SADTJ Volume 6 Issue 2 by SADTJ

November 2016 • Vol 6 Issue 2 • Communication methods and production techniques in ﬁxed prosthesis fabrication: a UK based survey. Part 1: Communication methods • Inlay-Retained Fixed Dental Prosthesis: A Clinical Option Using Monolithic Zirconia • A comparison of masticatory performance and efﬁciency of complete dentures made with High Impact and Flexible Resins: A Pilot study • Reactive dentures: a novel approach to decrease residual ridge resorption

SADTJ

ISSN 2077-2793

The Southern African Dental Technology Journal

6 UNIT ZIRCONIA FRAMEWORK ON TI-BASE. LABIAL CUTBACK AND LAYERED WITH GC LISI. STAIN AND GLAZE WITH GC LUSTRE PASTES. DONE BY JOHAN RAS, COMPODENT DENTAL LABORATORY

CEU 10

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you oﬀ, you will receive constructive criticism and suggestions on how to improve your writing, should your article not be published the first time round.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 6 Issue 2

In This Issue SADTJ Vol 6 Issue 1 March 2016

Editor

Axel Grabowski

Managing Editor Mariaan Roets

PUBLISHED BY

The Dental Technicians Association of South Africa

LAYOUT AND DESIGN Nicola van Rensburg

ADVERTISING ENQUIRIES m.roets@dentiworks.com

ADDRESS CHANGES

Elize Morris: dentasa@absamail.co.za

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

Communication methods and production techniques in ﬁxed prosthesis fabrication: a UK based survey. Part 1: Communication methods Vol 6 Issue 2.

Inlay-Retained Fixed Dental Prosthesis: A Clinical Option Using Monolithic Zirconia Vol 6 Issue 2.

A comparison of masticatory performance and efﬁciency of complete dentures made with High Impact and Flexible Resins: A Pilot study Vol 6 Issue 2.

Reactive dentures: a novel approach to decrease residual ridge resorption Vol 6 Issue 2.

DENTASA

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

Characterization of different water/powder ratios of dental gypsum using ﬁber Bragg grating sensors Vol 6 Issue 2.

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

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

SADTJ Vol 6 Issue 2

Editorâ&#x20AC;&#x2122;s Page As we all know, Mariaan took over as Managing Editor of the SADTJ. Two issues later, and true to her character, has not only found her feet, but has perfected the art of editing. Well done Mariaan, may you long continue. As all registered dental technicians are now eligible to acquire CPD credits through the SADTJ, this is a huge opportunity for Traders to advertise their wares. Please feel free to contact Mariaan for further information. I am happy to announce that the Western Cape has a new Branch Chairman. Welcome to Damien Storey, may your term be fruitful and long lasting. This will also take a load of our President, Michael Lazarevic, who was both Branch Chair and President. We sadly had to say farewell to Wicus Kruger, Branch Chair of North Gauteng. Wicus has moved to Windhoek, and we wish him well and thank him for the service he gave the association. Gerhard Combrink was elected to take over from Wicus, and we welcome Gerhard in his new position. As I reported at the AGM, the South Gauteng Branch still has no Branch Chair, which is very concerning. We are however very close to fill this vacancy. It is with sadness that we learnt of the unexpected passing of Robert Ho Tong on the 17/08/2016. The Editorial staff of the SADTJ, the DENTASA Executive and all colleagues send our sincere condolences to his family. The loss to the family and the Dental Technology family is huge. R.I.P Robert. May you all find this Edition of the SADTJ of great value and interest Editorially yours Axel

SADTJ Vol 6 Issue 2

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SADTJ Vol 6 Issue 2

OPEN This is an open access article

Communication methods and production techniques in fixed prosthesis fabrication: a UK based survey. Part 1: Communication methods

IN BRIEF

•

RESEARCH

•

Highlights the importance of dentisttechnician communication. Concludes that dentists must ensure that written prescriptions contain all the necessary information so that the dental technician can fabricate fixed prostheses correctly and without delay. Recommendations for improved communication are made with the ultimate goal of better patient service.

J. Berry,1 M. Nesbit,2 S. Saberi2 and H. Petridis*3

Statement of the problem The General Dental Council (GDC) states that members of the dental team have to ‘communicate clearly and effectively with other team members and colleagues in the interest of patients’. A number of studies from different parts of the world have highlighted problems and confirmed the need for improved communication methods and production techniques between dentists and dental technicians. Aim The aim of this study was to identify the communication methods and production techniques used by dentists and dental technicians for the fabrication of fixed prostheses within the UK from the dental technicians’ perspective. The current publication reports on the communication methods. Materials and methods Seven hundred and eighty-two online questionnaires were distributed to the Dental Laboratories Association membership and included a broad range of topics. Statistical analysis was undertaken to test the influence of various demographic variables. Results The number of completed responses totalled 248 (32% response rate). The laboratory prescription and the telephone were the main communication tools used. Statistical analysis of the results showed that a greater number of communication methods were used by large laboratories. Frequently missing items from the laboratory prescription were the shade and the date required. The majority of respondents (73%) stated that a single shade was selected in over half of cases. Sixty-eight percent replied that the dentist allowed sufficient laboratory time. Twentysix percent of laboratories felt either rarely involved or not involved at all as part of the dental team. Conclusion This study suggests that there are continuing communication and teamwork issues between dentists and dental laboratories.

INTRODUCTION Prosthodontics is a discipline that requires a synergy between the dentist and dental technician in order to fabricate intraoral prostheses with acceptable fit, function and aesthetics.1–3 Proper communication between the two parties is very important because, in the majority of cases, the dental technicians are remotely located and usually never actually see the patient. The General Dental Council’s (GDC) policy document Principles of dental team working4 states that: ‘Members of the dental team will work effectively together’, 1 Clinical Lecturer, Department of Adult Oral Health, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London; 2Senior Technical Instructor, Prosthodontic Unit, UCL Eastman Dental Institute, London; 3Senior Lecturer, Department of Restorative Dentistry, Prosthodontics Unit, UCL Eastman Dental Institute, London *Correspondence to: Dr Haralampos (Lambis) Petridis Email: c.petridis@ucl.ac.uk

Online article number E12 Refereed Paper - accepted 19 June 2014 DOI: 10.1038/sj.bdj.2014.643 © British Dental Journal 2014; 217: E12

and also that members have to ‘communicate clearly and effectively with other team members and colleagues in the interest of patients’, and that ‘if you ask a colleague to provide treatment, a dental appliance or clinical advice for a patient, make sure that your request is clear and that you give your colleague all the information they need’.4 The prerequisite for a proper prescription written by a qualified dentist has also been set in the Medical Devices Directive (MDD).5 A number of studies6–12 from different parts of the world have highlighted problems and confirmed the need for improved communication methods and production techniques between dentists and dental technicians, during the fabrication of fixed prosthodontic appliances. Problems seem to occur even within the same hospital setting.13,14 Communication issues have included lack of information regarding the prosthesis design and materials, the lack of understanding of the necessary technical steps and time required, and lack of proper shade communication.6–12 Most of the times, the final decision was left

with the technician, without proper feedback. All of the above issues, compounded by the time pressure for completion of the restorations as noted in some studies,8,11 may explain the finding that many dental technicians feel insufficiently valued in the dental team.11,12,15 A number of studies1,12,14,16 have highlighted the lack of suitable instruction to dental undergraduates regarding effective communication between dentists and technicians, and the lack of knowledge regarding dental prosthesis fabrication at the time of qualification as the main factors for the re-occurring problems. This has led to the introduction of inter-professional education schemes in Australia.17 The last survey of UK-based dental laboratories was published in 2009,12 and suggested that the GDC had failed in its aims published in The first five years; a framework for undergraduate dental education,18 as serious communications issues were identified.12 The purpose of this cross-sectional study was to identify the communication

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RESEARCH methods and production techniques used by dentists and dental technicians for the fabrication of fixed prostheses within the UK from the dental technicians’ perspective. The current publication reports on the communication methods.

MATERIALS AND METHODS A questionnaire was constructed to investigate communication methods and production techniques used between dentists and dental laboratories from the laboratories perspective. An effort was made to include a broad range of topics. At the same time elements of previously published research were incorporated in order to obtain meaningful results that would be comparable to past surveys. The final questionnaire consisted of 30 questions within the following subcategories: general information, communication methods, impression disinfection and suitability, production techniques, shade matching, and time and team management issues. The questionnaire was piloted among dental technicians both at UCL Eastman Dental Institute and in selected commercial laboratories. The Dental Laboratories Association (DLA, Nottingham, UK) was approached and approved the use of their database of e-mail contacts (782 addresses). A web-based survey tool, Opinio (ObjectPlanet Inc. Oslo, Norway), was utilised for the administration of the survey and assimilation of data. Settings were managed in order to ensure anonymity of respondents. The questionnaire weblink along with an introduction letter, were distributed through the DLA. The survey was ‘live’ for 6 weeks, and during that time the response rate was actively monitored and three e-mail reminders were sent. The collected data was presented as descriptive statistics and analysed using Fisher’s exact test, the Mann-Whitney test or the Spearman’s rank correlation (SPSS 12.0; SPSS Inc, Chicago). P-values of less than 0.025 were regarded as statistically significant. A significance level of 2.5% was chosen rather than the conventional 5% to avoid spuriously significant results arising from multiple testing. The null hypothesis was that factors such as the source of information used to answer the questionnaire, the location, and size of the dental laboratory, did not influence the communication methods and production techniques.

