Treatment of Anterior Open Bite using Clear Aligners: A Meta Analysis

Abstract

Background: Anterior open bite (AOB) is a challenging malocclusion that can impact oral function and aesthetics. Clear aligner therapy has been used as a potential approach to correct anterior open bite. Nonetheless, consensus lacks on the success of aligners to correct AOB. Further, the mechanism by which aligners work has not been fully described. Objectives: This study aimed to review the studies reporting on correction of anterior open bite with clear aligners to answer two main questions: (i) How successful is clear aligner therapy in treating anterior open bite? (ii) What are the mechanisms by which clear aligners achieve this correction (e.g., roles of Anterior teeth extrusion and Posterior teeth intrusion)? Methods: To evaluate the effectiveness of clear aligners in correcting AOB, a meta-analysis was conducted based on PRISMA guidelines. Search of PubMed and ProQuest databases identified a total of 582 citations. Studies were included if they were retrospective or prospective case series evaluating adults with AOB treated exclusively with the Invisalign appliance and reported quantitative pre- and post-treatment measurements of open bite closure. Seven studies published between 2017 and 2024 met these criteria and were analyzed. The primary outcome for the analysis was the mean difference in open bite correction achieved by the treatment. Robust meta-regression was used to examine the influence of AOB severity and treatment duration on the outcome. Additionally, we evaluated the relative contributions of Anterior teeth extrusion and Posterior teeth intrusion in achieving bite closure, based on results of cephalometric analyses to quantify changes in tooth position and open bite correction. Results: Identified studies were primarily conducted in the United States and Australia. The mean open bite correction across studies was 2.34 mm (95% CI: 3.22 to 1.47 mm). A trend towards decreased treatment efficacy was observed with increased AOB severity (coefficient = -1.58, 95% CI: -3.42 to 0.27, p = 0.06). Treatment duration, analyzed in a subset of five studies, however, was not significantly associated with treatment outcome (coefficient = 0.01, 95% CI: -0.60 to 0.62, p = 0.95). Anterior teeth extrusion was the primary mechanism contributing to AOB correction, supported by significant incisor extrusion reported in multiple studies (e.g., mean overbite correction of 3.27 mm, 95% CI: 2.95 to 3.59). Posterior teeth intrusion was reported in one study, with minimal and inconsistent contributions from Posterior teeth intrusion(e.g., molar intrusion of 0.1-0.6 mm). Conclusion: The Invisalign appliance is effective in treating AOB in adults. The severity of initial AOB may influence treatment success, with more severe cases having worse outcomes. Anterior teeth extrusion is the primary mechanism for correcting anterior open bite. Keywords: Anterior open bite, clear aligners, Invisalign, orthodontics, meta-analysis