Objective: This study evaluated the effects of 4 different surface conditioning methods on the bond strength of metal brackets bonded to ceramic surfaces with resin based cement, analyzed the impact of these treatments on porcelain.
Method: 32 Mental-Fused-Ceramic specimens (feldspathic porcelain) with glazed surfaces were used for each group. The specimens were randomly assigned to 1 of the following treatment conditions of the ceramic surface: (1) hydrofluoric acid gel + bonding agent, (2) hydrofluoric acid gel + silane (3) airborne particle abrasion (aluminum trioxide, 50μm) + silane, and (4) tribochemical silica coating (silicon dioxide, 30μm) + silane. Brackets were bonded to the conditioned ceramic specimens with a light-polymerized resin composite. All specimens were stored in water for 1 week at 37°C and then thermocycled (500 cycles, 5°C to 55°C, 60 seconds). The shear bond strength values were measured on a universal testing machine at a crosshead speed of 0.5 mm/min, and the failure types were classified with adhesive remnant index scores.
Result: In all 4 groups, the lowest shear bond strength values were found in the hydrofluoric acid-only samples. The highest bond strength were obtained with sandblasting plus silane and silicatization also, with no significant difference,but porcelain fracture increased in these two group. The hydrofluoric acid with silane have no significant difference with sandblasting plus silane and silicatization.
Conclusion: Except "hydrofluoric acid-only" group, the other three sets of porcelain surface treatments met the requirement of effective orthodontic bonding strength. silane coupling agent improved the retention of porcelain and resin bonding.