Effects of Repeated Bracket Bonding on Enamel Color Changes

Abstract

Objectives: The objective of the study is to evaluate the effects of repeated bracket bonding on the color changes of tooth enamel after in vitro coloration. Materials and Methods: Eighty-one premolars were equally divided into three groups. Samples in Group 1 (G1) represented nonorthodontic treatment patients, and the enamel surfaces were left intact. Samples in Group 2 (G2) and Group 3 (G3) represented orthodontic treatment patients with no repeated bonding and brackets bonded 3 times, respectively. After the brackets were bonded in G2 and G3, samples in all groups were kept in four different staining solutions for 96 h and received 24 h of photoaging. This cycle was repeated 3 times. Brackets were debonded and rebonded in G3 samples after each cycle, whereas brackets were only debonded once in G2 samples after the third cycle. The color changes were assessed using a spectrophotometer at baseline (T1) and after removing the brackets and cleaning the enamel surface (T2). Data (Delta E) were analyzed statistically with analysis of variance between groups, and with Paired t-test within groups. Results: Although the color changes for G1, G2, and G3 were significant (P < 0.05) within groups; the difference was similar between groups (P > 0.05). Conclusion: Repeated bracket bonding does not have a negative influence on the enamel color change after in vitro coloration when compared with intact enamel surface and single bonding.