The effect of different in-office bleaching techniques and etching procedures on bond strength of orthodontic brackets
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The aim of this study was to compare the effects of different in-office bleaching techniques and acid/laser etching on bond strength of orthodontic brackets. Ninety-six extracted human premolar teeth were used in the study. The teeth were randomly divided into four groups according to different in-office bleaching techniques (n=24); Group I: Diode laser-assisted bleaching, Group II: Er:YAG laser-assisted bleaching, Group III: In-office bleaching with LED, Group IV: Unbleached (control). After the samples were kept in artificial saliva for 2 weeks, each group were randomly divided into 2 subgroups according to etching methods; a-acid etching; b-laser etching. For laser etching Er,Cr:YSGG laser was used at 1.5W, 15Hz with 140s pulse duration for 20s. For acid etching, 37% phosphoric acid was used for 30s. The shear bond strength testing was performed using Instron Testing Machine with a crosshead speed of 1mm/min. Adhesive Remnant Index (ARI) scores were also measured. Data was analyzed using two-way ANOVA, Bonferroni, Kruskal Wallis and Mann Whitney U tests (p0.05). There were statistically significant differences between acid and laser etching within each group (p0.05), acid etching caused statistically higher ARI scores than laser etching groups (p<0.05). In conclusion in-office bleaching either with LED or laser before bracket bonding did not affect bond strength. Prior to bracket bonding, acid etching of enamel caused higher shear bond strength values than laser etching.