Amalgam or composite resin? Factors influencing the choice of restorative material

Practice Trends and Job Satisfaction of Dental Therapists in Canada: Results from a National Survey

The objective of this research was to evaluate the practice trends, clinical services and job satisfaction of dental therapists in Canada. Licenced Canadian dental therapists were recruited to participate in this cross-sectional study. A total of 124 dental therapists completed the survey (~68% response rate), with 57.3% of respondents being over the age of 50. Most respondents were actively engaged in full-time clinical practice in private dental offices. Indigenous dental therapists were significantly more likely to work outside of private dental offices providing care for Indigenous communities. Just over half of respondents were compensated by an annual salary, with the highest proportion of full-time practitioners earning between $75,000 and $99,000 per year. Dental therapists who were active in clinical practice performed a wide range of preventive, diagnostic, and treatment services consistent with their scope of practice. This research demonstrates that Canadian dental therapists are highly engaged and satisfied with their profession. Dental therapists can facilitate improved access to oral health care in less accessible areas of Canada; however, compensation packages and incentives to work in these less accessible areas must be addressed, as well as legal and regulatory requirements to ensure that dental therapists are licenced providers throughout Canada.

Declining US dental amalgam restorations in US Food and Drug Administration-identified populations: 2017-2023

BACKGROUND

In light of the Minamata Convention on Mercury and efforts to phase down dental amalgam use, tracking dental amalgam proportions across US Food and Drug Administration (FDA)-identified at-risk populations is of interest to optimize material selection aligned with patient needs.

METHODS

A retrospective observational study of Epic's Cosmos electronic health records data set was conducted to calculate the rates of dental amalgam restorations from 2017 through 2023 and stratified using the social vulnerability index (quartile 4 indicates the highest social vulnerability and quartile 1 indicates the lowest) and payer type (Medicare, Medicaid, self-pay, miscellaneous or other). The authors included the following FDA-identified at-risk populations: pregnant people, children younger than 6 years, people with preexisting neurologic conditions, and people with impaired kidney function (n = 1,897,976).

RESULTS

The overall rate of dental amalgam restoration placements in the general population declined from 21.8% in 2017 to 4.1% in 2023. Dental amalgam restoration trends, according to social vulnerability index quartile and payer type, decreased consistently across all 4 evaluated populations. Of all the social vulnerability index quartiles, quartile 4, representing the most socially vulnerable group, had the smallest decrease in dental amalgam placement rates among the FDA-identified populations examined.

CONCLUSIONS

The study results showed a decreasing trend in dental amalgam restorations from 2017 through 2023 among FDA-identified populations, consistent with the Minamata Convention on Mercury directive for a phasedown in dental amalgam use. Notwithstanding improvements, lingering disparities persist among the most vulnerable population.

PRACTICAL IMPLICATIONS

Even within the groups identified as most vulnerable to harm, more targeted interventions and strategies are required to improve treatment among the most socially vulnerable.

A Finite Element Method Study on a Simulation of the Thermal Behaviour of Four Methods for the Restoration of Class II Cavities

The possibility of dental pulp damage during dental procedures is well known. According to studies, during finishing and polishing without cooling, temperatures of up to 140 °C or more can be generated. There are many studies that have analysed the influence of the finishing and polishing of fillings on the mechanical parameters, but the analysis of thermal parameters has led to uncertain results due to the difficulty of performing this in vivo. Background: We set out to conduct a study, using the finite element method, to determine the extent to which the type of class II cavity and the volume of the composite filling influence the duration of heat transfer to the pulp during finishing and polishing without cooling. Materials and Methods: A virtual model of an upper primary molar was used, with a caries process located on the distal aspect, in which four types of cavities were digitally prepared: direct access, horizontal slot, vertical slot and occlusal-proximal. All four cavity types were filled using a Filtek Supreme XT nanocomposite. Results: The study showed that the filling volume almost inversely proportionally influences the time at which the dental pulp reaches the critical temperature of irreversible damage. The lowest duration occurred in occlusal-distal restorations and the highest in direct access restorations. Conclusions: based on the results of the study, a working protocol can be issued so that finishing and polishing restorations without cooling are safe for pulpal health.

The preventive effect of glass ionomer cement restorations on secondary caries formation: A systematic review and meta-analysis

OBJECTIVE

The objective is to compare the preventive effect on secondary caries of glass ionomer cement (GIC) restorations with amalgam or resin-composite restorations.

METHODS

Two independent researchers conducted a systematic search of English publications in PubMed, Web of Science, Cochrane and Scopus. They selected randomized clinical trials comparing secondary caries incidences around GIC restorations (conventional GIC or resin-modified GIC) with amalgam or resin-composite restorations. Meta-analysis of the secondary-caries incidences with risk ratio (RR) and 95% confidence interval (95% CI) as the effect measure was performed.

RESULTS

This review included 64 studies. These studies included 8310 GIC restorations and 5857 amalgam or resin-composite restorations with a follow-up period from 1 to 10 years. Twenty-one studies with 4807 restorations on primary teeth and thirty-eight studies with 4885 restorations on permanent teeth were eligible for meta-analysis. The GIC restorations had a lower secondary caries incidence compared with amalgam restorations in both primary dentition [RR= 0.55, 95% CI:0.41-0.72] and permanent dentition [RR= 0.20, 95% CI:0.11-0.38]. GIC restorations showed similar secondary caries incidence compared with resin-composite restorations in primary dentition [RR= 0.92, 95% CI:0.77-1.10] and permanent dentition [RR= 0.77, 95% CI:0.39-1.51]. Conventional GIC restorations showed similar secondary caries incidence compared with resin-modified GIC-restored teeth in both primary dentition [RR= 1.12, 95% CI:0.67-1.87] and permanent dentition [RR= 1.63, 95% CI:0.34-7.84].

CONCLUSIONS

GIC restorations showed a superior preventive effect against secondary caries compared to amalgam restorations, and a similar preventive effect against secondary caries compared to resin-composite restorations in both primary and permanent teeth. [PROSPERO Registration ID: CRD42022380959].

Application and limitations of configuration factor (C-factor) in stress analysis of dental restorations

OBJECTIVE

The configuration factor (C-factor) is an index used to evaluate the relationship between cavity configuration and the development of polymerization shrinkage stress in dental restorations. Although C-factor has been widely researched, its correlation with stress analysis in dental restorations remains controversial. This review aims to discuss the application and limitations of C-factor and define the restricted conditions under which the C-factor "rule of thumb" is applicable.

