Effect of thermocycling and surface treatments on the bond strength of a hybrid PICN ceramic.

This study evaluated the bond strength of a hybrid PICN ceramic before and after being subjected to 5000 cycles of thermocycling. PICNs are a promising alternative in the field of CAD/CAM dental restorations; however, their adhesive behavior with chemical surface treatments such as silane and 10-MDP, and micromechanical treatments such as hydrofluoric acid and sandblasting is not yet fully understood. AIM: To compare the bond strength of a hybrid PICN ceramic treated with different surface protocols before and after a thermocycling process. MATERIALS AND METHOD: An in-vitro experimental study was conducted. Forty PICN ceramic slices were prepared and divided into four groups. Each group received a specific surface treatment (sandblasting or acid etching) and a different adhesive technique (silane + adhesive or adhesive only). Composite cylinders of 3 mm diameter mm were bonded to each slice, and shear strength was measured on a universal testing machine immediately, and after a period of thermocycling. Statistics: Data were analyzed by ANOVA followed by Tukey's post hoc test. All statistics were analyzed with a 95% confidence interval. RESULTS: The group subjected to sandblasting followed by silane and universal adhesive achieved the highest adhesion values, both immediately and after thermocycling (16.3 MPa and 11.2 MPa, respectively), and the group subjected to hydrofluoric acid etching and adhesive had the lowest values, both immediately and after thermocycling (8.6 MPa and 5.4MPa). CONCLUSION: Cementation of a hybrid ceramic treated with sandblasting, silane and a 10-MDP-based adhesive ensures high bond values, even when aged under hot, humid conditions. Thermocycling significantly reduced the adhesive strength in all groups, the decrease being more noticeable in those that did not include silane.