RESULTS The number of responses totalled 248, which yielded a 32% response rate. Sixtyeight respondents answered only some of

the questions. The results presented in this paper pertain to the subchapters of general information, communication methods, shade matching, and time and team management issues. The subchapters and questions along with the results in parentheses are depicted in Table 1. The majority of the information (81%) used to answer the survey questions were sourced from memory and 19% of respondents used their laboratory records. Ninety percent of the respondents were based in England. This unequal distribution among England, Scotland, Wales and Northern Ireland did not permit any further analysis of this particular factor. The majority of dental laboratories (73%) completed work for less than 50 dentists and 13% worked with over 100 dentists. For analysis purposes the labs were grouped into three categories regarding size: small (43% working with up to 25 dentists), medium (38% working with 26-75 dentists) and large (19% working with 76+ dentists). The results of this study showed that the laboratory prescription and the telephone were the main communication tools used between dentists and dental technicians. Digital means, whether by e-mail or photography, also played an important role (Fig. 1). Statistical analysis of the results showed that a greater number of communication methods were used by large laboratories (Table 2) and that the source of information did not play a significant role. Almost a quarter of the respondents (24%) indicated that more than half of laboratory prescriptions had an inadequate amount of information on them throughout the course of treatment and 13% had to contact the dentists for further information. The two most frequently missing items from the laboratory prescription were the shade and the date required. These results were not influenced by the size of the laboratory or the source of information, with the exception of the responses about contact with the dentist for further information (p = 0.002). This was more common in the group providing information from records, where 22% reported having to contact the dentist over half the time, compared to only 10% in the memory group. Also, mid-sized laboratories reported a greatest percentage (79%) for shade missing compared (p = 0.01) to the two other groups (60%). Some of the additional comments in this section of the questionnaire indicated that the need for further communication was time consuming, with the dentist often being difficult to contact during normal surgery hours and also stressed the fact that some prescriptions were illegible or were not fully completed but had additional comments

Table 1 Relevant subchapters of the questionnaire with answers in percentages in parentheses GENERAL INFORMATION 1. Please indicate the source of the information that you will be giving: From memory (81%) From records (19%) 2. This survey is anonymous so please indicate the country that you are based in: England (90%) Scotland (4%) Northern Ireland (1%) Wales (5%) 3. Approximately, what number of dentists do you currently work with? 1–25 (43%) 26–50 (30%) 51–75 (8%) 76–100 (6%) 100+ (13%) COMMUNICATION METHODS 4. Please select all the methods of contact used by dentists to communicate with you: Laboratory prescription (98%) Telephone (93%) Text messaging (29%) Email (73%) Digital photography (67%) Other (10%) Please add any relevant comments 5. With regards to the laboratory prescriptions for fixed restorative work, what percentages have an inadequate amount of information on them throughout the course of treatment? 0-25% (54%) 26-50% (22%) 51-75% (16%) 76-100% (8%) 6. What percentage of laboratory prescriptions do you have to contact the dentist to obtain further information? 0-25% (65%) 26-50% (22%) 51-75% (8%) 76-100% (5%) 7. Please indicate the two most common items missing from the laboratory prescription when received from the dentist. Patient’s name (6%) Shade (75%) Date required (60%) Material to be used (32%) Tooth notation (18%) Other (9%) Please add any relevant comments SHADE MATCHING 25. What percentage of the time is a single shade (for example, A3 or B2) specified for crown and bridgework? 0-25% (7%) 26-50% (20%) 51-75% (33%) 76-100% (40%) 26. What percentage of dentists would send you a photograph of the patient’s teeth with the shade tab to help you with shading? 0-25% (81%) 26-50% (10%) 51-75% (7%) 76-100% (2%) 27. What percentage of dentists would send a patient to you to do the shade matching? 0-25% (75%) 26-50% (15%) 51-75% (9%) 76-100% (1%) TIME & TEAM MANAGEMENT ISSUES 28. Do you feel that the dentist generally allows you adequate time to complete the fabrication of the crown/bridge to the best of your ability, and return it to the dental practice? Yes (68%) No (32%) Please comment 29. How involved do you feel as part of the dental team? Completely involved (22%) Partly involved (52%) Rarely involved (24%) Not involved (2%) 30. Please add any further comments that you may have on the communication between the dentist and laboratory: (63 additional comments)

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RESEARCH

Laboratory prescription Telephone Text messaging Email Digital photography Other

100

150

200

250

Number of replies Fig. 1 Bar chart showing the methods of contact used by dentists in communicating with the dental laboratory Table 2 Fisher’s exact test relating size of laboratory to communication methods used Lab size

Small (n = 106) Number (%)

Medium (n = 95) Number (%)

Large (n = 47) Number (%)

P-value

Lab prescription

87 (82%)

86 (91%)

44 (94%)

0.08

Telephone

78 (74%)

83 (87%)

44 (94%)

0.004

Text messaging

19 (18%)

26 (27%)

18 (38%)

0.02

50 (47%)

72 (76%)

40 (85%)

<0.001

Digital photography

48 (45%)

60 (63%)

40 (85%)

<0.001

written on them such as ‘see e-mail’ or ‘I will call you to discuss’ or ‘please call me’. Regarding shade selection and communication, the results of this study showed that the majority of respondents (73%) received a single shade for over half of the cases and 81% rarely (0-25% of cases) received any photographs with the patient’s teeth and shade guide. Only a minority of dental technicians (9%) reported regularly seeing patients for shade matching. Statistical analysis showed that these results were not influenced by the source of information. A statistical significance (p = 0.02) was detected between the size of lab and a single shade chosen. Large laboratories were more likely to receive instruction for a single shade. However, with regards to sending a patient to the laboratory for shade taking there was a negative correlation (p = 0.02) suggesting that larger dental laboratories were less likely to see patients for shade taking. The last section on communication pertained to time and management issues. Sixty-eight percent of technicians replied that the dentist allowed sufficient time for fabrication of the definitive prosthesis and

its return to the dental practice. The majority (74%) of dental technicians felt that they were either completely or partly involved in the dental team. However, one-quarter of the respondents (26%) felt either rarely involved or not at all. A number of respondents seized the opportunity to further comment and the following is a small selection: ‘On the whole communication has got better but I feel the laboratory must make a stand with their clients to get the best treatment for both the patient and themselves.’ ‘I have worked in dentistry now for many years and the issue of lack of communication in the dental team has been a continuing one, which never seems to be resolved.’ ‘I feel that dentists need to realise how valuable the technician’s experience and knowledge are, and include them as part of the team and not consider them as a personal servant.’ ‘Would like a bit more appreciation shown!!!!!!’ ‘By far my happiest clients with the happiest patients are the ones that communicate with the laboratory and view it as part of a team effort to achieve the right result for the patient.’

‘I feel that in general dentists think of us as an afterthought, not really appreciated. Just a thank you now and again would be nice.’ ‘The main problem occurs when it is necessary to speak to the surgeon and he is unavailable due to surgery.’ ‘Technicians should attend more lectures and courses with the dentists to appreciate the dentist’s point of view and exchange opinions and ideas.’ ‘I am a laboratory owner and communicate with dental surgeons on a frequent basis. I find my contact to be almost invariably friendly and professional.’ ‘Private clients value technical support and involvement. NHS customers just tell me they want a crown that “drops on” and is completely clear of the occlusion.’ ‘Most surgeons give plenty of time, but some only give 1 week when it arrives in the lab after 2 days in the post.’ ‘I feel that the dentists do not check their impressions.’

DISCUSSION The purpose of this cross-sectional study was to identify the communication methods and production techniques used by dentists and dental technicians for the fabrication of fixed prostheses within the UK from the dental technicians’ perspective. The current publication reports on the communication methods and team issues. The last similar UK study was published in 2009.12 The response rate was 32%, which falls into the range of other published surveys of dental laboratories.10,11,12,19 The difference with the current survey was the fact that it was administered online, in the hope to make it more appealing and easy for respondents.20,21 Nevertheless, it has been shown22 that web and postal surveys yield similar response rates if certain protocols are followed. A limitation of the current survey was the fact that no distinction was made between those laboratories providing a fully private service, a fully NHS service or a mixed arrangement. These diverse cohorts might be experiencing different communication issues and might be utilising alternative fabrication methods. Juszczyk et al.10 in their 2009 survey used the same DLA database and reported that the majority (61%) of dental laboratories reported doing a mixture of NHS and private work. A previous study6 looking at the quality and prescription of single crowns in Wales reported more problems with NHS compared to privately funded work, but no statistics were possible due to the limited sample size. The majority of the information used to answer the survey questions were sourced by memory. Most of the published surveys have

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RESEARCH not focused on this issue with the exception of Hatzikyriakos et al.11 who reported a similar finding, and a previous survey23 where it was anecdotally reported that most of the answers were sourced by financial records. The use of memory may introduce personal bias and thus affect the accuracy of the information. The dental technicians could have exaggerated the degree of lack of information and unsatisfactory work received from the dentists. Similarly their personal bias could have affected the responses on their own laboratory procedures. In this study, however, the statistical analysis showed that the method of resourcing information did not play a significant role. The results of this study showed that the main method of communication between dentists and dental laboratories is still the written prescription and telephone contact. This is in agreement with the previous UK-based survey.12 Statistical analysis of the results showed that a greater number of communication methods were used by large laboratories and this is the first time that this has been reported. This could be a reflection on the degree of knowledge on the use of different communication methods within a larger group, or the need to have multiple modes of communication because of the logistics of maintaining contact with a larger number of dentists. The results of this study showed that in approximately half of the cases the laboratory prescription was lacking important information. This reaffirms the findings of past surveys.6,9,10 The statistical analysis also revealed that the group that based their answers on records reported even higher percentages for the need to obtain further information from the dentist, compared to technicians basing their answers on memory. This implies that the problem might have been under-reported in this survey. The two most common items missing from the written prescription were the ‘shade’ and ‘date required’, which is in conflict with the results reported by Stewart13 who reported the absence of the ‘departmental clinic’ and the ‘name of the prescribing dentist’ as the most frequent omissions. Statistical analysis of the results indicated that there was no statistical association between the size of the lab and the items missing from the prescription except for shade (p = 0.01). The analysis suggested that mid-sized laboratories reported the highest percentage of missing values (79%), with the percentage only around 60% in the two other groups. Shade selection may be a quite complex and individualised procedure24 yet this survey showed that dentists regularly chose a single shade for most of the cases. The

