Changes in apical base sagittal relationship in Class II malocclusion treatment with and without premolar extractions: A systematic review and meta-analysis.

OBJECTIVE: To evaluate the changes in apical base sagittal relationship in Class II treatment with and without premolar extractions. MATERIALS AND METHODS: Controlled studies evaluating ANB angle changes after Class II Division 1 malocclusion treatment with or without premolar extractions were considered. Electronic databases (PubMed, Embase, Web of Science, Scopus, The Cochrane Library, Lilacs, and Google Scholar) without limitations regarding publication year or language were searched. Risk of bias was assessed with Risk Of Bias in Non-randomized Studies-of Interventions tool of the Cochrane Collaboration. Mean difference (MD) and 95% confidence interval (CI) were calculated from the random-effects meta-analysis. Subgroup and sensitivity analyses were also performed. RESULTS: Twenty-five studies satisfied the inclusion criteria and were included in the qualitative synthesis. Eleven nonextraction and only one extraction Class II treatment studies presented untreated Class II control group. Therefore, meta-analysis was performed only for the nonextraction protocol. In treated Class II nonextraction patients, the average of the various effects was a reduction in the ANB angle of 1.56 degrees (95% CI: 1.03, 2.09, P < .001) compared with untreated Class II subjects. Class II malocclusions treated with two maxillary-premolar extractions and four-premolar extractions produced estimated mean reductions in ANB of -1.88 degrees and -2.55 degrees , respectively. However, there is a lack of low-risk-of-bias studies. CONCLUSIONS: According to the existing low quality evidence, the apical base sagittal relationship in nonextraction, two-maxillary and four-premolar extractions Class II treatments decreases -1.56 degrees , 1.88 degrees and 2.55 degrees , respectively. Further studies are necessary to obtain more robust information.