Effect of different treatment methods of polymeric porcelain surface on its adhesion to metal brackets

To analyze and discuss the effect of 4 different surface treatment methods on the bonding effect between polymerization porcelain and metal bracket s.

45 polymer-ceramics specimens were made and 40 of them were selected and randomly divided into 5 groups according to different surface treatment methods. A group: surface without special treatment. B group: 9.6% hydrofluoric acid gel combine with bonding agent, C group: 9.6% hydrofluoric acid gel combine with silane, D group: 35% phosphoric acid gel combine with bonding agent, E group: 35% phosphoric acid gel combine with silane. All specimens were stored in water for 24 hours at 37 ℃ after bonding 10 min utes and then cycled 500 cycles (5 ℃ to 55 ℃). To measure the shear bonding strength and record the damage cases and the adhesive remnant index.

The shear strength values were: 3.24 in the control group, 7.24 MPa in the hydrofluoric acid etching treatment group. 10.78 MPa in the hydrofluoric acid gel combined with silane group. 4.17 MPa in the phosphoric acid-only group, 6.84 MPa in the phosphoric acid gel combined with silane group. The results of each group were statistically different from those of the other four groups (P < 0.001). The rate of breakage after the removal of brackets of the hydrofluoric acid gel combined with silane group is higher than the others.

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.