Abstract:

Abstract:Objective To observe the losing ratio of the bond orthodontic brackets in fluorotic teeth by using different etching methods and find a way to decrease the losing ratio of the bond orthodontic brackets in fluorotic teeth. Methods 226 midrange fluorotic teeth from 14 patients were chosen. The teech were divided into 28 sections according to the direction.Then the 28 sections were randomly divided into four groups: etching 1 min group(n=56),etching 2 min group（n=57）,etching 3 min group（n=57） and etching twice group (n=56). The losing ratios of brackets and adhesive remnant index (ARI)were observed after 4,8 and 12 weeks. Results The losing ratios of brackets in etching 2 min group and etching twice group were lower than those in etching 1 min group and etching 3 min group(P<0.05). The ARI in etching 2 min group and etching twice group were higher than those in the other two groups(P<0.05). The losing ratio of brackets in etching twice group was lower than that in   etching 2 min group，but there was no significant difference between two groups(P>0.05). The ARI in etching twice group was higher than that in etching 2 min group,but there was no significant difference between two groups(P>0.05). The losing ratio of brackets on bicuspid teeth were higher thanthose on front teeth in each group. The losing ratio of brackets on bicuspid teeth in etching twice group was lower than those in the other groups(P<0.05). Conclusion Etching  2 min can reduce the losing ratio of the bond orthodontic brackets in fluorotic teeth. The losing ratio of the bond orthodontic brackets in etching twice group is lower than that in etching once group,ecially on bicuspid teeth.

Key words: fluorosis;dental acid etching;losing ratio;adhesive remnant index