Repair bond strength of composite resin to zirconia restorations after different thermal cycles

PURPOSE: This in vitro study investigated the repair bond strength of the zirconia ceramic after different aging conditions. MATERIALS AND METHODS: In order to imitate the failure modes of veneered zirconia restorations, veneer ceramic, zirconia, and veneer ceramic-zirconia specimens were prepared and were divided into 4 subgroups as: control (37℃ distilled water for 24 hours ) and 3000, 6000, 12000 thermal cycling groups (n=15). Then, specimens were bonded to composite resin using a porcelain repair kit according to the manufacturer recommendation. The repair bond strength (RBS) test was performed using a universal testing machine (0.5 mm/min). Failure types were analyzed under a stereomicroscope. Two-way ANOVA and Bonferroni test were used for statistical analysis. RESULTS: The RBS values of zirconia specimens were statistically significant and higher than veneer ceramic and veneer ceramic-zirconia specimens in control, 3000 and 6000 thermal cycling groups (P.05). Veneer ceramic specimens exhibited cohesive failure types, zirconia specimens exhibited adhesive failure types, and veneer ceramic-zirconia specimens exhibited predominately mixed failure types. CONCLUSION: Thermal cycling can adversely affect RBS of composite resin bınded to level of fractured zirconia ceramics.

Repair bond strength of resin composite to bilayer dental ceramics

PURPOSE: The purpose of this study was to investigate the effect of various surface treatments (ST) on the shear bond strength of resin composite to three bilayer dental ceramics made by CAD/CAM and two veneering ceramics. MATERIALS AND METHODS: Three different bilayer dental ceramics and two different veneering ceramics were used (Group A: IPS e.max CAD+IPS e.max Ceram; Group B: IPS e.max ZirCAD+IPS e.max Ceram, Group C: Vita Suprinity+Vita VM11; Group D: IPS e.max Ceram; Group E: Vita VM11). All groups were divided into eight subgroups according to the ST. Then, all test specimens were repaired with a nano hybrid resin composite. Half of the test specimens were subjected to thermocycling procedure and the other half was stored in distilled water at 37℃. Shear bond strength tests for all test specimens were carried out with a universal testing machine. RESULTS: There were statistically significant differences among the tested surface treatments within the all tested fracture types (P .00125). CONCLUSION: This study revealed that HF etching for glass ceramics and sandblasting for zirconia ceramics were adequate for repair of all ceramic restorations. The effect of ceramic type exposed on the fracture area was not significant on the repair bond strength of resin composites to different ceramic types.