H. Mohammed, M. Z . Rizk, K . Wafaie, M. Almuzian
What did the authors aim to do in this study?
The primary aim of this study is to explore the effectiveness of nickel titanium closing springs (NiTi-CS) & the elastomeric power chains (EPC) in orthodontic space closure and to assess the adverse periodontal effects, cost efficiency & patient - centered outcomes between both of these methods.
How did the authors evaluate?
The study was conducted by an electronic search of online databases such as Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Scopus, LILACS and Web of Science, along with reference lists and grey literature as well as hand search were conducted without any language restriction. Two authors blindly and in duplicate were involved in the study selection, quality assessment and the extraction of data. The two independent authors judged the methodological quality of all RCTs. Any dispute was resolved by a third author. An overall judgement of high, low or unclear risk of bias was given for every included RCT. Again, interrater agreement was assessed using the Kappa statistic. The protocol of this review included a visual inspection of a generated contour-enhanced funnel plot if 10 or more studies met the inclusion criteria. Besides, Begg’s rank correlation15 and Egger’s linear regression tests were pre-planned to examine publication bias.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 I2 statistic. The Cochrane’s collaboration tool was used to assess the risk of bias in the included RCTs. Each included study was assessed for the risk of bias in random sequence generation; allocation concealment; blinding of outcome assessors; incomplete outcome data; selective reporting; and other sources of bias.
What did the authors find?
The findings of the study stated that, an estimated standard error for two included studies was imputed following the guidelines in the Cochrane handbook for systematic reviews of interventions. A statistically significant mean difference favoring faster space closure with the NiTi-CS was observed. Both subgroups, split-mouth studies and parallel-arm studies showed a statistically significant effect estimate favoring the NiTi-CS. One study reported a mean rate of anchorage loss of 1.1 mm for the NiTi-CS group and 0.82 mm for the EPC group, over a period of four months. Another RCT reported a 0.46 mm of anchorage loss for the NiTi-CS group and 0.45 mm for EPC group while utilizing the transpalatal arch as a method of anchorage reinforcement and expressed the rate of anchorage loss per month. Both studies did not assess the impact of teeth inclination on anchorage loss in their assessment. GRADE assessment found that the overall quality of evidence for space closure outcome was moderate while it was low quality for the loss of anchorage outcome.
What did the authors conclude?
Both of NiTi closing springs and elastomeric chains are efficient force delivery systems in closing extraction space with space closure being the resultant of anterior teeth retraction, anchorage loss or combination.
There is moderate quality evidence suggesting that NiTi closing spring produces a faster rate of space closure than the elastomeric chain.
The evidence failed to find any difference in terms of anchorage loss between NiTi closing spring and elastomeric chain.
Future high-quality RCTs with parallel-groups that focus on adverse outcomes and patient-centred values are recommended.
What do we think about it?
The space closure is an important step in the orthodontic therapy & there are various mechanics employed to carry out the same in an efficient manner. Two commonly used methods are the friction & loop mechanics. Although each of them have their advantages & disadvantages, the most commonly preferred is the friction mechanics purely because of the ease of usage. In order to execute these mechanics, the Nickel titanium closing springs (NiTi-CS) & Elastomeric power chains (EPC) are most commonly used. And this brings about the question, which among the both is most efficient & numerous studies were conducted to answer it. But this systematic review gives the most detailed analysis with accuracy about how Niti-CS has a better effect in orthodontic space closure. This study also had limitations such as the quality of the studies considered was moderate to low because of the methodological shortcomings observed. Also, two of the RCT's considered had a split mouth design which might have led to a potential cross-over effect. Inspite of all these factors, the study still remains a trustworthy evidence to the effectiveness of NiTi-CS over the EPC and a reliable guide for clinicians for carrying out orthodontic therapy in patients in the best possible manner.
Mohammed H, Rizk MZ, Wafaie K, Almuzian M. Effectiveness of nickel-titanium springs vs elastomeric chains in orthodontic space closure: A systematic review and meta-analysis. Orthod Craniofac Res. 2018 Feb
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