Study Of Nd:YAG Laser Debonding Ceramic Orthodontic Brackets

This study was conducted for the purpose of using Nd:YAG Laser debonding ceramic orthodontic brackets, throught the test of the bonding strength, the temperature of dental pulp, comparing the difference about adhesive remnant index, the photomicrographs and the loss of elemant on emamel by scanning electron microscopy (SEM) after laser debonding and mechnical bonding ,try to find the best way to debond ceramic orthodontic brackets, increase the work efficient in orthodontic clinic as possible.This study included two parts. Part I ,50 healthy premolars extracted for orthodontic purpose were randomly divided into five groups, ten premolars were bonded mental brackets, the others were bonded ceramic brackets. The tooth specimen was stored in water for 24hr at room temperature. An MTS New 810 100 KN testing machine was used to apply shear force after different laser energy. An FLUKE 8 840A Multimeter was used to test the pulp cavity temperature. Part II, 24 healthy premolars were randomly divided into three groups, eight premolars were bonded mental brackets, mechnical debonding. Eight premolars were bonded ceramic brackets, mechnical debonding. Eight premolars were bonded ceramic brackets, laser debonding. Comparing the difference about adhesive remnant index by steromicrograph, thephotomicrographs and the loss of elemant on enamel by scanning electron microscopy (SEM).1. The results of the test of shear force after different laser energy and the pulp cavity temperature.The shear force of ceramic brackets was stastically high than mental brackets and stastically reduced after laser irradiation, from 11.63Mpa to 4.13Mpa. The best laser energy debonding ceramic brackets was 3watt, irradiate second, the pulp cavity temperature increased 3.65℃, this temperature wasn't damaged to dental pulp.2. The results of comparing the difference about adhesive remnant index, the photomicrographs and th loss of elemant on enamel by scanning electron microscopy (SEM) after laser debonding and mechnical debonding.The ARI was reduced from 70.8% to 26.4% after laser debonding . Scanning electron microscopy showed enamel fractures, cracks and transverse wave-like grooves after using plier, and a lot of remnant adhesive were on the enamel surface. The laser-treated surface showed very little change. The loss of enamel also reduced after laser irradiation.It is concluded that implused Nd:YAG laser-aided debonding ceramic brackets is a safe and easy and efficient way-the ideal way to debond ceramic brackets in clinic. It can reduce the lesion of debonding on enamel and increase the work efficient in orthodontic clinic.