The Post-Amalgam Era: Norwegian Dentists' Experiences with Composite Resins and Repair of Defective Amalgam Restorations

Clinical Difficulties Related to Direct Composite Restorations: A Multinational Survey

AIMS

Composite materials are widely used in dentistry for direct tooth restorations. However, they are highly sensitive to the working technique employed during the restorative procedure. Even minor procedural errors can have a significant impact on the quality including the longevity of the restoration. Hence the aim of this study was to determine the material preferences and analyse the clinical problems associated with direct composite restorations in a cohort of dentists.

METHODS

A 20-item online questionnaire was created in English and administered 1830 general dentists and specialists in 13 countries. The first section of the questionnaire included four questions to elicit demographic data, and the second section comprised 16 questions focused on material preferences for conservative restorations, durability of composite restorations, and the most challenging stages the dentists faced during the composite restorative procedures.

RESULTS

Respondents decided most often to use composite materials for the tooth restorations (OR 997.4, 95% CI 233.8-4254.8, P value <.001). Most respondents indicated that the durability of composite restorations was approximately 7 to 10 years (41.5%). Among the factors affecting durability, maintenance of a dry cavity was the most often reported reason (47.1%) and the foremost challenge faced by dentists (61.0%) during the composite restorative procedures.

CONCLUSIONS

Our study confirmed that resin-based composites are the most popular material for direct restoration in many countries. Although working with this material is difficult and involves multiple steps, maintaining a dry cavity during bonding, and material application may affect the therapeutic success and durability of these restorations. Clinicians need to be attentive to this issue and be prepared to adapt their decision-making and consider opting for alternative restorative materials, if appropriate.

Contact allergies to dental materials in patients

BACKGROUND

Concerns regarding contact allergies and intolerance reactions to dental materials are widespread among patients. Development of novel dental materials and less frequent amalgam use may alter sensitization profiles in patients with possible contact allergy.

OBJECTIVES

To analyse current sensitization patterns to dental materials in patients with suspected contact allergy.

METHODS

This retrospective, multicentre analysis from the Information Network of Departments of Dermatology (IVDK) selected participants from 169 834 people tested in 2005-2019 and registered with (i) an affected area of 'mouth' (and 'lips'/'perioral'), (ii) with the dental material in question belonging to one of three groups (dental filling materials, oral implants or dentures or equivalents) and (iii) with patch-testing done in parallel with the German baseline series, (dental) metal series and dental technician series.

RESULTS

A total of 2730 of 169 834 tested patients met the inclusion criteria. The patients were predominantly women (81.2%) aged ≥ 40 years (92.8%). The sensitization rates with confirmed allergic contact stomatitis in women (n = 444) were highest for metals (nickel 28.6%, palladium 21.4%, amalgam 10.9%), (meth)acrylates [2-hydroxyethyl methacrylate (HEMA) 4.8%] and the substances propolis (6.8%) and 'balsam of Peru' (11.4%). The most relevant acrylates were HEMA, 2-hydroxypropyl methacrylate, methyl methacrylate, ethylene glycol dimethacrylate and pentaerythritol triacrylate. Few men were diagnosed with allergic contact stomatitis (n = 68); sensitization rates in men were highest for propolis (14.9%) and amalgam (13.6%).

CONCLUSIONS

Allergic contact stomatitis to dental materials is rare. Patch testing should not only focus on metals such as nickel, palladium, amalgam and gold, but also (meth)acrylates and the natural substances propolis and 'balsam of Peru'.

