workstation design and body positioning of microscope workers and found that there was a statistically significant improvement in groups enrolled in educationtraining programme and education only programme, as compared to control group [5]. This demonstrates the need for education and training regarding ergonomic workplace settings and for modifications in microscopes being used [5]. Most light microscopes have eye piece fixed at acute angles relative to microscope body, which forces the user to flex the neck and upper back to view through the eye piece [4]. An ergonomic microscope with adjustable eyepiece, now commercially available, would allow the user to maintain neutral position of neck and upper back [4]. Although in most settings they have not replaced the traditional fixed angle microscopes due to the high purchase price [4]. When the neck is in flexed position for prolonged times, extensor muscles, tendons and ligaments are stretched, becoming lax and weak. This may lead to extensor muscle dysfunction after many years of this practice [4]. In our study group, 60% subjects declared suffering from refractive errors. According to a study by Fritzsche et al. on pathologists in Switzerland, about 90% of the occupational group suffered from ametropia and more than 50% had experienced an aggravation during their working years on microscope [3]. Similarly in our study, 60% ametropic microscope users reported an aggravation of ametropia during their working years, out of which 33.3% believed that microscope use was the sole reason for this aggravation. The relationship between higher myopia prevalence and occupations with extensive near-field work requirements is well documented, yet the conventional myopia

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OCCUPATIONAL CONCERNS: REGULAR MICROSCOPE USE

might present in these individuals in the same manner as in any other person not involved with that type of work [3,14,15]. Korniushina conducted a study on microscope users, subjects working with magnifying glasses, and computer users and found that the highest overstrain was observed after 4 years of work in microscope operators who might develop professional myopia due to deprivation of accommodation [16]. A clinical study by Risovic et al., to determine the presence of refractive errors and binocular dysfunction in a population of university students with heavy near visual demands found it to be the most important factor for higher incidence of myopia, worse convergence, and exophoria [17]. The limitation of our study was that the other factors like long hours of computer work and the possibility of ametropic students entering these professions in greater numbers could not be ruled out. Ninety four percent of subjects in our study reported some form of visual problem or a combination, ranging from eye discomfort, headache, dry eye, with maximum subjects complaining of eye fatigue during microscope use. A similar questionnaire study in Ireland by Flavin et al. highlighted that 56% of the pathology laboratory personnel suffered from visual problems associated with microscope use, including eye fatigue, eye discomfort, headache, dry eyes, dizziness and nausea [12]. Visual fatigue and discomfort may be a result of difficulty in accommodation and convergence of eye, monotonous work or working without break for prolonged periods [8]. Apart from the musculoskeletal and visual problems, microscope users in our study also complained of getting stressed with long working hours on microscope, lack of achievement of final diagnosis, reporting of microscopic findings and medico-legal complications that could arise with each case. According to a study by Fritzsche et al., every eighth pathologist in Switzerland suffered from burnout and depression and older pathologists were at higher risks [3]. We noted increased levels of stress in those using

ORIGINAL PAPER

microscope for more hours, which could have been due to increased physical fatigue and monotony of work. But according to the questionnaire, only 26% subjects believed that stress was due to physical fatigue only. Twenty six percent felt depressed and burnouted after using microscope, with maximum in subjects belonging to the group using microscope for more than 30 h. This percentage was much higher than that found by Fritzsche et al. (6.7% and 8.6%, respectively) [3]. Despite the results, Fritzsche et al. found burnout and depression to be the most common mental disease of pathologists [3]. In the present study, 74% subjects were satisfied with the comfort levels of their workplace regardless of the fact whether it was ergonomically optimized or not. The reasons given were presence of basic facilities like windows in reporting rooms (some having air-conditioners), sufficient and comfortable sitting area, adjustable chairs in some labs and provision of regular servicing of microscopes. It could also be explained as ignorance turned into bliss. Despite the above issues, most microscope users who took part in this study were optimistic about their work atmosphere, similar to the study by Fritzsche et al. [3].

CONCLUSION The most common occupational concerns of microscope users were musculoskeletal problems of neck and back regions, eye fatigue, aggravation of ametropia, headache, stress due to long working hours and anxiety during or after microscope use. Awareness about workplace ergonomics and CDC guidelines was poor and many subjects in the study did not have ergonomically optimized microscope and workplace. This study found the immediate need for increasing awareness about the various occupational hazards that can affect the microscope users so that they become alert about the risks and start taking all necessary precautions to prevent them. IJOMEH 2014;27(4)

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REFERENCES

1. Menaghan EG, Merves ES. Coping with occupational problems: The limits of individual efforts. J Health Soc Behav. 1984;25:406–23, http://dx.doi.org/10.2307/2136379. 2. Oxforddictionaries.com [Internet]. New York: Oxford University Press; 2000 [updated 2014 June; cited 2013 Dec 2]. Available from: http://www.oxforddictionaries.com/definition/american_english/occupational-hazard. 3. Fritzsche FR, Ramach C, Soldini D, Caduff R, Tinguely M, Cassoly E, et al. Occupational health risks of pathologists – Results from a nationwide online questionnaire in Switzerland. BMC Public Health. 2012;12:1054, http://dx.doi. org/10.1186/1471-2458-12-1054. 4. George E. Occupational hazard for pathologists. Microscope use and musculoskeletal disorders. Am J Clin Pathol. 2010;133:543–8, http://dx.doi.org/10.1309/AJCPUXDS5KJKRFVW. 5. Darragh AR, Harrison H, Kenny S. Effect of an ergonomics intervention on workstations of microscope workers. Am J Occup Ther. 2008;62(1):61–9, http://dx.doi.org/10.5014/ ajot.62.1.61. 6. Osha.gov [Internet]. Washington DC: United States Department of Labor [cited 2013 Dec 2]. Available from: https:// www.osha.gov/SLTC/ergonomics/index.html. 7. Kreczy A, Kofler M, Gschwendtner A. Underestimated health hazard: Proposal for an ergonomic microscope work station. Lancet. 1999;354(9191):1701–2, http://dx.doi.org/10.1016/ S0140-6736(99)03131-1. 8. Franco G. Health disorders and ergonomic concerns from the use of the microscope: A voice from the past. Am J Clin Pathol. 2011;135:170–1, http://dx.doi.org/10.1309/AJCPUYF00YHFHTHJ.

9. Lorusso A, Bruno S, Caputo F, L’Abbate N. Risk factors for musculoskeletal complaints among microscope workers. G Ital Med Lav Ergon. 2007;29(4):932–7. 10. Kalavar S, Hunting KL. Musculoskeletal symptoms among cytotechnologists. Lab Med. 1996;11:765–9. 11. Thompson SK, Mason E, Dukes S. Ergonomics and cytotechnologists: Reported musculoskeletal discomfort. Diagn Cytopathol. 2003;29:364–7, http://dx.doi.org/10.1002/ dc.10377. 12. Flavin RJ, Guerin M, O’Briain DS. Occupational problems with microscopy in the pathology laboratory. Virchows Arch. 2010;457(4):509–11, http://dx.doi.org/10.1007/s00428010-0965-x. 13. Falla D. Unravelling the complexity of muscle impairment in chronic neck pain. Man Ther. 2004;9:125–33, http://dx.doi. org/10.1016/j.math.2004.05.003. 14. Ting PWK, Schmid KL, Lam CSY, Edwards MH. Objective real-time measurement of instrument myopia in microscopists under different viewing conditions. Vision Res. 2006;46(15):2354–62, http://dx.doi.org/10.1016/j.visres. 2006.01.014. 15. McBrien NA, Adams DW. A longitudinal investigation of adult-onset and adult-progression of myopia in an occupational group: Refractive and biometric findings. Invest Ophthalmol Vis Sci. 1997;38(2):321–33. 16. Korniushina TA. Physiological mechanisms of the etiology of visual fatigue during work involving visual stress. Vestn Oftalmol. 2000;116(4):33–6. 17. Risovic DJ, Misailovic KR, Eric-Marinkovic JM, KosanovicJakovic NG, Milenkovic SM, Petrovic LZ. Refractive errors and binocular dysfunctions in a population of university students. Eur J Ophthalmol. 2008;18(1):1–6.