statistical analysis also showed that this was most common with large laboratories. No other UK studies reported on this parameter. This is consistent with the findings of Jenkins et al.6 in Wales, and Hatzikyriakos et al.9 in Greece who reported that a single shade tab was chosen 50% of the time. A useful adjunct to the written prescription would be a photograph of the tooth in question, ideally with the shade tab placed adjacent to it,14,19,24 but the extent of use has not been previously reported. This simple accessory measure, however, was only occasionally used according to the responses in this survey. If the dentist is not confident in shade matching, and is not prepared to use other measures such as photographs, an alternative solution would be to send the patient to the dental laboratory.7,24 Alternatively, some dentists arrange for the technician to visit the practice and meet the patient. However, the results showed that this method of communication was not a popular one. Statistical analysis showed that technicians working in large laboratories were less likely to see patients for shade taking (p = 0.02). No other comparable research data was sourced on the frequency of dental technician shade taking in the UK. However, in a study conducted in Greece11 almost 30% of shade selection was undertaken by the dental technicians. A possible explanation of the different results might be that the dental laboratory is not conveniently accessible for the patient, which further strengthens to use of photography as an aid to shade matching. Nowadays, many dentists within the UK use a postal service to send the impressions/casts to dental laboratories some distance from the practice. The vast majority (68%) of the dental laboratories felt that the dentist did allow them adequate time to complete the fabrication of the crown or bridge to the best of their ability and to return it back to the dental practice. This is in contrast with two previous studies in Greece11 and Ireland,8 which reported that the majority of dental technicians thought that they were pressured for time. Undergraduate training rarely involves the student undertaking any fixed prosthetic laboratory procedures and as a result the dentist may fail to understand the complexities of manufacture and especially the time required. The UK study by Juszczyk et al.12 reported that ‘54% of dental technicians working in a commercial laboratory did feel an integral part of the dental team’. In this survey 22% felt completely involved, the majority of 52% feeling partly involved. The questionnaire allowed the dental laboratory to pass on any additional comments on the survey

title. In general the comments indicated that communication methods have improved but there are still many unresolved issues. A number of papers1,14,25 have recommended that dental school curricula should reinforce the teaching of both the technical stages of laboratory fabrication as well as proper dentist-technician communication in order to ensure high quality team working later on. This has been recognised at Griffith University in Australia17 with the introduction of formalised inter-professional education between students of dentistry, dental technology, dental therapists and hygienists. The adoption of similar changes in the curricula of UK dental schools would be recommended. One more way of strengthening communication may be through organising more continuous professional development courses with participation from both parties encouraged.

CONCLUSIONS Within the limitations of this UK-based study, the following conclusions could be drawn: 1. The main methods of communication between the dentists and dental laboratories are written prescriptions and telephone contact. Newer technologies such as digital photography and e-mail are playing an increasing role 2. The number of communication methods used by laboratories is directly related to their size 3. The laboratory prescriptions often lack important information, such as shade. When shade was prescribed, it was usually a single tab 4. Dental laboratories were, in the main, content with the time allocated for the prescribed work to be fabricated 5. The majority of dental laboratories felt that they were part of the dental team, but there were still some elements of dissatisfaction that need to be improved upon. The authors acknowledge the Dental Laboratories Association for their valuable assistance in carrying out this survey and Dr Aviva Petrie for her advice regarding the statistical analysis. The authors declare that they have no conflict of interest with respect to the submitted work. 1. 2.

4. 5.

Christensen G J. A needed remarriage: dentistry and dental technology. J Am Dent Assoc 1995; 126: 116–117. Malament, K A, Pietrobon N, Nesser S. The interdisciplinary relationship between prosthodontics and dental technology. Int J Prosthodont 1996; 9: 341–354. Davenport J C, Basker R M, Heath J R, Ralph J P, Glantz P O, Hammond P. Communication between the dentist and the dental technician. Br Dent J 2000; 189: 471–474. General Dental Council. Principles of dental team working 2013. London: General Dental Council, 2013. Council of the European Communities. The medical

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RESEARCH devices directive. Council of the European Communities, 1993. 6. Jenkins S J, Lynch C D, Sloan A J, Gilmour A S. Quality of prescription and fabrication of single-unit crowns by general dental practitioners in Wales. J Oral Rehabil 2009; 36: 150–156. 7. Aquilino S A, Taylor T D. Prosthodontic laboratory and curriculum survey. Part III: Fixed prosthodontic laboratory survey. J Prosthet Dent 1984; 52: 879–885. 8. Leith R, Lowry L, O’Sullivan M. Communication between dentists and laboratory technicians. J Irish Dent Assoc 2000; 46: 5–10. 9. Lynch C D, Allen P F. Quality of communication between dental practitioners and dental technicians for fixed prosthodontics in Ireland. J Oral Rehabil 2005; 32: 901–905. 10. Afsharzand Z, Rashedi B, Petropoulos V C. Communication between the dental laboratory technician and dentist: work authorization for fixed partial dentures. J Prosthodont 2006; 15: 123–128. 11. Hatzikyriakos A, Petridis H P, Tsiggos N, Sakelariou S. Considerations for services from dental technicians in fabrication of fixed prostheses: A survey

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of commercial dental laboratories in Thessaloniki, Greece. J Prosthet Dent 2006; 96: 362–366. Juszczyk A S, Clark R K, Radford DR. UK dental laboratory technicians’ views on the efficacy and teaching of clinical-laboratory communication. Br Dent J 2009; 206: 532–533. Stewart C A. An audit of dental prescriptions between clinics and dental laboratories. Br Dent J 2011; 211: E5. Dickie J, Shearer A C, Ricketts D N. Audit to assess the quality of communication between operators and technicians in a fixed prosthodontic laboratory: educational and training implications. Eur J Dent Educ 2014; 18: 7–14. Bower E J, Newton P D, Gibbons D E, Newton J T. A national survey of dental technicians: career development, professional status and job satisfaction. Br Dent J 2004; 197: 144–148. Clark R K. The future of teaching of complete denture construction to undergraduates. Br Dent J 2002; 193: 13–14. Evans J, Henderson A, Johnson N. The future of education and training in dental technology: designing

18. 19. 20. 21. 22. 23. 24. 25.

a dental curriculum that facilitates teamwork across the oral health professions. Br Dent J 2010; 208: 227–230. General Dental Council. The first five years. 3rd ed. London: GDC, 2013. Rath C, Sharpling B, Millar B J. Survey of the provision of crowns by dentists in Ireland. J Irish Dent Assoc 2010; 56: 178–185. Couper M. Web surveys: a review of issues and approaches. Public Opin Q 2000; 64: 464–494. Sills S J, Song C. Innovations in survey research: an application of web surveys. Soc Sci Comput Rev 2002; 20: 22–30. Kaplowitz M D, Hadlock T D, Levine R. A Comparison of web and mail survey response rates. Public Opin Q 2004; 68: 94–101. MacEntee M I, Belser U C. Fixed restorations produced by commercial dental laboratories in Vancouver and Geneva. J Oral Rehabil 1988; 15: 301–305. Small B W. Shade selection for restorative dentistry. Gen Dent 2006; 54: 166–167. Barret P A, Murphy W M. Dental technician education and training-a survey. Br Dent J 1999; 18: 85–88.

COMMUNICATION METHODS AND PRODUCTION TECHNIQUES IN FIXED PROSTHESIS FABRICATION: A UK BASED SURVEY. PART 1: COMMUNICATION METHODS Question 1 What was the most frequent item missing from the lab slip? A Shade and Patient name B Time and Dentist name C Date required and Patients name D Shade and Date required Question 2 What is the percentage of respondents that used laboratory records to answer the survey? A 81% B 19% C 25% D 60% Question 3 What size laboratory communicates the most telephonically? A Medium B Small C Large Question 4 True or False that the web based survey yield better results as the postal survey. True or False This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/

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Question 5 How involved do most Technicians feel as part of the dental team A 22% B 24% C 2% D 52% Question 6 What was the significance level chosen for the testing? A 3% B 2.5% C 5% D 4%

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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 CEUâ&#x20AC;&#x2122;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 â&#x20AC;&#x201C; 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

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http://dx.doi.org/10.1155/2014/629786 Department of Medicine and Surgery, University of Salerno, Salerno, Italy

Case Correspondence Report should be addressed to Gabriele Augusti; g.augusti@libero.it Received 21 February 2014; Accepted 5 May 2014; Published 21 May 2014 Inlay-Retained Fixed Dental Prosthesis: A Clinical Option Using Academic Editor: Mine D¨undar Case Report Zirconia Monolithic Copyright © 2014 Davide Augusti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, the original work is properly cited. Inlay-Retained Fixed Dental Prosthesis: A provided Clinical Option Using 1 3 Different restorations to replace a single 1missing toothBorgonovo, in the posterior2 region are available in dentistry: traditional Monolithic Zirconia Davideindirect Augusti, Gabriele Augusti, Andrea Massimo Amato, and Dino Re1full-

coverage fixed dental prostheses (FDPs), implant-supported crowns (ISC), and inlay-retained FDPs (IRFDP). Resin bonded FDPs 1 represent a minimally invasive procedure; preexisting fillings can minimize tooth structure removal Department of Oral Rehabilitation, Istituto Stomatologico Italiano, University of Milan, Milan, Italyand give retention to the IRFDP, 2 transforming it Oral into an ultraconservative New high strength zirconia ceramics, withCa’ their stiffness and high Department of Surgery, Dental Clinic,option. Ospedale maggiore Policlinico, Fondazione IRCCS Granda, Milan, Italy mechanical 1 1 IRFDP rehabilitation. The case 2 report presented describes 3 properties, could be considered a right choice for an an IRFDP 3Davide Augusti, Borgonovo, Massimo Amato, and Dinotreatment Re1 Department of MedicineGabriele and Surgery,Augusti, University of Andrea Salerno, Salerno, Italy using a CAD/CAM monolithic zirconia IRFDP; clinical and laboratory steps are illustrated, according to the most recent scientific 1 protocols. Adhesive procedures are focused on theAugusti; Y-TZP and toothUniversity substrateof conditioning methods. Department of Oral Rehabilitation, Istituto Stomatologico Italiano, Milan, Milan, Italy Nice esthetic and functional Correspondence should be addressed to Gabriele g.augusti@libero.it 2 integration of indirect restoration at two-year follow-up confirmed the success of this conservative approach. Department of Oral Surgery, Dental Clinic, Ospedale maggiore Policlinico, Fondazione IRCCS Ca’ Granda, Milan, Italy 3 Received 21 February 2014;and Accepted May 2014;of Published 21 May 2014 Department of Medicine Surgery,5University Salerno, Salerno, Italy Academic Editor:should Mine D¨ Correspondence beundar addressed to Gabriele Augusti; g.augusti@libero.it Copyright 2014 Davide et al. This2014; is an open access21article distributed under the Creative Commons Attribution License, Received 21©February 2014;Augusti Accepted 5 May Published May 2014

which permits unrestricted use, distribution, and reproduction in any medium, provided the original is properly 1. Introduction Historically, cast resin bondedwork FDPs were cited. produced

