Effect of thermocycling on shear bond strength of cemented zirconia-reinforced lithium silicate (Celtra Duo)

Purpose: The aim of the present in vitro study is to evaluate the effect of thermocycling on the shear bond strength (SBS) of cemented zirconia-reinforced lithium silicate (ZLS) discs (Celtra Duo). Materials and Methods: Thirty-six Celtra Duo ceramic discs cemented (n = 36) to composites discs background (Master dent) by adhesive resin cement (Biscem). The baseline group (n = 12) did not subject to thermocycling, the second group (n = 12) was subject to 2500 thermal cycle, and the third group was subject to 5000 thermal cycles, then SBS and the failure mode were evaluated. Results: There was a statistically significant difference between the groups (P = 0.001) where the value of SBS (Mpa) was significantly decreased in both 2500 thermocycling group (P = 0.021) and 5000 thermocycling group (P = 0.001) when compared with their corresponding level measured at baseline group. In addition, there was a significant decrease in bond strength of 5000 thermocycling group when compared with its corresponding value in the 2500 thermocycling group (P = 0.001). Conclusion: Based on the results of the present study and within the limitations of this in vitro study, it can be concluded that the SBS of cemented ZLS restorations will be decreased when samples are subjected to thermocycling to simulate the clinical situation.