Super pulse CO2 laser for bracket bonding and debonding

Abstract

A super pulse and a normal pulse CO2 laser were used to carry out enamel etching and bracket debonding in vitro and in vivo. The shear bond strength of the orthodontic brackets attached to laser-etched and conventional chemically-etched extracted premolars was measured. The pulp cavity temperature was also measured using the same laser irradiation conditions as the shear test. Both super pulse and normal pulse CO2 laser etching resulted in a lower shear bond strength (super pulse: 6.9 ± 3.4 kg, normal pulse: 9.7 ± 5.2 kg) than that of chemical etching (15.3 ± 2.8 kg). Furthermore, the super pulse CO2 laser was able to create debonding at 2 watts within a period of less than 4 seconds (2.9 ± 0.9 seconds). The super pulse, when irradiating the ceramic brackets from above, during debonding showed a 1.4°C temperature increase in the dental pulp at 2 watts and an increase of 2.1°C at 3 watts. While etching, directly irradiating the enamel surface at 3 watts, the dental pulp showed a temperature increase of 3.5°C. These temperature increases were within the physiologically acceptable limits of the pulp. These results indicate that, in orthodontic treatments, super pulse CO2 laser debonding is more useful than laser etching.