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.

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Case Report

Ceramic veneers with minimum preparation Leonardo Fernandes da Cunha1, Rachelle Reis2, Lino Santana1, Jose Carlos Romanini3, Ricardo Marins Carvalho4, Adilson Yoshio Furuse5

Department of Dentistry, Master of Science Program in Clinical Dentistry, Positivo University, Curitiba, Brazil, 2 Private Practice, Bauru, Brazil, 3 Romanini Dental Prosthetic Lab, Londrina, Brazil, 4 Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, Canada, 5Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil 1

Correspondence: Dr. Adilson Yoshio Furuse Email: furuseay@yahoo.com.br

ABSTRACT The aim of this article is to describe the possibility of improving dental esthetics with low‑thickness glass ceramics without major tooth preparation for patients with small to moderate anterior dental wear and little discoloration. For this purpose, a carefully defined treatment planning and a good communication between the clinician and the dental technician helped to maximize enamel preservation, and offered a good treatment option. Moreover, besides restoring esthetics, the restorative treatment also improved the function of the anterior guidance. It can be concluded that the conservative use of minimum thickness ceramic laminate veneers may provide satisfactory esthetic outcomes while preserving the dental structure.

Key words: Ceramic veneers, dental ceramics, dental esthetics

INTRODUCTION The esthetic treatment of anterior teeth has always presented a challenge in clinical practice. With the improvement of dental materials, many restorative options such as resin composites, all‑ceramic crowns, and ceramic veneers became available. In these circumstances, dentists and patients must choose the best alternative to improve oral condition and esthetic results. Ceramic laminate veneers may be indicated when there is anterior dental wear and enough remaining sound dental structure. This treatment option has been used due to ceramics’ color stability, biocompatibility, mechanical properties, and esthetic outcome.[1] The idea of minimally invasive dental restorations is essential for successful restorations. [2,3] Thus,

minimum thickness ceramic laminate veneers have been increasingly indicated. Such esthetic treatments, however, must not be conducted without an appropriate restorative planning. The preparation design and the amount of remaining dental structure have significant effects on load to failure of ceramic veneers.[4] This concept of planning may be used to assist the cosmetic intervention and develop esthetically beautiful smiles. Therefore, the dentist and laboratory technician must follow a proper protocol to achieve higher clinical success rates. It is important to emphasize that the clinician should have a good understanding of the ceramic type to establish the appropriate cementation procedure that will contribute to long‑lasting restorations.[5] Hence, the aim of this paper is to describe minimum thickness ceramic

How to cite this article: da Cunha LF, Reis R, Santana L, Romanini JC, Carvalho RM, Furuse AY. Ceramic veneers with minimum preparation. Eur J Dent 2013;7:492-6. Copyright © 2013 Dental Investigations Society. 492

DOI: 10.4103/1305-7456.120645

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laminate veneers as a restorative solution to improve the esthetics of the smile.

was applied three times on both maxillary and mandibular anterior teeth.

CASE REPORT

No provisionals were required due to the minimal preparation performed, with no dentin exposure. On a subsequent appointment after 2 weeks, shade selection was performed and impression taken using retraction cords (Ultrapak Cord #000, Ultradent Products Inc., South Jordan, UT, USA) [Figure 4]. This technique was selected to provide gingival sulcus enlargement without using impregnated cords with hemostatic or astringent solutions. The impressions were taken using a vinyl polysiloxane material (Express XT, 3M ESPE, Seefeld, Germany). The trays were loaded with the heavy‑bodied impression material, while the light‑bodied impression materials were simultaneously spread on the teeth.

A 34‑year‑old female patient with enamel hypoplasia on anterior upper incisors was referred to treatment. Radiographic images and clinical exam were conducted. Clinically, enamel hypoplasia and discrepancies in shape, form, and color were observed [Figure 1a‑c]. Diagnostic casts and waxed‑up restorations to define shape and form were previously obtained to assist the treatment planning. Due to the case characteristics, ceramic laminate veneers of minimum thickness were indicated for the four maxillary incisors. Dental preparation consisted of slightly grinding the incisal edges of the lateral incisors and left central incisor with a #2135‑diamond bur (KG Sorensen, Barueri, SP, Brazil) [Figure 2]. Enamel surfaces were then polished with sequential aluminum oxide discs from coarse to ultrafine (3M Sof‑Lex, 3M ESPE, Seefeld, Germany). At the same appointment, in‑office bleaching was performed with 35% hydrogen peroxide (Mix One, Villevie, Joinville, SC, Brazil) following the manufacturer’s instructions [Figure 3]. The bleaching agent

a

Ceramic laminate veneer restorations were fabricated with a lithium disilicate‑reinforced glass ceramic material (IPS e.max Press, Ivoclar‑Vivadent, Liechtenstein), using the heat press technique. A layering ceramic (IPS e.max Ceram, Ivoclar‑Vivadent) was further applied to improve the incisal edge optical characteristics [Figure 5a]. The veneers’ internal surfaces to be bonded were etched with hydrofluoric acid (Porcelain Etchant

b

c Figure 1: (a) Preoperative view of patient’s smile with enamel hypoplasia. (b) Close‑up view of the anterior teeth. Note the compromised esthetics due to enamel hypoplasia and anatomic discrepancies of form, shape, and color. (c) Close‑up view of the right maxillary anterior teeth

Figure 2: The teeth preparation was limited to enamel

Figure 3: Application of 35% hydrogen peroxide gel on the surface of the anterior teeth

Figure 4: Retraction cords in position previously to the impression technique

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9,5%, Bisco Inc., Schaumburg, IL, USA) for 20 seconds, washed under running water, dried with an air syringe, and primed (Porcelain Primer, Bisco Inc., Schaumburg, IL, USA). A try‑in paste (RelyX Veneer Try‑in, 3M ESPE, Seefeld, Germany) was used to select the proper color of the luting cement. The color TR was selected. The laminate veneers were then washed to remove try‑in paste and excess of silane[6] and carefully air‑dried. One coat of the bonding resin of Adper ScotchBond (3M ESPE, Seefeld, Germany) was applied and light‑cured [Figure 5b]. During the cementation, veneers were cemented separately one‑by‑one by conditioning with phosphoric acid and applying the same bonding resin on the tooth surface. The laminate veneer restoration was bonded with a light‑curable resin‑based luting agent (RelyX Veneer, 3M/ESPE, Seefeld, Germany). The cement was applied to the veneers that were gently seated with finger pressure. Excess cement was removed with an explorer and a microbrush. The light polymerization was performed with a LED‑curing unit (Radii‑cal SDI, Bayswater, Victoria, Australia) for 30 s from buccal, incisal, mesial, and distal aspects of each tooth. Restorations were checked for any occlusal interference. The final restorative phase was achieved by polishing the marginal areas with a silicone instrument (rubber point Jiffy, Ultradent Products Inc., South Jordan, UT, USA). Immediate final restorations can be observed in Figures 6a‑d. Figure 7 shows the 10‑month‑follow‑up treatment.

a

b Figure 5: (a) Completed minimum thickness anterior porcelain laminate veneers restorations on the working cast. (b) Application of the bonding system

a

b

c

d

Figure 6: (a and b) Frontal and close‑up views of the anterior teeth after placing the veneers. (c and d) Frontal and lateral views of the smile

