Trends in Material Choice for Posterior Restorations in an Israeli Dental School: Composite Resin Versus Amalgam

A survey of amalgam use to guide dental education curriculums

OBJECTIVES

To identify behavioral, preferential, and professional factors influencing the use of amalgam in private practices; and to compare the incidence of the placement of amalgam versus composite resin restorations in the province of Ontario and its pedagogical implications on dental curricula.

METHODS

Participants responded anonymously to a 23-question online survey about their current use of dental amalgam and composite resins as well as their opinions regarding both dental materials. The explanatory variables were associated bivariately with the outcome variables, and the most significant predictors were identified using the multivariate analysis.

RESULTS

Higher percentages of amalgam use were reported among clinicians who trained in Canada only (P = .009), who graduated before 1980 (p = <.001) and who work outside private practice (p = <.001). Familiarity with amalgam was higher among clinicians who are female (p = <.001), older (p = <.001), trained only in Canada (p = .017), who graduated prior to 2000 (p = <.001), and who work in locations with populations over 100,000 (p = .042). Familiarity with composite resin was higher among clinicians who graduated more recently (p = .002). A higher percentage of females (p = <.001), younger clinicians (p = <.001), recent graduates (p = <.001), and clinicians who work in private practice (p = .043) suggested that over 50% of dental student training time be allocated to amalgam.

CONCLUSIONS

Decreased amalgam use was reported by later dental graduates and private practitioners; this may be impacted by familiarity with dental amalgam. As amalgam remains a safe and effective dental material, its removal may not be prudent. Dental educators play a crucial role in the future of amalgam opinion and use.

Teaching and placement of dental amalgam restorations at South African dental schools

Introduction

This paper set out to investigate the relationship between teaching and clinical practice of direct posterior restoration placement at tertiary dental institutions in South Africa.

Methods

A cross-sectional study using a mixed methods approach was conducted, and all the South African dental schools were invited to participate. The quantitative phase of the study analyzed the Conservative Dentistry department's records of direct restorations at a single dental school. The number of amalgam and tooth-colored restorations placed by students in the fourth and fifth year of the program from 2004 to 2019 were compared. During the qualitative phase, semi-structured interviews were held with staff from the four dental schools involved with the teaching of direct posterior restorations.

Results

The predominant direct posterior restoration placed in student clinics over a 15-year period at a South African dental school was tooth colored (75%). Teaching times do not correspond to a decrease in the placement of dental amalgam restorations for both one-surface and two-surface posterior restorations and a concomitant increase in the tooth-colored restorations.

Discussion

Academic staff involved in teaching identified that South Africa's ratification of the Minamata Convention has consequences for dental education and training. However, all schools reported that dental amalgam would continue to be taught in the absence of an appropriate alternative.

Resin Composite Versus Amalgam Restorations Placed in United States Dental Schools

OBJECTIVES

To investigate the latest teaching policies for posterior resin composite placement versus amalgam and to determine the actual numbers of posterior resin composites versus amalgam restorations placed in American dental schools from 2008 to 2018.

METHODS

Emails were sent to the deans of all 66 dental schools in the United States to collect data in the forms of: 1) Questionnaire on current teaching policies of posterior composite and amalgam restorations; and 2) Data entry form to collect the actual numbers of posterior composite and amalgam restorations placed in their clinics. Descriptive statistics were used to summarize ratios of posterior restorations. Inferential analysis (chi-square test and z-test) was employed to compare posterior restoration proportions over time and within each year. Level of significance was set at 0.05.

RESULTS

For the teaching questionnaire, the response rate was 52% (n=34). Seventy-six per cent of the responding schools reported that they assign 50% or more of their preclinical restorative teaching time towards posterior resin composite placement, while 50% of the responding schools devoted 25% or less towards amalgam teaching. Data entry response rate was 26% (n=17). In 2008, amalgam and resin composite restorations were placed almost equally. However, resin composite restorations were placed significantly more frequently from 2009 onwards in all responding schools. The results revealed a significant ongoing increasing trend in placing posterior resin composites in all responding schools over time (p<0.05).