Academic Editor: Mine D¨undar exclusively using noble metals like high-gold alloys; nowaDifferent indirect restorations to replace a single missing tooth in the region available in dentistry: traditional fullThe availability of new treatments or technologies in dentistry days a posterior wide range of are new materials are available: hybrid Copyrightfixed © 2014 Davide Augusti(FDPs), et al. This is an open accesscrowns article distributed under the Creative Commons Attribution License, coverage dental prostheses implant-supported (ISC), and inlay-retained FDPs (IRFDP). Resin bonded FDPs has two consequences: on one side it expands the range of microfilled or fiber-reinforced composites (FRC), ceramics which permits unrestricted use, distribution, and reproduction any medium, original is properly represent a minimally invasive procedure; preexisting fillings canin minimize tooth provided structure the removal andwork give retention to cited. the IRFDP, therapies given to patients and on the other hand it stimulates with a high content of glass particles (i.e., lithium disilitransforming it into an ultraconservative option. New high strength zirconia ceramics, with their stiffness and high mechanical the development decision-making for specific cate, glass-infiltrated zirconia. or describes alumina), high treatment strength Different of indirect restorations replace a single missing in the posterior region are available in dentistry: traditional fullproperties, could be consideredtoaalgorithms right choice for an IRFDPtooth rehabilitation. The case report presented anor IRFDP medical conditions [1, dental 2]. monolithic ceramics (densely sinteredaccording zirconia/alumina polycrystal) to coverage fixed prostheseszirconia (FDPs),IRFDP; implant-supported crowns (ISC), and FDPs (IRFDP). Resin bonded FDPs using a CAD/CAM clinical and laboratory steps areinlay-retained illustrated, to the most recent scientific Different indirect restorations to replace a single missing be used as frameworks for subsequent veneering or to fabrirepresent aAdhesive minimally invasive procedure; preexisting fillings can minimize tooth structure removal andNice give esthetic retentionand to the IRFDP, protocols. procedures are focused on the Y-TZP and tooth substrate conditioning methods. functional tooth in the posterior region available dentistry: tradicate the monolithic [8, 9]. All-ceramic transforming into anare ultraconservative option. New high strength zirconia with their stiffness and highrestorations mechanical integration of itindirect restoration at in two-year follow-up confirmed success ceramics, ofrestorations this conservative approach. properties, could considered a right (FDPs), choice forimplantan IRFDP rehabilitation. The case report presented describes an IRFDP treatment tional full-coverage fixedbe dental prostheses offer an excellent optical behavior promoting biomimetic a CAD/CAM monolithic zirconia IRFDP; clinical and laboratory stepsand are their illustrated, according to the most recent scientific supportedusing crowns (ISC), and inlay-retained FDPs (IRFDP) integration surfaces showed minimal plaque accuprotocols. procedures aretime focused the Y-TZP and mulation tooth substrate methods. Nice [3–5]. The last oneAdhesive is considered a less andonexpensive whenconditioning exposed intraorally [10].esthetic and functional restoration two-yearFDPs follow-up the success of this conservative approach. solution integration compared of toindirect the others. Resinatbonded rep-confirmedDuring clinical function, dental restorations are subjected resent a minimally invasive procedure; preexisting fillings to biting and chewing forces; stress applied during mastica1.8 1. cast resin FDPs were produced canIntroduction minimize tooth structure removal and give retention to tionHistorically, may range between 441 bonded and 981 N in the molar region. exclusively using noble metals like high-gold alloys; the IRFDP, transforming it into an ultraconservative option According to DIN standards and to some authors, nowaFDPs The of new treatments or technologies in dentistry days a withstand wide rangeocclusal of newforces materials are than available: hybrid [6]. availability In fact, it has been demonstrated that a high amount should of more 1000 N in a has two consequences: one side expands preparations the range of microfilled or resistance fiber-reinforced composites (FRC), ceramics of coronal dentin is lostonduring the itprosthetic static fracture test [11]. 1. Introduction Historically, cast resin bonded FDPs were produced therapies givenfor to patients and onfull-coverage the other hand it stimulates withNew a high content of ceramics, glass particles (i.e., disiliof abutments conventional FDPs with an high strength with theirlithium stiffness and exclusively using noble metalsorlike high-gold alloys; nowathe development of decision-making algorithms for specific cate, glass-infiltrated zirconia. alumina), or high strength overall calculated toothtreatments substanceor removal of 63%intodentistry 73% [7]. high mechanical properties (i.e., resistance to fracture and/or The availability of new technologies days a wide range of new materials are available: hybrid medical conditions [1, 2]. ceramics (densely sintered zirconia/alumina polycrystal) to has Different two consequences: on one side expands the range of microfilled or fiber-reinforced composites (FRC), indirect restorations to itreplace a single missing be used as frameworks for subsequent veneering orceramics to fabritherapies given to patients and on the other hand it stimulates with a high content of glass particles (i.e., lithium disilitooth in the posterior region are available in dentistry: tradicate monolithic restorations [8, 9]. All-ceramic restorations the development of decision-making algorithms for specific cate, glass-infiltrated zirconia. or alumina), or high strength tional full-coverage fixed dental prostheses (FDPs), implantoffer an excellent optical behavior promoting biomimetic medical conditions [1, 2]. and inlay-retained FDPs (IRFDP) ceramics (densely sintered zirconia/alumina polycrystal) to supported crowns (ISC), integration and their surfaces showed minimal plaque accuDifferent indirect restorations to replace a single missing be used as frameworks for subsequent veneering or to fabri[3–5]. The last one is considered a less time and expensive mulation when exposed intraorally [10]. tooth in the posterior are available in dentistry: cateDuring monolithic restorations [8, 9]. restorations All-ceramicare restorations solution compared toregion the others. Resin bonded FDPstradirepclinical function, dental subjected tional full-coverage fixed dental prostheses (FDPs), implantoffer an excellent optical behavior promoting biomimetic resent a minimally invasive procedure; preexisting fillings to biting and chewing forces; stress applied during masticasupported crowns and removal inlay-retained FDPs (IRFDP) integration and their surfaces showed plaqueregion. accucan minimize tooth(ISC), structure and give retention to tion may range between 441 and 981 Nminimal in the molar [3–5]. The last one is considered a less time and expensive mulation when exposed intraorally [10]. the IRFDP, transforming it into an ultraconservative option According to DIN standards and to some authors, FDPs solution compared to thedemonstrated others. Resinthat bonded FDPs repDuring clinicalocclusal function,forces dentalofrestorations subjected [6]. In fact, it has been a high amount should withstand more thanare 1000 N in a resent a minimally invasive procedure; preexisting fillings to biting and chewing forces; stress applied during masticaof coronal dentin is lost during the prosthetic preparations static fracture resistance test [11]. can minimize for tooth structure removal and give retention to tionNew may high rangestrength between ceramics, 441 and 981 N intheir the molar region. of abutments conventional full-coverage FDPs with an with stiffness and the IRFDP, transforming it into an ultraconservative option According to DIN standards and to some authors, FDPs overall calculated tooth substance removal of 63% to 73% [7]. high mechanical properties (i.e., resistance to fracture and/or [6]. In fact, it has been demonstrated that a high amount should withstand occlusal forces of more than 1000 N in a of coronal dentin is lost during the prosthetic preparations static fracture resistance test [11]. of abutments for conventional full-coverage FDPs with an New high strength ceramics, with their stiffness and overall calculated tooth substance removal of 63% to 73% [7]. high mechanical properties (i.e., resistance to fracture and/or

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(b)

Figure 1: (a) Intraoral occlusal view of edentulous area before treatment. (b) Intraoral lateral view of tooth gap; the interabutment distance measured was 11 mm.

considered acceptable; no marginal leakage, discoloration, or secondary caries of the previous composite restorations were clinically detected. Informed consent was obtained from the patient and the inlay-retained full zirconia FDP treatment planning was approved. Figure 2: Standardized inlay preparations; previous composite fillings were removed.

fatigue), could be considered a right choice in an IRFDP rehabilitation [12]. New zirconia color infiltration techniques can improve the color matching when monolithic restorations were planned [13]. Zirconia still presents a challenge when used with adhesive techniques due to their single-phase tetragonal crystalline structure that is not etchable by commonly used agents such as hydrofluoric acid. Debonding of the adhesive interface and delimitation and microcracks of the ceramic veneering material were the most long term failures observed and reported [14â&#x20AC;&#x201C;16]. A correct FDP and tooth cavity surfaces conditioning before adhesive cementation procedures is necessary to avoid mechanical and biological complications [17, 18].

