Clinical effects of maxillary protraction in different stages of dentition in skeletal class III children: A systematic review and meta-analysis.

Objectives: This systematic review and meta-analysis aimed to evaluate the effectiveness of using maxillary protraction during different stages of the dentition by assessing changes in the jaws and inclination of incisors.

Materials And Methods: MEDLINE (PubMed), Embase, Cochrane, Web Of Science, China National Knowledge Infrastructure and Wanfang Databases were searched without time limitations up to 15 January 2022. Google Scholar was used to search grey literature. We included cohort studies that compared the effect of maxillary protraction by analysing primary outcomes and were grouped in age-related conditions. Mean differences and 95% confidence intervals were used for statistical analysis, followed by Grading of Recommendations Assessment, Development and Evaluation analysis.

Results: Six studies were finally included. The heterogeneity test showed P ≥ .1 and I  ≤ 50%, and a fixed-effect model was applied. Patients in the early treatment group (ETG) were mainly in the early-mixed dentition stage, while patients in the late treatment group (LTG) were in the late-mixed and early-permanent dentition stage. Meta-analysis showed that there were no statistical differences (P > .05) between the ETG and LTG groups in terms of SNA (the angle composed by point Sella-Nasion-Subspinale), SNB (the angle composed by point Sella-Nasion-Supramentale), ANB (the angle composed by point Subspinale-Nasion-Supramentale), Wits, U1/SN (the angle composed by the axis of upper incisors and Sella-Nasion plane) and L1/MP (the angle composed by the axis of lower incisors and the mandibular plane).

Conclusion: Our analysis showed that maxillary protraction applied in the late-mixed or early-permanent dentition stage did not cause different effects on the maxillary growth, the correction of the intermaxillary relationship, the inhibition of mandibular growth and dental tipping of skeletal class III patients when compared to that in the early-mixed dentition stage. Collectively, these data provide a theoretical basis for widening the applicable age period of maxillary protraction and choosing the best treatment opportunity for children patients after a comprehensive assessment.