In vivo evaluation of tooth colour alterations during orthodontic retention: A split-mouth cohort study

To assess in vivo colour alterations of teeth following removal of fixed orthodontic appliances during retention.

The Department of Orthodontics at the Aristotle University of Thessaloniki. Forty-eight patients after orthodontic treatment.

Debonding and cleaning procedures after orthodontic treatment were performed using two different carbide burs attached to a low or high-speed handpiece, respectively, in a non-blinded cohort study with split-mouth design. Spectrophotometric colour data of teeth were recorded: (a) after debonding, (b) three months later, prior to and following finishing with Soflex discs, and (c) after 1 year. The CIE Lab colour parameters were measured for each tooth, and the corresponding ΔΕ differences were calculated. The effect on colour was assessed with 3-way mixed ANOVA and Bonferroni's comparisons test (a < 0.05).

Orthodontic debonding and cleaning procedures were found to have statistically significant effects on the CIE colour parameters of treated teeth, since the L* values decreased 0.6 units (P < 0.001), a* values were stable (0.0 units) and b* values increased 1.4 units (P < 0.001), during the first retention year. Finishing temporarily decreased the enamel colour differences. Total ΔΕ differences for all types of teeth measured ranged from 1.4 to 2.1 units. The greatest changes were exhibited during the first 3 months in teeth on which high-speed rotary instruments were used (1.6 units).

The clinical relevance of this study points out that the colour of natural teeth following removal of fixed orthodontic appliances changes in long-term.