ObjectivesThe aim of this review was to systematically evaluate the failure rates of miniscrews related to their specific insertion site and explore the insertion site dependent risk factors contributing to their failure.Search methodsAn electronic search was conducted in the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Knowledge, Scopus, MEDLINE and PubMed up to October 2017. A comprehensive manual search was also performed.Eligibility criteriaRandomised clinical trials and prospective non-randomised studies, reporting a minimum of 20 inserted miniscrews in a specific insertion site and reporting the miniscrews’ failure rate in that insertion site, were included.Data collection and analysisStudy selection, data extraction and quality assessment were performed independently by two reviewers. Studies were sub-grouped according to the insertion site, and the failure rates for every individual insertion site were analysed using a random-effects model with corresponding 95% confidence interval. Sensitivity analyses were performed in order to test the robustness of the reported results.ResultsOverall, 61 studies were included in the quantitative synthesis. Palatal sites had failure rates of 1.3% (95% CI 0.3–6), 4.8% (95% CI 1.6–13.4) and 5.5% (95% CI 2.8–10.7) for the midpalatal, paramedian and parapalatal insertion sites, respectively. The failure rates for the maxillary buccal sites were 9.2% (95% CI 7.4–11.4), 9.7% (95% CI 5.1–17.6) and 16.4% (95% CI 4.9–42.5) for the interradicular miniscrews inserted between maxillary first molars and second premolars and between maxillary canines and lateral incisors, and those inserted in the zygomatic buttress respectively. The failure rates for the mandibular buccal insertion sites were 13.5% (95% CI 7.3–23.6) and 9.9% (95% CI 4.9–19.1) for the interradicular miniscrews inserted between mandibular first molars and second premolars and between mandibular canines and first premolars, respectively. The risk of failure increased when the miniscrews contacted the roots, with a risk ratio of 8.7 (95% CI 5.1–14.7).ConclusionsOrthodontic miniscrew implants provide acceptable success rates that vary among the explored insertion sites. Very low to low quality of evidence suggests that miniscrews inserted in midpalatal locations have a failure rate of 1.3% and those inserted in the zygomatic buttress have a failure rate of 16.4%. Moderate quality of evidence indicates that root contact significantly contributes to the failure of interradicular miniscrews placed between the first molars and second premolars. Results should be interpreted with caution due to methodological drawbacks in some of the included studies.Electronic supplementary materialThe online version of this article (10.1186/s40510-018-0225-1) contains supplementary material, which is available to authorized users.

The aim of this study is to explore the effectiveness of nickel titanium closing springs (NiTi-CS) and elastomeric power chains (EPC) in orthodontic space closure and to assess the adverse periodontal effects, cost efficiency and patient-centred outcomes between both of these methods. Methods: An electronic search of online databases (Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Scopus, LILACS and Web of Science), reference lists and grey literature as well as hand search were conducted without language restriction up to November/2017. Two authors blindly and in duplicate were involved in study selection, quality assessment and the extraction of data. Only randomized clinical trials (RCTs) were included. The quality of the studies was assessed using the Cochrane Collaboration's risk of bias tool.95% confidence intervals and mean difference for continuous data were calculated. A meta-analysis that generated a random-effect model for the comparable outcomes was conducted, and heterogeneity was measured using I 2 statistic. Results: Of 187 records, 4 RCTs met the criteria and were included in the quantitative synthesis featuring 290 test quadrants. Faster space closure with NiTi-CS was observed with a mean difference of (0.20 mm/month, 95% CI: 0.12 to 0.28). Loss of anchorage appears to be similar within both groups when synthesized qualitatively. With exception to anchorage loss, secondary outcomes could not be investigated in the included trials.Conclusions: There is a moderate quality of evidence suggesting a faster orthodontic space closure with the NiTi-CS when compared to EPC. A comparable amount of anchorage loss was observed regardless of the utilized method of space closure. Further high-quality RCTs with parallel-groups, reporting on the adverse effects and patientcentred values, are recommended. K E Y W O R D Smeta-analysis, nickel-titanium, power chain elastic, space closure, systematic review

BackgroundThis review aims to compare the effectiveness of en masse and two-step retraction methods during orthodontic space closure regarding anchorage preservation and anterior segment retraction and to assess their effect on the duration of treatment and root resorption.MethodsAn electronic search for potentially eligible randomized controlled trials and prospective controlled trials was performed in five electronic databases up to July 2017. The process of study selection, data extraction, and quality assessment was performed by two reviewers independently. A narrative review is presented in addition to a quantitative synthesis of the pooled results where possible. The Cochrane risk of bias tool and the Newcastle-Ottawa Scale were used for the methodological quality assessment of the included studies.ResultsEight studies were included in the qualitative synthesis in this review. Four studies were included in the quantitative synthesis. En masse/miniscrew combination showed a statistically significant standard mean difference regarding anchorage preservation − 2.55 mm (95% CI − 2.99 to − 2.11) and the amount of upper incisor retraction − 0.38 mm (95% CI − 0.70 to − 0.06) when compared to a two-step/conventional anchorage combination. Qualitative synthesis suggested that en masse retraction requires less time than two-step retraction with no difference in the amount of root resorption.ConclusionsBoth en masse and two-step retraction methods are effective during the space closure phase. The en masse/miniscrew combination is superior to the two-step/conventional anchorage combination with regard to anchorage preservation and amount of retraction. Limited evidence suggests that anchorage reinforcement with a headgear produces similar results with both retraction methods. Limited evidence also suggests that en masse retraction may require less time and that no significant differences exist in the amount of root resorption between the two methods.Electronic supplementary materialThe online version of this article (10.1186/s40510-017-0196-7) contains supplementary material, which is available to authorized users.

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