2. Diagnosis and Treatment Planning A 52-year-old patient referred to the Department of Oral Rehabilitation (Istituto Stomatologico Italiano, University of Milan) with a need for a 3-unit FDP. The patient rejected any implant therapy planned with a previous reconstructive surgery procedure (major sinus lift). Good oral hygiene, low susceptibility to caries, coronal height over 5 mm, parallel abutments previously restored with composite fillings, and a mesiodistal edentulous gap of 11 mm were suggested for an IRFDP rehabilitation, with a minimally invasive approach compared to conventional retained full-coverage FDP (Figures 1(a) and 1(b)). The bone level of the vital abutment teeth was radiologically investigated; no signs of active bone resorption or any periodontal and periapical pathology was revealed. The maximum mobility of grade 1 for the element 1.7 was

3. Preparation and Impression The inlay preparations were designed with rounded proximal boxes and internal edges, smooth round corners, and rectangular-based preparation floors with 2.5 mm occlusal reduction, without bevels at occlusal or gingival margins. The isthmus width of the preparation was 2 mm for premolar and 3 mm for molar abutments. The minimum axial reduction (shoulder with rounded internal angle) was set at 1.5 mm and the convergence preparation angle was added up to approximately 6 degrees (Figure 2). The minimum dimensions of the connector were 3 Ă&#x2014; 3 mm, to enhance optimum mechanical stress distribution. Prepared dentin was sealed with an adhesive system (Scotch Bond Universal, 3M ESPE) to prevent contamination by bacteria and components coming from the impression and provisional cementation materials. The impression was made using a VPS material with a one-step technique (Elite HD + putty soft, Elite HD + regular body, and Elite HD + light body, Zhermack SpA, Badia Polesine, Italy) (Figures 3(a) and 3(b)). Alginate impression of the lower arch and occlusal registration were finally performed. Inlay cavities were then filled with temporary restorations.

4. Try-In Fabrication Impressions were poured with Type IV gypsum (GC-Fuji Rock EP) and stone casts were mounted in an articulator. An IRFDP resin mock-up was fabricated for the clinical tryin; two different indirect laboratory light cured composite resins were used for the inlays (Sinfony, 3M ESPE) and the intermediate crown (Rigid Transparent-Blue Resin, Zirkonzahn GmbH) fabrication. Complete indirect resin photo polymerization was obtained using a laboratory curing unit (3M ESPE Alfa Light Unit) (Figures 4(a) and 4(b)). The fit of the structure in the oral cavity was controlled using a low-viscosity silicone material (Fit-Checker, GC,

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Figure 3: (a) Occlusal view of the final elastomeric impression. (b) Close-up of silicon impression; light body material reproduced every preparation fine details.

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Figure 4: (a) Type IV gypsum master cast with the composite resin try-in of the IRFDP. (b) Close-up of the mock-up; the occlusal contacts were verified by the technician using the articulator.

making any necessary adjustments with a fine diamond bur (Figures 6(a) and 6(b)).

5. CAD-CAM Procedures

Figure 5: Occlusal view of the try-in seated in the oral cavity.

Tokyo, Japan) which demonstrated no friction and marginal integrity (Figure 5). The occlusion was checked with a 40 đ?&#x153;&#x2021;đ?&#x153;&#x2021;m occlusal paper (Bausch BK9, Bausch KG, Germany), both in maximum intercuspidation position and during eccentric movements,

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The adjusted composite resin mock-up was sent to the laboratory and scanned with a fully automated optical striplight scanner (S600 ARTI, Zirkonzahn GmbH); the lower master cast was also digitally acquired (accuracy â&#x2030;¤ 10 đ?&#x153;&#x2021;đ?&#x153;&#x2021;m). Interarch relationships were finally checked with a virtual articulator software to simulate occlusal movements. Presintered zirconia blank (Prettau Zirconia, Zirkonzahn GmbH) was milled with a dedicated 5 + 1 axes machine (milling unit M5, Zirkonzahn GmbH). The milled IRFDP was refinished with a tungsten carbide bur and color infiltrated with acidfree special color liquids (Colour Liquid Prettau, Zirkonzahn GmbH) using a metal-free brush.

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Figure 6: (a) Interarch relationships were highlighted with a 40 đ?&#x153;&#x2021;đ?&#x153;&#x2021; occlusal paper. (b) Details of the contacts area; excessive occlusal pressure at the margins of the restoration will be corrected in the laboratory.

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Figure 7: (a) Monolithic zirconia restoration on master cast: occlusal view. (b) Lateral close-up; brown stains were used in the cervical area.

Figure 8: IRFDP conditioned for final adhesive cementation.

After a drying stage, the sintering process was carried out in a sintering furnace (Zirkonofen 600, Zirkonzahn GmbH) until it reached 1540â&#x2C6;&#x2DC; C for 12 hours (Figures 7(a) and 7(b)).

6. Placement The temporary restorations were removed using a manual excavator; a rubber dam was placed, isolating the preparations from the oral cavity. Abutments were cleaned using a pumice paste over a rotating brush; the cavities were treated with an intraoral sandblaster (CoJet Prep, 3M ESPE), washed out for one minute, and gently air dried. Enamel and dentin

surfaces were etched for 30 s and 15 s, respectively, with 35% orthophosphoric acid and rinsed for 30 s with air/water spray. A dual-curing universal dental adhesive (ScotchBond Universal, 3M ESPE) was applied to enamel and dentin with a microbrush for 20 s, evaporated, and left uncured. The inner side of the IRFDP was sandblasted with Al2O3 particles (50 đ?&#x153;&#x2021;đ?&#x153;&#x2021;m, 2.8 bar, 1 cm), rinsed with water spray for 60s, and ultrasonically cleaned in 95% ethyl alcohol for 10 minutes. A MDP containing primer (Clearfil Ceramic Primer, Kuraray, Japan) was applied to the zirconia surface as recommended by the manufacturer (Figure 8). A self-adhesive dual-curing resin cement (Panavia SA, Kuraray, Japan) was dispensed directly into the cavities using the endo tip. The solid zirconia restoration was first placed in site with a finger pressure; an ultrasonic insertion tip was used to complete the seating process, increasing the cement flow. The placement of IRFDP after adhesive procedures is resumed in Figures 9(a) to 9(d). Excess composite resin was carefully removed using a spatula and dental floss (Oral-B Superfloss, P&G, USA). Glycerine gel was applied at the margins to prevent an oxygen inhibition layer at the interface; subsequently a prolonged light curing was performed from mesiobuccal, mesiopalatal, distobuccal, distopalatal, and occlusal directions for 90 seconds each (Bluephase LED curing light, Ivoclar). Margins were finished and polished with diamond burs, rubber points, and diamond polishing paste.

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Figure 9: (a) Operative field isolation with dental dam. (b) Selective phosphoric acid etching. (c) Etched enamel and dentin surfaces. (d) A resin composite dual-curing cement was used.

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Figure 10: (a) Occlusal view of the luted IRFDP just after rubber dam removal. (b) Lateral view of the rehabilitation: function and esthetic were restored.

7. Esthetic and Functional Result Intraoral view of the luted restoration after rubber dam removal is shown in Figures 10(a) and 10(b). Nice esthetic and functional integration of the monolithic IRFDP confirms the success of the rehabilitation at 10 days (Figures 11(a) and 11(b)). Marginal integrity, absence of chipping [12]. and good gingival health status were observed at 2-year followup (Figure 12); the patient was also highly satisfied with the selected rehabilitation.

8. Discussion It is generally accepted that partial restorations conserve sound tooth structures and are preferred over complete coverage restorations. In particular, when abutment teeth contain restorative fillings adjacent to the missing tooth, IRFDPs are considered a very minimally invasive option. The weakest parts of IRFDPs are the connectors and the retainers; in this study a standardized inlay preparation

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design was used to increase the stability and retention of the densely sintered ceramic restoration [6]. Monolithic high strength ceramic FDPs demonstrated higher in vitro resistance to fracture load than metal ceramic; zirconia based materials used for IRFDPs also showed greater mechanical behavior than lithium disilicate glass-ceramic and fiberreinforced composites [12, 19]. For zirconia IRFDP the mean fracture strength was reported to be 1248 Âą 263 N when the interabutment distance was 10 mm [20]. In the last years, the demand for esthetics and biocompatibility led to the use of zirconia CAD/CAM materials in fixed prosthodontics [3]. A prospective clinical study determined the success rate of three- to four-unit posterior FDPs with Y-TZP frameworks after five years of function; the authors reported a survival rate of 85% [21]. Few studies have investigated the clinical performance of these ceramics for IRFDP rehabilitations [17, 22]. Debonding of the adhesive interface represents a common failure of the IRFDPs. The interabutment forces developed during clinical function might stress the retainer

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Figure 11: (a) 10-day follow-up: occlusal view. (b) 10-day follow-up: lateral view.

Acknowledgment The authors are grateful to Mr. Agostino Caprini, Odontocap Dental Laboratory, Italy, for his meticulous work in producing the zirconia IRFDP.

References Figure 12: 2-year follow-up: occlusal view.

framework and luting interface; rigid connectors, with their low bending behavior, have been suggested as a possible cause of debonding [11]. Another explanation might be that inadequate bond strength values are reached between the restoration and tooth substrates. In fact, a definitive cementation protocol for high strength ceramics has not been validated yet; sandblasting of the inner side of zirconia has been suggested in the literature to increase surface roughness and promote micromechanical interlocking [18]. Different air-blasting protocols associated with chemical primers (i.e., formulations containing MDP molecules or silane coupling agents) are the most recommended conditioning methods for zirconia restorations [15, 23]; however, some studies have shown that bond strength might decrease over time due to aging of the interface and lead to failure [24]. Adequate evidences about long term safety and efficacy of solid zirconia IRFDP are required before these kinds of treatment could be recommended as acceptable for general clinical practice [6, 14].