METHODS

A thorough literature review was conducted on the application and limitations of C-factor in stress analysis of dental restorations. This was principally based on MEDLINE/PubMed and Web of Science databases and a review of the relevant studies and publications in scientific papers in international peer-reviewed journals for the specific topic of C-factor and polymerization shrinkage.

RESULTS

The C-factor alone cannot provide an accurate prediction of the shrinkage stress of restorations and the mechanical behavior of material-tooth interfaces. C-factor is only applicable under one condition not typically seen in clinical practice: low, near-rigid compliance.

SIGNIFICANCE

Conditions for the application of C-factor have been explicitly defined. A more accurate and precise understanding and utilization of the C-factor is of benefit as it contributes to better understanding of polymerization shrinkage behavior of restorations.

Five-Year Clinical Performance of Complex Class II Resin Composite and Amalgam Restorations-A Retrospective Study

The aim of this retrospective study was to investigate the clinical performance of posterior complex resin composite (RC) and amalgam (AM) restorations after a five-year period. One hundred and nineteen complex Class II restorations placed by dental students were evaluated using the USPHS criteria. Data were analyzed using Chi-square, Mann-Whitney, and Wilcoxon tests at a 0.05 level of significance. After five years, the percentages of clinically satisfactory complex Class II RC and AM restorations were 78% and 76.8%, respectively. The main reasons for the failure of AM restorations included secondary caries (Bravo-10.1%), defective marginal adaptation (Charlie-8.7%), and fracture of the tooth (Bravo-7.2%). RC restorations presented failures related to the fracture of the restoration (Bravo-16%) and defective marginal adaptation (Charlie-8.2%). There was a significantly higher incidence of secondary caries for AM restorations (AM-10.1%; RC-0%; p = 0.0415) and a higher number of fractures for RC restorations (AM-4.3%; RC-16%; p = 0.05). Regarding anatomy, AM restorations presented a significantly higher number of Alfa scores (49.3%) compared to RC restorations (22.4%) (p = 0.0005). The results of the current study indicate that complex class II RC and AM restorations show a similar five year clinical performance.

COVID-19 Reflections on Restorative Treatments of Permanent First Molars

BACKGROUND AND AIM

It is important to provide appropriate dental care for newly erupted permanent first molars (PFMs) since they are susceptible to caries. As the coronavirus disease 2019 (COVID-19) pandemic has led to significant changes in the way dental services are provided to patients, the purpose of this study is to examine the procedure records assigned to PFMs of 6-15 year-olds during the pandemic and analyze the restorative material preferences of the residents of public dental hospitals.

MATERIALS AND METHODS

Procedure records of patients aged between 6-15 years were extracted from the Public Oral and Dental Health Center, Bursa, Türkiye. All teeth groups except PFMs were excluded, while extracted, survived (restorative/endodontic/prosthetic procedures), and prevented (fissure sealant application) PFMs were analyzed retrospectively. Furthermore, restorative material preferences were analyzed by arch location, cavity surfaces, and dentition types.

RESULTS

Strong positive correlation was seen between age and PFM extraction (r=0.973; p<0.001) and age and PFM restorative treatments (r= 0.966; p<0.001); a negative correlation was detected between age and fissure sealants (r= -0.984; p<0,001) performed on PFMs of 8-15-year-olds. Amalgam was most often preferred as the restorative material (p<0.05).

CONCLUSION

The distribution of treatments and dental restorations can vary based on many factors, and the pandemic conditions may have changed treatment preferences to favor preventive dentistry. The excess of multi-surface restorations may be related to the delay of treatment applications during COVID-19.

Development of functional fillers as a self-healing system for dental resin composite

OBJECTIVES

To evaluate the incorporation of repairing capsules containing different monomers and polymerization modulators on the self-healing efficiency of an experimental photopolymerizable resin-based composite.

METHODS

Self-healing capsules containing different monomers and polymerization modulators were prepared by emulsion polymerization: TC_DHEPT (TEGDMA and DHEPT), BTC_DHEPT (Bis-GMA, TEGDMA, and DHEPT), and BTC_BPO (Bis-GMA, TEGDMA, and BPO). The capsules were analyzed through Fourier transform infrared spectroscopy and scanning electron microscopy. The capsules were added into experimental photopolymerizable resin composites establishing the following groups: ER (Control without capsules), ER+BPO, ER+BPO+TC_DHEPT, and ER+BTC_BPO+BTC_DHEPT. Filtek Z350 resin composite (3 M ESPE) was used as a commercial reference. The materials were tested for degree of conversion (DC), flexural strength (σf), elastic modulus (Ef), fracture toughness (virgin K_IC), self-healing efficiency (healed K_IC), and roughness. For statistical analysis, the significance value was established at an a = 0.05 level.

RESULTS

When compared to the control material, the incorporation of repairing capsules did not affect DC, σf, and Ef. Fracture toughness was statistically similar between the experimental groups (p ≤ 0.05). Healed K_IC was statistically different between the groups ER+TC_DHEP and ER+BTC_BPO+BTC_DHEPT; the self-healing efficiency was higher for ER+TC_DHEPT. Surface roughness was statistically similar among all groups.

CONCLUSIONS

The use of self-healing capsules promoted repair of the material. Studies with material aging after the self-healing process are necessary to better demonstrate the effectiveness of this system.

CLINICAL SIGNIFICANCE

The self-healing system seemed to be a promising technology to be used in self-repaired restorative materials, which may prevent restoration fractures.

Biodegradation of Dental Resin-Based Composite—A Potential Factor Affecting the Bonding Effect: A Narrative Review

In recent years, although resin composite has played an important role in the restoration of tooth defects, it still has several disadvantages, including being biodegraded by saliva, bacteria and other enzymes in the oral cavity, which may result in repair failure. This factor is not conducive to the long-term survival of the prosthesis in the mouth. In this article, we review the causes, influencing factors and prevention methods of resin biodegradation. Biodegradation is mainly caused by esterase in saliva and bacteria, which breaks the ester bond in resin and causes the release of monomers. The mechanical properties of the prosthesis can then be affected. Meanwhile, cathepsin and MMPs are activated on the bonding surface, which may decompose the dentin collagen. In addition, neutrophils and residual water on the bonding surface can also aggravate biodegradation. Currently, the primary methods to prevent biodegradation involve adding antibacterial agents to resin, inhibiting the activity of MMPs and enhancing the crosslinking of collagen fibers. All of the above indicates that in the preparation and adhesion of resin materials, attention should be paid to the influence of biodegradation to improve the prosthesis’s service life in the complex environment of the oral cavity.

