The effect of extraction of lower primary canines on the morphology of dental arch: A systematic review and meta-analysis.

BACKGROUND: The beneficial effect of the extraction of primary canines in the resolution of incisor irregularity and its side effects are controversial. AIM: To systematically review the effects of the extraction of primary canines in incisor irregularity and dental arch morphology. DESIGN: Controlled non-randomized (non-RCT) and randomized clinical trials (RCT) evaluating children treated with extraction of primary canines compared with those without intervention. RESULTS: A total of 984 articles were found, of which two RCTs and one non-RCT met the inclusion criteria. Both had a low RoB. A high level of evidence was observed through GRADE. A meta-analysis showed the extraction of primary canines produced a significant decrease in incisor irregularity (95% CI: -3.56, -2.09 mm). This decrease, however, was associated with a reduction of arch length (95% CI: -1.58, -0.94 mm), intermolar width (95% CI: -0.61, -0.22 mm), and overjet (95% CI: -075, -018). A mild overbite increase was found (95% CI: 0.10, 0.76 mm). CONCLUSION: A high level of evidence showed that the extraction of primary canines improved incisor irregularity in the mixed dentition. Side effects included reduced arch length and intermolar width. A slight reduction in overjet and a mild increase in overbite were also observed. When they are not part of the treatment goal, these occlusal changes can be prevented by installing a lingual arch.