CONCLUSIONS

Data analysis revealed a clear trend towards an increase in posterior resin composite restoration placement and a decrease in the number of amalgam restorations. However, the time assigned for posterior resin composite teaching is not aligned with quantity of restorations placed. Review and adjustment of the time allocated for teaching and training of each material are suggested.

Practice-based analysis of direct posterior dental restorations performed in a public health service: Retrospective long-term survival in Brazil

The aim of this retrospective study was to evaluate the survival and associated factors for the longevity of direct posterior restorations and to verify whether the geographic location of public health units could influence the long-term survival of such restorations. Data were extracted from electronic patient files of the Brazilian public oral health services. The sample comprised 2,405 class I and II restorations performed 4 to 24 years ago (mean, 8.9 years) in 351 patients (6.8 teeth/patient) across 12 public health units located in different city regions (42 professionals—55 restorations). The restoration was considered successful if it had not been repaired or replaced at the time of evaluation; failure was defined as replacement of the restoration, the need for endodontic treatment, tooth/restoration fracture or tooth extraction. Data were analyzed using the Kaplan-Meier test for restoration survival and Cox regression to evaluate the factors associated with failure. The majority of the restorations involved the use of amalgam (85%), involved a single face (70%), and were without pulp/dentin capping (85%). The overall survival rate was 95%, and the mean observation time was 8.9 years. The restoration survival was 79% (95% CI: 60.6–89.5) over 24 years, and the mean survival time was 22.2 years (95% CI: 21.9–22.6 years). The annual failure rate up to 24 years was 0.9%. After the adjustment, only the number of restored faces and the geographic location where the restoration was performed remained associated with failure of the restoration. The direct posterior restorations performed at the evaluated public health service units presented high survival rates. The restorations of people with lower access to POHS had lower survival rates. Class I restorations presented higher survival rates than class II restorations with two or more faces, regardless of the restorative material used.

Fall of amalgam restoration: a 10-year analysis of an Australian university dental clinic

BACKGROUND

The use of amalgam in Dentistry has decreased since the 1980s. This study aimed to (i) assess the time trend in the usage of amalgam and composite in posterior teeth at Griffith University Dental Clinic from 2010 to 2019; (ii) to test whether this trend varied according to the dental health provider.

METHODS

We analysed clinic records from 2010 to 2019. Prais-Winsten analyses were performed, and the average annual percentages change (AAPC) for amalgam and composite was estimated.

RESULTS

There were 397,013 procedures, including 80,995 direct posterior restorations. Amalgam use decreased from 12.9% in 2010 to 0.5% in 2019 among students, while composite use increased from 87.1% to 99.5% of posterior restorations. The annual increase of the composite was 1.4% per year for students, while amalgam decreased by 30.2% per year on average. A similar trend was noted among the dentists.

CONCLUSIONS

A significant decrease in the use of amalgam was observed over time for both students and professionals. This trend raises questions about curriculum reviews, focusing on the repair, maintenance and safe removal of amalgam while reinforcing the learning on Minimally Invasive Dentistry and composite restorations based on the patient's caries risk.

Dental educators' attitudes towards the teaching of dental amalgam

OBJECTIVE

To ascertain dental educators' attitudes towards the teaching of dental amalgam at dental schools in Australia and identify preferred curricular approaches in a potentially "amalgamless" profession.

METHODS

A mixed methods analysis was employed based on an open-ended response survey followed by a closed-ended questionnaire. Identification of key issues from the survey helped frame the questionnaire. Participants included those with expertise in operative and restorative dentistry, with direct involvement in curriculum development or delivery, at Australian dental schools.

RESULTS

Participants numbered fifteen and represented seven of the nine dental schools in Australia. Key themes identified and explored included the following: (in)consistency of approach to teaching restorative dentistry; a perceived disconnect between undergraduate study and the "real world"; a need for a focus on teaching of alternatives to dental amalgam (80 per cent (strongly) agreeing); the contradictory nature of the evidence base and literature that is not readily understood; the need for more post-graduate education relating to adhesive restorative materials (86 per cent (strongly) agreeing); the need for dental amalgam to continue to be available; formal understandings (guidelines) as to the use of dental amalgam; dental schools in Australia being heard on these issues; and the relevance of this issue (100 per cent (strongly) agreeing the issue is topical and important).

