En masse versus two-step retraction of the anterior segment.

Data sourcesMedline, Scopus, Web of Science, PubMed and the Cochrane Central Register of controlled Trials (CENTRAL). Handsearching of references lists of included studies.Study selectionRandomised controlled clinical trials (RCTs) and prospective controlled clinical trials (pCCTs) of orthodontic patients treated with pre-adjusted fixed appliances, requiring space closure in the maxillary arch, comparing en masse retraction and two-step retraction. No initial restriction on language or date of publication. Retrospective studies were excluded.Data extraction and synthesisData extraction was performed independently by two reviewers, using customised data extraction forms, and any disagreement resolved by third reviewer. Cochrane risk of bias tool was used to assess the quality of RCTs. The Newcastle-Ottawa scale was used to assess the quality of pCCTs. A random effects model was used in anticipation of heterogeneity.ResultsEight studies (four RCTs; four pCCTs) involving a total of 334 patients were included. Two RCTs were considered to be at low risk of bias and two at high risk of bias. Three pCCTs were considered to be of high quality and one of low quality. Four studies contributed to the meta-analysis; one pCCT and three RCTs. There was a statistically significant difference in favour of en masse/miniscrew combination for anchorage preservation Std. Mean Difference (SMD) = 2.55 mm (95% CI; - 2.99 to - 2.11 and upper incisor retraction SMD = - 0.38 mm (95% CI; - 0.70 to - 0.06). Narrative synthesis suggests that en masse retraction requires less time than two-step retraction with no difference in the amount of apical root resorption.ConclusionsEn masse and two-step retraction are effective forms of space closure, with en masse being superior in anchorage preservation and incisor retraction if used in conjunction with miniscrews, when compared to two-step retraction with conventional anchorage. En masse treatment duration is less; however, no differences are noted in apical root resorption. Limited evidence suggested anchorage reinforcement with headgear produces similar results with both retraction methods.