Aim: A successful restoration is the result of the proper adhesion between dental tissue, cement and restoration material. The long-term durability of this bond is mandatory for clinical success. The aim of the present study is to investigate the influences of three different thermal cycle applications on resin cement-glass ceramic shear bond strength. Methodology: In the present study, a single CAD/CAM glass ceramic block and five different resin cements (Panavia V5, RelyX U200, G-CEM LinkForce, RelyX Veneer,and Variolink Esthetic) were used. A total of 240 sections 2 mm in thickness were obtained under water cooling in a precision cutting machine with the aid of a diamond saw. Cementation of glass ceramic samples was conducted in accordance with the instructions of the manufacturer, and the cemented samples were incubated at 37 °C for 24 hours. Afterwards, samples were randomly divided into four groups according to thermal cycle: control group, 1750, 3500 and 7000 cycles (n = 12). Following aging procedures, the samples were tested for shear bond. Statistical analyses were done by using the IBM SPSS 20.0 program. While the ANOVA test was used for intra-group statistical analyses, LSD multi- comparison analysis was used for detection of the inter-group differences. Statistical significance was set at p < 0.05.

Results: Although an overall reduction was seen in shear bond of all cement groups following thermal cycle applications, this reduction was found to be statistically significant for Panavia V5, RelyX Veneer and Variolink Esthetic (p<0.05). Following 1750 cycles of thermal cycle application, Panavia V5 and G-Cem LinkForce with dual-cure property showed higher shear bond strength than RelyX Veneer and Variolink Esthetic with light-cure structure (p<0.05).

Conclusion: The reduction in bond strength following the thermal cycle procedure is associated with water absorption in the resin cement-glass ceramic interface. So resin cement preferred for cementation of restorations is among the key parameters for clinical success.