Post-treatment stability of anterior open bite treated with clear aligners in adults: a systematic review and meta-analysis

Objective To evaluate the short- to intermediate-term post-treatment stability of anterior open bite (AOB) correction achieved with clear aligner therapy (CAT) in adult patients and to synthesize the available evidence regarding the biomechanical mechanisms associated with treatment stability and relapse. Methods A systematic search of PubMed/MEDLINE, Scopus, ScienceDirect, and Google Scholar was conducted to identify studies evaluating post-treatment stability following clear aligner therapy for anterior open bite in adults. Studies reporting a minimum post-treatment follow-up of six months were considered eligible. Risk of bias was assessed using the ROBINS-I tool, and the certainty of evidence was evaluated according to the GRADE approach. Owing to differences in outcome definitions, categorical and cephalometric post-treatment findings were synthesized separately. A random-effects meta-analysis was performed only as an exploratory comparison of POSI = 0 at follow-up between clear-aligner therapy and TAD-based treatment. Owing to the anticipated methodological and clinical heterogeneity, pooled estimates were interpreted cautiously. Results Four observational studies initially included 116 adults treated with clear aligners, of whom 88 had usable post-treatment follow-up data. Two comparative studies, comprising 44 participants (22 treated with CAT and 22 with TAD-based treatment), contributed to the exploratory meta-analysis. Although the minimum eligibility threshold was six months, all included studies reported mean follow-up durations exceeding 12 months, ranging from approximately 14 to 30 months. The limited evidence suggested that correction was mainly associated with dentoalveolar changes; however, the included studies were not designed to establish treatment mechanisms. An exploratory meta-analysis found no statistically significant difference in the probability of POSI = 0 at follow-up between clear-aligner therapy and TAD-based treatment (RR = 0.81; 95% CI: 0.55–1.21). This comparison should be regarded as exploratory, given the limited number of comparative studies and important clinical and methodological differences between them. Overall certainty of evidence was rated as low to very low. Conclusion Limited observational evidence suggests that anterior open bite correction achieved with clear aligners in adults may be maintained over short- to intermediate-term follow-up. Methodological limitations and heterogeneity restrict confidence in these findings, and long-term stability remains uncertain.