Effect of four different surface treatments on shear bond strength of three porcelain repair systems: An in vitro study

BACKGROUND: Ceramic fracture in metal ceramic restorations are serious and pose an aesthetic and functional dilemma both for the patients and the dentist. This has created a demand for the development of practical repair options which do not necessitate the removal and remake of entire restorations. AIM: To evaluate and compare the effect of four different surface treatments on shear bond strength of metal ceramic specimens with three commercially available porcelain repair systems. MATERIALS AND METHODS: Specimens were fabricated with a base-metal ceramic alloy and divided into three groups, to evaluate three porcelain repair systems. Each group was divided into four subgroups based on surface treatment (A) sandblasting, (B) sandblasting followed by etching with 9% HF (Hydrofluoric acid) on surrounding ceramic, (C) Use of a diamond bur on exposed metal followed by etching with 37% H(3)PO(4) and (D) Control groups (D(1), D(2), D(3) for three groups of porcelain repair system which was not subjected to further treatment after finishing with 240 grit silicon carbide paper grinding. Shear bond strength of each group of specimens based on surface treatment were evaluated with a universal testing machine after storing in distilled water for 7 days. One way ANOVA and Tukey-HSD procedure were used to compare the mean values between and among the groups. RESULTS: The mean shear bond strength of group III (10.402 ± 1.055) were significantly higher than group I (8.647 ± 0.990) and group II (8.099 ± 0.600) for all surface treatments. However the mean values of shear bond strength of sub-group A were significantly higher than sub-group C and D but were not significantly higher than sub-group B. CONCLUSION: The results of this study suggest that in fractured metal ceramic restorations the exposed metal surface treated with sandblasting or sandblasting and etching the surrounding ceramic surface with HF can increase the shear bond strength of the repaired metal ceramic area. Porcelain repair systems which contain hybrid composites and 4-META as primer had increased bond strength.