Comparison Of Dental Arches Changes In Non-extraction Treatment With Self-ligating And Conventional Brackets: A Meta Analysis

Objective:To evaluate changes in dental arch width and the anterior teeth protrusion produced byself-ligating brackets and conventional bracket on the correction of mild and moderate dentalcrowding in non-extraction cases, and analyze the characteristics and application of self-ligatingbracket.Methods:Following the principles of evidence-based medicine, a literature search was carried out ininternational databases (Pubmed, ISI, EMBASE, the Cochrane Central Register of ControlledTrials), Chinense Language databases (CNKI，VIP，CBM，Wanfang),and using handing searchup till December31th2013,exhaustive search all randomized controlled trails on changes beforeand after treatment in the dental arch width and in the anterior teeth protrusion betweenself-ligating bracket and conventional bracket in non-extraction cases, Two reviewers accordingto the inclusion and exclusion criteria, independently finished literature filtering, data extractionand methodological quality evaluation and disagreements were solved by discussion. Originaloutcome data, if possible, were subjected to statistical pooling by Review manger5.2forMeta-analysis.Results:Nine studies matched the inclusion criteria, including4English literatures and5Chineseliteratures, a total of450patients(Self-ligating bracket group240cases, conventional bracketgroup210cases).In non-extraction cases：1. The meta-analysis revealed that significant differences were found in maxillary inter-caninewidth, inter-first premolar width and inter-second premolar width between self-ligating bracketand conventional bracket, the specific values were:[MD=0.02,95%CI (-0.67,0.72), P=095],[MD=0.26,95%CI (-0.62,1.14), P=057],[MD=0.19,95%CI (-0.51,0.88), P=052].2. The meta-analysis revealed that no significant difference was found in maxillary inter-molarwidth between self-ligating bracket and conventional bracket [MD=-0.01,95%CI (-0.25,0.24),P=0.66].3. The meta-analysis revealed that there was no significant difference in mandibular inter -canine width, inter-first premolar width or inter-second premolar width between self-ligatingbracket and conventional bracket, the specific values were:[MD=0.02,95%CI (-0.67,0.72), P=0.95],[MD=0.43,95%CI (0.17,0.70),P=0.001],[MD=0.19,95%CI (-0.51,0.88),P=0.52].4. The meta-analysis revealed that significant difference was found in mandibular inter-molarwidth between self-ligating bracket and conventional bracket[MD=0.59,95%CI (0.33,0.84), P＜0.00001].5. The change of the proclination of upper and lower incisors: the meta-analysis revealedthat significant difference was found in upper incisors proclination between self-ligating bracketand conventional bracket[MD=-3.25,95%CI (-4.99,-1.51),P=0.0003]; and there is no significantdifference in lower incisors proclination between self-ligating bracket and conventionalbracket[MD=-0.44,95%CI (-1.52,0.64), P=0.43].Conclusion:In crowding cases treated with non-extration, there were an overall increase in theproclination of upper and lower incisors in the two bracket groups. Compared with cases treatedwith conventional appliance, the cases treated with self-ligating brackets resulted in less upperincisors protrusion increase and greater upper inter-canine, upper inter-premolar and lowerintermolar arch widths increases., but the advantage of self-ligating brackets is not obvious.