Biomechanical performance of resin composite on dental tissue restoration: A finite element analysis

This study investigates the biomechanical performance of various dental materials when filled in different cavity designs and their effects on surrounding dental tissues. Finite element models of three infected teeth with different cavity designs, Class I (occlusal), Class II mesial-occlusal (MO), and Class II mesio-occluso-distal (MOD) were constructed. These cavities were filled with amalgam, composites (Young's moduli of 10, 14, 18, 22, and 26 GPa), and glass carbomer cement (GCC). An occlusal load of 600 N was distributed on the top surface of the teeth to carry out simulations. The findings revealed that von Mises stress was higher in GCC material, with cavity Class I (46.01 MPa in the enamel, 23.61 MPa in the dentin), and for cavity Class II MO von Mises stress was 43.64 MPa, 39.18 MPa in enamel and dentin respectively, while in case of cavity Class II MOD von Mises stress was 44.67 MPa in enamel, 27.5 in the dentin. The results showed that higher stresses were generated in the non-restored tooth compared to the restored one, and increasing Young's modulus of restorative composite material decreases stresses in enamel and dentin. The use of composite material showed excellent performance which can be a good viable option for restorative material compared to other restorative materials.

Nature-mimicking layering with composite resins through a bio-inspired analysis: 25 years of the polychromatic technique

OBJECTIVES

For decades, the dental community has discussed which materials would be the ideal substitutes for lost tooth structure. Initially, the biomimetic approach advocated that feldspathic ceramics would be the material of choice for enamel. However, given the complexity of obtaining excellent dental technicians and the financial cost, are composite resins a suitable replacement? The optical properties with opalescence and fluorescence effects, as well as this material's high fracture toughness, indicate it as a long-lasting restorative material. However, because this material depends on the operator's expertise, knowledge of layering techniques and the selection of each material for the different layers is required. Thus, knowledge of the polychromatic technique through a bioinspired approach is necessary to obtain results of life-like restorations. This article aims to review the polychromatic layering technique (PLT), considering the optical and mechanical properties of dentin and enamel and correlating these properties with current composite resins to guide clinicians in selecting the most suitable restoratives for their clinical challenges.

CLINICAL CONSIDERATIONS

The polychromatic layering technique is revisited, cross-referencing the properties of dentin and enamel with current composite resin restoratives and their biomimetic properties. The effectiveness and predictability of the PLT are corroborated in clinical cases of varying degrees of difficulty requiring different layering strategies.

CONCLUSION

After the bio-inspired analysis, using nature as a model to be understood and followed, it is possible to note how the polychromatic technique remains current and viable in mimicking nature, providing esthetic and natural results in the layering of composite resins.

CLINICAL SIGNIFICANCE

Composite resins effectively replicate the optical and mechanical characteristics of natural dentin and enamel through the bioinspired approach presented by the polychromatic layering technique.

Direct restorations and enhanced caries prevention among 20- to 60-year-olds attending Helsinki City Public Dental Service - a register-based observation

OBJECTIVE

Our retrospective register-based observational study evaluated age-specific aspects and changes in volume and content of direct restorative procedures, pulp cappings and enhanced caries prevention measures given to adults.

METHODS

Data included all treatments provided for 20- to 60-year-olds visiting the Helsinki City Public Dental Service (PDS) in 2012 and 2017. For both years, the data were aggregated into 5-year age groups. Data included means of DMFT indices, number and size of direct restorations, number of specific codes for pulp cappings and enhanced prevention.

RESULTS

Around half of all patients received restorations, 39,820 (50.9%) in 2012 and 43,392 (45.9%) in 2017. The greatest increase in DMFT means by age cohort was found for the 2012 age cohort of 25- to 29-year-olds and the smallest for the 2012 age cohort of 45- to 49-year-olds. In each same-age group and each age cohort, the enhanced prevention in 2017 was less frequent than in 2012. The proportion of two-surface restorations accounted for 44.7% of procedures in 2012 and 45.9% in 2017, followed by an increasing proportion of one-surface restorations, from 28.3% in 2012 to 32.9% in 2017. Associations between restoration size and age group were highly significant (p < .001).

