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 physico-mechanical and biological behavior of the materials tested.

A Randomized Double-blind Clinical Trial of Dentin Surface Treatments for Composite Restorations in Noncarious Cervical Lesions: A 36-month Evaluation.

OBJECTIVE:: This randomized, double-blind clinical trial aimed to evaluate the influence of different dentin surface treatments in noncarious cervical lesions (NCCLs). METHODS AND MATERIALS:: Twenty-nine patients participated in this study. One hundred sixty-five NCCLs were selected and randomly assigned to three groups: G0 (control group) with phosphoric acid etching for 15 seconds; G1: phosphoric acid etching for 30 seconds; and G2: ultrasound probe applied for 30 seconds on the dentin surface. Class V composite resin restorations were performed (Z350, 3M ESPE, St Paul, MN, USA). The restorations were evaluated at baseline and at six, 12, 24, and 36 months according to the World Dental Federation criteria. Survival curves were obtained using the Kaplan-Meier method and the log-rank test. Comparisons between groups and times were performed using the McNemar and Chi-square tests (α =0.05). RESULTS:: The presence of failures due to retention was statistically different among the groups ( p=0.012), and G0 and G2 showed better clinical performance than did G1. Sensitivity decreased over time in all groups. Marginal discoloration, postoperative sensitivity, and marginal adaptation were not different among the groups ( p>0.05). CONCLUSIONS:: The studied dentin surface treatments showed similar clinical performance to the conventional technique at 36 months in terms of marginal discoloration, marginal adaptation, and postoperative sensitivity. In contrast, increased acid-etching time resulted in a higher risk of failure due to retention over time in composite Class V restorations.

Influence of Surface Treatment on Composite Adhesion in Noncarious Cervical Lesions: Systematic Review and Meta-analysis.

The purpose of this study was to analyze the influence of dentin surface treatments on the retention rate of resin composite restorations in non-carious cervical lesions (NCCLs). Seven randomized clinical trials were included in this review. Data regarding retention rate, type of surface treatment, and the main characteristics of studies were analyzed. Two reviewers performed a literature search up to December 2016 in eight databases: PubMed (Medline), Lilacs, Ibecs, Web of Science, BBO, Scopus, Scielo and The Cochrane Library. Only clinical trials evaluating dentin surface treatments in resin composite restoration in NCCLs were included. Noncontrolled clinical trials, reviews, editorial letters, case reports, case series and studies published in a language other than English, Portuguese, or Spanish were not included. The included studies evaluated different surface treatments, such as using an adhesive system with a frictional technique, drying the dentin, and removing sclerotic dentin by using a bur and applying EDTA before primer use. The analysis considering the mechanical removal of dentin surface with a bur and the application of an adhesive system in a frictional mode showed these treatments improved retention rates of the resin composite restorations in NCCLs ( p<0.05). There is evidence in the literature suggesting that the mechanical removal of dentin surface with a bur and the application of an adhesive system in a frictional mode could improve the retention rates of resin composite restorations in NCCLs. However, the studies showed high heterogeneity, and additional clinical trials are needed to determine the best dentin treatment option in NCCLs.