9. Conclusion Within the limits of a preliminary application, the technique described in this case report allows a minimally invasive approach for single-tooth substitution, as an alternative to a full-coverage FDP or an implant-supported crown.

Conflict of Interests The authors declare that there is no conflict of interests regarding the publication of this paper.

[1] I. Denry and J. R. Kelly, “State of the art of zirconia for dental applications,” Dental Materials, vol. 24, no. 3, pp. 299–307, 2008. [2] T. Miyazaki, Y. Hotta, J. Kunii, S. Kuriyama, and Y. Tamaki, “A review of dental CAD/CAM: current status and future perspectives from 20 years of experience,” Dental Materials Journal, vol. 28, no. 1, pp. 44–56, 2009. [3] M. Sasse and M. Kern, “CAD/CAM single retainer zirconiaceramic resin-bonded fixed dental prostheses: clinical outcome after 5 years,” International Journal of Computerized Dentistry, vol. 16, no. 2, pp. 109–118, 2013. [4] D. Augusti, G. Augusti, and D. Re, “Prosthetic restoration in the single-tooth gap: patient preferences and analysis of the WTP index,” Clinical Oral Implants Research, 2013. [5] A. J. Raigrodski, M. B. Hillstead, G. K. Meng, and K. H. Chung, “Survival and complications of zirconia-based fixed dental prostheses: a systematic review,” Journal of Prosthetic Dentistry, vol. 107, no. 3, pp. 170–177, 2012. [6] C. Monaco, P. Cardelli, M. Bolognesi, R. Scotti, and M. Ozcan, “Inlay-retained zirconia fixed dental prosthesis: clinical and laboratory procedures,” European Journal of Esthetic Dentistry, vol. 7, no. 1, pp. 48–60, 2012. [7] S. Wolfart, F. Bohlsen, S. M. Wegner, and M. Kern, “A preliminary prospective evaluation of all-ceramic crown-retained and inlay-retained fixed partial dentures,” International Journal of Prosthodontics, vol. 18, no. 6, pp. 497–505, 2005. [8] F. Beuer, H. Aggstaller, D. Edelhoff, W. Gernet, and J. Sorensen, “Marginal and internal fits of fixed dental prostheses zirconia retainers,” Dental Materials, vol. 25, no. 1, pp. 94–102, 2009. [9] D. Edelhoff, H. Spiekermann, and M. Yildirim, “Metal-free inlay-retained fixed partial dentures,” Quintessence International, vol. 32, no. 4, pp. 269–281, 2001. [10] D. Re, G. Pellegrini, P. Francinetti, D. Augusti, and G. Rasperini, “In vivo early plaque formation on zirconia and feldspathic ceramic,” Minerva stomatologica, vol. 60, no. 7-8, pp. 339–348, 2011. [11] M. Ozcan, W. Koekoek, and G. Pekkan, “Load-bearing capacity of indirect inlay-retained fixed dental prostheses made of particulate filler composite alone or reinforced with E-glass

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[12] [13] [14]

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fibers impregnated with various monomers,” Journal of the Mechanical Behavior of Biomedical Material, vol. 12, pp. 160–167, 2012. Y. Zhang, J. J. Lee, R. Srikanth, and B. R. Lawn, “Edge chipping and flexural resistance of monolithic ceramics,” Dental Materials, vol. 29, no. 12, pp. 1201–1208, 2013. S. Rinke and C. Fischer, “Range of indications for translucent zirconia modifications: clinical and technical aspects,” Quintessence International, vol. 44, no. 8, pp. 557–566, 2013. A. D. Izgi, E. Kale, and S. Eskimez, “A prospective cohort study on cast-metal slot-retained resin-bonded fixed dental prostheses in single missing first molar cases: results after up to 7.5 years,” The Journal of Adhesive Dentistry, vol. 15, no. 1, pp. 73–84, 2013. D. Re, D. Augusti, G. Augusti, and A. Giovannetti, “Early bond strength to low-pressure sandblasted zirconia: evaluation of a self-adhesive cement,” European Journal of Esthetic Dentistry, vol. 7, no. 2, pp. 164–175, 2012. B. Ohlmann, P. Rammelsberg, M. Schmitter, S. Schwarz, and O. Gabbert, “All-ceramic inlay-retained fixed partial dentures: preliminary results from a clinical study,” Journal of Dentistry, vol. 36, no. 9, pp. 692–696, 2008. C. Monaco, P. Cardelli, and M. Ozcan, “Inlay-retained zirconia fixed dental prostheses: modified designs for a completely adhesive approach,” Journal of the Canadian Dental Association, vol. 77, p. b86, 2011. D. Re, D. Augusti, I. Sailer, D. Spreafico, and A. Cerutti, “The effect of surface treatment on the adhesion of resin cements to Y-TZP,” The European Journal of Esthetic Dentistry, vol. 3, no. 2, pp. 186–196, 2008. C. A. Mohsen, “Fracture resistance of three ceramic inlayretained fixed partial denture designs. An in vitro comparative study,” Journal of Prosthodontics, vol. 19, no. 7, pp. 531–535, 2010. M. A. Kiliçarslan, P. Sema Kedici, H. Cenker Küçu¨ kes¸men, and B. C. Uludaˇg, “In vitro fracture resistance of posterior metalceramic and all-ceramic inlay-retained resin-bonded fixed partial dentures,” Journal of Prosthetic Dentistry, vol. 92, no. 4, pp. 365–370, 2004. T. Kern, J. Tinschert, J. S. Schley, and S. Wolfart, “Five-year clinical evaluation of all-ceramic posterior FDPs made of InCeram Zirconia,” The International Journal of Prosthodontics, vol. 25, no. 6, pp. 622–624, 2012. M. Abou Tara, S. Eschbach, S. Wolfart, and M. Kern, “Zirconia ceramic inlay-retained fixed dental prostheses—first clinical results with a new design,” Journal of Dentistry, vol. 39, no. 3, pp. 208–211, 2011. R. Zandparsa, N. A. Talua, M. D. Finkelman, and S. E. Schaus, “An in vitro comparison of shear bond strength of zirconia to enamel using different surface treatments,” Journal of Prosthodontics, vol. 23, no. 2, pp. 117–123, 2014. J. Perdigao, S. D. Fernandes, A. M. Pinto, and F. A. Oliveira, “Effect of artificial aging and surface treatment on bond strengths to dental zirconia,” Operative Dentistry, vol. 38, no. 2, pp. 168–176, 2013.

INLAY-RETAINED FIXED DENTAL PROSTHESIS: A CLINICAL OPTION USING MONOLITHIC ZIRCONIA Question 7 What occlusal forces should FDPs be able to withstand in a static fracture resistance test? A More than 800 N B More than 600 N C More than 1000N D More than 1500N Question 8 Is it true or false that Zirconia still presents a challenge when used with adhesive techniques due to their single-phase tetragonal crystalline structure? True or False Question 9 What material showed greater mechanical behavior when used for IRFDPs? A B C

Zirconia based materials Fibre-reinforced composites Lithium disilicate glass-ceramic

Question 10 Can pre-existing fillings be removed and used to give retention to IRFDP A Yes B No Question 11 True or false that sandblasting the inner side of zirconia will help promote micromechanical interlocking. True or False

SADTJ Vol 6 Issue 2

Dentistry Section Section Dentistry

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

Original OriginalArticle Article

A Comparison of Masticatory Performance and Efficiency of Complete Dentures Made with High Impact and Flexible Resins: A Pilot Study

Puja PujaHazari Hazari11,,anjali anjaliBHoyar BHoyar22,,Sunil SunilKumar KumarmiSHra miSHra33,,naveen naveenS. S.yaDav yaDav44,,HarSH HarSHmaHajan maHajan55

ABStrAct ABStrAct Background: Background: In In patients patients with with extensive extensive tooth tooth loss, loss, restoration restoration of of masticatory masticatory function function and and aesthetics aesthetics isis main main concern concern for for aa prosthodontist. prosthodontist. Aim Aimof ofStudy: Study:This Thisstudy studyaimed aimedto toevaluate evaluateand andcompare comparedifferences differences inin masticatory masticatory efficiency efficiency of of patients patients treated treated with with complete complete dentures dentures made made with with either either high high impact impact or or flexible flexible resins. resins. Setting Settingand anddesign: design:The Thesample samplesize sizeconsisted consistedof of10 10study studysub subjects. jects. Two Two sets sets of of dentures dentures first first conventional conventional followed followed by by flexible flexible dentures dentures were were fabricated fabricated for for each each subject subject and and both both the the sets sets of of dentures dentures were were accessed accessed for for masticatory masticatory performance performance and and efficiency. efficiency. Materials Materials and and Methods: Methods: This This study study compared compared the the masticatory masticatory performance performance and and efficiency efficiency of of dentures dentures by by means means of of standardized standardized mesh meshsieves. sieves.Masticatory Masticatoryefficiency efficiencywas wascalculated calculatedby byrecording recordingthe the total total number number of of chewing chewing cycles cycles and and time time required required to to completely completely

