[Effects of different resin removal methods on shear bond strength of rebonded orthodontic brackets].

PURPOSE: To compare the shear bond strength (SBS) of rebonded orthodontic metal brackets with different resin removal methods. METHODS: Forty extracted premolars were chosen as samples and divided into 4 experimental groups. The teeth were bonded with brackets. The brackets from 3 groups were debonded while adhesive remnants were removed from bracket bases by methods of grinding, sandblasting, and direct flaming, respectively and then rebonded. The SBS values of all rebonded brackets were determined after pH cycling experiment for 30 days. Some rebonded bracket bases were selected and observed under scanning electron microscope (SEM). The data was analyzed by one-way ANOVA test using SPSS 13.0 software package. RESULTS: Statistical analysis revealed a significant difference of SBS values among the 4 experimental groups (P<0.05). The SBS values of the group by direct flaming was significantly lower compared to the other groups (P<0.05). There was no significant difference of SBS values among the other groups. CONCLUSIONS: The rebonded brackets after resin removal by grinding and sandblasting have a similar SBS compared to the initial brackets adhesive.