The air-abrasion technique versus the conventional acid-etching technique:A quantification of surface enamel loss and a comparison of shear bond strength

The purpose of this study was to quantify the surface enamel loss that resu lts when an air-abrasive technique is used and to compare the shear bond st rength of different prebonding and bonding methods. Enamel loss was determi ned for 2 enamel-conditioning methods: acid etching with 37% phosphoric aci d; and sandblasting with 50 mu m aluminum oxide particles under different c onditions. A profilometer was used to determine the surface enamel loss. Fo rty-two bovine teeth were divided into 7 groups (N = 6). The statistical co mparison of the different groups was carried out by analysis of variance. T he results showed that under certain conditions the enamel loss associated with sandblasting is equal to or smaller than that resulting from acid etch ing. In addition, the effectiveness of different prebonding and bonding tec hniques used in the bonding of orthodontic brackets was evaluated by means of shear bond strength measurements. For bonding, 1 resin and 1 glass ionom er cement were evaluated; for prebonding, a sandblaster, 2 different polyac rylic acids and phosphoric acid were tested. Seventy bovine teeth were divi ded into 7 groups (N = 10) and then stored in water for 24 hours. An Instro m testing machine was used to determine bond strengths, and the 7 groups we re compared by means of analysis of variance. The significance of post hoc tests was predetermined at P < .003. The results showed that the bond stren gth of the sandblasted groups was significantly lower than that of the etch ing groups. This indicates that sandblasting is not an alternative for the acid-etching technique currently used in orthodontic practice.