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

Abstract

Objectives: To evaluate the biaxial flexural strength (BFS), surface roughness (Ra) and micro tensile bond strength (μTBS) of two CAD/CAM materials after different surface treatments.

Materials and methods: For μTBS, 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 mm² bars. Half of the specimens were thermocycled and submitted to μTBS 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 (α = 0.05).

Results: For RC, SC and HF after TC showed significantly higher μTBS values. For PIC HF after TC showed higher μTBS 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 μTBS 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.

Keywords: Computer-aided design; Flexural strength; Lava ultimate; Polymer-infiltrated ceramic; Resin composite; Surface roughness; μ-TBS.