Effect of using a self-etching primer to repair resinous CAD-CAM materials: An in vitro study

Statement of problem: A consensus is lacking regarding the optimal surface treatment for repair protocols that ensures reliable bonding to computer-aided design and computer-aided manufacture (CAD-CAM) resin composite in intraoral applications. Purpose: The purpose of this in vitro study was to compare the microshear bond strength promoted by 3 bonding strategies to repair commercially available CAD-CAM resin composites. Material and methods: Three CAD-CAM resin composites (Cerasmart, Brilliant, Tetric CAD) and a hybrid ceramic (Vita Enamic) were pre-aged for 5000 thermal cycles and allocated into groups according to surface repair treatments: hydrofluoric acid etch, silane, and Monobond Etch & Prime, airborne-particle abrasion and Monobond Etch & Prime, or only Monobond Etch & Prime. Transparent Ø8×0.5-mm polyethylene tubes were placed on the treated surfaces and were filled with flowable resin composite. Half of the specimens (n=4) were microshear bond strength tested after 24 hours and the other half after thermal cycle testing, and the surface topography was examined. Data were analyzed with 2-way repeated measures ANOVA and the Bonferroni test (α=.05) Results: After 24 hours, for the Cerasmart, Tetric CAD, and Brilliant resin specimens, the Monobond Etch & Prime strategy presented the lowest microshear bond strength values (P<.003). In the Vita Enamic group, no differences were found among groups after 24 hours. After 10 000 cycles, values decreased in all groups (P<.05). The airborne-particle abrasion with Monobond Etch & Prime strategy promoted the highest values. Conclusions: Airborne-particle abrasion combined with a single component self-etching primer provided a simplified clinical alternative for repairing resin-containing CAD-CAM materials.