Abstract: Objective: To investigate the influence of different silane coupling agents and different adhesive materials to the shear bond strength of metal brackets bonded to porcelain surface. Methods: 90 porcelain specimens were deglazed by 1000 grit water sandpaper and etched with 9.6%HF acid for 120s, rinsed with distilled water and dried before applying the silane primer. All specimens were divided randomly into 3 groups according to different silane coupling agents application, Each group was subdivided into 3 subgroups depending on different adhesive material, every subgroup had 10 porcelain facets. 90 metal brackets were bonded to ceramic specimens with 3 adhesive material. All specimens were stored in artificial saliva bath at 37℃ for 24 hours. after brackets bonded for 60min, then the specimens were underwent shear testing with Instron universal testing machine. Results: The shear bond strength of the groups treated with silane primer were higher than that without silane primer (p<0.05). There was not any statistically significant in the shear bond strength between the group of one-mix silane coupling agent and the group of two-mix silane coupling agent (p>0.05). The shear bond strength of the group with light-cured composite resin was higher than the others (p<0.05). The groups treated without silane coupling agent showed lower porcelain fracture than the groups treated with silane coupling agent. Conclusions: Silane coupling agent can improve the shear bond strength between metal brackets and porcelain surface. The group of light-cured composite resin treated with two-mix silane coupling agent can get the highest shear bond strength.

Key words: shear bond strength, silane coupling agent, porcelain bonding