CONCLUSION

There is a broad consensus of dental educators at Australian dental schools as how best to approach the teaching of amalgam if a phase-down is to occur and the issues any such approach may face.

The Dental Amalgam Phasedown in New Zealand: A 20-year Trend

BACKGROUND AND OBJECTIVES

Information on the choice of material and performance of restorations placed in a dental practice annually is limited. The Minamata Convention on Mercury is likely to affect the use of amalgam worldwide. The objective of this research was to investigate the use of restorative materials at the University of Otago Faculty of Dentistry in New Zealand from 1998 to 2017.

METHODS

Data from the Faculty of Dentistry's database from the years of interest were compiled. These data included information on the characteristics of restorations, including information on the material used and number of surfaces involved for each restoration. The tooth in which each restoration was placed was categorized by arch, tooth type, and deciduous or permanent dentition.

RESULTS

Records identified 227,514 permanent restorations placed from January 1998 to December 2017, of which 91.7% were direct restorations. Among direct restorations, composite resin was the most commonly used material, followed by amalgam, glass ionomer, and compomer. The use of amalgam for direct restorations decreased from 52.3% of direct restorations in 1998 to 7.1% in 2017. A corresponding increase was observed in the use of tooth-colored direct restorations, particularly composites. Among indirect restorations, porcelain fused to metal, gold, and stainless steel (in pediatric applications) were the materials most frequently used.

CONCLUSIONS

Despite having no official policy on reducing the use of dental amalgam, the Faculty of Dentistry is following the global trend in reducing its use, with composite resin now well established as the predominant restorative material used. If the current rate of decline persists unchecked, the Faculty of Dentistry could transition to being amalgam free by 2020, although it seems likely that the characteristics and principles of use of the material (and its removal) will be taught for some time to come. This knowledge is important to planning curriculum changes needed to prepare graduates for clinical practice.

Fluorescence-aided selective removal of resin-based composite restorative materials: An in vitro comparative study

AIM

During removal of resin-based composite (RBC) restorations, removal of adjacent sound tooth structure can easily occur. The aim of the study was to compare the fluorescence-aided identification of restorations (FAIR) method with the conventional method (CM) using white light illumination for the selective removal of tooth-colored RBC restorations.

MATERIALS AND METHODS

Sixty extracted teeth were used to prepare 15 sets of models, each with four teeth. Cavities were prepared in each tooth and a digital three-dimensional scan of each model was taken in STL format. The teeth were then restored with either Admira Fusion, GRADIA DIRECT X, or TPH Spectra LV (20 teeth for each). Five dentists removed the restorations from sets of 12 teeth (six each using FAIR, and six using CM). From a postoperative scan, changes in intercuspal cavity width were measured using the 3D tool CAD software.

RESULTS

Using FAIR, changes in cavity width were not significant (P = .17), and there was no significant interoperator variance (P = .3). In contrast, when using CM, there was a significant increase in cavity width (P = .0025), and considerable interoperator variance (P = .03). FAIR allowed faster completion of the task of restoration removal (average time 100.23 seconds, vs 165.13 seconds from CM).

CONCLUSION

The FAIR method facilitates the selective removal of tooth-colored RBC restorations, with reduced time and less inadvertent removal of sound tooth structure.

CLINICAL SIGNIFICANCE

By enhancing the differentiation between the restorative material and adjacent tooth structure, the FAIR method facilitates removal of tooth-colored restorations, while concurrently prevents unnecessary removal of healthy tooth structure. The same approach may have applications for removal of resin-based materials such as resin cements under restorations, resin fissure sealants, and orthodontic brackets bonding resins.

Next generation of dentists moving to amalgam-free dentistry: Survey of posterior restorations teaching in North America

OBJECTIVES

The dental field is gradually reducing the use of amalgam and moving towards adhesive restoration. This change is in accordance with the advancement and improvement of composite resin materials and adhesion systems. Consequently, posterior cavity preparations teaching should be re-examined to determine whether dental schools are adapting their curriculum to fit the current trends in dentistry and what rationale supports their decisions.

