Effect of different surface treatments on the micro tensile bond strength to dentin, biaxial flexural strength and roughness of CAD/CAM resin composite and polymer infiltrated ceramic

Objectives: To evaluate the biaxial flexural strength (BFS), surface roughness (Ra) and micro tensile bond strength (mu TBS) of two CAD/CAM materials after different surface treatments. Materials and methods: For mu TBS, 64 human molars were used and 32 blocks of resin composite (RC-Lava Ultimate) and polymer-infiltrated ceramic (PIC -Vita Enamic). The blocks and teeth were distributed into 16 groups according to the factors "surface treatment" (HF: 10% hydrofluoric acid; APA: Al2O3 sandblasting; SC: silicate-Al2O3 sandblasting; MEP: Monobond Etch and Prime) and "thermal cycling" (TC). After cementation, the blocks were sectioned into 1 mm(2) bars. Half of the specimens were thermocycled and submitted to mu TBS test. For BFS, RC and PIC discs were made and distributed according to the surface treatments and after mechanical cycling, submitted to BFS test. Roughness, EDS, SEM, and Weibull analyses were also performed. Data were analyzed by (1 or 2-way) ANOVA and Tukey test (alpha = 0.05). Results: For RC, SC and HF after TC showed significantly higher mu TBS values. For PIC HF after TC showed higher mu TBS than the other groups. For RC, the BFS was higher for MEP than Al2O3 and SC. For PIC, none of the surface treatments influenced BFS. Conclusion: The highest mu TBS for RC was obtained with SC followed by silanization and for PIC, HF followed by silanization. The RC showed lower strength after Al2O3 blasting. For PIC all surface treatments resulted in similar BFS.