Preparation of Silica Aerogel/Resin Composites and Their Application in Dental Restorative Materials

As the most advanced aerogel material, silica aerogel has had transformative industrial impacts. However, the use of silica aerogel is currently limited to the field of thermal insulation materials, so it is urgent to expand its application into other fields. In this work, silica aerogel/resin composites were successfully prepared by combining silica aerogel with a resin matrix for dental restoration. The applications of this material in the field of dental restoration, as well as its performance, are discussed in depth. It was demonstrated that, when the ratio of the resin matrix Bis-GMA to TEGDMA was 1:1, and the content of silica aerogel with 50 μm particle size was 12.5%, the composite achieved excellent mechanical properties. The flexural strength of the silica aerogel/resin composite reached 62.9546 MPa, which was more than five times that of the pure resin. Due to the presence of the silica aerogel, the composite also demonstrated outstanding antibacterial capabilities, meeting the demand for antimicrobial properties in dental materials. This work successfully investigated the prospect of using commercially available silica aerogels in dental restorative materials; we provide an easy method for using silica aerogels as dental restorative materials, as well as a reference for their application in the field of biomedical materials.

The effects of amalgam contamination and different surface modifications on microleakage of dentin bonded to bulk fill composite when using different adhesive protocols

BACKGROUND

To evaluate the effect of amalgam contamination, different surface treatments, and adhesive protocols on dentin microleakage to bulk-fill composite resin material.

METHODS

Forty teeth were fixed in (polyvinyl siloxane) PVS molds, and the Class II cavities were placed on mesial and distal aspects. Thirty teeth were restored by amalgam and thermocycled to 10,000 cycles (5 and 55 °C, 30-s dwell time). The rest were restored with Filtek one Bulk Fill composite without amalgam predecessor. Samples were divided into: G1 (dentin pretreated with 2% chlorhexidine gluconate), G2 (0.5 mm of dentin was removed), G3 (no surface modification), and G4 (control, where composite was bonded to sound dentin without amalgam predecessor.). Single Bond Universal Adhesive system was used to bond the composite material, by using the etch-and-rinse protocol in the mesial cavity preparation and self-etch protocol in the distal. Specimens underwent thermocycling for 5000 cycles, then embedded in silver nitrate and sectioned for stereomicroscope examination. Descriptive statistics, Mann-Whitney U test, and Kruskal-Wallis test were used to analyze the results at p < 0.05.

RESULTS

The highest microleakage score values (4.00) were found in the G2, and G4 in etch-and-rinse protocol. While the lowest scores were found in G2 when using self-etching protocol (1.5). Lower microleakage values were associated with the chlorhexidine treatment group for both adhesive protocols. No significant differences were found between amalgam contaminated and non-contaminated groups.

CONCLUSIONS

Amalgam contamination did not affect microleakage. Self-etching adhesive protocol significantly reduced microleakage for all groups irrespective of the surface treatment. Chlorhexidine pretreatment improved microleakage for both adhesive protocols but had no significant effect.

Novel calcium phosphate ion-rechargeable and antibacterial adhesive to inhibit dental caries

OBJECTIVES

This study aimed to develop an antibacterial and calcium (Ca) and phosphate (P) rechargeable adhesive and investigate the effects of dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) on dentin bonding, biofilm response, and repeated Ca and P ion recharge and re-release capability for the first time.

MATERIALS AND METHODS

Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA), and bisphenol A glycidyl dimethacrylate (BisGMA) formed the adhesive (PEHB). Three groups were tested: (1) Scotchbond (SBMP, 3 M) control, (2) PEHB + 30% NACP, and (3) PEHB + 30% NACP + 5% DMAHDM. Specimens were tested for dentin shear bond strength, and Ca and P ion release, recharge, and re-release. Biofilm lactic acid production and colony-forming units (CFU) on resins were analyzed.

RESULTS

The four groups had similar dentin shear bond strengths (p > 0.1). Adhesive with DMAHDM showed significant decrease in metabolic activity, lactic acid production, and biofilm CFU (p < 0.05). The adhesives containing NACP released high levels of Ca and P ions initially and after being recharged.

CONCLUSION

This study developed the first Ca and P ion-rechargeable and antibacterial adhesive, achieving strong antibacterial activity and Ca and P ion recharge and re-release for long-term remineralization.

CLINICAL RELEVANCE

Considering the restoration-tooth bonded interface being the weak link and recurrent caries at the margins being the primary reason for restoration failures, this novel calcium phosphate-rechargeable and antibacterial adhesive is promising for a wide range of tooth-restoration applications to inhibit caries.

Comparison of Self-Etching Adhesives and Etch-and-Rinse Adhesives on the Failure Rate of Posterior Composite Resin Restorations: A Systematic Review and Meta-Analysis

The aim of this study was to perform a systematic review with meta-analysis on the comparison of self-etching adhesives and etch-and-rinse adhesives with respect to the failure rate of posterior composite resin restorations. The study protocol was registered in PROSPERO (CRD42017078015), following PRISMA recommendations and PICO search strategy. Literature search was performed in the following databases: MEDLINE, ISI Web of Science, LILACS, SCOPUS, and Cochrane Library through July 2021. Six studies from five randomized clinical trials were included in the qualitative synthesis. The funnel plot detected important bias (all studies out of the funnel area). The meta-analysis showed a positive summary Cohen H effect size of 0.406 (95% CI: 0.100; 0.713, p = 0.009), favoring etch-and-rinse adhesives. The total number of failures (including restorations that required replacement and those that did not require replacement) were attributed to either marginal adaptation (five studies) or marginal staining (one study). A very low certainty of the evidence was obtained through GRADE analysis. In conclusion, current available evidence indicates that etch-and rinse adhesives performed better (with a low effect size) than self-etching adhesives in terms of failure rates in posterior composite restorations.

Development of 4-META/MMA-TBB resin with added benzalkonium chloride or cetylpyridinium chloride as antimicrobial restorative materials for root caries

To develop antimicrobial restorative materials for root caries, we assessed a 4-META/MMA-TBB resin (Bondfill SB Plus, Sun Medical) containing benzalkonium chloride (BAC) or cetylpyridinium chloride (CPC) at 1.25, 2.5, and 5.0 wt%. The same resin without antibacterial agent was used as control. The degree of conversion was measured by attenuated total reflectance-Fourier transform infrared spectroscopy. The 3-point flexural strength test was conducted according to ISO 4049. The antimicrobial effect against three oral bacteria (Streptococcus mutans, S. sobrinus, and Actinomyces naeslundii) was assessed using agar diffusion tests. The shear bond strength to root dentin was assessed after 24 h of storage in water with or without 10,000 thermal cycles. The shear bond strength data were statistically compared using a linear mixed-effects model (α = 0.05). The specimen with 5.0 wt% BAC showed a significantly higher degree of conversion than the control, but it also had significantly lower flexural strength and lower shear bond strength after thermal cycling than the other specimens. When BAC or CPC was added at ≥ 2.5 wt%, the resins inhibited the growth of the three investigated microbes. In conclusion, both BAC and CPC showed significant antimicrobial effects when added at 5.0 wt% to the 4-META/MMA-TBB resin. Up to 2.5 wt%, neither antimicrobial agent affected the degree of conversion, flexural strength, or shear bond strength of the resin.