METHODS

An online questionnaire was constructed to assess the time dedicated to teaching composite materials and amalgam, in addition to the principles of posterior preparations, for composite restorations in North American dental schools.

RESULTS

A total 33 schools responded to the questionnaire. A large variation was found in teaching methods and techniques of posterior restorations. The reasoning for teaching amalgam restorations was diverse as were the principles of composite resin preparation taught.

CONCLUSION

No agreed principles of cavity preparation for resin composite restorations were found, as opposed to explicit agreement on amalgam cavity preparations. The results demonstrate a lack of clear guidelines for cavity preparation of resin composite restorations. Dental schools may benefit when a consensus on this topic is achieved.

Direct Posterior Restorations: A 13-Year Survey of Teaching Trends and Use of Materials

Objective:

The study aimed to evaluate teaching trends and use of materials in direct posterior restorations during a 13-year period in an Israeli dental school.

Methods:

Data registered in computerized files, relating to posterior restorations performed in the student clinic during the past 13 years (2004-2016), were collected. The restorative materials used (ie, amalgam vs composite), the type of tooth, and the number of surfaces restored were analyzed.

Results:

Data analysis included 26,925 restorations performed during 13 years. The number of one-surface composite restorations increased from 54.7% (n=330) to 81.9% (n=873). Two-surface restorations increased from 33.3% (n=254) to 64.3% (n=721). The percentage of amalgam restorations in three-surface restorations decreased from 72.08% to 51.34% (n=173). Analysis of tooth type showed that in 2016, the number of composite restorations performed in premolars reached 80.87% (n=723) and in molars 63.50% (n=1035). The percentage of composite restorations in the mandible and the maxilla was virtually equal.

Conclusions:

A clear trend in favor of composite resin restorations is evident in the 13-year survey and suggests a move toward an amalgam-free era.

Reparative Dentistry: Possibilities and Limitations

Purpose of Review

Defective dental restorations are amongst the most common encounters in general dental practice. Replacement of defective restorations is often costly and commonly results in the sacrifice of sound tooth structure, thereby compromising the vitality of the dental pulp, potentially resulting in the acceleration of the restoration cycle and premature loss of the restored tooth. With advances in adhesive dentistry, ‘reparative dentistry’ is becoming an important area of minimally invasive dentistry. This article highlights the detrimental biological effects of restoration replacement and provides an overview of current knowledge and understanding of restoration repair as a safe and effective alternative approach to replacement.

Recent Findings

The literature reviewed showed that a growing body of evidence from clinical studies indicates that repaired restorations have similar survival outcomes in patients with low and medium caries risk compared to replaced restorations and are clinically acceptable over a 12-year follow-up of clinical service. Teeth with repaired restorations are less likely to require aggressive interventions such as endodontic treatment or extraction compared to those with replaced restorations.

Summary

Repair options should be carried out wherever possible as minimally interventional procedures in order to increase the longevity of the remaining part of the restoration and the restored tooth unit. Restoration replacement should be considered as the last resort when there are no other viable alternatives.

In vitro aging behavior of dental composites considering the influence of filler content, storage media and incubation time

Objective

Over time dental composites age due to mechanical impacts such as chewing and chemical impacts such as saliva enzymes and food ingredients. For this research, the focus was placed on chemical degradation. The objective of this study was to simulate hydrolysis by using different food simulating liquids and to assess their impact on the mechanical parameter Vickers microhardness (MHV) and the physicochemical parameter contact angle (CA).

Methods

Specimen of three composites (d = 6 mm, h = 2 mm; n = 435) classified with respect to their filler content (wt%), namely low-filled, medium-filled and highly-filled, were stored for 0, 14, 30, 90 and 180 days in artificial saliva (pH 7), citric acid (pH 3; pH 5), lactic acid (pH 3; pH 5) and ethanol (40%vol; 60%vol) and assessed regarding to MHV and CA. Statistics: Kruskal-Wallis test, stepwise linear regression, bivariate Spearman Rank Correlation (p < 0.05).

