Purpose
The aim of this study was to evaluate the effectiveness of silica‐lasing method for improving the composite resin repair of metal ceramic restorations.
Materials and Methods
Sixty Ni‐Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne‐particle abraded using 50 μm aluminum oxide particles. Specimens were divided into six groups that received the following surface treatments: group 1—airborne‐particle abrasion alone (AA); group 2—Nd:YAG laser irradiation (LA); group 3—silica coating (Si‐CO); group 4—silica‐lasing (metal surface was coated with slurry of opaque porcelain and irradiated by Nd:YAG laser) (Si‐LA); group 5—silica‐lasing plus etching with HF acid (Si‐LA‐HF); group 6—CoJet sand lased (CJ‐LA). Composite resin was applied on metal surfaces. Specimens were thermocycled and tested in shear mode in a universal testing machine. The shear bond strength values were analyzed using ANOVA and Tukey's tests (α = 0.05). The mode of failure was determined, and two specimens in each group were examined by scanning electron microscopy and wavelength dispersive X‐ray spectroscopy.
Results
Si‐CO showed significantly higher shear bond strength in comparison to other groups (p < 0.001). The shear bond strength values of the LA group were significantly higher than those of the AA group (p < 0.05). No significant difference was found among lased groups (LA, Si‐LA, Si‐LA‐HF, CJ‐LA; p > 0.05). The failure mode was 100% adhesive for AA, Si‐LA, Si‐LA‐HF, and CJ‐LA. LA and Si‐CO groups showed 37.5% and 87.5% cohesive failure, respectively.
Conclusion
Silica coating of Ni‐Cr alloy resulted in higher shear bond strength than those of other surface treatments.