Ahmed Elkhadem BDS, MS
There is insufficient evidence to determine whether orthodontic treatment is more or less efficient with self-ligating brackets (SLBs) than conventional brackets (CBs).
No differences in patient outcomes were identified among a small number of studies comparing SLBs and CBs.
In patients requiring orthodontic treatment, will using self-ligating brackets SLBs improve clinical outcomes compared to conventional brackets CBs?
The authors searched three electronic databases for articles published between 1950 and April 2009. For review, they selected randomized controlled trials (RCTs) and controlled clinical trials (CCTs) investigating the influence of bracket type on alignment efficiency, subjective pain experience, bond failure rate, arch dimensional changes, rate of orthodontic space closure, periodontal outcomes, and root resorption. They also chose studies that involved patients with full arch, fixed orthodontic appliance(s) treated with SLBs or CBs. No restrictions relating to publication status or language of publication were applied. They also searched the grey literature including electronic clinical trial databases, conference proceedings, abstracts, and reference lists.
The authors identified 17 studies for review. Meta-analysis of the influence of bracket type on subjective pain experience failed to demonstrate a significant advantage for either type of appliance at any given interval (4 hours, 24 hours, 72 hours and 7 days after placement). Meta-analysis of other outcomes was unfeasible because of inadequate information. The authors did not find any articles discussing the influence of bracket type on oral health related quality of life. They found no statistically significant difference between SLBs and CBs regarding root resorption. Only one study considered the rate of orthodontic space closure, but it was inappropriate to draw conclusions from this study because of its very small sample size. There were insufficient data to allow meta-analysis of torque expression and arch dimensional changes.
There is insufficient evidence to support the use of self-ligating fixed orthodontic appliances over conventional appliance systems or vice versa. Self ligating brackets do not confer particular advantage with regard to subjective pain experience.
Source of Funding:
Importance and Context:
In vitro studies suggest that SLBs are superior to CBs in regard to frictional resistance 1. Demonstrating clinical evidence of superiority of one bracket "system" over another in clinical trials may help alleviate debates and aid orthodontists in making treatment decisions.
Strengths and Weaknesses of the Systematic Review:
The authors applied an extensive search through electronic databases and grey literature, but a list of excluded studies and the reasons why they were excluded was not provided, possibly due to space limitations and editorial privilege. Publication bias was not assessed. In addition, there was inconsistency in the type of SLBs used throughout the selected studies including passive and active self-ligation systems. This imposed heterogeneity during pooling of data since each SLB has a different closing mechanism.2
Strengths and Weaknesses of the Evidence:
This review examined many outcome measures in response to a single question about the clinical difference between SLBs and CBs. Three of these outcomes were not patient centered: apical root resorption, bond failure rate and arch dimensional changes. These endpoints may or may not reflect improvement in treatment outcome and patient satisfaction. The authors included 17 studies, four of which had a high risk of bias. In addition, only six reported a priori sample calculation. This may result in increased risk of false- negative results and undermine the power of these studies. The authors performed four meta-analyses for only one outcome measure: subjective pain experience. The meta-analyses discussing pain experience 4 hours, 24 hours and 7 days after appliance placement showed consistency across their results, while meta-analysis of 72 hours after placement showed moderate heterogeneity. The authors did not perform any sensitivity-analysis. The term "orthodontic efficiency" is repeated many times in the article without a definition, leaving the reader to speculate that this term indicates the speed or the time frame of treatment with respect to alignment and space closure.
Implications for Dental Practice:
The debate about the effectiveness of SLBs over CBs in clinical trials is unresolved. With this in mind, the choice of using either type of bracket depend on the orthodontist's clinical expertise, patient needs and preferences. Reference:
1. Ehsani S, Mandich MA, El-Bialy TH, Flores-Mir C. Frictional resistance in self-ligating orthodontic brackets and conventionally ligated brackets. A systematic review. Angle Orthod 2009;79(3):592-601
2. Harradine NW. Self-ligating brackets: where are we now? J Orthod 2003;30(3):262-73.