DISCUSSION When ceramic veneers are considered, different restorative approaches have been proposed, depending on the thickness of the veneer and the color of the remaining dental structure. In the case of improving esthetics by changing the form and texture of teeth with no severe discoloration, veneers of smaller thickness may be indicated. After being informed about advantages and disadvantages of each restorative option, the patient opted for the conservative ceramic veneers of minimum thickness. The long‑lasting esthetics and little preparation of the underlying dental structure were among main reasons for this decision. Thus, in the presented clinical situation, the dental preparation was restricted to the enamel. Besides the optical characteristic similar to the dental structure, glass‑ceramic materials have good bonding characteristics to the dental structure. This increased retention is mainly related to the use hydrofluoric 494

a

b Figure 7: (a) Palatal view of the seated restorations after 10 months. (b) Facial view of the restorations 10 months after seating

acid to etch their internal surfaces, associated with the use of silane‑coupling agents. [7] Moreover, when the dental preparation is restricted to the enamel, improved and more reliable bonding may be obtained.[8] European Journal of Dentistry, Vol 7 / Issue 4 / Oct-Dec 2013

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In the present case report, the dental bleaching was conducted at the same appointment of the dental preparation. This procedure, however, could be considered controversial due to the fact that bleaching may influence the extent of dental preparation. The decision of bleaching at the same clinical was based on the idea that ultrathin veneers were planned from the beginning. Dental bleaching may be considered a safe treatment[9] and may be associated with other therapies as demonstrated in the present case. Since practically no dental preparation was conducted, the patient reported no post‑treatment pain. It is important to note that the color selection should be delayed, as bleached teeth usually appear whiter and chalky immediately after bleaching. The try‑in paste was used to select the cement color only after the application of the silane‑coupling agent. This paste helps obtaining a more predictable final result.[10] The try‑in paste was removed by rinsing with water spray, followed by air‑drying. This protocol of using and rinsing the try‑in paste after the application of the silane coupling agent has been proposed to improve the bond strength of the resin‑based cement to the ceramics.[6,11] While rinsing, the excess of unreacted silane was removed. This excess has been reported to be washable with water at room temperature, and, if not removed, could compromise the coupling of the luting material to the ceramic by hydrolysis. The inner layer attached to the glass‑ceramic is considered hydrolytically stable due to its covalent links to the silica and is not removable by the rinsing procedure.[12,13] A light‑cured resin‑based cement was employed. This type of cement is an appropriate choice for luting indirect veneers in terms of bond strength and increased working time.[14,15] The working time is considered critical for the positioning and adaptation of the veneer. The use of light‑cured materials for the cementation of veneers, however, is based on the idea that the light could easily pass through the indirect restoration due its translucency and reduced thickness. A concern related to light transmittance through ceramic materials and its influence on cement degree of conversion and mechanical properties has been raised.[16] It should be noted that even when dual‑cured resin cements are employed, the light activation plays an important role on material’s degree of conversion. [17] Another aspect to be considered when cementing veneers with materials that relies on the ability of light transmission through the ceramics is that not all light‑curing devices are equal[18] and that different curing properties may be European Journal of Dentistry, Vol 7 / Issue 4 / Oct-Dec 2013

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achieved for the same curing unit if used with a fiber optic or a polymer light guide tip.[19] For this reason, light‑cured resin cements should be light activated carefully, both at cervical, medium and incisal areas of the veneer. The ultimate success of esthetic treatments is only achieved when the patient is educated and motivated to maintain good oral health. The patient contribution and periodic control by the dentist is imperative to the long‑term success of the treatment.

CONCLUSION The minimum thickness anterior ceramic laminate veneers may be a conservative and esthetic alternative to reestablish the form, shape, and color of anterior teeth.

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

11. 12. 13. 14.

15. 16.

Guess PC, Schultheis S, Bonfante EA, Coelho PG, Ferencz JL, Silva NR. All‑ceramic systems: Laboratory and clinical performance. Dent Clin North Am 2011;55:333‑52. Bloom DR, Padayachy JN. Aesthetic changes with four anterior units. Br Dent J 2006;200:135‑8. Radz GM. Minimum thickness anterior porcelain restorations. Dent Clin North Am 2011;55:353‑70. Schmidt KK, Chiayabutr Y, Phillips KM, Kois JC. Influence of preparation design and existing condition of tooth structure on load to failure of ceramic laminate veneers. J Prosthet Dent 2011;105:374‑82. Vargas MA, Bergeron C, Diaz‑Arnold A. Cementing all‑ceramic restorations: Recommendations for success. J Am Dent Assoc 2011;142 Suppl 2:20‑4S. Pegoraro TA, da Silva NR, Carvalho RM. Cements for use in esthetic dentistry. Dent Clin North Am 2007;51:453‑71. Land MF, Hopp CD. Survival rates of all‑ceramic systems differ by clinical indication and fabrication method. J Evid Based Dent Pract 2010;10:37‑8. De Munck J, Van Landuyt K, Peumans M, Poitevin A, Lambrechts P, Braem M, et al. A critical review of the durability of adhesion to tooth tissue: Methods and results. J Dent Res 2005;84:118‑32. Kihn PW. Vital tooth whitening. Dent Clin North Am 2007;51:319‑31. ALGhazali N, Laukner J, Burnside G, Jarad FD, Smith PW, Preston AJ. An investigation into the effect of try‑in pastes, uncured and cured resin cements on the overall color of ceramic veneer restorations: An in vitro study. J Dent 2010;38 Suppl 2:e78‑86. Manso AP, Silva NR, Bonfante EA, Pegoraro TA, Dias RA, Carvalho RM. Cements and adhesives for all‑ceramic restorations. Dent Clin North Am 2011;55:311‑32. Hooshmand T, van Noort R, Keshvad A. Bond durability of the resin‑bonded and silane treated ceramic surface. Dent Mater 2002;18:179‑88. Hooshmand T, van Noort R, Keshvad A. Storage effect of a pre‑activated silane on the resin to ceramic bond. Dent Mater 2004;20:635‑42. Sarabi N, Ghavamnasiri M, Forooghbakhsh A. The influence of adhesive luting systems on bond strength and failure mode of an indirect micro ceramic resin‑based composite veneer. J Contemp Dent Pract 2009;10:33‑40. Walls AW. The use of adhesively retained all‑porcelain veneers during the management of fractured and worn anterior teeth: Part 1. Clinical technique. Br Dent J 1995;178:333‑6. Pick B, Gonzaga CC, Junior WS, Kawano Y, Braga RR, Cardoso PE. Influence of curing light attenuation caused by aesthetic indirect restorative materials on resin cement polymerization. Eur J Dent 2010;4:314‑23. 495


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Di Francescantonio M, Aguiar TR, Arrais CA, Cavalcanti AN, Davanzo CU, Giannini M. Influence of viscosity and curing mode on degree of conversion of dual‑cured resin cements. Eur J Dent 2013;7:81‑5. Ozturk B, Cobanoglu N, Cetin AR, Gunduz B. Conversion degrees of resin composites using different light sources. Eur J Dent 2013;7:102‑9. Galvão MR, Caldas SG, Bagnato VS, de Souza Rastelli AN, de Andrade MF. Evaluation of degree of conversion and hardness of dental composites photo‑activated with different light guide tips. Eur J Dent 2013;7:86‑93.

