Does orthodontic treatment have a permanent effect on tooth color? : A systematic review and meta-analysis.

Objectives: Aim of this systematic review was to assess the effect of orthodontic treatment with fixed appliances on the tooth color of patients.

Methods: Nine databases were searched up to May 2017 for clinical cohort studies on the effect of fixed appliance treatment on tooth color. After elimination of duplicate studies, data extraction, and risk of bias assessment according to the Cochrane guidelines, random effects meta-analyses of mean differences (MD) or means and their 95% confidence intervals (CIs) were performed, followed by GRADE (Grading of Recommendations Assessment, Development and Evaluation) assessment of the quality of evidence.

Results: Three nonrandomized and one randomized study with a total of 138 patients (46% male, 54% female) with average age of 15.7 years were included. Tooth color of treated patients was significantly altered during or after orthodontic treatment (4 studies; average of 3.2 ∆E units; 95% CI = 2.0-4.4 ∆E units), which was more than the variation among controls (1 study; MD = 1.9 ∆E units; 95% CI = 1.7-2.2 ∆E units). However, the quality of evidence was very low, due to the inclusion of nonrandomized studies, bias, and imprecision. Re-analysis of raw study data indicated that significant differences in clinically discernable treatment-induced color changes were seen between chemically and light-cured adhesives and among the various tooth categories.

Conclusion: Existing evidence of very low quality indicates that orthodontic treatment might be associated with alterations of tooth color, which are however not consistently clinically discernible. Treatment-induced color alterations might be dependent on bonding material and tooth type, but evidence supporting this is weak.