CONCLUSIONS

The volume of direct restorative procedures and enhanced prevention measures were strongly age-dependent. Restorative treatment procedures were more frequent in older age groups than in younger age groups, and vice versa for enhanced prevention and pulp cappings. The magnitude of restorative treatment decreased slowly from 2012 to 2017, and overall enhanced preventive treatment was limited.

How French dentists manage defective restorations: Evidence from ReCOL the French dental practice-based research network--A survey study

OBJECTIVES

The objective of this study was to describe the knowledge, opinions and practices about the defective restoration (DR) management of French general dental practitioners (GDPs).

METHODS

A cross-sectional, online survey-based study was carried out amongst 378 GDPs - members of the dental practice-based research network in France (ReCOL). Bivariate comparisons were made using Fisher's exact test to assess the association of the respondent characteristics (age, gender…) with the decision to repair DRs, and responses to clinical cases.

RESULTS

The response rate was 82.9%. 50.4% of the respondents declared they at least sometimes consider DRs repair in their clinical practice instead of DRs total replacement. For the 89.8% who at least rarely repaired DRs, the main characteristic determining the therapeutic strategy was the defect size (71%, mainly inclined to repair small defects), followed by the defect type (marginal defect or crack for more than 60% of the respondents) and the material of initial restoration (composite for 63.5%). When shown clinical photographs illustrating DRs, most of respondents proposed a replacement with inlay/onlay or crown.

CONCLUSIONS

This study indicates that a significant proportion of French GDPs do not make sufficient use of DR repair on a routine basis. A lack of knowledge of the concept seems to explain at least part of this situation. Collective and individual efforts from the profession are still needed to promote DR repair and therefore more often apply MinimalIntervention Dentistry.

CLINICAL SIGNIFICANCE

This survey shows that MID is not yet sufficiently used in routine practice in France regarding DR management. Further efforts (continuing education toward MID, public funding revaluation for MID strategies…) are needed to help GDPs to implement MID into everyday practice.

Characterization of Contemporary Conventional, Bulk-fill, and Self-adhesive Resin Composite Materials

OBJECTIVE

To evaluate the physical and biological properties of different types of flowable resin composites and their bonding ability to dentin, comparing the performance of self-adhesive and bulk-fill materials with a conventional control.

METHODS AND MATERIALS

Four flowable resin composites were tested: two self-adhesive (Y-flow [SA_YF]; and Dyad Flow [SA_DF]); one bulk-fill (Filtek Bulk Fill Flow [BF]); and one conventional composite (Opallis Flow [OF]). The microshear bond strength (μSBS) to dentin (bovine samples) was investigated at 24 hours and 6 months of storage. The materials were also characterized by degree of conversion, cross-link density, water contact angle, color stability, and cell viability (ISO 10993-5/2009) analyses. Data were analyzed using Analysis of Variance and Tukey tests (α=0.05).

RESULTS

The μSBS values were higher for control specimens at 24 hours, whereas the resin-dentin bonds were similarly distributed among the groups after aging. Adhesive failure was the most frequent pattern observed at both time intervals. SA_YF was the only material that increased the bond strength over time. Degree of conversion increased in the following order: SA_YF (28.6±1.4%) < BF (49.7±0.8%) < OF (60.0±2.0%) = SA_DF (63.6±2.3%). Cross-link density was similar among all materials. The self-adhesive composites were more hydrophilic than the other types, with BF showing the lowest water contact angle and the greatest color alteration. All resin composites had a biocompatible behavior.

CONCLUSION

Chemical composition appeared to be an influential factor affecting the physicomechanical and biological behavior of the materials tested.

Composite versus Amalgam Restorations Placed in Canadian Dental Schools

OBJECTIVES

To investigate the latest teaching policies of posterior composite placement versus amalgam and to determine the actual numbers of posterior composites versus amalgam restorations placed in Canadian dental schools, over the years from 2008 to 2018.

