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 (ΔE) 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.

Keywords: Enamel color change, external coloration, internal coloration, repeated bonding