| Objective: To research the effects of different surface treatments on the bond strength of metal brackets bonded to Ceramage polymer-ceramics and analyze the impact of bond strength of these treatments between Ceramage polymer-ceramics and metal bracket, and discuss the discrepancy of surface breakage after orthodontic brackets removed and the discrepancy of surface microstructure of porcelain under different treatments.Methods: 40 Ceramage polymer-ceramics specimens were randomly divided into 5 groups by the following treatment conditions of the surface: A:surface without special treatment, B:9.6% hydrofluoric acid gel combine with bonding agent, C: 9.6%hydrofluoric acid gel combine with silane, D: 35 % phosphoric acid gel combine with bonding agent, E:35% phosphoric acid gel combine with silane. Brackets were bonded to the Ceramage polymer-ceramics specimens with a light-polymerized resin composite.All specimens were stored in water for 24 hours at 37°C after bonding 10 minutes and then cycled 500 cycles( 5°C to 55°C).To measure the shear bonding strength and record the damage cases and the adhesive remnant index.Results:The lowest shear bond strength values were found in the no specific treatment group(3.24MPa).The shear bond strength of the phosphoric acid-only group(4.17MPa) is slightly lower than the hydrofluoric acid etching treatment group(7.24 MPa).But the Ceramage polymer-ceramics fracture increased in hydrofluoric acid etching treatment group.The highest bond strength were obtained with hydrofluoric acid gel and silane(10.78MPa).The results of each group were have statistically significant difference among each group(P <0.001).Conclusion:Beside the the surface with no special treatment group and the 35%phosphoric acid gel combine with bonding agent group, other three groups can achieve clinical orthodontic required shear bonding strength effectively. The combination of silane coupling agent can significantly improve the shear bondingstrength and increase the breakage of Ceramage polymer-ceramics significantly at the same time. As to the high shear bonding strength and low rate of breakage after the removal of brackets, we recommend 35% phosphoric acid etching combining with silane coupling agent in clinical. |
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