Abstract
Objective: The aim of the study was to evaluate the influence of Er:YAG laser irradiation on the debonding of metal and ceramic brackets and enamel damage ex vivo. Background data: The principle of safe bracket debonding is to degrade the adhesive resin strength connecting the tooth and bracket.
Removal of adhesive resin from tooth surfaces without iatrogenic damage (enamel loss) is generally the main problem of the otherwise very successful method of aesthetic straightening of teeth. Methods: Forty ceramic and metal brackets (Clarity Advanced and Victory Series; 3M Unitek, Monrovia, CA) were standardly bonded to buccal polished enamel surfaces of 30 caries-free human third molars.
Two types of adhesive resins (Transbond XT Light Cure Adhesive; 3M Unitek, and Variolink II Professional Set; Ivoclar Vivadent AG) were used. Before debonding, the brackets in the laser group were irradiated with the Er:YAG laser (FJFI CVUT) 280mJ, 250s long, repetition rate 6Hz, spot focus 1mm, and 140sec.
The control group was debonded without the laser irradiation. During the bracket irradiation, temperature changes inside the tooth were monitored using a thermal image infrared camera.
The enamel surface was investigated by SEM. Results: It has been observed that bracket removal was easier after the Er:YAG laser irradiation, and temperature rise was limited (from 2.0 degrees C to 3.2 degrees C) also for metal brackets.
As against the nonirradiated samples, SEM investigation has confirmed no damage to enamel. Conclusions: Irradiation with Er:YAG laser radiation before debonding of ceramic brackets significantly decreases the bonding failure and amount of remaining adhesive.