DEBONDING OF CERAMICS SELF-LIGATING BRACKETS BY DIODE LASER

Background: Fractures and cracks have been reported during conventional debonding procedures of ceramics brackets by removing plier. The aim of this study was to develop a method to reduce debonding force and enamel fracture during debonding process of self-ligating ceramic brackets by using laser irradiation with diode laser. Study: Ninety human premolars and molars extracted for orthodontic reasons were used in this study. Polycrystalline ceramic self-ligating brackets with metal clip were bonded using adhesive and dual cured composite. The samples were thermocycle in 1800 cycles at temperature up to 55 8C during 10 s. Thermocouple for temperature measurement was placed in the hole prepared on the oral tooth side. Tensile force for debonding was measured with custom made machine. All teeth were randomly divided in the three groups: control- plier debonding and laser debonding u0001 5 seconds, 3 W (group 1) and 4 W (group 2) energy, CW, spot size 2 mm, 2 mm distance Results: Significantly (p ¼ 0.023) lower tensile force for brackets debonding using laser irradiation (15 J and 20 J) in premolar group compared with controls was found. There was no significant difference between two premolar laser groups nor between all three molar groups. There was significantly (p u003c 0.001) pulp temperature increase between all three premolars group. There was significantly (p u003c0.001) pulp temperature increase between control molar group and molar laser debonding groups Conclusion: Diode laser is safe clinical tool and significantly reduce tensile force for orthodontic brackets debonding from premolars. During laser debonding temperature increase in pulp chamber is below threshold of 55 8C.