Rheological and Mechanical Properties of Resin-Based Materials Applied in Dental Restorations

Resin-based materials have been prevalent for dental restorations over the past few decades and have been widely used for a variety of direct and indirect procedures. Typically, resin-based dental materials are required to be flowable or moldable before setting and can provide adequate mechanical strength after setting. The setting method may include, but is not limited to, light-curing, self-curing or heating. In this review, based on different indications of resin-based dental materials (e.g., dental filling composite, dental bonding agent, resin luting cement), their rheological and mechanical properties were reviewed. Viscous and flexible properties were focused on for materials before setting, while elastic properties and mechanical strength were focused on for materials after setting. At the same time, the factors that may affect their rheological and mechanical properties were discussed. It is anticipated that the insightful information and prospections of this study will be useful to the future development and fabrication of resin-based dental restorative materials.

Functional fillers for dental resin composites

Dental resin composites (DRCs) are popular materials to repair caries. Although various types of DRCs with different characteristics have been developed, restoration failures still exist. Bulk fracture and secondary caries have been considered as main causes for the failure of composites restoration. To address these problems, various fillers with specific functions have been introduced and studied. Some fillers with specific morphologies such as whisker, fiber, and nanotube, have been used to increase the mechanical properties of DRCs, and other fillers releasing ions such as Ag⁺, Ca²⁺, and F^-, have been used to inhibit the secondary caries. These functional fillers are helpful to improve the performances and lifespan of DRCs. In this article, we firstly introduce the composition and development of DRCs, then review and discuss the functional fillers classified according to their roles in the DRCs, finally give a summary on the current research and predict the trend of future development.

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.

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.

Hydrolysis-resistant and stress-buffering bifunctional polyurethane adhesive for durable dental composite restoration

A new elastic polyurethane (PU) adhesive was reported in this study to improve the stability and durability of the dental adhesion interface. A polyurethane oligomer was synthesized by the solution polymerization method, and a diluent and solvent were added to prepare PU adhesives. The water sorption, water solubility, contact angle, thermal stability, degree of conversion and mechanical properties of the PU adhesives were evaluated. Experimental applications for tooth restoration (microtensile bond strength and microleakage) were also performed, and cytotoxicity test was carried out. The water sorption and solubility of the PU adhesives were significantly lower than those of three commercial adhesives. The microtensile bond strength of the PU adhesives was improved after thermocycling test, and the extent of microleakage was diminished when compared with that of commercial adhesives. Biocompatibility testing demonstrated that the PU adhesive was non-toxic to L929 fibroblasts. This study shows the ability of PU adhesive to improve the stability and durability of the dental adhesion interface and may refocus the attention of scientists from rigid bonding to flexible bonding for dental adhesion, and it sheds light on a new strategy for the stable and durable bonding interface of dentine adhesives.

Risk Factors for Failure of Direct Restorations in General Dental Practices

The aim of this retrospective noninterventional multicenter practice-based study was to analyze factors influencing the survival of direct restorations. Records from patients who visited 5 private practices regularly were searched for the presence of direct restorations. Data were recorded from 7,858 patients with 27,407 direct restorations being detected at least 6 mo before the last recall visit. Multilevel Cox proportional hazard models were used to evaluate the association between clinical factors and time until failure. Within 228 mo, 5,493 failures could be observed. Median survival time was 207 mo. The annual failure rates were 3.8%, 4.0%, 4.6%, 4.9%, and 3.9% for class I, II, III, IV, and V restorations, respectively. Class II and IV restorations showed a 1.1-times (95% CI, 1.0 to 1.2) and 1.2-times (95% CI, 1.1 to 1.2) higher failure rate than class I restorations ( P ≤ 0.029). Patients aged <20 y and >60 y showed up to a 1.4-times higher failure rate than patients aged 20 to 60 y ( P ≤ 0.015). Restorations that underwent check-up twice a year or more showed a significantly higher failure rate than those that did so less than twice a year ( P < 0.001). Furthermore, the dentists significantly influenced time until failure ( P < 0.001). Regarding the restorative material, composites showed up to a 2.1-times longer time until failure than GIC ( P ≤ 0.020). Moderate failure rates were observed for direct restorations in the private practice setting after up to 18.5 y. Within the limitations of the present study, several factors on the levels of practice (i.e., dentist), patient (i.e., age), and tooth (i.e., restorative material, restored surfaces according to the classification of Black) were significant predictors for the failure rate. Therefore, treatment decision should take into account most relevant factors (German Clinical Trials Register DRKS00015228).

Synthesis of an anti-cariogenic experimental dental composite containing novel drug-decorated copper particles

Secondary caries is one of the most major cause for re-placement of dental composite restorations. Targeting the survival of cariogenic bacteria residing on the restoration surface may reduce this problem. The present study aims to evaluate the antibacterial potential as well as assess the physical and chemical properties of experimental dental composites containing novel drug-decorated copper particles (DDCP) as adjunct antibacterial filler particles. These were incorporated at concentrations of 0%, 0.5%, 0.10%, 0.20%, and 0.25% (w/w) into experimental composite consisting of methacrylate monomers and silanized silica fillers. RESULTS: Direct contact test revealed that the anti-cariogenic potential of experimental composites was more than the control groups. The cell viability assay showed no toxic effect on MC3T3-E1 cell lines in the MTT assay. The microhardness of experimental composites increased as the percentage of DDCP increased, however, the degree of cure was increased only up till the concentration of 0.20%. The release kinetics of the composites reveals that even after 28 days there was a steady and slow release of copper particles signifying the sustained anti-cariogenic effect. CONCLUSION: The experimental composites have good anti-cariogenic potential, which was sustained for one month without any deleterious effect on the physical and chemical properties of resin dental composites.

