Effect of Preheating Cycles on Microshear Bond Strength of Nanohybrid Resin Composite Luted to CAD/CAM Ceramic

Objective: This study aimed to investigate the microshear bond strength of adhesive resin cement Leucite-reinforced CAD/CAM ceramic and compare it with that prewarmed nanohybrid composite. Materials methods: Sixty Empress CAD plates were prepared. Each plate received five Tygon tube micro-cylinders filled bonding agents creating 5 resinous on each plate. In first group (GpA), they cement, composite as a agent was applied in second (GpB), after warming at 50?, third (GpC), two prewarming cycles performed. Light-curing for 20seconds applied. Micro-shear testing (?SBS) performed using universal machine crosshead speed 1 mm/min until failure occurred. The ?SBS calculated MPa by dividing load (Newton) over respective surface area (mm 2 ).Data tabulated analyzed showed normal distribution when checked Kolmogorov–Smirnov test. One-way ANOVA used between tested groups data followed Tukey HSD post-hoc test pairwise comparisons. Significant level set 5% (?=0.05). Results: One- way significant difference (p < 0.001). Where heated (two cycle) highest mSBS compared other 0.05). Nevertheless, (one an improved group, but increase insignificant (p=0.081). Conclusion: pre-heated composites seem be potential alternative lute restorations.