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vol. 92 • suppl no. 2

ClInICAl InVESTIGATIOnS

Mastication Improvement After Partial Implant-supported Prosthesis Use T.M.S.V. Gonçalves1, C.H. Campos1, G.M. Gonçalves2, M. de Moraes2, and R.C.M. Rodrigues Garcia1*

Abstract: Partially edentulous patients may be rehabilitated by the placement of removable dental prostheses, implant-supported removable dental prostheses, or partial implant fixed dental prostheses. However, it is unclear the impact of each prosthesis type over the masticatory aspects, which represents the objective of this paired clinical trial. Twelve patients sequentially received and used each of these 3 prosthesis types for 2 months, after which maximum bite force was assessed by a strain sensor and food comminution index was determined with the sieving method. Masseter and temporal muscle thicknesses during rest and maximal clenching were also evaluated by ultrasonography. Each maxillary arch received a new complete denture that was used throughout the study. Data were analyzed by analysis of variance for repeated measures, followed by the Tukey test (p < .05). Maximum bite force and food comminution index increased (p < .0001) after implant-supported dental prosthesis and implant fixed dental prosthesis use, with the higher improvement found after the latter’s use. Regardless of implant-retained prosthesis type, masseter muscle thickness during maximal clenching also increased (p <

.05) after implant insertion. Partial implant-supported prostheses significantly improved masseter muscle thickness and mastication, and the magnitude of this effect was related to prosthesis type (International Clinical Trial Registration RBR-9J26XD). Key Words: clinical trials, mastication, removable prosthodontics, fixed prosthodontics, oral rehabilitation, ultrasound. Introduction Posterior teeth play important roles in comminuting food, and postcanine teeth loss significantly reduces masticatory performance (van der Bilt et al., 2006). Moreover, loss of a first-molar occlusal pair is a key factor in prosthetic restoration (Fueki et al., 2011). Several prosthetic options are available to restore chewing function in patients with missing teeth (Abt et al., 2012; de Freitas et al., 2012). However, few studies (Kapur, 1991; Liedberg et al., 2004) have determined the effects of prosthetic treatment on mastication in partially edentulous patients, and their findings are controversial. Kapur (1991) reported that removable dental prostheses (RDPs) and partial implant fixed dental

prostheses (IFDPs) achieved similar chewing efficiency. In contrast, Liedberg et al. (2004) showed higher food comminution in patients with fixed dental prostheses than in RDP wearers. Because masticatory impairment can adversely affect quality of life (Lepley et al., 2010), the effects of different prostheses on mastication are important to determine. Several methods have been used to evaluate mastication, including occlusal force measurements (Goshima et al., 2010; Muller et al., 2012; Ohara et al., 2013), sieving test (Gotfredsen and Walls, 2007; van der Bilt, 2011), color-changeable gum test (Goshima et al., 2010; Muller et al., 2012), and muscle thickness evaluation (Bhoyar et al., 2012; Muller et al., 2012; Ohara et al., 2013). In addition, correlations among bite force, chewing performance, and masticatory muscle thickness (Raadsheer et al., 1999; Muller et al., 2012) have been established, and it is known that masticatory muscle action is influenced by occlusal factors, such as partial edentulism (Bhoyar et al., 2012). Thus, masticatory muscle function can be reduced by severe tooth loss or a soft diet consumption, as typically selected by edentulous patients, leading to muscle atrophy (Tsai et al., 2012). Dental implants are increasingly used to replace missing teeth (Abt et al., 2012; de Freitas et al., 2012), and studies have

DOI: 10.1177/0022034513508556. 1Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas, Avenida Limeira, 901,13414903, Piracicaba, São Paulo, Brazil; 2Department of Oral and Maxillofacial Surgery, Piracicaba Dental School, University of Campinas, Avenida Limeira, 901, 13414-903, Piracicaba, São Paulo, Brazil; *corresponding author, regarcia@fop.unicamp.br © International & American Associations for Dental Research 189S

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shown masticatory improvements in implant-supported overdenture wearers (Carlsson and Lindquist, 1994; Feine et al., 1994; Geertman et al., 1999; van Kampen et al., 2004). However, the effect of implant therapy is unclear in partially edentulous patients’ chewing, which was the aim of this study. The tested hypothesis was that the increased retention and stability provided by implants would be predictive of masticatory improvements and could affect muscle thickness. Materials & Methods Experimental Design

The Ethics Committee of Piracicaba Dental School, University of Campinas (Piracicaba, Brazil), approved this research (protocol 011/2010). In this longitudinal, single-center clinical trial, subjects served as their own (paired) controls. Study participation was voluntary, and subjects provided written informed consent before enrollment (International Clinical Trial Registration RBR-9J26XD). Subjects were selected with edentulous maxilla and partial edentulous mandible, using old and ill-fitting removable dentures. Each patient received a new, complete maxillary denture that was used throughout the study, while a sequence of 3 mandibular treatments was performed: conventional RDPs, implantsupported removable dental prostheses (IRDPs), and IFDPs. All treatments were accomplished with no cost to the subjects, and each prosthetic treatment was used for 2 months before masticatory evaluation. We measured the maximum bite force (MBF), food comminution index (FCI), and masticatory muscle thickness. The poor conditions of the old prostheses did not allow for masticatory evaluation at baseline. Subject Selection

Eligible subjects had no maxillary teeth and only mandibular canines and incisors, with sufficient bone in the posterior mandible to allow for implant installation. Subjects were in good general health and free of temporomandibular disorder,

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parafunctional habits, or uncontrolled systemic disease that would prevent oral surgery. Sample size was estimated on the basis of a previous study (Miyaura et al., 2000) (bidirectional α of 0.05 and β of 0.20), and 9.6 subjects were required to detect differences. We added 25% to compensate patient drawback, with a total sample of 12. Patients seeking prosthetic treatment at Piracicaba Dental School, University of Campinas, were contacted (n = 120), but 12 were excluded because of advanced periodontal disease, 33 because of the retention of lower molars and/or premolars, and 57 because of insufficient bone height for implant insertion (evaluated by panoramic radiography and/or computed tomography). Three patients refused to participate. Thus, 15 were selected, but 1 died during the research period and 2 were excluded because of bone resorption complications, yielding a final sample of 12 volunteers (4 men, 8 women) with a mean age of 62.6 ± 7.8 yrs (range, 48-80 yrs). Clinical Procedures

Subjects received general dental treatment, including periodontal and dental care for remaining teeth. New complete maxillary dentures and mandibular RDPs were assembled with conventional techniques. RDP frameworks were made of cobaltchromium alloy, with lingual major bar and circumferential or bar clasp retainers as the RPD design. Lingual rests were located on the lower canine cingulum and provided indirect retention to rotational movements. Prostheses were installed and adjusted in patients’ mouths with bilateral balanced occlusion scheme. After 2 months of prosthesis use, mastication was evaluated. Subjects received 2 implants (Titamax; Neodent, Curitiba, Brazil) per side in the mandibular premolar and molar region. The correct implant position and inclination were established with a surgical guide, and a conventional 2-step technique was used (Blanes et al., 2007). After 1 week, RDPs were adjusted and relined with resilient soft lining material (Ufi Gel P; Voco, Cuxhaven, Germany)

for use during the 4-month osseointegration period. The posterior implants were exposed and received ball abutments (O’ring; Neodent) according to the manufacturer’s instructions. Conventional RDP acrylic base was relieved, and the capsules were captured directly in the mouth to improve passive fit (de Freitas et al., 2012), transforming the RDP into an IRDP. Occlusal adjustments were performed to maintain bilateral balanced occlusion. Masticatory variables were again evaluated after 2 months of IRDP use. At final step, IRDP was replaced by 3-unit metal-ceramic IFDP assembled with conventional techniques (Blanes et al., 2007). All IFDPs were screwed over abutments (Mini Pilar; Neodent) attached to implants, according to manufacturer’s instructions. The screw holes were covered with compound resin, and occlusal adjustment was performed. After 2 months of IFDP use, masticatory function was evaluated. Masticatory Function Evaluation