Results

While stored in artificial saliva, acid and ethanol the CA decreased especially for the low- and medium-filled composites. It was shown that rising the filler content caused less surface changes in the CA. Storage in ethanol led to a significant decrease of MHV of all composites. Regression analysis showed that the effect of in vitro aging on MHV was mainly influenced by the composite material and therefore by filler content (R² = 0.67; p < 0.05). In contrast, the CA is more influenced by incubation time and filler content (R² = 0.2; p < 0.05) leading to a higher risk of plaque accumulation over time. Significance: In vitro aging showed significant changes on the mechanical and physicochemical properties of dental composites which may shorten their long-term functionality. In conclusion, it can be stated, that the type of composite material, especially rising filler content seems to improve the materials’ resistance against the processes of chemical degradation.

In Vitro Detection of Caries Around Amalgam Restorations Using Four Different Modalities

Objective:

The aim of this study was to evaluate the ability of PTR-LUM (The Canary System, CS), laser fluorescence (DIAGNOdent, DD), LED fluorescence (Spectra), and visual inspection (ICDAS II) to detect natural decay around bonded amalgam restorations in vitro.

Methods:

Seventeen extracted human molars and premolars, consisting of visually healthy (n=5) and natural cavitated (n=12) teeth were selected. For the carious teeth, caries was removed leaving some decayed tissue on the floor and or wall of the preparation. For sound teeth, 3 mm. deep cavity preparations were made and teeth were restored with bonded-amalgam restorations. Thirty-six sites (13 sound sites; 23 carious sites) were selected. CS and DD scans were performed in triplicate at 2, 1.5, 0.5, and 0 mm away from the margin of the restoration (MOR). Spectra images were captured for the entire surface, and dentists blinded to the samples provided ICDAS II scoring.

Results:

Canary Numbers (Mean±SE) for healthy and carious sites at 2, 1.5, 0.5, and 0 mm from the MOR ranged from 12.9±0.9 to 15.4±0.9 and 56.1±4.0 to 56.3±2.0, respectively. DD peak values for healthy and carious sites ranged from 4.7±0.5 to 13.5±2.99, and 16.7±3.7 to 24.5±4.4, respectively. For CS and DD, sensitivity/specificity for sites at 2.0, 1.5, 0.5, 0 mm ranged from 0.95-1.0/0.85-1.0, and 0.45-0.74/0.54-1.0, respectively. For ICDAS II, sensitivity and specificity were 1.0 and 0.17, respectively. For Spectra, data and images were inconclusive due to signal intereference from the amalgam restoration.

Conclusions:

Using this in-vitro model, CS and DD were able to differentiate between sound and carious tissue at the MOR, but larger variation, less reliability, and poorer accuracy was observed for DD. Therefore, CS has the potential to detect secondary caries around amalgam restorations more accurately than the other investigated modalities.

Attitudes of dentists and interns in Riyadh to the use of dental amalgam

Background

Studies investigating the attitudes of Saudi dentists to the use of amalgam for restorations are relatively rare. Considering the goals set forth by the Minamata Convention on Mercury, it appears prudent to investigate the attitudes of experienced dentists and fresh dental graduates to the use of amalgam. The aim of this study was to assess the attitudes of Saudi dentists and interns working in Riyadh, Saudi Arabia to the use of amalgam. Using a convenience sampling methodology, a total of 400 Saudi dentists and interns were contacted to request their participation in this cross-sectional questionnaire-based study. The questionnaire consisted of socio-demographic and practice characteristics such as gender, type of practice, as well as their service sector and questions related to the use of dental amalgam. The data obtained was analyzed using Chi square tests to compare differences in distribution between groups. P values of less than 0.05 were considered statistically significant.

Results

The overall response rate was 84% (336 of 400 potential participants). The majority of the participants (80.7%) did not use dental amalgam for restorations in their clinical practice frequently. A significantly higher number of participants working in private sector did not use amalgam frequently (P = 0.004), agreed on replacing good amalgam restoration with composite resin (P < 0.000) and on stopping the use of amalgam as a final restoration (P = 0.017) compared to participants working in public sector. A significantly higher number of interns did not use amalgam in their clinical practice frequently (P < 0.000), agreed on replacing good amalgam restoration with composite resin (P = 0.002) and on stopping the use of amalgam as a final restoration (P < 0.000) compared to dentists.

