[Pulsed Nd:YAG laser-aided debonding for removing the metal brackets].

Objective: To explore the possibility of pulsed Nd:YAG laser-aided debonding for removing orthodontic metal brackets and to compare the method with the conventional mechanical debonding method.

Methods: Fifty healthy premolars extracted for orthodontic purpose were randomly divided into five groups (10 teeth in each group). There were four experimental groups and one control group. Every tooth was bonded with bracket. Laser was used to irradiate the teeth in experimental groups with different electric currents (13.0, 13.5, 14.0, 14.5 A). During the irradiation, the brackets received 4.9 N of force until the brackets off. The time needed for debonding and the temperature change of the pulp cavity were recorded. The teeth in control group were debonded using mechanical method. The adhesive remnant index (ARI) was calculated using stereomicroscope and imagetool software. All samples were examined with a scanning electron microscope.

Results: The time taken between the four groups were (67.70 ± 7.18), (35.90 ± 4.28), (24.90 ± 3.76), (6.90 ± 2.33) s, highly statistical difference was found in the time needed for debonding (P < 0.01). The temperature in the pulp cavity among the four groups were (20.97 ± 3.10), (12.75 ± 3.14), (8.99 ± 2.47), (2.91 ± 1.88)°C, and statistical differences were found in temperature change of the pulp cavity (P < 0.05). ARI of three experimental groups and the control group were (8.55 ± 5.02)%, (15.42 ± 7.37)%, (5.55 ± 3.79)%, (13.72 ± 6.69)%, and (74.36 ± 29.44)%. The enamel surface of the control group was coarse with deep scratchs. The enamel surface was smooth and clean in the experimental groups.

Conclusions: Pulsed Nd:YAG laser-aided debonding for removing metal brackets was feasible. Laser-aided debonding was better than conventional mechanical debonding method. The method reduced the damage to the enamel surface.