Three-dimensional measurement of residual adhesive and enamel loss on teeth after debonding of orthodontic brackets: an in-vitro study.

Introduction: The purpose of this study was to evaluate 3-dimensionally the changes on tooth surfaces after debonding orthodontic brackets and after removing residual adhesive and finishing.

Methods: Sixty premolars were randomly divided into 2 groups, and brackets were bonded according to the manufacturers' instructions. Two types of orthodontic adhesives were used: resin-modified glass ionomer cement (group 1) and resin-coated adhesive precoated brackets (group 2). The brackets were debonded on a testing machine at a cross-head speed of 1 mm per minute. Models were made of each tooth before bonding, after debonding, and after removal of residual adhesive. The models were scanned with a 3-dimensional laser scanning machine, and the scanned images were analyzed by using modified analytical software.

Results: The Mann-Whitney test showed significant differences in adhesive thickness and enamel loss between the 2 groups (P <.001). The mean (+/- SD) thickness for group 1 was 31.2 microm (+/- 26.5 microm), and the mean (+/- SD) thickness for group 2 was 102.7 microm (+/- 79.71 microm). The means (+/- SD) for enamel losses after cleaning and finishing the enamel surfaces were 22.8 microm (+/- 17.67 microm) for group 1 and 50.5 microm (+/- 31.27 microm) for group 2.

Conclusions: Adhesive thickness and enamel loss due to orthodontic procedures can successfully be measured in vitro by using 3-dimensional laser scanning technology.