| Objective:1.To investigate the effects of self-ligating brackets and conventional brackets on the efficiency of maxillary incisors movement in rabbits.2.To evaluate the efficiency of self-ligating brackets for malocclusion.3.To provide theoretical basis for the choice of appliance in orthodontic clinical practice.Methods:1.32New Zealand rabbits were chosen. The maxillary incisors were treated with self-ligating brackets or conventional brackets respectively. The distance between the incisors was measured from the day1to14after60g force was applied with a Vernier Caliper. Radiographs were taken to observe the root changes.2.A detail inclusion and exclusion criteria were established. And then the comprehensive search strategy of literature was made to search the studies.3.Several electronic databases were searched, such as PubMed (1966～2010.06), Embase (1974～2010.06), Cochrane Library (2010,issue2) CBM(1978～2010.06), CNKI (1994～2010.06),VIP (1989～2010.06) and so on.Several Chinese journals were hand searched for possible missing articles. The studies of randomized controlled trials (RCTs) which addressed the efficiency of self-ligating brackets compared with conventionally ligated brackets were selected and reviewed.4.According to the principle of Cochrane handbook, data extraction and quality assessment were performed by two reviewers independently.5.Rev Man5software that provided from the Cochrane Collaboration was used for data analyses.Results:1.A tipping movement was observed in both groups.2.The distance between the teeth in the group of self-ligating brackets was significantly greater than that in the group of conventional brackets during the first3days(p<0.05). Between days4to14, the distance between the teeth was increased in both groups. However, no significant difference was observed (p>0.05). The mean distance between the incisors was2.45±0.09mm in the group of self-ligating brackets and2.49±0.07mm in the group of conventional brackets at the days14.3.Four RCTs involving284patients were included.4.Meta-analyses showed that for extraction group, there was no significant difference between self-ligating brackets and conventionally ligated brackets in terms of the mean treatment time to alignment [MD=10.00,95%CI (-27.67,47.67),P=0.60].While for non-extraction group, there were significant differences between self-ligating brackets and conventionally ligated brackets in terms of the mean treatment time to alignment [MD=-23.48,95%CI(-44.74,-2.22),P=0.03]. There was no significant difference in intercanine changes between two appliances in extraction group[MD=0.11,95%CI(-1.06,1.28), P=0.85].For non-extraction group, the difference in intercanine changes was no significant [MD=0.34,95%CI(-0.21,0.88), P=0.22]. Neither self-ligating brackets nor conventionally ligated brackets showed to be more clinically effective than each other during making interfirstpremolar[MD=0.73,95%CI(-0.20,1.66), P=0.12] and intersecondpremolar [MD=0.29,95%CI(-0.74,1.32), P=0.58]. There was no significant difference in intermolar changes between two appliances in extraction group [MD=0.72,95%CI(-0.42,1.86),P=0.22],yet for non-extraction group the difference was statistically significant [MD=-1.08,95%CI(-1.77,-0.38),P=0.003]. There was no significant difference in mandibular incisor inclination changes between two appliances [MD=-0.12,95%CI(-1.42,1.18), P=0.86],and maxillary incisor inclination changes as well(P>0.05).Conclusions:1.In the necessary treatment period, self-ligating brackets are no more efficient than conventional brackets during orthodontic tooth movement.2.There was little difference in intercanine and incisor inclination changes related to the two appliances in both groups. While for non-extraction group, self-ligating brackets showed less treatment time, and more effective in the term of intermolar width changes. 3.More multicenter, large sample, and high quality randomized controlled trials which addressed the treatment efficiency of self-ligating brackets compared with conventionally ligated brackets are needed to increase the reliability. |
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