Qualitative Evaluation of the Bracket-Adhesive-Enamel Junction of Metal Orthodontic Brackets: A Preliminary Report

Abstract

Objectives. The purpose of this in vitro investigation was to evaluate qualitatively the surface topography at the bracket-adhesive-enamel junction, bonded to the buccal and lingual surfaces of premolars with compos­ite resin and resin-modified glass-ionomer orthodon­tic adhesives, using two methods of adhesive removal: a dental explorer and a micro brush.

Methods. Forty premolar surfaces were allocated to four groups of 10/ each, 20/buccal and 20/lingual surfaces. The brackets were bonded to the surface of the enamel and any ex­tra adhesive was removed with a dental explorer or a micro brush. Specimens were evaluated and scored by two calibrated independent raters, at the bracket-adhesive-enamel junction, for adhesive overlap on the bracket, the smoothness of the surface, as well as the presence of projections and depressions, using a digi­tal microscope. The Fisher-exact statistical test was conducted to compare the different groups.

Results. Regardless of the method used to remove the adhe­sives, all groups showed partial or complete overlap of the adhesive on the bracket. No statistical difference was found between the groups for adhesive overlap (P=1.0). However, resin-modified glass-ionomer was found to be statistically significantly (P<0.05) better than composite resin in both smoothness and the lack of projections or depressions, regardless of the instru­ment of removal.

Conclusion. Removing excess adhe­sive with a dental explorer or a micro brush is not an ideal method for adhesive removal, as partial or com­plete overlap of the adhesive on the bracket existed in all groups. On the other hand, resin-modified glass-ionomer was a superior material to composite resin for better smoothness and surface topography at the bracket-adhesive-enamel junction.