Conclusions

Within the limitations of this study, dental amalgam seems to be less frequently used among the surveyed Saudi dentists and interns working in Riyadh. Fresh dental graduates used amalgam less frequently compared to experienced dentists. Furthermore, private dental practitioners showed a propensity to replace existing well-placed amalgam restorations with resin composite which reinforces their market-oriented attitude reported in earlier studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-016-2294-x) contains supplementary material, which is available to authorized users.

Restoration Survival: Revisiting Patients' Risk Factors Through a Systematic Literature Review

A literature review was conducted to investigate the influence of patient-related factors on restoration survival in posterior permanent teeth as well as to report the methods used to collect these factors. The selection of articles on longitudinal clinical studies investigating the survival of posterior restorations (except full crowns and temporary fillings) and including patient-related factors was performed by applying predefined criteria. The review was organized into two parts, the first describing how patient factors were assessed in the studies (n=45) and the second presenting the statistical significance (n=27) and size of the effect (n=11) of these factors on restoration survival. Patient-related factors mentioned in the studies included age; gender; caries risk; caries activity/severity; decayed, missing, filled teeth; number of restorations; oral hygiene; and bruxism, among others. Sixteen studies included the patient age or age range in the analysis, which was found to be significant in 47% of the studies. Regarding gender, four of 17 reports found a significant effect on survival, showing more failures for men in three studies. The caries risk profile or related variables were included in the analysis of 15 studies, and a significant effect on survival was reported for high-caries-risk individuals (or related variables) in 67% of these studies. Bruxism was also found to influence restoration survival in three of six studies where this variable was investigated. Some issues were found regarding the reporting of methods used to classify patients according to risk and were thoroughly discussed. In view of the information gathered in this review, the assessment of patient factors along with other variables should become part of clinical studies investigating restoration survival, since several of these factors were shown to influence the failure of restorations, regardless of the material type.

Does the adhesive strategy influence the post-operative sensitivity in adult patients with posterior resin composite restorations?: A systematic review and meta-analysis

OBJECTIVES

A systematic review and meta-analysis were performed on the risk and intensity of postoperative sensitivity (POS) in posterior resin composite restorations bonded with self-etch (SE) and etch-and-rinse (ER) adhesives.

SOURCE

A comprehensive search was performed in the MEDLINE via PubMeb, Scopus, Web of Science, LILACS, BBO and Cochrane Library and SIGLE without restrictions. The abstracts of the annual conference of the IADR (1990-2014), unpublished and ongoing trials registry were also searched. Dissertations and theses were searched using the ProQuest Dissertations and Periodicos Capes Theses databases.

STUDY SELECTION

We included randomized clinical trials that compared the clinical effectiveness of SE and ER used for direct resin composite restorations in permanent dentition of adult patients. The risk/intensity of POS was the primary outcome. The risk of bias tool of the Cochrane Collaboration was used. The meta-analysis was performed on the studies considered 'low' risk of bias.

DATA

After duplicates removal, 2600 articles were identified but only 29 remained in the qualitative synthesis. Five were considered to be 'high' risk of bias and eleven were considered to be 'unclear' in the key domains, yielding 13 studies for meta-analysis. The overall relative risk of the spontaneous POS was 0.63 (95% CI 0.35 to 1.15), while the stimuli-induced POS was 0.99 (95% CI 0.63 to 1.56). The overall standardized mean difference was 0.08 (95%CI -0.19 to 0.35). No overall effect was revealed in the meta-analyses, meaning that no influence of the ER or SE strategy on POS.

SIGNIFICANCE

The type of adhesive strategy (ER or SE) for posterior resin composite restorations does not influence the risk and intensity of POS. CRD42014006617.

