Weight changes during the initial phase of orthodontic treatment with clear aligners versus fixed appliances: a pilot prospective cohort study.

Objective: The aim was to assess adult patients' weight changes during the initial phase of orthodontic treatment (OT) with clear aligner therapy (CAT) versus fixed bracket systems (FBS).

Methods: This pilot prospective cohort study included systemically-healthy adults who were treated with CAT or FBS. Participants with eating disorders and/or undergoing dietary programs were excluded. Weight was assessed using a calibrated digital scale at the start of OT (T1), 6-8 weeks (T2), and 12-16 weeks (T3) after starting OT. A questionnaire was used to record demographic variables, diet and exercise habits, self-reported compliance and discomfort during OT, and use of analgesics. Repeated measures analysis of variance was used to assess the association between treatment type (FBS versus CT) and time-period (T1, T2, T3) on participants' weight while adjusting for baseline covariates such as age, gender, height, and weight.

Results: Forty-two participants (CAT group: 22 and FBS group: 20) were analysed. In the CAT group, there was a slight initial mean weight gain of 0.2 Kg (~ 0.4 pounds) (T2-T1), and 0.8 Kg (~ 1.7 pounds) overall mean weight loss between T1 and T3. For the FBS group, there was a slight initial weight loss of 0.3 Kg (~ 0.7 pounds) (T2-T1) and no overall change between T1 and T3. Treatment type (CAT versus FBS) was not significantly associated with weight changes during the initial phase of OT.

Conclusions: There were no significant differences in the weight changes during the initial phase of OT with CAT compared with FBS.

Clinical relevance: Clear aligner therapy should not be advertised as a weight loss strategy.