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

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

IntrOductIOn IntrOductIOn The The restoration restoration of of masticatory masticatory function function and and aesthetics aesthetics isis an an important important aim aim inin dentistry dentistry mainly mainly when when patients patients present present with with extensive extensive tooth tooth loss. loss. The The loss loss of of tooth tooth inin elderly elderly patients patients not not only only impairs impairs the the stomatognathic stomatognathic system system but but also also their their psychological psychological status status and and quality quality of of life life [1,2]. [1,2]. The The important important criteria’s criteria’s for for the the success success of of dentures dentures are are patient’s patient’s expectations expectations and and the the ability ability of of the the denture denture to to replace replace the the lost lost masticatory masticatory efficiency. efficiency. For For long long polymethyl polymethylmethacrylate methacrylate(PMMA) (PMMA)has hasdominated dominatedthe thefield fieldof ofdenture denture base basematerials materialsbut buttoday todayflexible flexibledentures dentureshave haveemerged emergedas asaamajor major competitor competitor to to PMMA PMMA dentures. dentures. Flexible Flexible dentures, dentures, also also known known as as nylon nylon dentures, dentures, are are considered considered perfect perfect alternatives alternatives to to conventional conventional and andpartial partialacrylic acrylicdentures. dentures.Flexible Flexibledentures denturesmade madeof ofthermoplastic thermoplastic material, material, are are resistant resistant to to breakage breakage and and very very comfortable comfortable for for the the edentulous edentulous patients. patients. These These dentures dentures are are easy easy to to wear wear and and very very pleasant pleasant for for patients patients as as they they are are much much thinner, thinner, stay stay firmly firmly inin place place and and more more retentive retentive when when compared compared to to conventional conventional dentures. dentures. They They do do not not cause cause any any allergic allergic reactions, reactions, are are light light inin weight weight and and take take minimum minimum space space inin the the oral oral cavity. cavity. Further Further studies studies have have proved proved that that these these flexible flexible dentures dentures have have less less solubility solubility and and sorption sorption values values than than heat heat cure cure PMMA PMMA [3,4]. [3,4]. Though Though widely widely used used for for partial partial dentures dentures the the flexible flexible material material isis not not usually usuallyused usedfor forcomplete completedentures. dentures.The Thecriteria criteriaof ofbetter bettermasticatory masticatory performance performanceand andmasticatory masticatoryefficiency efficiencyof ofdentures denturesmay maychange changethe the future future prospective prospective of of denture denture base base materials. materials. Thus, Thus, itit isis of of utmost utmost importance importance to to study study the the masticatory masticatory performance performance and and masticatory masticatory efficiency efficiency inin cases cases of of rehabilitation rehabilitation with with the the flexible flexible dentures dentures for for elderly elderly individual individual for for detailed detailed diagnosis diagnosis and and prognosis, prognosis, which which will will improve improve their their quality quality of of life. life. Journal Journalof ofClinical Clinicaland andDiagnostic DiagnosticResearch. Research.2015 2015Jun, Jun,Vol-9(6): Vol-9(6):ZC29-ZC34 ZC29-ZC34

SADTJ Vol 6 Issue 2

The The null null hypothesis hypothesis to to be be tested tested inin this this study study was was that that there there was was no nodifference differenceininmasticatory masticatoryperformance performanceand andmasticatory masticatoryefficiency efficiency of of patients patients treated treated with with complete complete dentures dentures made made with with high high impact impact PMMA PMMA resins resins and and flexible flexible thermoplastic thermoplastic material. material.

AIM AIM Of Of Study Study This Thisstudy studyaimed aimedto toevaluate evaluateand andcompare comparedifferences differencesininmasticatory masticatory efficiency efficiencyof ofpatients patientstreated treatedwith withcomplete completedentures denturesmade madewith withhigh high impact impact resins resins and and flexible flexible resins. resins.

MAterIAlS MAterIAlS And And MethOdS MethOdS This This cross-sectional, cross-sectional, prospective prospective study study was was conducted conducted at at Peoples Peoples College College of of Dental Dental Sciences Sciences and and Research Research Centre, Centre, Bhopal Bhopal inin 2013. 2013. The The study study group group comprised comprised of of randomly randomly selected selected 10 10 completely completely edentulous edentulous patients patients (6 (6 males males && 44 females) females) reported reported to to the the Department Departmentof ofProsthodontics. Prosthodontics.The Theinclusion inclusionand andexclusion exclusioncriteria’s criteria’s were were as as follows: follows:

Inclusion Inclusion criteria criteria Only Only healthy healthy edentulous edentulous patients patients and and denture denture wearers wearers for for the the first first time time were were included included inin the the study. study. Patient’s Patient’s ages ages were were between between 454565 65 years. years. Patients Patients were were advised advised orthopantomographs orthopantomographs to to rule rule out out hard hard tissue tissue abnormalities abnormalities and and Temporomandibular Temporomandibular Joint Joint (TMJ) (TMJ) dysfunctions. dysfunctions.The Thenature natureof ofthe thestudy studywas wasexplained explainedand andan aninformed informed consent consent was was taken taken from from the the patient. patient.

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

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

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

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

Group1

Group2

Group1

Group2

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

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

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

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

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

[table/fig-4]: Centrifugal machine

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

Journal of Clinical andVol Diagnostic Research. 2015 Jun, Vol-9(6): ZC29-ZC34 SADTJ 6 Issue 2

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

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

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

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

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

Component Masticatory performance [wet weight]

0.39842±0.108021

Group-2 Peanuts

0.37559±0.071501

*Group-1 Carrots

0.47661±0.10911

Group-2 Carrots

0.36345±0.11708

*Group-1 Peanuts

0.67738±0.124438

Group-2 Peanuts

0.66472±0.127126

*Group-1 Peanuts

0.36389±0.10030

Group-2 Peanuts

0.35021±0.07785

*Group-1 Carrots

0.43789±0.12623

Group-2 Carrots

0.32453±0.11239

*Group-1 Peanuts

0.66214±0.13257

Group-2 Peanuts

0.63659±0.10326

63.4±11.98

†

Masticatory performance [dry weight]

†

Swallowing threshold [dry weight]

†

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

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

mean±Standard Deviation

†

Swallowing threshold [wet weight]

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

*Group-1 Peanuts †

*Group-1 †

Group-2

*Group-1 Group-2

†

* Group-1 Group-2

†

66.2±13.55

70.7±13.86

76.3±17

0.90±0.126068

0.87±0.093044

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Confidence interval (95% level)

t –value

df**

p- value (5% level)

1.1705

0.2719 §

-0.0212 to 0.0669

3.1774

0.0112 ‡

0.0325 to 0.1937

0.3709

0.7193 §

-0.0645 to 0.0898

0.6669

0.5216 §

-0.0327 to 0.0600

2.5610

0.0306 ‡

0.5533

0.5936 §

-0.0789 to 0.1300

0.6347

0.5414 §

-12.78 to 7.18

1.8196

0.1022 §

12.56 to 1.36

0.9329

0.3752 §

-0.0457 to 0.1100

0.0132 to 0.2134

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

‡

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

No significant difference; ¦ Number of patients;

degree of freedom

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

Satisfaction response as average by number of subjects

Group-1

Group-2

Retention of maxillary dentures

Group-1

Group-2

Retention of mandibular dentures

Group-1

Group-2

Speech

Group-1

Group-2

Chewing efficiency with soft food

Group-1

Group-2

Chewing efficiency with medium food

Group-1

Group-2

Chewing efficiency with hard food

Group-1

Group-2

Comfort of maxillary denture

Group-1

Group-2

Comfort of mandibular denture

Group-1

Group-2

Overall satisfaction

Group-1

Group-2

Satisfaction Factors Esthetics

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

Group

Satisfaction response as Good by number of subjects

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

dIScuSSIOn

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

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

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

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

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

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

[5]

clInIcAl IMplIcAtIOnS

[9]

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

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

referenceS

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

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

www.jcdr.net

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

ParTiCularS oF ConTriBuTorS: 1. Senior Lecturer, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India. 2. Professor, Department of Maxillofacial Prosthodontics and Implantology, Peoples College of dental sciences, Bhopal, Madhya Pradesh, India. 3. Reader, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India. 4. Professor, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India. 5. Reader, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India. name, aDDreSS, e-mail iD oF THe CorreSPonDinG auTHor: Dr. Puja Hazari, Senior Lecturer, Department of Maxillofacial Prosthodontics and Implantology, Peoples Dental Academy, Bhopal, Madhya Pradesh-462037, India. E-mail: hazaripuja@yahoo.in

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

FinanCial or oTHer ComPeTinG inTereSTS: None.

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Journal of Clinical and Diagnostic Research. 2015 Jun, ZC29-ZC34 SADTJ VolVol-9(6): 6 Issue 2

A COMPARISON OF MASTICATORY PERFORMANCE AND EFFICIENCY OF COMPLETE DENTURES MADE WITH HIGH IMPACT AND FLEXIBLE RESINS: A PILOT STUDY

Question 12

True or False that the success of dentures is determined by the patients expectations and to replace the lost masticatory efficiency

True or False Question 13

True or False that studies have showed that Flexible Dentures have more solubility and sorption values.

True or False Question 14 A 6 Months B 6 weeks C 3 months D 2 weeks

How many months were patients given to evaluate masticatory performance of both dentures?

Question 15 Which Mandibular denture was found more aesthetic and had better retention? A Flexible B Heat cure PMMA Question 16

Flexible Material can be used where a Patient is allergic to PMMA.

True or False Question 17 The masticatory performance ratio was found to be more for hard food in: A Flexible Dentures B Conventional Dentures

SADTJ Vol 6 Issue 2

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Novel treatment (new drug/intervention; established drug/procedure in new situation)

1.4

CASE REPORT

REACTIVE DENTURES: A NOVEL APPROACH TO Reactive dentures: a novelRIDGE approach to decrease DECREASE RESIDUAL RESORPTION residual ridge resorption Kesava K Reddy,1 Renuka G S Prasanna,2 K J Sundaresh,3 Rachappa Mallikarjuna4

artment of Prosthodontics, ge of Dental Sciences, nagere, Karnataka, India artment of Prosthodontics, asanamba Dental College, an, Karnataka, India artment of Conservative Endodontics, KM Shah al College & Hospital, andeep Vidyapeeth, dara, Gujarat, India artment of Pedodontics Preventive Dentistry, KM Dental College and ital, Vadodara, Gujarat,

espondence to achappa Mallikarjuna, achappa@gmail.com

SUMMARY The need for reduction of traumatic forces transmitted through the prosthesis has long been recognised and studies have shown that either a soft acrylic resin/silicone rubber can serve as a stress distributor and absorb some of the forces applied to the teeth. These dentures permit reaction to impacting forces which allows independent movement of one or more teeth in function unlike the conventional dentures. A completely edentulous patient with adequate inter-ridge distance was selected for the case, the dentures with soft liner placed between the patient’s teeth and denture base were fabricated. This report presents a completely new technique to reduce the ridge resorption and facilitate patient comfort.