Fabrication and characterization of remineralizing dental composites containing hydroxyapatite nanoparticles

The aim of this study was to fabricate and characterize dental composites containing hydroxyapatite nanoparticles (HApNPs). Four dental composites were produced from the same organic matrix (70 wt% Bis-GMA and 30 wt% TEGDMA), with partial replacement of BaBSi particles (65 wt%) by HApNPs in the following concentrations (wt%): E0 (0) - control, E10 (10), E20 (20) and E30 (30). Ca²⁺ and PO₄^3- release was evaluated in solutions with different pHs (4, 5.5, and 7) using atomic emission spectroscopy with microwave-induced nitrogen plasma while the enamel remineralization potential was evaluated in caries-like enamel lesions induced by S. mutans biofilm using micro-CT. The following properties were characterized: degree of conversion (DC%), microhardness (KHN), flexural strength (FS), elastic modulus (EM) and translucency (TP). The higher the HApNPs content, the higher the Ca²⁺ and PO₄^3- release. The ions release was influenced by pH (4 > 5.5 > 7) (p < 0.05). All composites loaded with HApNPs were able to remineralize the enamel (E30 = E20 > E10) (p < 0.05). Contrarily, E0 was not able of recovering the enamel mineral loss. E0 and E10 presented highest DC%, while E20 and E30 showed similar and lowest DC%. KHN and FS were decreased with the addition of HApNPs, while EM was not influenced by the incorporation of HApNPs. E10 presented statistically similar TP to E0, while this property decreased for E20 and E30 (p < 0.05). Incorporation of HApNPs into dental composites promoted enamel remineralization, mainly at potentially cariogenic pH (= 4), while maintained their overall performance in terms of physicomechanical properties.

Penetration of Different Impression Materials into Exposed Dentinal Tubules during the Impression Procedure

Adhesive restorations have been shown to guarantee excellent performance and longevity, although this comes with some disadvantages. Among these, the vulnerability of dentine to different agents has been widely evaluated. The aim of this study was to evaluate the possible penetration of impression materials into freshly cut dentine. Dentine from 27 teeth was impressed with polyether (Impregum Penta L) (nine teeth) and with polyvinyl siloxane (Aquasil Ultra LV) (nine teeth). The surface of nine teeth after the impressions were used as the control. Specifically, the extroflections caused by the imprinting of the dentinal tubules on the impression material, the so-called impression tags, were measured. Furthermore, the presence of the material inside the tubules was examined. Scanning electron microscopy analysis showed material tags for all of the experimental groups. The mean lengths (±SD) were 22.6 (±11.0) µm for polyether, 21.8 (±12.8) µm for polyvinyl siloxane and 11.3 (±7.0) µm for the tooth control, with mean diameters (±SD) of 2.8 (±0.5), 2.4 (±0.7) and 3.1 (±0.7) µm, respectively. Fractal analysis showed fractal dimensions of 1.78 (±0.03), 1.77 (±0.03) and 1.71 (±0.03), respectively. These data demonstrated that the impression materials can remain inside the dentinal tubules, which can adversely affect the adhesive procedures.

Comparison of Shear Bond Strength of Three Commercially Available Esthetic Restorative Composite Materials: An In Vitro Study

Introduction

Dental caries remains to be one of the most prevalent diseases encountered in the field of dentistry. Several restorative materials have been introduced with variable properties and among them, composite restorative materials are most widely used nowadays because of their superior esthetic property as well as minimal hard tissue removal. Shear bond strength of a restorative material plays a key role in deciding the restoration’s longevity. Hence, for a better selection of the composite material, shear bond strength needs to be evaluated.

Aim

The study aim was to analyze the shear bond strength of three commercially available esthetic restorative composite materials—Dentsply Ceram X, 3M ESPE™ Filtek™ Z350 XT, and GC Solare Sculpt to the tooth surface.

Materials and methods

Thirty extracted human mandibular permanent molars that were caries-free were selected and erected in acrylic blocks. The uniform dentinal surface was exposed by cutting with a diamond disk. These were then randomly divided into three groups—groups I, II, and III based on the restorative material which was used, i.e., Ceram X, 3M ESPE™ Filtek™ Z350 XT, and Solare Sculpt, respectively. The restorative materials were applied on the dentinal surface of the prepared tooth specimens with the help of plastic molds, followed up by storing them in distilled water until they were subjected to shear bond strength testing. The collected data were examined by applying a one-way analysis of variance (ANOVA) and Turkey’s post hoc test.

Results

The Ceram X (21.6155 ± 2.20717) and Solare Sculpt (19.8747 ± 3.99732) were comparable in terms of shear bond strength values; however, they depicted significantly higher bond strength compared to 3M ESPE™ Filtek™ Z350 XT (12.8068 ± 3.99732).

Conclusion

Among the three materials compared in this study, Ceram X produced higher shear bond strength to tooth surface when compared to Solare Sculpt and 3M ESPE™ Filtek™ Z350 XT.

Clinical significance

Restoration failure continues to be a major problem taking a toll on the dentists’ time and patient satisfaction. Thus, the demand for restorative materials with better shear bond strength as well as excellent esthetics is on the rise. Thus, this particular study compares the shear bond strength of three commercial esthetic nanocomposites.

How to cite this article

Preethy NA, Jeevanandan G, Govindaraju L, et al. Comparison of Shear Bond Strength of Three Commercially Available Esthetic Restorative Composite Materials : An In Vitro Study. Int J Clin Pediatr Dent 2020;13(6):635–639.

Do bulk-fill resins decrease the restorative time in posterior teeth? A systematic review and meta-analysis of in vitro studies

The aim of the present study was to compare the restorative time for filling cavities in posterior teeth using bulk-fill and conventional resin composites through a systematic review and meta-analysis. A search for clinical trials and laboratory studies was performed in PubMed/MEDLINE, Scopus, the Latin American and Caribbean Health Sciences Literature database, the Brazilian Library in Dentistry, Cochrane Library, Clinical Trials, and ReBEC (Registro Brasileiro de Ensaios Clínicos) databases without publication year or language restriction. Two reviewers identified eligible studies according to the inclusion criteria: bulk-fill compared to conventional resin in class I or II, and the restorative time as an outcome. A meta-analysis of the restorative time mean difference between composites was performed (inverse variance method, random effects model; Z-test, P ≤ .05). From the 662 eligible studies, 133 were selected for full-text analysis; three were included in the systematic review and in the meta-analysis. Overall, the restorative time was lower when bulk-fill was used (P = .0007, Z = 3.37), as the subgroup full-body bulk-fill (P < .00001, Z = 21.00). There was no difference in restorative time between flowable bulk-fill and conventional resins (P = .08, Z = 1.76). Moderate-to-substantial heterogeneity was detected. Full-body bulk-fill composites decrease the restorative time in posterior teeth compared to conventional resins. Full-body bulk-fill resins require a shorter restorative time to perform restorations in posterior teeth than conventional resins, but the same is not valid for flowable bulk-fill resin composites.