MBF was measured with bite force transducer (Spider 8; Hottinger Baldwin Messtechnik GmbH, Darmstadt, Germany) (Fernandes et al., 2003). Sensors (FSR no. 151, 1.2-mm diameter, 5.6-mm thickness; Interlink Electronics Inc., Camarillo, CA, USA) were placed in the bilateral first molar regions, and signals were recorded and analyzed by Catman Easy software (version 1.0; Hottinger Baldwin Messtechnik GmbH). Subjects were requested to occlude with maximum force for 7 s, and the procedure was repeated after 5-min rest. The average of the 2 measurements was calculated and recorded in newtons (N). The reproducibility of the MBF method was verified in 10 subjects chosen at random. Two measurements were performed, and a high intraclass correlation coefficient was found (r = 0.94). FCI was evaluated with Optocal artificial test material (Pocztaruk et al., 2008). Subjects were instructed to chew a 3.7-g portion in the habitual manner for 20 strokes (van der Bilt and Fontijn-Tekamp, 2004) while a single calibrated operator counted the cycles. The comminuted

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particles were collected, dried, and vibrated in a sieving machine (Bertel Indústria Metalúrgica, Caieiras, Brazil) through a stack of sieves with variably sized mesh (0.5 mm to 5.6 mm). Materials retained on sieves were weighed on a 0.001-g analytical balance (Mark; BEL Engineering, Milan, Italy), and the FCI was calculated as the percentage weight of the comminuted material that passed through the 2.8-mm sieve (van der Bilt and Fontijn-Tekamp, 2004). Real-time imaging of the bilateral masseter and anterior temporalis muscle thickness was performed ultrasonographically (SSA-780 A-APLIO Mx, 38 mm/7-18 MHz; Toshiba Medical System Co., Tokyo, Japan). Muscle thickness was measured directly on the instrument’s screen (Fig. 1) with an accuracy of 0.01 mm (Castelo et al., 2010). A pilot study was performed on 2 days with 10 subjects selected at random. The ultrasound measurement error (Se) was calculated by Dahlberg’s (1940) formula: Se = √Σd 2/2n, where d is the difference between 2 measurements and n is the number of recordings. The masseter muscle thickness errors in contracted and relaxed positions were 0.13 and 0.16 mm, respectively, and those for the anterior temporalis were 0.17 and 0.16 mm. These values are considered small, revealing the method’s accuracy (Georgiakaki et al., 2007). Additionally, a Pearson correlation coefficient performed between the 2 measurements revealed a strong and significant correlation (r = 0.85-0.98) (p < .0001). Each trial was conducted in a darkened room with the subject seated in an upright position. All measurements were performed by a single calibrated operator to avoid interoperator error (Emshoff et al., 2003). A standardized protocol was used to establish the correct location of the muscle site (Emshoff et al., 2003). Initially, the muscles were identified by palpation (masseter: area of greatest lateral distention, ~ 2 cm above the inferior mandibular border; anterior temporalis: anterior to the anterior border of the hairline) (Castelo et al., 2010), and a line was drawn on the subject’s skin, showing the specific area where the trans-

Figure 1. Example of an ultrasound image of masseter muscle thickness (mm) during maximum muscle contraction. The intensive white line at the lower part of the image is the echo of the lateral surface of the ramus mandibularis (A), and the narrow white line at the top represents the outer fascia of the masseter muscle (B). The masseter is seen as a dark area between the fascia (B) and the lateral surface of the ramus (A) measured perpendicular to the ramus.

ducer should be placed. After gel application, the probe was held perpendicular to the muscle, avoiding excessive pressure on the tissue, until the reflection of the bone was depicted as a sharp white line. The thickest part of the muscles was measured perpendicular to the muscle long axis (Fig. 1) (Castelo et al., 2010). Three measurements were performed for each muscle at rest and in the maximum voluntary clenching (MVC). Final muscle thickness values were obtained by averaging these values (Castelo et al., 2010). Statistical Analyses

Data distributions were assessed by Shapiro-Wilk tests, which revealed normal distributions. Analysis of variance for repeated measures was performed with SAS software (release 9.1, 2003; SAS Institute Inc., Cary, NC, USA), and Tukey-Kramer tests were used for comparisons among the prosthetic treatments. Pearson correlations were calculated among masticatory muscle thickness, MBF, and FCI. Statistical significance was set to p < .05.

Results MBF increased (p < .0001) after implant insertion (Fig. 2) with gain of 140 N observed between RDP and IRDP use, while an increment of 306 N was detected from RDP to IFDP use, growing 79% and 172%, respectively. A similar trend was observed for FCI, with the highest values verified after IFDP use (p < .0001) (Fig. 3). Multiple comparisons among RDP, IRDP, and IFDP use revealed that FCI rose up to 91% when comparing RDP to IRDP use, while the improvement found between RDP and IFDP use was 209% on average. The left and right masseter and anterior temporalis muscle thicknesses during rest and MVC are presented in the Table. Regardless of side and prosthesis type, masseter muscle thickness during MVC increased after implant insertion (p < .05), rising from 5.9% to 9.3% in respect to muscle site and prosthesis type. No differences were observed in masseter or temporalis muscle thickness 191S

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Figure 2. Graph showing mean value of maximum bite force (N) and standard deviations in relation to the prosthetic treatment. Maximum bite force was significantly higher for the implantsupported removable dental prosthesis (IRDP) and implant fixed dental prosthesis (IFDP) (*p < .0001). RDP, removable dental prosthesis.

Figure 3. Graph showing mean value of food comminution index (%) and standard deviation in relation to the prosthetic treatment. The use of implant-supported removable dental prostheses (IRDPs) and implant fixed dental prostheses (IFDP) significantly increased the chewing capacity (*p < .0001). RDP, removable dental prosthesis.

at rest or temporalis muscle in MVC (all p > .05). Pearson correlation analysis performed between muscle thicknesses and masticatory variables revealed weak and nonsignificant correlations (p > .05).

Discussion Given the common occurrence of tooth loss, increasing life spans, and retention of more teeth into advanced age, evidence is needed to inform the

clinical management of tooth loss (Abt et al., 2012). Studies comparing different prostheses must eliminate confounding factors (Abt et al., 2012), and these can be achieved most reliably by intraindividual comparison of restoration alternatives. This paired study provides sufficient evidences for the effects of prosthetic treatment on masticatory function in partially edentulous patients. Simple, accurate, and reliable methods were used to quantify mastication provided by each dental restorative procedure. As expected, MBF was higher after IFDP and IRDP use than after RDP use. Although no other paired study on this topic has been published, our MBF findings are in accordance with those of Miyaura et al. (2000) and Ohara et al. (2013). Nevertheless, greater bite forces are associated with higher masticatory capacity (Lepley et al., 2010), as confirmed by the FCI results of the present study. Previous studies (Carlsson and Lindquist, 1994; Feine et al., 1994; Geertman et al., 1999; van Kampen et al., 2004) with similar methodologies also agree with these results, although they had evaluated completely edentulous patients. In contrast, Kapur (1991) revealed no difference in mastication between RDP and IFDP wearers; however, this similarity might be due to the chewing platform reduction in IFDP group. Authors pointed out that this reduction was necessary to prevent damage to the blade implants system (Kapur, 1991). In our case, mandibular prosthesis occlusion was based on the nonchanged maxillary denture, keeping the chewing platform similar in all prostheses. The increased masticatory function may be related to the drastic reduction in RPD rotational movement after implant insertion, which allowed the development of stronger jaw elevator muscles (Lepley et al., 2010), increasing the ability to comminute test material. It is important to highlight the advantages of IRDP therapy compared to IFDP in relation to the reduced cost and small amount of implants needed (de Freitas et al., 2012). Therefore, IRDP therapy properly restores masticatory function of partially edentulous patients, representing a reliable and

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Table. Masseter and Anterior Temporalis Muscle Thicknesses in Relation to Prosthesis Type, Jaw Position, and Side, mm (Mean ± Standard Deviation) Prostheses Muscle

