Stability of maxillary protraction therapy in children with Class III malocclusion: a systematic review and meta-analysis

The objective of this study was to evaluate the stability of treatment effects of maxillary protraction therapy in Class III children. Multiple electronic databases were searched from 01/1996 to 10/2016. Randomized clinical trials, controlled clinical trials, and cohort studies with untreated Class III controls and a follow-up over 2 years were considered for inclusion. The methodological quality of the studies and publication bias were evaluated. Mean differences and 95% confidence intervals (CI) of six variables (SNA, SNB, ANB, mandibular plane angle, overjet, and lower incisor angle) were calculated. Ten studies were included in the qualitative analysis, and four studies were included in the quantitative analysis. Compared with the control group, after treatment, the treated group showed significant changes: SNA +1.79A degrees (95% CI: 1.23, 2.34), SNB -1.16A degrees (95% CI -2.08, -0.24), ANB +2.92A degrees (95% CI 2.40, 3.44), mandibular plane angle +1.41A degrees (95% CI 0.63, 2.20), overjet +3.94 mm (95% CI 2.17, 5.71) and lower incisor angle -3.07A degrees (95% CI -4.92, -1.22). During follow-up, the changes in five variables reflected significant relapse. Overall, the treated group showed significant changes only in ANB +1.66A degrees (95% CI 0.97, 2.35) and overjet +2.41 mm (95% CI 1.60, 3.23). Maxillary protraction can be a short-term effective therapy and might improve sagittal skeletal and dental relationships in the medium term. But some skeletal and dental variables showed significant relapse during the follow-up period. Long-term studies are still required to further evaluate its skeletal benefits. The study evaluated the medium-term stability of skeletal and dental effects of maxillary protraction in Class III children and discussed whether the therapy can reduce the need for orthognathic surgery.