Evaluation of Different Enamel Surface Treatment on the Bracket Bonding

Abstract

Objective: To evaluate and compare the effects of different enamel conditioning techniques on the shear bond strength of brackets, the failure sites following debonding and the surface morphology of the enamel. 
 Methods: In this study, 72 human premolars were randomly divided into six groups of 12 specimens each. The enamel surfaces of the teeth were etched with 37% phosphoric acid in group PA, deproteinized using sodium hypochlorite and 37% phosphoric acid in group NaOCl + PA, sandblasted and etched with 37% phosphoric acid in group AA + PA, conditioned by self-etching primer in group TPSEP, deproteinized using sodium hypochlorite and conditioned by self-etching primer in group NaOCl +TPSEP, sandblasted and conditioned by self-etching primer in group AA + TPSEP. After enamel conditioning procedures, brackets were bonded to the treated enamel surface, and shear bonding test was performed. After deboning, ARI scores were calculated for all groups. Two samples from each group before bonding procedure were inspected by SEM to study the surface topography of enamel following different conditioning techniques. Data were subjected to analysis of One-way variance, Scheff post hoc, Chi-square and Spearman’s tests. 
 Results: The mean bond strength values for groups NaOCl and PA have a higher mean shear bond strength among other groups while self-etching primer in group TPSEP had a lower shear bond strength. A significant difference was observed in the bond strengths between groups (p < 0.001). However, non-significant difference found in ARI in all groups (P = 0.118).SEM observation revealed different etching patterns on the enamel surface after pretreatment.
 Conclusions: Enamel surface pretreatments, using a combination of sodium hypochlorite or sandblasting before phosphoric acid and self-etching primer, result in increased shear bond strength of orthodontic brackets as well as the surface roughness of enamel.