Evaluation of Preheating Composite Resins for Repairing Resin Nanoceramic Restorations

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Objective: Resin nanoceramic dental restorations may need repair. This study evaluates the microshear bond strength of two composite resins applied at two temperatures to repair two resin nanoceramic materials. Materials and Methods: Ninety-six specimens were sliced from Lava Ultimate and CeraSmart resin nanoceramic blocks and subjected to thermal aging. Following surface roughness measurements, specimens were divided into eight subgroups (n=12) based on the repair material and application temperature. Resin nanoceramic specimens were repaired using a Teflon mold with RubyComp P or RubyCompNano composite resins at 23°C or 50°C. All specimens were subjected to a microshear bond test at a 0.5 mm/min crosshead speed until failure. Failure types were classified at 5X magnification. Statistical analysis of microshear bond strength test results was performed by a three-way ANOVA test, followed by post hoc Tukey’s pairwise comparisons (α=0.05). The relationship between failure modes and resin nanoceramic, composite resin, or preheating was analyzed with a chi-square test. Results: Surface roughness of resin nanoceramics was not statistically different (p>0.05). The resin nanoceramic type and preheating of repair materials had a significant effect on microshear bond strength (p=0.006, p