Background: Unsightly colour changes may occur in the enamel around bonded orthodontic brackets.
Aim: To determine the enamel colour changes around orthodontic brackets bonded with different adhesives.
Methods: One hundred extracted upper first premolars were divided into five equal groups. Fiducial holes were drilled in the buccal and palatal surfaces of the teeth and metal orthodontic brackets were bonded to the buccal surfaces with different combinations of adhesives and primers. The teeth were immersed in a tea-coffee solution for one week. The brackets were then debonded and the teeth polished. The colour of the enamel surface was measured around each fiducial hole before bonding (baseline), after debonding and after polishing. The colour differences (deltaE) were compared using one-way ANOVA and the paired t-test.
Results: There were no significant differences between the five adhesive groups in baseline-debonding deltaE and baseline-polishing deltaE, but statistically significant differences were found between the baseline-debonding deltaE on the buccal and palatal surfaces and the baseline-debonding deltaE versus baseline-polishing deltaE on the buccal surfaces. Although statistically significant, the colour changes would not be visible to many observers. Approximately 75 per cent of the staining was attributed to the enamel components.
Conclusions: The type of adhesive and the methods of application had no effect on enamel colour change. Most of the colour change was attributed to uptake of stain by the components of the enamel, not the resin tags.