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Oral Medicine Orthodontics

In mixed-dentition patients, what is the short-term effectiveness of functional appliances (FAs) compared to untreated controls on mandibular dimensions?


This Systematic Review Summary is adapted from the article published on the ADA Center for Evidence-Based Dentistry website: The effects of functional appliances on mandibular growth during mixed dentition are unlikely to be of clinical importance

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Clinical Question

In mixed-dentition patients, what is the short-term effectiveness of functional appliances (FAs) compared to untreated controls on mandibular dimensions?

Main Results

Four RCTs met the inclusion criteria (338 participants, of which 168 were in the treatment group and 170 in the control group). Heterogeneity in age, interventions, and outcomes were observed, and follow-up times ranged from 15 to 18 months. Two RCTs had a low risk of bias, and one trial had a high risk of bias. The risk of bias for another trial was unclear. Independent quality as assessed by two reviewers showed very good agreement (k statistic = 0.75). Meta-analysis showed that the average effect was a increase of 1.79 mm (a statistically significant finding) in the annual mandibular growth in comparison to the control group (SMD = 0.61, 95 percent confidence interval, 0.30 to 0.93).


The analysis of mandibular skeletal effect in mixed dentition cases with FAs versus an untreated control revealed that the increases in skeletal changes are statistically significant, but clinically insignificant .


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1 Comment

  1. James Noble May 28, 2013

    Skeletal, not dental age, should be the determining factor in initiating orthodontic treatment with a functional appliance. The fact that these authors looked at the mixed dentition suggests that the study is inherently flawed in design. The Class II RCT trials that were examined also are problematic in many aspects. This has been discussed extensively in textbooks and the literature and a good paper that review it is the following: Darendeliler MA. Validity of randomized clinical trials in evaluating the outcome of Class II treatment. Semin Orthod 2006;12:67-79.

    What we do know based on evidence from McNamara and Bacetti (who they quote) is that success is determined by timing the use of a functional appliance with skeletal age, assessed with CVMS stage, hand/wrist x-rays and presence of secondary sexual characteristics. Skeletal age and dental age are not correlated well unfortunately and its sad that the authors use this in their title. If a functional appliance is initiated based on the above named skeletal factors, we may find not only a statistical but clinical significance in an RCT.

    Further, I believe we as orthodontists need to understand the biology of how they are effective, which is not necessary based on growth at the condyle due to mandibular posturing, but the real MOA is due to forces at the craniofacial sutures (see 3rd article down: http://www.cda-adc.ca/jcda/vol-74/issue-10/891.pdf)

    James Noble


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