METHODS

Emails were sent to Chairs/Heads of Restorative Departments and Clinic Directors of all 10 Canadian dental schools to collect data in the forms of: 1) Questionnaire on current teaching policies of posterior composite and amalgam restorations; 2) data entry form to collect the actual numbers of posterior composite and amalgam restorations placed in their clinics.

RESULTS

For the teaching questionnaire, the response rate was 90% (n=9). Seven (78%) of the responding schools reported that they assign 25%-50% of their preclinical restorative teaching time towards posterior composite placement. While, three (33%) of the responding schools allocated 50%-75% of their restorative teaching towards amalgam placement. Data entry response rate was 80% (n=8). Amalgam material was dominant in the restoration distribution from 2008 to 2012. While from 2013 to 2018, resin composite material was dominant in all eight responding schools. Linear regression analysis revealed a significant increasing trend in placing posterior composites in all the responding schools over time (p<0.05).

CONCLUSIONS

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

Can removal of amalgam restorations reduce health complaints in patients with medically unexplained physical symptoms?

Design Three groups of non-equivalent patients using a prospective cohort study design. Patients who credited their medically unexplained symptoms (MUPS) to their dental amalgam restorations (amalgam cohort) were compared to two other groups: patients with MUPS who did not credit their symptoms to amalgam (MUPS cohort) and those who recognised themselves as healthy (healthy cohort). All participants initially filled in a questionnaire (Q1) which included the primary outcome: General Health Complaints index (GHC-index). The SF-36 Physical and Mental Component Summary was also included as a secondary outcome. Other outcomes, including blood, were collected but results will be reported in other publications. Patients in the amalgam and MUPS cohorts were assessed by their general physician (GP) to ensure their complaints met the criteria for MUPS. The amalgam cohort then had their amalgams removed by their dentist and, one year later, filled in the questionnaire again (Q2). The MUPS and healthy cohorts completed the Q2 two years after the Q1.Cohort selection Recruitment information for the amalgam cohort was sent to all dentists and GPs in Norway, and advertised via the Directorate of Health website and the Norwegian Dental Association. Once potential participants were identified, they were required to be assessed by both a dentist and GP to declare that oral and systemic diseases were adequately treated. The risk of deterioration of dental and medical health through participation in the study was also disclosed. For the amalgam cohort, patients had to have at least one amalgam filling and attribute the presence of these restorations to unexplained health complaints which had been present for at least three months. Patients in the MUPS cohort were recruited by their GP. These patients also had to have had unexplained health complaints for at least three months; however, the key difference being they did not attribute these complaints to amalgams. The healthy cohort was primarily recruited via dentists taking part in the study and patients self-assessed as being healthy. Both the MUPS and healthy cohorts were recruited regardless of amalgam status.Data analysis Descriptive statistics presented continuous data, and categorical data were presented as frequencies. Differences between the cohorts were analysed with analysis of variance (ANOVA) with covariate adjustment. Potential predictors of the primary outcome variable were analysed using multivariate analysis.Results In the amalgam, MUPS and healthy cohorts, 32, 28 and 19 patients, respectively, completed participation in the study. The GHC-index significantly reduced (p <0.001) between Q1 and Q2 in the amalgam cohort but not in the other cohorts. The change in the GHC-index (change in score) was greater in the amalgam cohort compared to the MUPS cohort and this was statistically significant (p = 0.004), indicating a greater reduction in health complaints.Conclusions General health complaints in patients with MUPS, that attributed their symptoms to their dental amalgams, reduced after removal of dental amalgam restorations.