Removable Dental

Implant-supported Removable

Implant Fixed Dental

Rest

10.3 ± 1.6a

10.3 ± 1.7a

10.6 ± 1.7a

MVC

11.8 ± 1.5a

12.5 ± 1.3b

12.8 ± 1.4b

Rest

10 ± 1.4a

10.3 ± 1.7a

10.3 ± 1.9a

MVC

11.8 ± 1.9a

12.5 ± 2b

12.9 ± 2b

Masseter Right

Left

Anterior temporal Right Rest

3.2 ± 0.8a

3.3 ± 0.7a

3.4 ± 0.7a

MVC

4.2 ± 0.9

a

4.3 ± 0.9

4.3 ± 1a

Rest

3.2 ± 0.7a

3.2 ± 0.7a

3.3 ± 1a

MVC

4.1 ± 0.8

4.2 ± 0.7

4.2 ± 0.8a

a

Left a

a

MVC = maximum voluntary clenching. a,bDifferent letters indicate significant differences among treatments. Repeated measures analysis of variance, Tukey honestly significant difference, p < .05.

more affordable treatment to be offered in the clinical routine. MBF is considered a key factor of masticatory function (Muller et al., 2012), and masseter muscle thickness was shown to be a major contributing factor of bite force (Raadsheer et al., 1999). Furthermore, periodontal mechanoreceptors play a key role in masticatory force control during food chewing (Trulsson, 2006; Abt et al., 2012), revealing the importance of tooth maintenance. In the present study, the effects of the implant therapy were clearly observed in both MBF and masseter muscle thickness during clenching. Similar muscle changes were observed by a previous study (Bhoyar et al., 2012) after 3-month use of new complete dentures. In addition, Tsai et al. (2012) described that the constant intake of soft food could result in masticatory muscle atrophy (Bhoyar et al., 2012; Muller et al., 2012). Thus, it could be suggested that the enlarged masseter muscle thickness may be related to the higher intake of chewy food, which requires a more vigorous action of the masticatory muscles, explaining the mas-

seter thickness changes. Despite the differences in masseter muscle thickness during MVC, no change in muscle thickness at rest was observed, which was predictable given the short duration of each treatment. Future studies with longterm follow-up are needed to evaluate changes in masticatory muscles over time. Although our data show a dramatic masticatory improvement after implant insertion, special attention must be given to the relatively small sample and short follow-up period. Based on the statistical estimation, it seems unlikely that increasing sample size would change the results. Nevertheless, a paired experimental design was used avoiding bias, since each subject acts as one’s own control. The short-term follow-up allowed the analysis of different treatments in the same subject without drawbacks. In addition, measurements were performed only after the complete adaptation of subjects to each prosthetic treatment, when no more chewing complaints were reported. Mastication can be evaluated by objective and subjective methods (Gotfredsen and Walls, 2007; van der Bilt, 2011). In

this study, only objective parameters of mastication were evaluated because subjective chewing assessment is, in general, too optimistic because of the great variability in tooth loss adaptation (Gotfredsen and Walls, 2007; van der Bilt, 2011). Therefore, the single-sieve method was selected because it is a convenient and reliable method to evaluate the capacity of food comminution (van der Bilt, 2011). Our data show the real impact of different prosthetic treatments on mastication in partially edentulous patients. However, future investigations should determine the consequences of masticatory improvement on nutritional intake, swallowing threshold, chewing ability, and quality of life. Conclusions The IRDPs and IFDPs significantly increased MBF and FCI, with the magnitude of the masticatory improvements closely related to prosthesis type. The use of implants also increased masseter muscle thickness during contraction. 193S

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Acknowledgments This study was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico and Fundação de Amparo a Pesquisa do Estado de São Paulo (grant 2010/12251-0), Brazil. The authors declare no conflicts of interest with respect to the authorship and/or publication of this article. References Abt E, Carr AB, Worthington HV (2012). Interventions for replacing missing teeth: partially absent dentition. Cochrane Database Syst Rev 2:CD003814. Bhoyar PS, Godbole SR, Thombare RU, Pakhan AJ (2012). Effect of complete edentulism on masseter muscle thickness and changes after complete denture rehabilitation: an ultrasonographic study. J Investig Clin Dent 3:45-50. Blanes RJ, Bernard JP, Blanes ZM, Belser UC (2007). A 10-year prospective study of ITI dental implants placed in the posterior region: I. Clinical and radiographic results. Clin Oral Implants Res 18:699-706. Carlsson GE, Lindquist LW (1994). Ten-year longitudinal study of masticatory function in edentulous patients treated with fixed complete dentures on osseointegrated implants. Int J Prosthodont 7:448-453. Castelo PM, Gaviao MB, Pereira LJ, Bonjardim LR (2010). Evaluation of changes in muscle thickness, bite force and facial asymmetry during early treatment of functional posterior crossbite. J Clin Pediatr Dent 34:369-374. Dahlberg G (1940). Statistical methods for medical and biological students. New York, NY: Interscience Publications. de Freitas RF, de Carvalho Dias K, da Fonte Porto Carreiro A, Barbosa GA, Ferreira MA (2012). Mandibular implant-supported removable partial denture with distal extension: a systematic review. J Oral Rehabil 39:791-798. Emshoff R, Emshoff I, Rudisch A, Bertram S (2003). Reliability and temporal variation of masseter muscle thickness measurements

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utilizing ultrasonography. J Oral Rehabil 30:1168-1172. Feine JS, Maskawi K, de Grandmont P, Donohue WB, Tanguay R, Lund JP (1994). Withinsubject comparisons of implant-supported mandibular prostheses: evaluation of masticatory function. J Dent Res 73:1646-1656. Fernandes CP, Glantz PO, Svensson SA, Bergmark A (2003). A novel sensor for bite force determinations. Dent Mater 19:118-126. Fueki K, Igarashi Y, Maeda Y, Baba K, Koyano K, Akagawa Y, et al. (2011). Factors related to prosthetic restoration in patients with shortened dental arches: a multicentre study. J Oral Rehabil 38:525-532. Geertman ME, Slagter AP, van’t Hof MA, van Waas MA, Kalk W (1999). Masticatory performance and chewing experience with implant-retained mandibular overdentures. J Oral Rehabil 26:7-13. Georgiakaki I, Tortopidis D, Garefis P, Kiliaridis S (2007). Ultrasonographic thickness and electromyographic activity of masseter muscle of human females. J Oral Rehabil 34:121-128. Goshima K, Lexner MO, Thomsen CE, Miura H, Gotfredsen K, Bakke M (2010). Functional aspects of treatment with implant-supported single crowns: a quality control study in subjects with tooth agenesis. Clin Oral Implants Res 21:108-114. Gotfredsen K, Walls AW (2007). What dentition assures oral function? Clin Oral Implants Res 18(suppl 3):34-45. (Published erratum in Clin Oral Implants Res 19:326-328, 2008.) Kapur KK (1991). Veterans Administration Cooperative Dental Implant Study: comparisons between fixed partial dentures supported by blade-vent implants and removable partial dentures. Part III: comparisons of masticatory scores between two treatment modalities. J Prosthet Dent 65:272-283.

