Tooth positioner effects on occlusal contacts and treatment outcomes

Objective: To determine if an increase in tooth contacts is the principal effect of tooth positioner wear. Materials and Methods: Patient charts from a consecutive series were reviewed until a sample of 100 cases that used a tooth positioner was obtained. One hundred control cases were randomly selected from patients treated at the same period. Malocclusion severity and finished occlusion were assessed with the American Board of Orthodontics (ABO) Discrepancy Index (DI) and Objective Grading System (OGS) score, respectively. Finish casts for each patient were mounted on a Galleti articulator. Occlusal registrations were obtained with silicone-based impression material from casts fabricated from impressions taken at the time of fixed appliance removal (control) or at the end of the tooth positioner treatment (experimental). The number of the perforations and transparent areas on the occlusal registrations were quantified. Results: There was no significant difference (P = .20) in the number of total occlusal contacts between the two groups. However, the OGS score of the tooth positioner group (16.7) was significantly (P = .0009) better than for the control group (19.9). Conclusions: Tooth positioners were effective in improving the occlusal finish, but the effects were independent of an increase in occlusal contacts. Positioners primarily improved first order alignment by tipping teeth into an improved intercuspation.