Effectiveness of Silica-Lasing Method on the Bond Strength of Composite Resin Repair to Ni-Cr Alloy

PurposeThe 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 MethodsSixty Ni-Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne-particle abraded using 50 m aluminum oxide particles. Specimens were divided into six groups that received the following surface treatments: group 1airborne-particle abrasion alone (AA); group 2Nd:YAG laser irradiation (LA); group 3silica coating (Si-CO); group 4silica-lasing (metal surface was coated with slurry of opaque porcelain and irradiated by Nd:YAG laser) (Si-LA); group 5silica-lasing plus etching with HF acid (Si-LA-HF); group 6CoJet 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 ( = 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. ResultsSi-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. ConclusionSilica coating of Ni-Cr alloy resulted in higher shear bond strength than those of other surface treatments.