[Amalgam and alternatives-discussions on mercury reduction in the environment]

Dental amalgam has been successfully used for the restoration of carious lesions for more than 180 years. It is clinically characterized by high longevity and low technique sensitivity. For decades, dental amalgam has been discussed in the public, especially due to its roughly 50% mercury content. Since the Minamata Convention was published in 2013 with the primary goal of reducing the anthropogenic mercury release into the environment, the previously muted amalgam discussion has received fresh impetus. Another considerable disadvantage of amalgam is its silver/greyish color, which simply no longer matches patients' esthetic demands.The present paper describes the basic problems with amalgam against the background of multiple biological, clinical, and health policy factors. Possible consequences of the Minamata Convention concerning legal regulations as well as the use of dental biomaterials and therefore also relating to the future national healthcare system are discussed. Finally, possible amalgam alternatives and the urgent need for biomedical research towards restorative dentistry are presented, embedded into the crucial question of whether we are actually conducting the correct debate.

Amalgam Phase-Down Part 2: UK-Based Knowledge, Opinions, and Confidence in the Alternatives

Introduction:

Amalgam use has recently been phased down, and the potential for a phase-out is being investigated.

Objectives:

The study aimed to identify knowledge of the phase-down and opinions of a potential phase-out of amalgam by UK primary care clinicians and assess their confidence in using different materials in different situations.

Methods:

An anonymized, prepiloted cross-sectional e-survey was used to assess primary care clinicians’ knowledge and opinions of the amalgam phase-down and potential phase-out and their confidence in using amalgam and the alternatives in different situations. In total, 11,902 invitations were distributed through British dentist and therapist associations. Prior hypotheses were tested alongside descriptive statistics.

Results:

Response rate was 13% (n = 1,513). Knowledge of the amalgam phase-down was low, with just 3% clinicians correctly identifying all patient groups in whom amalgam use should be avoided in the United Kingdom. Postgraduate education on posterior composite placement was high (88%), but a large majority had personal and patient-centered concerns over the suitability of the alternatives and lacked confidence when placing composite in comparison to amalgam in difficult situations (P < 0.0001). Logistic regressions revealed that the best predictors of high confidence in placing mesio-occluso-distal composites and composites in difficult situations were being a private general dentist or being primarily a composite user.

Conclusion:

Primary care clinicians have major personal and patient-centered concerns regarding the amalgam phase-down (of which they have limited knowledge) and potential phase-out. Many lack confidence in using the alternative, composite, to restore posterior teeth in difficult situations, whereas confidence in using amalgam in similar situations is high. Effective education of clinicians and understanding patients’ needs, alongside policy changes, are required to enable a successful amalgam phase-down and potential phase-out.

Knowledge Transfer Statement:

This study shows that UK primary care clinicians are worried about the phase-down of amalgam for themselves and their patients. Many lack confidence in the alternative, composite, when used in difficult situations, which is in stark contrast to amalgam. Knowledge of the phase-down is limited. There is a need for more effective education of clinicians, an understanding of patients’ values, and policy changes to ensure the success of the phase-down and potential phase-out of amalgam.

Mercury in Dental Amalgam, Online Retail, and the Minamata Convention on Mercury

The Minamata Convention on Mercury (ref. 1) is a global treaty to protect human and environmental health from adverse effects of the toxic element mercury and its compounds. During the Third Conference of Parties (COP-3) in November 2019, elimination of the use of dental amalgam in oral health care was discussed. Dental amalgam is one of the most commonly used restorative materials in oral health care due to its strength and longevity (ref. 2). However, the use of mercury in an amalgam adds to global environmental mercury pollution and can contribute to adverse health effects on humans and other organisms. The outcomes of the COP-3 meeting included a call for information on the availability at a national scale, the economic and technical feasibility of alternatives, and the associated risks or benefits. In this feature, we discuss the risks and benefits of dental amalgam, the global tracking of availability and procurement, and the implications and realities for global phase out. We suggest a better accounting of mercury use in dental amalgam is needed with sales being made only to registered practitioners via a Know Your Customer approach.

Awareness about dental amalgam among Turkish dentists and patients: a questionnaire and search engine based cross-sectional study

OBJECTIVES

There has been considerable controversy concerning the health risks and benefits of using mercury-containing amalgam. This study aimed to evaluate the Turkish dentists' and patients' preference and opinion about amalgam and to assess Internet search trends about amalgam.

