Clinical Relevance The clinical behavior of pure ormocer composite is reliable when used in class II restorations after 24 months of evaluation. SUMMARY Objective: The aim of this study was to evaluate the clinical performance of class II restorations made using pure ormocer and methacrylate composites in a period of 24 months, using a split-mouth double-blinded randomized design. Methods and Materials: Thirty patients received two class II restorations (n=60) performed with different composites: GrandioSO (methacrylate, nanohybrid) and Admira Fusion (pure ormocer, nanohybrid). The universal adhesive system (Futurabond M+) was applied in all restorations using the self-etching mode. The composites were placed by the incremental technique. The restorations were evaluated using the FDI World Dental Federation criteria after 7 days and 6, 12, and 24 months postoperatively. Results: After 24 months, 23 patients attended the recall and 46 restorations were evaluated. Fisher's statistical analysis (5%) showed no difference between the materials. One pure ormocer restoration and one methacrylate restoration presented small fractures. Only one tooth suffered a fracture of the remaining tooth structure. Admira Fusion presented, respectively, 100%, 95.66%, and 100% of acceptable performance in general scores for esthetic, functional, and biological properties. GrandioSO presented, respectively, 100%, 91.31%, and 95.66% of acceptable performance in the same scores. Conclusion: After 24-month follow-up, nonsignificant differences between the tested composites was detected. Both materials provided acceptable clinical performance in class II restorations.

SUMMARY Objective: Erosive/abrasive challenges can potentially compromise bonding to dentin. Aiming to improve the quality and stability of bonding to this substrate, this study investigated the combined effect of erosion and toothbrush abrasion on the microtensile bond strength (μTBS) stability to dentin using a universal adhesive system in total and self-etching modes, associated or not associated with deproteinization. Methods: Bovine dentin specimens were divided into five groups according to the organic matrix condition (n=20): control (C); erosion (E); erosion + abrasion (EA); erosion + sodium hypochlorite (EH); erosion + abrasion + sodium hypochlorite (EAH). The groups were further divided (n=10) according to the mode of application (total or self-etching) of a universal adhesive. After the bonding procedure, composite blocks were built up, and the samples were cut to obtain sticks for μTBS testing. For each specimen, one-half of the sticks was immediately tested, and the other one-half was tested after artificial aging (5000 thermocycles, 5°C and 55°C). Results: Three-way analysis of variance (α=5%) showed a significant difference for the triple interaction ( p =0.0007). Higher μTBS means were obtained for the EH and EAH groups compared with the E and EA groups. The control group showed immediate μTBS values similar to that of the E and EA groups for both bond strategies. Conclusions: Erosion and erosion/abrasion did not significantly influence the immediate μTBS to dentin. Artificial aging reduced μTBS values for the groups C, E, and EA using the total-etching mode. Deproteinization maintained the bond stability to artificially aged eroded and eroded/abraded dentin.