CASE PRESENTATION A 55-year-old male patient reported with a history of loss of teeth over the last 2 months. His medical history was non-contributory. Clinical examination revealed completely edentulous maxillary and mandibular arches with adequate inter-ridge distance; therefore, this case was ideal to place a soft liner of 2 mm thickness in between teeth and denture base.

TREATMENT Conventional procedures of primary impression, border molding followed by final impression and jaw relation were performed. Teeth arrangement was done except that a diastema of 0.5 mm was kept between each posterior tooth. Flasking and dewaxing were carried out to obtain stone moulds. Tin foil was used to make spacers of 2 mm thickness (figure 1) which were cut to the length and width of the posterior teeth. Diatoric holes were placed in the posterior teeth (figure 2) and covered with the spacer. The mould was then packed with heat cure denture base resin (DPI, India) and allowed to stay in the hydraulic press for 20 min for initial polymerisation. After this, the flasks were reopened, the initially polymerised denture base resin was carefully separated (figure 3), spacers were removed and this space was

y KK, et al. BMJ Case Rep 2013. doi:10.1136/bcr-2012-008420

Two millimetre thickness of spacer.

BACKGROUND

The forces of mastication are predominantly the impact forces that are applied to a tooth on a denture and are carried directly to the denture base and transmitted to the supporting tissues.1 One of the main causes of resorption of denture-supporting structures is the traumatic force transmitted through the prosthesis;2 3 dentures with resilient liner in between teeth and denture base reduce these impact forces.

cite: Reddy KK, anna RGS, daresh KJ, et al. BMJ e Rep Published online: ase include Day Month r] doi:10.1136/bcr-2012420

Figure 1

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packed with heat cured acrylic denture reliner (Supersoft, GC Company, USA) (figure 4) and then trial closed with initially set denture base resin. The flasks were kept in hydraulic press for bench curing after which they were kept for curing according to the manufacturer’s instructions. The dentures were trimmed, finished and polished (figure 5). Finished dentures were then tried on patient for correct fitness (figures 6 and 7). After ensuring the correct fitness of dentures, the patient was educated about the usage and subsequent visit for follow-up.

OUTCOME AND FOLLOW-UP After the ﬁrst 4 weeks of follow-up, the results were found to be satisfactory, and currently the patient is under annual follow-up for the assessment of dentures in function and for comfort in mastication.

Figure 2

Diatoric holes in posterior teeth. 1

Novel treatment (new drug/intervention; established drug/procedure in new situation)

Figure 5

Figure 3 Flask with spacer and initially polymerised denture base resin.

DISCUSSION The periodontal ligament being resilient serves to cushion the impacting forces applied to natural teeth. The same principle can be used in dentures in which an elastic material can be imposed to absorb some of the forces imparted during function so that the trauma to the basal seat would be reduced and the forces would be more widely distributed over the basal seat.1 In literature, authors have suggested different positions of placing the soft liner in the denture. Baker4 presented a report on an experimental denture in which a resilient material was placed in between the teeth and the denture base. These dentures permit occlusal reaction to impacting forces which allows independent movement of one or more teeth in function unlike the conventional denture. Parker1 conducted a pilot study on the reduction of traumatic impact by sandwiching a resilient resin layer within denture base which acts as a shock absorber. The author suggested that since the area of the exposed surface is much smaller, less plasticiser may leach out of the resin.2 In the present study, a soft liner was placed in between teeth and denture base. Soft liners can be grouped as acrylic resin-based soft liners, silicone-based soft liners and treatment liners (tissue conditioners). The acrylic- and silicone-based soft liners are also available as heat-polymerised and auto -polymerised.

Figure 4 Soft liner packed in place of denture base resin. 2

Denture with soft liner.

Failure of bond between polymethyl methacrylate (PMMA) and resilient lining materials has been a signiﬁcant reason for the limited use of soft-lined dentures. One of the requirements of resilient denture liner is a satisfactory bond between the liner and the denture base.5 Hence, a soft denture liner that has excellent bonding strength towards PMMA denture base resin can be used most effectively. Soft denture lining materials that have a bond strength of 4.5 kg/cm2 are acceptable for clinical use.6

Figure 6

Soft-lined denture—intraoral—left lateral.

Figure 7

Soft-lined denture—intraoral—right lateral. Reddy KK, et al. BMJ Case Rep 2013. doi:10.1136/bcr-2012-008420

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Novel treatment (new drug/intervention; established drug/procedure in new situation) The ﬁnal selection of the liner was based on ease of manipulation, adaptability and bonding with the denture base resin. In the present case, a heat-cured acrylic soft liner (Super Soft, GC Company, USA) was used. Since 1 mm thickness seems to be a less to decide the action of liner and 3 mm seems to be more to incorporate as it decreases the strength of denture base1 and also produces rubber ball effect, a 2 mm thick liner was selected.7 The patients with adequate interarch distance so as to place 2 mm thick liner were selected for this case. The dentures of the patient in this study were functionally satisfactory. The patient reported that he could eat all types of daily food items with soft liner dentures. The patient reported that grinding was better with soft liner dentures; this could be because denture liners may affect force perception during mastication and also the lining material improves the occlusal balance by their deformation because of elasticity.8

Contributors All authors have made substantive contribution to this manuscript, and all have reviewed the ﬁnal paper prior to its submission. Competing interests None. Patient consent Obtained. Provenance and peer review Not commissioned; externally peer reviewed.

REFERENCES 1 2 3 4 5 6 7

Learning points ▸ ▸ ▸ ▸

Parker HM. Impact reduction in complete and partial dentures, a pilot study. J Prosthet Dent 1966;16:227–45. El Charkawi HG. The effect of resilient layer and occlusal reactive complete dentures on the residual alveolar ridge. J Prosthet Dent 1988;59:598–602. Murata H, Taguchi N, Hamada T, et al. Dynamic viscoelasticity of soft liners and masticatory function. J Dent Res 2002;81:123–8. Baker CR. Occlusal reactive prosthodontics. J Prosthet Dent 1967;17:566–9. Kutay O. Comparison of tensile and peel bond strengths of resilient liners. J Prosthet Dent 1994;71:525–31. Kawano F, Dootz ER, Koran A, et al. Comparison of bond strength of six soft denture liners to denture base resin. J Prosthet Dent 1992;68:368–71. Qudah S, Harrison A, Huggett R. Soft lining materials in prosthetic dentistry: a review. Int J Prosthodont 1990;3:477–83. Darbar UR, Huggett R, Harrison A. Stress analysis techniques in complete denture. J Dent 1994;22:259–64.

Technique to reduce residual ridge resorption. Patent’s comfort in wearing dentures. Increased mastication efﬁciency with dentures. Close mimicking of denture to natural dentition.

http://group.bmj.com/group/rights-licensing/permissions. REACTIVE DENTURES: A NOVEL APPROACH TO DECREASE RESIDUAL BMJ Case Report Fellows may re-use this article for personal use and teaching without any further permission. Become a Fellow of BMJ Case Reports today and you can: RIDGE RESORPTION ▸ ▸ ▸ ▸

Submit as many cases as you like Enjoy fast sympathetic peer review and rapid publication of accepted articles Access all the published articles Re-use any of the published material for personal use and teaching without further permission

Question 18 How big was the diastema between each posterior tooth? For information on Institutional Fellowships contact consortiasales@bmjgroup.com A 0.2 Visit casereports.bmj.com for more articles like this and to become a Fellow B 0.5 C 1.0 D 0.8 Question 19 A B C D

Thickness of the foil spacer used

2mm 3mm 1.5mm 1mm

Question 20

True or False that the periodontal ligament being resilient serves to cushion the impacting forces applied to natural teeth.

True or False Reddy KK, et al. BMJ Case Rep 2013. doi:10.1136/bcr-2012-008420

SADTJ Vol 6 Issue 2

Question 21

True or False that for clinical use soft denture lining materials should have a bond strength of 3.5kg/cm²?

True or False Question 22 A B C

The Patient reported that with the soft liner his grinding was

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SADTJ Vol 6 Issue 2

CHARACTERIZATION OF DIFFERENT WATER/ POWDER RATIOS OF DENTAL GYPSUM USING FIBER BRAGG GRATING SENSORS

2.8

INTRODUCTION

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MATERIALS AND METHODS

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RESULTS

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DISCUSSION

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CONCLUSIONS

ACKNOWLEDGEMENTS

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REFERENCES

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CHARACTERIZATION OF DIFFERENT WATER/POWDER RATIOS OF DENTAL GYPSUM USING FIBER BRAGG GRATING SENSORS

Question 23 True or False that the setting reaction of gypsum mixed with water is a exothermic chemical reaction. True or False Question 24 A B C D

I II III IV

Question 25 A B C D

What type of dental gypsum was analysed?

How many w/p ratios were examined?

6 5 4 3

Question 26 What was the temperature at which the water was mixed with the gypsum powder? A B C D

21˚C 25˚C 23˚C 18˚C

Question 27

True or False that the humidity was set at 60 % for all experiments.

True or False Question 28

Does Fig. 4 and 5 show that the maximum strain and temperature variation values increase as the w/p ratio also increases?

A Yes B No

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Question 29 The greater the amount of water used, the fewer the nuclei per unit volume and hence â&#x20AC;Ś A more expansion B less expansion Question 30 True or false that the change in water amount aďŹ&#x20AC;ects the setting expansion of the gypsum product, which will compromise the accuracy of the fit of the fabricated prosthetic work. True or False

SADTJ Vol 6 Issue 2

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