Effectiveness of Transpalatal Arch (TPA) in Molar Movement: A Systematic Review and Meta-analysis

Molar movement control is a fundamental aspect of orthodontic treatment, particularly in managing anchorage and achieving desired occlusal outcomes. The transpalatal arch (TPA) is a commonly used passive or active appliance designed to provide anchorage reinforcement and facilitate specific molar movements. Despite its widespread application, there is limited consensus regarding its quantitative effectiveness. This systematic review and meta-analysis assesses the effectiveness of the TPA in molar movement during orthodontic treatment.

An extensive search of major electronic databases was conducted up to the year 2023 to identify studies evaluating the application of the TPA in molar movement. Data regarding study design, participant characteristics, types of TPA used, and numerical outcomes related to molar displacement were systematically extracted. For each outcome, point estimates and corresponding 95% confidence intervals were computed to assess pre- and post-treatment changes.

Fourteen studies underwent detailed qualitative synthesis, with 2 classified as low risk, 7 with some concerns, and 5 as high risk of bias. Nine studies were included in the meta-analysis. The pooled change in mesial movement U6-PTV (mm) for the TPA group was 2.73 (95% CI: 1.90-3.50), vertical movement U6-PP (mm) was 1.24 (95% CI: 0.96-1.52), vertical movement U6-FH (mm) was 1.34 (95% CI: 0.36-2.32), and mesial tipping U6-FH (°) was 2.94 (95% CI: 1.51-4.37).

This review underscores the TPA's versatility and effectiveness as an anchorage device. Evaluating TPA's full range of applications, beyond comparisons with skeletal devices, is crucial. Future research should incorporate three-dimensional digital models and consider pubertal growth stages for more accurate assessments.