Evaluation of biofilm formation on novel copper-catalyzed azide-alkyne cycloaddition (CuAAC)-based resins for dental restoratives

OBJECTIVE

For the past several decades, the resins used in dental restorations have been plagued with numerous problems, including their implication in biofilm formation and secondary caries. The need for alternative resins is critical, and evaluation of biofilm formation on these resins is essential. The aim of this study was to evaluate in vitro biofilm formation on the surface of novel copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC)-based resins and composites.

METHODS

CuAAC-based resins/composites made from varying azide monomers and different copper concentrations were compared with BisGMA-TEGDMA resins/composites that served as the control. Biofilms were formed using a mono-species model containing a luciferase-expressing strain of Streptococcus mutans. Luciferase activity was measured and the number of viable bacteria was enumerated on biofilms associated with each resin and composite.

RESULTS

A significant reduction (p<0.05) in luciferase activity, and the number of viable bacteria recovered from biofilms on CuAAC-based resins and composites was observed in comparison to biofilms associated with the BisGMA-TEGDMA controls.

SIGNIFICANCE

CuAAC-based resins do still allow for the formation of biofilms; however, the statistically significant reduction of growth that was associated with the CuAAC resin may enhance the longevity of restorations that incorporate CuAAC-based materials.

Influence of a hydrophobic monomer on the physical and mechanical properties of experimental surface sealants

This study evaluated the effect of adding the hydrophobic monomer 1,12 dodecanediol dimethacrylate (DDDMA) to experimental sealants with and without thermocycling on degree of conversion (DC), water sorption (WS), water solubility (WSB), color stability (ΔE), and micro-shear bond strength (μSBS). Five experimental and one commercially available sealant (Bisco - BIS) were tested. The experimental sealants were formulated by mixing different percentages of DDDMA monomers and urethane dimethacrylate (UDMA). The photoinitiator system was composed by camphorquinone (CQ) and tertiary amine 4-ethyl benzoate dimetilamiono (EDBA). Ethanol was used as a solvent. The experimental groups were named sequentially according to the monomeric content (DDDMA/UDMA): S40/40 (40/40), S50/30 (50/30), S60/20 (60/20), S70/10 (70/10) and S80/0 (80/0). Data were analyzed separately by one-way ANOVA, followed by Tukey's test (p<0.05). The values of DC ranged from 94.59% (S40/40) to 54.02% (S80/10). BIS showed the highest WS value (p<0.05) and S40/40, S50/30, S60/20 and S80/0 showed the lowest WS values of all tested sealants. WSB values ranged from 7.88 µg/mm3 (BIS) to 13.27 µg/mm3 (S70/10). The highest ΔE value was 11.05±2.88 for BIS and the highest μSBS value was found for S60/20. No significant difference was observed in bond strength between sealants and bovine enamel after thermocycling. Adding DDDMA to the composition of surface sealants can improve its performance, once the monomer increased the degree of conversion and the color stability.

Has the implementation of the Minamata convention had an impact on the practice of operative dentistry in Jordan?

Objective

To assess Jordanian dentists’ current perception and attitudes towards amalgam and composite restorations four years after the Minamata treaty was endorsed and suggest decision making factors that may influence the type of restoration requested by patients.

Methods

The cross-sectional study was conducted through structured questionnaires distributed to dentists in Amman, Jordan from June 2017 to February 2018.

Results

Of the 1686 dentists who were contacted 758 dentists (response rate 45%) responded to the questionnaire either by email or via field visits. Jordanian dentists used more composite restorations than amalgam. Recurrent caries followed by fracture of the restoration were the main reasons for replacement of both fillings by dentists. However, dentists suggested that the main reason patients requested replacement of amalgam was for ‘staining’. In addition, a large proportion of the dentists had experienced patients who had asked either for replacement of amalgam (77%) or refused an amalgam filling (99%) for aesthetic reasons. In the opinion of the dentists, only 20% patients requested replacement of amalgam because of the mercury content.

Conclusion

The findings of this survey suggest that a ‘phase-down’ of dental amalgam is being implemented in Jordan's dental clinics but it is not associated with commitment to the Minamata Convention, rather to current dental practice trends and patients’ aesthetic demands.

Anterior restoration longevity among nursing facility residents: a 30-year retrospective study

AIM

To assess factors influencing anterior dental restoration longevity among the institutionalized elderly.

METHODS

Among a sample of Eastern Iowa nursing facility dental patients, one anterior restoration placed from 1985 to 2014 was selected at random from each subject. Kaplan-Meier survival curves were generated, with restoration failures defined as subsequent restorative codes involving the same surface; endodontic procedures; or extractions. Bivariate and multivariable Cox proportional hazards modeling were performed.

RESULTS

In multivariable analyses, the 1985 to 1999 cohort (n = 496) had longer restoration survival in in females < 75 years old versus males < 75 years old (P = 0.016), males ≥75 years old (P = 0.026) and females ≥75 years old (P = 0.030); one- versus three-surface restorations (P < 0.001); and restorations placed by faculty/residents versus pre-doctoral students (P = 0.009). The 2000 to 2014 cohort (n = 521) had longer restoration survival in females < 75 years old versus males ≥75 years old (P = 0.012) and females ≥75 years old (P = 0.019); residents who paid out-of-pocket versus those on Medicaid (P = 0.019); and composite resin versus glass ionomer cement restorations (P < 0.001).

CONCLUSIONS

Knowing how long restorations last, and what factors affect their longevity, could improve treatment planning, informed consent, and communication with residents and caregivers, and also help inform practice guidelines for restorative care among the institutionalized elderly.

Should my composite restorations last forever? Why are they failing?

Composites resins have become the first choice for direct anterior and posterior restorations. The great popularity is related to their esthetic appearance and reduced need of sound tissue removal as compared with former treatments. Several studies have demonstrated that composite restorations may last long in clinical service. In this review we discuss the factors playing a role on the long-term longevity. Composite restorations have demonstrated a good clinical performance with annual failure rates varying from 1% to 3% in posterior teeth and 1% to 5% in anterior teeth. Factors related to the patients such as caries risk and occlusal stress risk, in addition to socioeconomic factors, may affect the survival significantly. Characteristics of the clinical operators, particularly their decision making when it comes to observing or approaching an existing restoration, are decisive for longevity. Cavity features such as the number of restored walls, composite volume, and presence of endodontic treatment are of major importance and may dictate the service time of the restorative approach. The choice of restorative composite seems to have a minor effect on longevity provided that appropriate technical procedures are used. The main reasons for failure in posterior teeth are secondary caries and fracture (restoration or tooth/restoration), while in anterior teeth esthetic concerns are the main reasons leading to restoration failures. Composite resin restorations can be considered a reliable treatment as long as both the professional and the patient are aware of the factors involved in restoration failures.