METHODS

The study consists of three stages. The first two stages of the study are cross-sectional studies to verify both the patients' perception with amalgam restorations and dentists' attitudes regarding the use of dental amalgam. The third stage of the study evaluated the Internet search trends of Turkish people about mercury and amalgam related concerns between 2004 and 2018.

RESULTS

A total of 320 patients (180 female, 140 male) and 1,211 dentists (533 female, 678 male) participated in this study. Majority of the patients have no idea about the type of dental restorations and effect of dental materials on their health. 188 (58.8%) participants stated that they would not prefer amalgam restoration in their teeth as amalgam is unaesthetic. A total of 24% (291) of the dentists used amalgam routinely; 9.5% (156) of them used amalgam rarely, and 63.1% (764) did not use amalgam at all. The reason for not using amalgam included the patients' desire and unaesthetic properties. According to the Internet search trends, Turkish people do not know as much about amalgam as people in the rest of the world.

CONCLUSION

Awareness about dental amalgam is low among patients studied. Although dentists do not use dental amalgam frequently, they disagree on banning dental amalgam.

Assessing the perceived impact of post Minamata amalgam phase down on oral health inequalities: a mixed-methods investigation

Background

Data from countries that have implemented a complete phase out of dental amalgam following the Minamata agreement suggest increased costs and time related to the placement of alternatives with consumers absorbing the additional costs. This aim of this study was to investigate the impact of a complete phase out of dental amalgam on oral health inequalities in particular for countries dependent on state run oral health services.

Methods

A mixed methods component design quantitative and qualitative study in the United Kingdom. The quantitative study involved acquisition and analysis of datasets from NHS Scotland to compare trends in placement of dental amalgam and a survey of GDPs in Yorkshire, UK. The qualitative study involved analysis of the free text of the survey and a supplementary secondary analysis of semi-structured interviews and focus groups with GDPs (private and NHS), dental school teaching leads and NHS dental commissioners to understand the impact of amalgam phase down on oral health inequalities.

Results

Time-trends for amalgam placement showed that there was a significant (p < 0.05) reduction in amalgam use compared with composites and glass ionomers. However dental amalgam still represented a large proportion (42%) of the restorations (circa 1.8 million) placed in the 2016–2017 financial year.

Survey respondents suggest that direct impacts of a phase down were related to increased costs and time to place alternative restorations and reduced quality of care. This in turn would lead to increased tooth extractions, reduced access to care and privatisation of dental services with the greatest impact on deprived populations.

Conclusion

Amalgam is still a widely placed material in state run oral health services. The complete phase down of dental amalgam poses a threat to such services and threatens to widen oral health inequalities. Our data suggest that a complete phase out is not currently feasible unless appropriate measures are in place to ensure cheaper, long-lasting and easy to use alternatives are available and can be readily adopted by primary care oral health providers.

Effectiveness of a universal adhesive for repair bonding to composite and amalgam

The study aimed to compare the repair bond strength of aged composite and amalgam repaired with resin composite after various mechanical and adhesive surface treatments. Specimens were aged by thermal cycling (10,000 cycles, 5-55°C) and randomly subjected to one of three surface treatments: diamond bur abrasion, aluminum oxide air abrasion, or silica coating. Conventional bonding or a universal adhesive with incorporated silane was applied afterward (each n = 16) and resin composite was attached. In the control groups (each n = 16), resin composite was attached using one of the above adhesives without prior mechanical surface conditioning. After further thermal cycling, the shear bond strength (SBS) and failure modes were assessed. Statistical analyses were performed using ANOVA, Weibull statistics, two sample t-tests, and Chi²-test (P < 0.05). The SBS of the repaired amalgam was significantly lower than that of the composite and mechanical pretreatment significantly increased SBS. The universal adhesive significantly improved the SBS of the repaired amalgam compared to the conventional bonding agent and mechanical pretreatment increased the number of cohesive/mixed failures. Amalgam restorations may be repaired using resin composites, but the resulting SBS is lower than that obtained with composite.

