Evaluation of Etching Time and Concentration on Shear Bond Strength of Metallic Brackets Using a ۱۰-MDP Containing Adhesive

Background Bonding is the most commonly used technique to attach brackets to tooth surfaces. Objectives The aim of this study was to determine the effects of time and concentration of etching with phosphoric acid on shear bond strength (SBS) of orthodontic brackets after using ۱۰-MDP containing adhesive. Methods Fifty intact premolars were randomly divided into ۵ groups (n = ۱۰). They were mounted in resin blocks. In control group a gel without phosphoric acid and in-group ۲, ۳, ۴, and ۵, phosphoric acid ۳۷% for ۵ or ۱۵ seconds and phosphoric acid ۱۵% for ۵ or ۱۵ seconds was used respectively. Clearfil SE Bond was used as an adhesive resin for all samples. After bonding of brackets, they were put under ۳۰۰ thermocycling aging regime and after that the bracket/tooth SBS was measured by universal testing machine. The adhesive remnant index (ARI) was evaluated under a stereomicroscope. Data were statistically analyzed using two-way ANOVA and Kruskal-Wallis test. Results The highest mean SBS belonged to the ۱۵% phosphoric acid etching in ۱۵ seconds while the lowest value was seen in ۳۷% phosphoric acid etching in ۵ seconds. The effect of etching time on SBS was not significant (P = ۰.۳۱) but the effect of concentration in SBS has been significant (P < ۰.۰۰۱). In terms of ARI, in application of ۱۵% phosphoric acid, more than ۵۰% of the resin remained on tooth surface. In application of ۳۷% phosphoric acid, all the resin remained on tooth surface. Conclusions In using of Clearfil SE bond, containing ۱۰-MDP, preparing enamel by ۱۵% phosphoric acid had created strong enough SBS.

کلیدواژه ها:

Orthodontics ، etching ، Shear strength ، ۱۰ ، MDP