Dentists' restorative decision-making and implications for an 'amalgamless' profession. Part 4: clinical factor

BACKGROUND

The Minamata Convention embodies a worldwide reduction in the production and use of mercury and mercury-containing products and processes, including a phase-down of dental amalgam. This will change the approach to the use of direct restorative materials in the near future. There is little research as to the influence of clinical factors on dentists' decision-making which may be of use when determining the impact of any change.

METHODS

An online survey relating to aspects of and attitudes to the use of direct restorative materials was distributed to all dentists who were members of the Australian Dental Association and/or members or fellows of the Royal Australasian College of Dental Surgeons. Data were statistically analysed.

RESULTS

There were 408 respondents to the survey. Eighty-seven per cent of respondents (strongly) disagreed that amalgam was a technically more difficult material to place compared with resin composite, 82% (strongly) disagreed that placement time for amalgam was longer than that for resin composite and 69% (strongly) disagreed that amalgam was more difficult to finish than resin composite. Eighty-three per cent of respondents stated they were confident in their ability to place amalgam restorations. Where physical properties were of importance, indirect restorations were preferred (e.g. parafunction) 54%. The factors considered most important when choosing a direct restorative material included moisture control and aesthetics; least important factors were cost and time to place.

CONCLUSIONS

There is consensus that amalgam is not more technically difficult to use, place or finish than resin composite and vice versa. There is recognition that both amalgam and resin composite have limitations in terms of physical properties. When choosing a direct restorative material, clinical factors considered to be of greatest importance are moisture control, aesthetics and the need to apply minimally invasive approaches. There is little difference in the opinions of users and non-users of amalgam with respect to these findings.

Flexural strength and microhardness of anterior composites after accelerated aging

BACKGROUND

This study aimed to evaluate the flexural strength and microhardness of three different anterior composites after 10 000 thermocycles.

MATERIAL AND METHODS

The mechanical properties of a nano-fill composite (Filtek Ultimate Universal Restorative (FUR) (Enamel)), a nano-hybrid composite (Clearfil Majesty ES2 (ES2) (Enamel)), and a micro-hybrid composite (G Aenial Anterior (GAA)) were investigated in this study. For the microhardness test, 8-mm diameter and 2-mm thickness composite discs were used (n = 10), and for the flexural strength test, 25x2x2 mm bar-shaped specimens were prepared (n = 13). The specimens were tested at 24 h and after 10 000 thermocycles. Data were analyzed using two-way analysis of variance and the post-hoc Tukey test (p < .05). Correlations between hardness and flexural strength were calculated using Pearson's correlation analysis.

RESULTS

There was a significant difference in the microhardness values of the materials (p < .05). FUR exhibited significantly higher microhardness than ES2 and GAA. However, the flexural strength of three composites was statistically similar at 24 h (p > .05). Pearson correlation analysis revealed that there was a negative relationship between the mean hardness and flexural strength values (correlation coefficient = -0.367, p = .043). After 10 000 thermocycles, microhardness values of each material and flexural strength of ES2 and GAA decreased significantly according to 24 h.

CONCLUSIONS

The nano-fill composite FUR displayed significantly higher microhardness values. However, each resin composite was statistically similar for flexural strength values. Ten thousand thermocycles significantly affected microhardness and flexural strength. Key words:Flexural strength, microhardness, anterior composites.

Fifty years of Brazilian Dental Materials Group: scientific contributions of dental materials field evaluated by systematic review

Objective

A systematic review was conducted to analyze Brazilian scientific and technological production related to the dental materials field over the past 50 years.

Material and Methods

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (Prisma) statement. Searches were performed until December 2014 in six databases: MedLine (PubMed), Scopus, LILACS, IBECS, BBO, and the Cochrane Library. Additionally, the Brazilian patent database (INPI - Instituto Nacional de Propriedade Industrial) was screened in order to get an overview of Brazilian technological development in the dental materials field. Two reviewers independently analyzed the documents. Only studies and patents related to dental materials were included in this review. Data regarding the material category, dental specialty, number of documents and patents, filiation countries, and the number of citations were tabulated and analyzed in Microsoft Office Excel (Microsoft Corporation, Redmond, Washington, United States).

Results

A total of 115,806 studies and 53 patents were related to dental materials and were included in this review. Brazil had 8% affiliation in studies related to dental materials, and the majority of the papers published were related to dental implants (1,137 papers), synthetic resins (681 papers), dental cements (440 papers), dental alloys (392 papers) and dental adhesives (361 papers). The Brazilian technological development with patented dental materials was smaller than the scientific production. The most patented type of material was dental alloys (11 patents), followed by dental implants (8 patents) and composite resins (7 patents).

Conclusions

Dental materials science has had a substantial number of records, demonstrating an important presence in scientific and technological development of dentistry. In addition, it is important to approximate the relationship between academia and industry to expand the technological development in countries such as Brazil.

Association between History of Dental Amalgam Fillings and Risk of Parkinson's Disease: A Population-Based Retrospective Cohort Study in Taiwan

The impact of dental amalgam on the development of Parkinson's disease (PD) is still uncertain, although a positive association between dental amalgam and PD has been found in a few case-control studies. The patients with amalgam fillings restored between 2000 and 2008 were identified by using the National Health Insurance Research Database (NHIRD) in Taiwan. The same number of patients who had no new amalgam filling restored was matched by sex, age, and treatment date. Both cohorts were followed up from the treatment date until the date of diagnosis of PD, death, or the end of the year 2008. The individuals who received amalgam fillings had a significantly higher risk of PD afterward (adjusted hazard ratio [HR]=1.583, 95% confidence interval [CI]=1.122-2.234, p=0.0089) than those who did not. In the individuals who received amalgam fillings, being diagnosed with diabetes or hyperlipidemia demonstrated a significantly lower HR of PD occurrence than in the patients without diabetes or hyperlipidemia (HR=0.449, 95% CI=0.254-0.794, p=0.0059; HR=0.445, 95% CI=0.260-0.763, p=0.0032) after adjusting for comorbidities and Charlson-Deyo Comorbidity Index (CCI) scores. Meanwhile, hypertension increased the hazard risk of PD (HR=1.645, 95% CI=1.098-2.464, p=0.0159). The patients exposed to dental amalgam fillings were 1.583 times more likely to have PD afterward compared to their non-exposed counterparts after adjusting for comorbidities and CCI scores.

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.