Understanding the management and teaching of dental restoration repair: Systematic review and meta-analysis of surveys

OBJECTIVES

Repair instead of complete replacement is recommended to manage partially defective restorations. It is unclear if and why such treatment is taught at dental schools or practiced by dentists. We aimed to identify barriers and facilitators for repairs using a systematic review and meta- and qualitative analysis.

SOURCES

Electronic databases (PubMed, CENTRAL, Embase, PsycINFO) were searched.

STUDY SELECTION

Quantitative studies reporting on the proportion of (1) dentists stating to perform repairs, (2) dental schools teaching repairs, (3) failed restorations having been repaired were included. We also included qualitative studies on barriers/facilitators for repairs. Random-effects meta-analyses, meta-regression and a thematic analysis using the theoretical domains framework were conducted.

DATA

401 articles were assessed and 29, mainly quantitative, studies included. 7228 dentists and 276 dental schools had been surveyed, and treatment data of 30,172 restorations evaluated. The mean (95% CI) proportion of dentists stating to perform repairs was 71.5% (49.7-86.4%). 83.3% (73.6-90.0%) of dental schools taught repairs. 31.3% (26.3-36.7%) of failed restorations had been repaired. More recent studies reported significantly more dentists to repair restorations (p=0.004). Employment in public health practices and being the dentist who placed the original restoration were facilitators for repairs. Amalgam restorations were repaired less often, and financial aspects and regulations came as barriers.

CONCLUSIONS

While most dentists state to perform repairs and the vast majority of dental schools teach repairs, the proportion of truly repaired restorations was low. A number of interventions to implement repair in dental practice can be deduced from our findings.

CLINICAL SIGNIFICANCE

Partially defective restorations are common in dental practice. While repairs are taught and dentists are aware of the recommendation towards repairs, the actually performed proportion of repairs seems low.

Longevity of 2- and 3-surface restorations in posterior teeth of 25- to 30-year-olds attending Public Dental Service-A 13-year observation

OBJECTIVES

The aim of this patient document-based retrospective study among 25- to 30-year-old Finnish adults was to evaluate longevity of 2- and 3-surface posterior restorations according to type of tooth, size of restoration, and restorative material used.

METHODS

Data were extracted from electronic patient files of the Helsinki City Public Dental Service (PDS), Finland. A total of 5542 2- and 3-surface posterior composite and amalgam restorations were followed indirectly from 2002 to 2015. Longevity of restorations was illustrated using Kaplan-Meier curves. Annual failure rates (AFRs) of the restorations were calculated separately by type of tooth, size, and material. Differences in longevity were statistically tested with log-rank tests.

RESULTS

Composite restorations formed the majority (93%). The longest median survival times and the smallest failure rates were found for teeth in the upper jaw, for premolars, and for 2-surface restorations. Median survival time of all restorations was 9.9 years (95% CI 9.6, 10.2) and re-intervention of restorations occurred less often in the maxilla (AFR 4.0%) than in the mandible (AFR 4.7%). Median survival time of composite restorations was greater for 2-surface than for 3-surface restorations: in premolars 12.3 vs. 9.6 years (p<0.001) and in molars, 9.2 vs. 6.3 years (p<0.001); for molar amalgams the difference (8.0 vs. 6.3 years) was non-significant (p=0.38). Median survival time of 2- and 3-surface restorations in premolars exceeded that in molars (12.0 vs. 8.7 years; p<0.001).

CONCLUSIONS

Longevity of posterior composite multisurface restoration is comparable to amalgam longevity.

CLINICAL SIGNIFICANCE

Regarding material choices for posterior multisurface restorations, composite and amalgam perform quite similarly in molars, 3-surface restoration being challenge for both materials.