Functional orthodontic appliance treatment provides small beneficial changes in skeletal patterns

shutterstock_41854831 - removable orthodontic appliance

The aim of this review was assess the effectiveness of functional appliances on mandibular growth in the short term.

Functional appliances consist of a range of removable and fixed devices that are designed to alter the position of the mandible, both sagittally and vertically, with the aim of inducing supplementary lengthening of the mandible by stimulating increased growth at the condylar cartilage.

The electronic databases PubMed, Embase, Ovid Medline, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, and Google Scholar were searched for randomised controlled trials. Reference lists of the retrieved articles were hand-searched and no language restrictions were applied. The selection process and the quality assessment were undertaken independently and in duplicate by two authors. A meta-analysis was attempted by using random-effects models. Clinical and statistical heterogeneity was examined, and a sensitivity analysis was performed.

Four articles, based on data from 338 patients (168 treated vs 170 controls) with Class II malocclusion in the mixed dentition, were selected for the final analysis. The quality analysis of these studies showed that the statistical methods were at the medium-high level.

The outcome measurements chosen to evaluate the efficacy of the various functional appliances were condylion pogonion( Co-Pg),  pogonion-occlusal line perpendiculare + condylion-occlusal line perpendiculare (Pg/Olp + Co/Olp), and condylion-gnathion (Co-Gn) and the values were annualized and standardized to a uniform scale with the standardized mean differences (SMD).

A random-effects meta-analysis showed a statistically significant difference of 1.79 mm in annual mandibular growth of the treatment group compared with the control group (SMD = 0.61, 95% CI, 0.30 to -0.93; chi-square test, 5.34; 3 df; P = 0.15; I(2) = 43.9%; test for overall effect, Z = 3.83 and P = 0.0001).  A sensitivity analysis without the one study with the highest risk of bias showed a substantially similar outcome of 1.91 mm (SMD = 0.65, 95% CI, 0.25 to 1.25; chi-square test, 4.96; 2 df; P = 0.08; I(2) = 59.7%; test for overall effect, Z = 3.19 and P = 0.001).

The reviewers concluded:

This meta-analysis showed that, when functional appliance treatment is provided in early adolescence, there are small beneficial changes in skeletal patterns, but these are probably not very clinically significant.

Marsico E, Gatto E, Burrascano M, Matarese G, Cordasco G. Effectiveness of orthodontic treatment with functional appliances on mandibular growth in the short term. Am J Orthod Dentofacial Orthop. 2011 Jan;139(1):24-36. Review. PubMed PMID: 21195273.

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Derek Richards

Derek Richards is a specialist in dental public health, Director of the Centre for Evidence-Based Dentistry and Specialist Advisor to the Scottish Dental Clinical Effectiveness Programme (SDCEP) Development Team. A former editor of the Evidence-Based Dentistry Journal and chief blogger for the Dental Elf website until December 2023. Derek has been involved with a wide range of evidence-based initiatives both nationally and internationally since 1994. Derek retired from the NHS in 2019 remaining as a part-time senior lecturer at Dundee Dental School until the end of 2023.

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