Ten-Year Survival of Class II Restorations Placed by General Practitioners

The aim of this retrospective practice-based study was to investigate the survival of direct class II restorations placed by a group of general dental practitioners (GDPs) and to analyze the effect of practice-, patient-, and tooth/restoration-related factors. Electronic patient files of 24 general dental practices were used for collecting the data for this study. From the patient files, survival rates of 222,836 composites, amalgams, glass ionomers, and compomers placed in 61,121 patients by 67 GDPs between 1999 and 2011 were analyzed by Kaplan-Meier statistics and a multiple Cox regression. The investigated group of GDPs placed restorations with a satisfactory survival (mean AFR₁₀, 4.9%; 95% confidence interval, 2.1 to 7.7), although a wide variation in annual failure rate (AFR) existed between the different operators, varying between 2.6% and 7.0%. Restorations placed in young adults (21-30 y old) survived longest, whereas they showed a shorter survival in children (hazard ratio [HR], 1.553) and the elderly (HR, 1.593). Restorations in molar teeth, restorations placed in endodontically treated teeth, and multisurface restorations are more at risk for reintervention. However, restoration size (included surfaces) has a greater impact on restoration survival in premolar teeth. For the future, improved data collection at the practice/operator, patient, and tooth/restoration level (e.g., risk assessment and diagnoses) will provide the opportunity to evaluate even more extensively the risk factors involved. Knowledge Transfer Statement: The results of this study give insight into the long-term survival of direct dental restorations and the influencing practice-, patient-, and tooth/restoration-related variables.

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.

Longevity of direct restorations in Dutch dental practices. Descriptive study out of a practice based research network

OBJECTIVES

The aim of this retrospective practice-based study was to investigate the longevity of direct restorations placed by a group of general dental practitioners (GDPs) and to explore the effect of practice/operator, patient, and tooth/restoration related factors on restoration survival.

METHODS

Electronic Patient Files of 24 general dental practices were used for collecting the data for this study. From the patient files, longevity of 359,548 composite, amalgam, glass-ionomer and compomer placed in 75,556 patients by 67 GDPs between 1996 and 2011 were analyzed. Survival was calculated from Kaplan-Meier statistics.

RESULTS

A wide variation in annual failure rate (AFR) exists between the different dental practices varying between 2.3% and 7.9%. Restorations in elderly people (65 years and older, AFR 6.9%) showed a shorter survival compared to restorations placed in patients younger than 65 years old (AFR 4.2%-5.0%). Restorations in molar teeth, multi-surface restorations and restorations placed in endodontically treated teeth seemed to be more at risk for re-intervention.

CONCLUSION

The investigated group of GDPs place restorations with a satisfactory longevity (mean AFR 4.6% over 10 years), although substantial differences in outcome between practitioners exist. Several potential risk factors on practice/operator, patient, and tooth/restoration level have been identified and require further multivariate investigation.

Class II Resin Composites: Restorative Options

Tooth-coloured, resin composite restorations are amongst the most frequently prescribed forms of dental restoration to manage defects in posterior teeth. The attainment of a desirable outcome when placing posterior resin composite restorations requires the clinician to have a good understanding of the benefits (as well as the limitations) posed by this material, together with a sound knowledge of placement technique. Numerous protocols and materials have evolved to assist the dental operator with this type of demanding posterior restoration. With the use of case examples, four techniques available are reported here. CPD/Clinical Relevance: This article explores varying techniques for the restoration of Class II cavities using resin composite.

Do clinical experience time and postgraduate training influence the choice of materials for posterior restorations? Results of a survey with Brazilian general dentists

The aims of this study were to evaluate the materials available for posterior restorations and to assess whether clinical experience time and post-graduate training influence dentists' choices. A cross-sectional study was conducted using a questionnaire with closed questions applied to dentists (n=276) of a mid-sized city of the southern Brazil. Information was collected regarding sociodemographic variables, level of specialization, time since graduation and working place. In addition, options regarding posterior restorations including the first choice of material, type of composite resin (if used) and use of rubber dam were also collected data. Data were submitted to descriptive analysis and the associations were evaluated using chi-square and Fisher's exact tests (α=0.05). The response rate was 68% (187). Direct composite resin was broadly indicated (73.2%) as the first-choice for posterior restorations. Most professionals used microhybrid composite (74.5%) and 42.6% of the participants used rubber dam for placement of posterior composite restorations. Dentists with more time of clinical practice used less composite (p=0.014). Specialists used more frequently rubber dam to restore posterior teeth than did non-specialists (p=0.006). The results of this survey revealed that direct composite was the first choice of dentists for posterior restorations; microhybrid was the preferred type of composite and the use of rubber dam for composite resin placement in posterior teeth was not frequent; time since graduation and level of specialization affected dentists' choices.

Knowledge and attitudes of general dental practitioners towards posterior composite restorations in northern saudi arabia

INTRODUCTION

The restoration of posterior teeth with composite restoration is a common clinical practice nowadays. Opinions regarding posterior composite restorations vary among dentists. The aim of the present study was to determine the knowledge and opinions of general dental practitioners towards composite resins for posterior teeth restorations.

MATERIALS AND METHODS

A questionnaire was devised to elicit information regarding placement of composite restoration in posterior teeth in northern Saudi Arabia. It was distributed to 230 dentists by hand and e-mail. A response rate 136 (59%) was obtained. The questionnaire sought details about case selection criteria for composite restoration, problems associated with composites and reasons for selecting composite restoration in posterior teeth. The data was processed and analysed by SPSS statistical software 19. Frequencies and percentages were calculated for various responses of the participants.

RESULTS

Regarding the selection of composite restoration in posterior teeth, 97% of the dentists did not prefer composite placement for class I restoration with heavy occlusal contacts. 83% of the participants did not select composite for class II restoration. 78% of the respondents opted for restoring composites in small defects. Patients' aesthetic demands (90%), amalgam replacement (22%) and restoration of endodontically treated teeth (42%) were the contributing factors. Regarding the problems associated with posterior composite restorations. Recurrent caries (87%), post-operative sensitivity (84%), restoration fracture (83%) and polymerization shrinkage (73%) were the major problems reported by respondents associated with composite restorations. The other minor concerns were wear (60%), contact build up in case of class II cavity restorations (51%) and isolation for composite restorations (36%). Conservative cavity preparation (78%), aesthetics (73%) and patient preference (65%) were the main reasons for choosing composite restoration for the posterior teeth.

CONCLUSION

Posterior composites are not popular among dentists practicing in northern Saudi Arabia and there is a need of continued professional education and clinical training for the dentists for posterior composite restorations.

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.