Influence of Tm: YAP laser irradiation on tensile strength for bracket debonding

摘要

The aim of our study was the investigation of tensile strength needed for bracket debonding. A diode-pumped Tm:YAP microchip laser generating a continuous 2um radiation with a maximum output power of 4W was used for debonding purposes. A group of 60 brackets was debonded using classical and laser irradiation methods - the dose from 1 W to 4 W for 60 s. The tensile strength without laser irradiation was in the range from 39.6 N (full ceramic bracket group) to 63.7 N (ceramic bracket with metal slot group). After irradiation, the tensile strength was lowered from 35.1 N (full ceramic bracket group) to 48.8 N (ceramic bracket with metal slot group). The results of our study generally agree with the previous studies, substantiating the fact that lasers can be used effectively to thermally soften the adhesive resin for removal of ceramic brackets. From the practical point of view the conclusion is that during laser irradiation thermal ablation occurs and the bracket is removed from the enamel together with the rest of the adhesive resin. Laser debonding is easier and certain heat diffusion occurred.