Long-term stability of maxillary molar distalization in the treatment of Angle Class II malocclusion: A systematic review and meta-analysis.

OBJECTIVES

This study aimed to evaluate the long-term skeletal and dental stability following maxillary molar distalization for Angle Class II malocclusion and to explore potential relapse-related factors.

METHODS

A systematic search of twelve electronic databases and six manual sources was conducted. After data extraction and risk of bias assessment, meta-analyses using random-effects models were performed. Heterogeneity was explored through subgroup analyses and sensitivity analyses. The certainty of evidence was rated using the GRADE approach.

RESULTS

9 non-randomized clinical trials involving 223 Class II malocclusion patients were included. Meta-analyses of 5 skeletal and 9 dental treatment effects were conducted. While skeletal changes were minimal and not statistically significant, significant mesial relapse of the first molar (1.80 mm, p = 0.002, I = 90%) and the second molar (3.19 mm, p = 0.007, I = 93%) was observed. Besides, the first molar showed notable extrusion (1.18 mm, p = 0.002, I = 85%) and mesial inclination (1.46°, p = 0.004, I = 18%). Subgroup analyses identified a significant age-related effect on vertical changes of the first molar, with greater extrusion in younger patients (≤ 18 years). The certainty of evidence was rated low to very low.

CONCLUSIONS

Over a mean follow-up of 4.2 years, skeletal changes were minimal, while maxillary molars showed significant mesial relapse. The first molar also exhibited measurable extrusion and mesial inclination, with younger patients showing greater vertical changes. However, these findings were based on low to very low certainty of evidence due to non-randomized study designs and high heterogeneity, warranting cautious interpretation and further validation.

CLINICAL RELEVANCE

Identifying long-term relapse patterns and patient-related factors after maxillary molar distalization can help orthodontists optimize treatment planning, select appropriate cases, and develop individualized retention strategies to improve long-term stability.