Miyaura K, Morita M, Matsuka Y, Yamashita A, Watanabe T (2000). Rehabilitation of biting abilities in patients with different types of dental prostheses. J Oral Rehabil 27:1073-1076. Muller F, Hernandez M, Grütter L, Aracil-Kessler L, Weingart D, Schimmel M (2012). Masseter muscle thickness, chewing efficiency and bite force in edentulous patients with fixed and removable implant-supported prostheses: a cross-sectional multicenter study. Clin Oral Implants Res 23:144-150. Ohara Y, Hirano H, Watanabe Y, Edahiro A, Sato E, Shinkai S, et al. (2013). Masseter muscle tension and chewing ability in older persons. Geriatr Gerontol Int 13:372-377. Pocztaruk Rde L, Frasca LC, Rivaldo EG, Fernandes Ede L, Gavião MB (2008). Protocol for production of a chewable material for masticatory function tests (Optocal–Brazilian version). Braz Oral Res 22:305-310. Raadsheer MC, van Eijden TM, van Ginkel FC, Prahl-Andersen B (1999). Contribution of jaw muscle size and craniofacial morphology to human bite force magnitude. J Dent Res 78:31-42. Trulsson M (2006). Sensory-motor function of human periodontal mechanoreceptors. J Oral Rehabil 33:262-273. Tsai CY, Lin YC, Su B, Yang LY, Chiu WC (2012). Masseter muscle fibre changes following reduction of masticatory function. Int J Oral Maxillofac Surg 41:394-399. van der Bilt A (2011). Assessment of mastication with implications for oral rehabilitation: a review. J Oral Rehabil 38:754-780. van der Bilt A, Fontijn-Tekamp FA (2004). Comparison of single and multiple sieve methods for the determination of masticatory performance. Arch Oral Biol 49:193-198.

Lepley C, Throckmorton G, Parker S, Buschang PH (2010). Masticatory performance and chewing cycle kinematics: are they related? Angle Orthod 80:295-301.

van der Bilt A, Engelen L, Pereira LJ, van der Glas HW, Abbink JH (2006). Oral physiology and mastication. Physiol Behav 89: 22-27.

Liedberg B, Norlen P, Owall B, Stoltze K (2004). Masticatory and nutritional aspects on fixed and removable partial dentures. Clin Oral Investig 8:11-17.

van Kampen FM, van der Bilt A, Cune MS, Fontijn-Tekamp FA, Bosman F (2004). Masticatory function with implant-supported overdentures. J Dent Res 83:708-711.

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THIS ARTICLE WITH COMPLIMENTS FROM

With Compliments TEL: 012 460 9991 505 Charles Street MENLO PARK 0102

Tel: 012 460 9991 Fax: 012 460 9993 e-mail : nico@dtm.co.za

TAX SEASON OPENED ON 1 JULY: HERE’S WHAT YOU NEED TO KNOW, AND DO “Giving money and power to government is like   

giving whiskey and car keys to teenage boys” (P.J. O’Rourke)

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Once again tax season has opened for individuals, and whilst we can chuckle at jokes about the pain of   paying taxes, they remain of   course an integral part of life. July 2017

Tax Season Opened On 1 July: Here’s What You Need to Know, and Do

By now you should have already gathered all your supporting documentation. This is an important task as not getting your tax 100% correct canOPENED lead ON to1queries and audits from SARS, which is clearly something TAX SEASON JULY: HERE’S WHAT YOU NEED TO KNOW, AND DO Documentation to avoid. Whilst you won’t have to submit this with your tax return, you need to keep it available, for five “Giving money  and  power  to  government  is  like you will need is giving  whiskey  and  car  keys  to  teenage  boys” … years, in case SARS asks for it. Once an audit is open or if you must prove the item you need to retain Do you have to (P.J. O'Rourke) submit a tax documents for longer. return? Submission deadlines

Once again tax season has opened for individuals, and whilst we can chuckle at jokes about the pain of paying taxes, they remain of course an integral part of life.

However, if you are going to do your return at a SARS branch, then bring all your documentation and your Your Suppliers! By now you should have already gathered all your I.D. with you.Vet Good Stakeholder supporting documentation. This is an important task as not Relationships Will Boost Your Profits

getting your tax 100% correct can lead to queries and audits from SARS, which is clearly something to avoid. Whilst you won’t have to submit this with your tax return, you need to keep it available, for five years, in case SARS asks for it. Once an audit is open or if you must prove the item you need to retain documents for longer.

Documentation How to ensure you will need is … you get high quality suppliers  Getting the most out of suppliers

However, if you are going to do your return at a SARS branch, then bring all your documentation and your

I.D. with you. Your IRP5. If you changed jobs during the year, you will have at least one other IRP 5. If you get any retirement funding, the Documentation you will need is … relevant institution will send you an IRP 3 (a).

andinvestment income IRP 3 (b) Directors for any received. any retirement funding, the relevant institution will send you an IRP 3 (a). Shareholders:

Companies Medical Forget certifi cates from your medical aid plus any medical expenses incurred not covered by Act Compliance Medical certificates from your medical aid plus any medical expenses incurred not covered by Requirements medical aid. medical aid.

A logbook if you receive a car allowance.

Any retirement funding certificates received.

Any other documentation that will affect your return e.g. if you had a capital gain or loss during the tax year.

Your IRP5. If you changed jobs during the year, you will have at least one other IRP 5. If you get

There’s Hope If You

IRP 3 (b) for any investment income received.

Check that the tax certificates you receive are correct and if you find an error, go back to whoever sent you the documentation and get them to issue a corrected certificate. SARS populate your tax return with information received from third parties (IRP5, IRP 3 etc) and the only way to change the populated data on your tax return is to get the tax certificates re-issued. This can be a very cumbersome process.

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A logbook if you receive a car allowance. unanimous onsent” rectify Any retirement funding certificates received. onompliance? Any other documentation that will affect your return e.g. if you had a capital gain or loss during the What the SCA tax year. aid  Do you have to submit a tax return?

Check that the tax certificates you receive are correct and if you find an error, go back to whoever sent you the documentation and get them to issue a corrected certificate. SARS populate your tax return with u Pay TaxIfon you earn R350,000 orreceived less - from third parties (IRP5, IRP 3 etc) and the only way to change the populated data information on your tax return is to get the tax certificates re-issued. This can be a very cumbersome process. tions?

From a single employer,

Do you have to submit a tax return? ain • You have no other tax deductions, such as a car allowance or retirement funding, ogy: New If you earn R350,000 or less l in Financial • You earn less than R23,800 in interest from South Africa (if you are less than 65 years old) or From(if a single employer, R34,500 in interest you are 65 or over),

Will this be • ood for us?  

You have with no other tax deductions, such as a car allowance or retirement funding, You are a non-resident only exempt dividend income. You earn less than R23,800 in interest from South Africa (if you are less than 65 years old) or

in interest (if you are 65 or over), Then you are one ofR34,500 the lucky people who don’t need to complete a tax return. There are a couple of ews Again: ry Audit exceptions here, so if in doubt speak to your accountant. If you submit a return where you were not You are a non-resident with only exempt dividend income. ation required to, this may, due to the SARS systems, lead to an automatic imposition of penalties and this may you are one of the lucky people who don’t need to complete a tax return. There are a couple of in turn lead toThen unnecessary disputes with SARS. exceptions here, so if in doubt speak to your accountant. If you submit a return where you were not

x Deadlines

required to, this may, due to the SARS systems, lead to an automatic imposition of penalties and this may

in turn to unnecessary disputes with SARS. submit a tax return anyway. Of course if you arelead due a refund, then you should Of course if you are due a refund, then you should submit a tax return anyway.

Submission deadlines

Submission deadlines

Important dates to file your tax returns for the 2016/2017 tax year are as per the table below. Important dates to file your tax returns for the 2016/2017 tax year are as per the table below.

Be honest when compiling your return. Check that everything is correct and accurate. Finally, be alert to

the scammers out your there who always seem to target SARS relatedistransactions. Be honest when compiling return. Check that everything correct and accurate. Finally, be alert to the scammers out there who always seem to target SARS related transactions.

VET YOUR SUPPLIERS! GOOD STAKEHOLDER RELATIONSHIPS WILL BOOST YOUR PROFITS Suppliers play a strategic role in your business because if they fail to deliver on time or with the required quality, they can cause delays in your organisation. These delays will inevitably have a knock-on effect to your customers.

