Repair of aged polymer-based CAD/CAM ceramics treated with different bonding protocols.

PURPOSE: The aim of this study was to compare the microtensile bond strength (muTBS) of different CAD/CAM polymer-based ceramics to a repair composite resin using various bonding protocols. MATERIALS AND METHODS: Three different CAD/CAM polymer-based ceramics (LAVA Ultimate [LU], 3M ESPE; VITA Enamic [VE], VITA Zahnfabrik; and CeraSmart [CS], GC) were used. Ceramic slices were obtained and subjected to thermal cycling between 5 degrees C and 55 degrees C for 5,000 cycles with a 30-second dwell time. The samples were randomly separated into the following groups: universal adhesive (UB); hydrofluoric acid (HF); sandblasting (SN); HF + UB; HF + ceramic primer (PR) + adhesive (GB); SN + UB; and SN + PR + GB. The repair composite resin (G-aenial Universal Flo, GC) was applied to the samples and subjected to re-aging between 5 degrees C and 55 degrees C for an additional 5,000 cycles. Parallel sections were removed from the specimens, and multiple beam-shaped micro sticks (1.0 mm x 1.0 mm x 10 mm) were prepared for each group. Subsequently, the muTBS test was performed, and the obtained data were statistically analyzed via one- and two-way analysis of variance and Tukey post hoc tests. Scanning electron microscopy (SEM) analysis was also performed. RESULTS: Significant differences were found among the experimental groups (P < .05). The muTBS values of the UB bond groups were higher than those with the GB bond. The effect of pretreatment on muTBS (eta(P)(2) = 0.556) was more significant than ceramic type (eta(P)(2) = 0.481), and this result was supported by the SEM images. CONCLUSION: Pretreatment before application of universal adhesive is still needed to repair hybrid ceramic restorations with composite resins.