Long term stability of molar position postdistalization: A systematic review and meta-analysis

Abstract

Background: Molar distalization has generated additional attention with the advent of skeletal anchorage devices. However, relapse after distalization is one of the challenges and the quantum of relapse following distalization, especially over the long-term remains controversial. This systematic review and meta-analysis aim to evaluate the long-term vertical and sagittal stability of molars postdistalization.

Methods: A systematic search was conducted in electronic databases (PubMed, Scopus, Ovid, Embase, Cochrane and LILACS) up to April 11, 2025. Studies assessing molar position changes after active distalization and during follow-up periods were included. Data extraction and risk of bias assessments were performed using the ROBINS-I tool for non-randomized studies. A meta-analysis was conducted to quantify relapse in vertical and sagittal dimensions.

Results: From the 2594 studies initially identified, six studies (all nonrandomized control trials) were included for the systematic review and five studies were included for the meta-analysis. All studies showed moderate risk of bias. The mean relapse in the sagittal plane was 1.58 ± 0.84 mm (35%) linearly and 2.98 ± 2.07° (53%) angularly. In the vertical plane, it relapsed by 1.44 ± 1.26 mm. Meta-analysis showed a net distalization in the molar position in long-term sagittal plane by 2.77 mm (95% CI 2.33-3.20) and 1° distally (95% CI -2.37° to 4.38°), and in the vertical plane by -0.65 mm (95% CI -2.27 to 0.96). The I² ranged from 60% to 98% indicating high heterogeneity. The relapse was minimal for the incisal, skeletal, and soft tissues parameters.

Conclusions: Long-term assessment following molar distalization demonstrated conclusive evidence of relapse in the sagittal and vertical direction. There was greater relapse in the vertical than in the sagittal direction. There was minimal literature assessing the relapse in the transverse direction. Hence, this systematic review advocates the need for long-term retention postdistalization.

Keywords: Distalizers; Molar distal movement; Molar distalization; Stability.