How to ensure you get high quality suppliers Best practice dictates that vetting procedures are in place that cover, at least: A review of the supplier’s financials to establish that the business has the financial means to remain sustainable and to deliver to its customers.

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QUESTIONNAIRE Split Cast Mounting: Review and New Technique

1.5

Question 1: Which material offers a easier and hygienic method to secure the master cast to the sandwich and upper member of the articulator? A) Sticky wax B) Adhesive bandage C) Plaster D) Masking tape Question 2: The â&#x20AC;&#x153;split castâ&#x20AC;? is a mandibular cast constructed in two parts with a horizontal division. A) True B) False Question 3: Of the following, what does the split-cast mounting procedure allow for? A) Verification of the eccentric jaw relation record B) To program the articulator by means of centric records C) Ease of removal and replacement of casts Question 4: Using a _____, the combined primary and secondary base cast are mounted on the upper member of the articulator. A) Wax bite registration B) Putty matrix C) Facebow Question 5: Which illustration represents the cheaper and simpler technique to stabilize the split mounting? A) Figure. 3 B) Figure. 1 C) Figure. 4 D) Figure. 7

Occupational Concerns Associated with Regular Use of Microscope Question 6: How many professionals and technicians were involved in this survey? A) 30 B) 45 C) 50 D) 100

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2.8


Question 7: One of the more unexplored areas of occupational hazards with regular microscope use is? A) Anxiety B) Fatigue C) Eye Strain D) Visual discomfort Question 8: Did 37 people answer â&#x20AC;&#x153;yesâ&#x20AC;? when asked whether they were satisfied with the comfort levels of the workplace/microscope? A) Yes B) No Question 9: Which part of the body is mostly associated with musculosceletal problems? A) Shoulder B) Back C) Wrist D) Neck Question 10: Prevalence of musculoskeletal problems was found in maximum numbers in those using the microscope for _____ years. A) 1-5 B) 6-10 C) 11-15 D) 16-20 Question 11: CDC guidelines for microscope use do not allow the microscope users to work for more than six hours per a day. A) True B) False Question 12: Awareness about workplace ergonomics and CDC guidelines were ______. A) Poor B) Adequate C) Above average D) Excellent

Ceramic Veneers With Minimal Preparation

1.6

Question 13: The idea of minimally invasive dental restorations is essential for successful restorations. A) True B) False

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Question 14: The laminate veneers in this study were fabricated from which of the following materials? A) Zirconia B) Porcelain C) Lithium Disilicate Question 15: The long lasting esthetics and little underlying dental structure were not the main reasons for choosing minimally invasive veneers. A) True B) False Question 16: Dental bleaching may be considered a safe treatment? A) True B) False Question 17: The ____ layer attached to the laminated veneers is considered to be hydrolytically stable. A) Outer B) Inner

Mastication Improvement After Partial Implant-supported Prosthesis Use Question 18: Each patient received a new complete maxillary denture while a sequence of _____ mandibular treatments were preformed. A) 2 B) 3 C) 5 D) 7 Question 19: Within the experimental design, which of the following was measured? A) Masticatory force B) FCC C) MBF Question 20: How many implants did each subject receive during treatment? A) 2 B) 3 C) 4 D) 1

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Question 21: Reproducibility of the MBF method was verified in 8 subjects chosen at random. A) True B) False Question 22: MBF was significantly higher with which type of prosthesis? A) Implant supported removable dental prosthesis B) Removable dental prosthesis C) Implant fixed dental prosthesis Question 23: The use of implants increased masseter muscle thickness during contraction. A) True B) False

Tax Season Opened on 1 July: Hereâ&#x20AC;&#x2122;s What You Need To Know, And Do

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Question 24: Should you by now have gathered all your supporting documentation? A) Yes B) No Question 25: If you get any retirement funding, the relevant institution will send you at least one other IRP5. A) True B) False Question 26: Of the following which correct supporting documentation is required by SARS? A) IRP3(a) for any investment income received B) Medical expenses covered by medical aid C) Any retirement funding certificates received Question 27: Other documentation to be included that will affect your return e.g. if you had a capital gain or loss during the tax year. A) True B) False Question 28: Do you have to submit a tax return if you earn more than R350 000 a year? A) Yes B) No

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Question 29: Will you have to submit a tax return if you earn less than R23 800 in interest from South Africa? A) Yes B) No Question 30: Submitting a tax return when not required can lead to an automatic imposition of penalties and disputes with SARS. A) True B) False

9.9

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THE DENTAL WAREHOUSE & VITA IN SOUTH AFRICA

Two strong partners for your needs

TOLLFREE 0800 111 796


From 1 November 2017 DENTASA is VAT registered Membership fees will ONLY increase with the added 14% VAT

1 NOVEMBER 2017 DENTASA IS NOW VAT REGISTERED

Please send your VAT number to the Office to enable us to update our records DENTASA VAT number: 4800279699

VAT

DENTASA had no choice but to register for VAT as discussed at the 2017 AGM. It was also decided that membership fees will not be increased additionally to the 14% VAT that has to be added. Please email your VAT registration number to dentasa@absamail.co.za to enable us to update all our records. We thank you for your support.

DENTASA

105 Club Avenue Waterkloof Heights Pretoria 0181 012 â&#x20AC;&#x201C; 460 1155 dentasa@absamail.co.za www.dentasa.org.za

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Find DENTASA here:

https://www.facebook.com/groups/dentasa/

@DENTASA

www.dentasa.org.za

dentasa@absamail.co.za Phone: 012-460 1155 Fax to email: 086 233 7122 Office Hours: Mon-Fri 08:00-13:00 Southern African Dental Technology Journal COPYRIGHT©

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Misty Hills Hotel & Conference Centre & Spa The Spirit of Africa! Nestled in the foothills of the Swartkop mountains on the threshold of the beautiful Kromdraai Valley in Muldersdrift, Misty Hills is one of the most popular hotel and conference venues in Gauteng. This charming stonebuilt hotel, embodies the ethos of Africa. Set in more than 60 acres of lush botanical gardens, Misty Hills is the ideal venue for the 2018 DENTASA Summit & AGM. Experience the splendour of rich African hospitality in the heart of Gauteng. Each of the 195 stone-built thatched rooms and suites is furnished to complement the indigenous South African surroundings and lavishly decorated with brightly coloured African fabrics, artworks and handmade furniture. The property boasts the world-famous Carnivore Restaurant; a truly authentic African dining experience where diners can feast on a sumptuous variety of game and domestic meats in a uniquely African style.

The Spirit of Africa! We are looking at hosting an exciting and fun weekend for the DENTASA members and not just a Summit & AGM and lectures for CPD credits. As it is a hotel not close to any places to go, we are hoping that most delegates will stay at Misty Hills and enjoy the whole weekend and all it has to offer, with us. A weekend where we show our loyalty to all our members and create an even better vibe to carry us all together as an Association in unity towards the future. We have secured one of the restaurants to host our “After Party” on Friday evening after the Trader’s Cocktail function, which will be turned into a cash bar. All delegates will be in the same location and with a little bit of live music, who knows which Animal the Spirit of Africa will bring out in each of us…. On Saturday evening we have a mass invasion into the fantastic Carnivore restaurant. It offers a true taste of the Spirit of Africa, with meats cut onto your plate from a Masaai spear unimaginable in other parts of the world. (Crocodile, Zebra, kudu, and your non-exciting ones like beef chicken and lamb). As we will have the closed-up terrace to ourselves, we can secure some form of entertainment as well. We are looking forward to change things around a little and bring excitement into the best annual event in the whole of the dental profession!

Sadtj Volume 7 Issue 1  

Southern African Dental Journal Volume 7 Issue 1

Sadtj Volume 7 Issue 1  

Southern African Dental Journal Volume 7 Issue 1

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