Dentists' restorative decision-making and implications for an 'amalgamless' profession. Part 1: a review

The Minamata Convention has agreed to a worldwide reduction and ultimate elimination in the production and use of mercury containing products. This will have implications for the practice of dentistry. Australian organizations' pronouncements on the issue are limited and research examining the Australian context dated. The restoration of teeth with direct materials has changed significantly since the 1980s. Up to this time amalgam was the material of choice for direct posterior restorations. Its properties and guidelines for placement were, and remain, well established. Resin composite has replaced amalgam as the material of choice in many clinical situations. Despite inherent clinical disadvantages compared to amalgam, there continues to be a shift toward greater use of resin composite. There is consensus worldwide that the restoration of posterior teeth using resin composite now exceeds that of amalgam. The reasons for this are reviewed in this article along with current evidence and commentary relating to direct restorative and evidence-based decision-making, minimally invasive approaches, and approaches to education. The implications for these in an 'amalgamless' profession are identified.

Longevity of Direct Restorations in Stress-Bearing Posterior Cavities: A Retrospective Study

The aims of this retrospective clinical study were to compare the longevities of direct posterior amalgam restorations (AMs) and resin composite restorations (RCs) that were subjected to occlusal stresses and to investigate variables predictive of their outcome. A total of 269 AMs and RCs filled in Class I and II cavities of posterior teeth were evaluated with Kaplan-Meier survival estimator and multivariate Cox proportional hazard model. Seventy-one retreated restorations were reviewed from dental records. The other 198 restorations still in use were evaluated according to modified US Public Health Service (USPHS) criteria by two investigators. The longevity of RCs was significantly lower than that of AMs (AM = 8.7 years and RC = 5.0 years, p&lt;0.05), especially in molars. The prognostic variables, such as age, restorative material, tooth type, operator group, diagnosis, cavity classification, and gender, affected the longevity of the restorations (multivariate Cox regression analysis, p&lt;0.05). However, among the restorations working in oral cavities, their clinical performance evaluated with modified USPHS criteria showed no statistical difference between both restoratives. In contrast to the short longevity of RCs relative to AMs, the clinical performance of RCs working in oral cavities was observed to be not different from that of AMs. This suggests that once a RC starts to fail, it happens in a rapid progression. As posterior esthetic restorations, RCs must be observed carefully with periodic follow-ups for early detection and timely repair of failures.

Incorporating New Materials and Techniques into Clinical Practice

This article outlines the subjects presented and discussed at the December 2012 IADR Dental Materials Innovation Workshop held at King’s College London. Incorporating new materials and techniques into clinical practice was considered from 4 perspectives: (1) Accelerating the “research to regulatory approval” process was presented with current developments in the United States, with the National Institutes of Health/Food and Drug Administration process as a working example; (2) intellectual property and regulatory requirements were discussed across the well-established US and EU frameworks, as well as the more recently developed procedures across Brazil, Russia, India, and China; (3) the challenges and opportunities of incorporating innovations into dental education were considered with reference to the future needs of both students and faculty; and (4) the key but difficult and unpredictable step of translating such innovations into routine dental practice was then explored. Constructive and far-ranging discussion among the broadly based Workshop participants (from dental research, education, practice, and industry, as well as environmental organizations and the World Health Organization) mapped out key issues for the future. The focus was on facilitating the more timely adoption of improvements in both materials and techniques to improve patient health and health systems, while minimizing environmental impact.

Longevity of posterior dental restorations and reasons for failure

Tooth-coloured restorative materials are being used increasingly more often in Class II preparations in permanent teeth. Using a practice-based study design, we aimed to assess the survival time of Class II restorations and to identify factors relevant to their longevity. Class II restorations (n = 4,030), consisting of resin composites (81.5%), compomers (12.7%), amalgams (4.6%), and glass-ionomer cement restorations (1.2%), were placed in 1,873 patients with a median age of 15 yr. In total, 92.7% of restorations were placed due to primary caries and 5.8% were replacements. After an average follow-up period of 4.6 yr, 61.6% of the restorations were successful, 11.2% had failed, and 27.2% were not available for evaluation (owing to patient drop-out). The mean annual failure rate was 2.9% for resin-composite restorations and 1.6% for amalgams. For resin-composite restorations, secondary caries was the most common reason for replacement (73.9%), followed by loss (8.0%), fracture (5.3%), and marginal defects (2.4%). Multilevel Cox-regression analyses identified young age of the patient, high previous caries experience, deep cavities, and saucer-shaped preparation technique as predisposing to shorter longevity of resin-composite restorations. One brand of resin composite had a shorter survival time than the others.