Feasibility and safety of a novel laser-induced adhesive for orthodontic debonding

This study evaluates the feasibility and safety of a laser-induced reversible adhesive (LIRA) by assessing intrapulpal temperature changes (ITC), shear bond strength (SBS) following laser irradiation, and optimal adhesive removal methods.

Thirty premolars were used to measure ITC under laser powers of 1 W, 2 W, and 3 W until the temperature exceeded the 5.6 ℃ threshold. For SBS testing, one hundred and twenty premolars were divided into twelve groups based on bracket type (metal/ceramic) and laser treatment (untreated, 1 W-4 s, 2 W-4 s, 1 W-8 s, 2 W-8 s, and 3 W-4 s). Adhesive remnant index (ARI) was recorded. Additionally, one hundred thirty-five premolars were assigned to nine groups based on laser power (1 W, 2 W, 3 W) and adhesive removal methods (ultrasonic scaler, tungsten carbide bur, diamond bur) for surface roughness and removal time assessment. Statistical analysis was performed using ANOVA, t-tests, and the Kruskal-Wallis test (α=0.05). Furthermore, the debonding resin-enamel interface and enamel surface morphology were observed by scanning electron microscopy (SEM).

The time to exceed the temperature threshold decreased with increasing laser power. The 1 W-8 s and 2 W-8 s groups showed the lowest SBS (p < 0.05). Ultrasonic scaler removal exhibited significantly lower enamel roughness (p < 0.05), while removal time showed no significant difference at 2 W laser power (p > 0.05).

LIRA may provide a potentially safer and more efficient strategy for orthodontic bracket bonding, achieving efficient debonding while minimizing enamel damage and ensuring pulp safety.