Skip to main content
Toggle Menu of ADA WebSites
ADA Websites
Partnerships and Commissions
Toggle Search Area
Toggle Menu
e-mail Print Share

Associated Topics

Effectiveness of orthodontic treatment with functional appliances on mandibular growth in the short term

Marsico, E., Gatto, E., Burrascano, M., Matarese, G., Cordasco, G. . American Journal of Orthodontics & Dentofacial Orthopedics. 2011;139(1):24-36

INTRODUCTION: The aim of this study was to analyze the current literature for the best evidence (randomized clinical trials) about the efficacy of functional appliances on mandibular growth in the short term. METHODS: A survey of articles published up to September 2009 was performed by using the following electronic databases: PubMed, Embase, Ovid Medline, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, and Google Scholar. The reference lists of the retrieved articles were hand-searched for possible missing articles. No language restriction was applied during the identification of the published studies. A methodologic scoring process was developed to identify which randomized clinical trials were stronger methodologically. The selection process and the quality assessment were undertaken independently and in duplicate by 2 authors. A meta-analysis was attempted by using random-effects models. Clinical and statistical heterogeneity was examined, and a sensitivity analysis was performed. RESULTS: Electronic searches identified the following items: 146 articles were retrieved from PubMed, 45 from Cochrane Central Register of Controlled Trials, 29 from Ovid, 42 from LILACS, 628 from Web of Science, and 1000 from Google Scholar. Thirty-two articles fulfilled the specific inclusion criteria and were identified as potentially appropriate randomized clinical trials to be included in this meta-analysis. Only 4 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 Co-Pg, Pg/Olp + Co/Olp, and Co-Gn and the values were annualized and standardized to a uniform scale with the standardized mean differences (SMD). The results of the meta-analysis from the random-effects model 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). The sensitivity analysis 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). CONCLUSIONS: The analysis of the effect of treatment with functional appliances vs an untreated control group showed that skeletal changes were statistically significant, but unlikely to be clinically significant. Copyright ACopyright 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

The effects of functional appliances on mandibular growth during mixed dentition are unlikely to be of clinical importance

Nikolaos Pandis DDS, MS, dr. med. dent .


Systematic Review Conclusion

The effects of treatment on mandibular growth with functional appliances versus untreated controls in mixed dentition showed clinically insignificant skeletal changes.

Critical Summary Assessment

Heterogeneity in baseline characteristics, interventions and outcome assessment weakened the strength of the evidence.

Evidence Quality Rating

Limited Evidence

Structured Abstract

Clinical Questions:

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

Review Methods:

The authors searched six databases for articles published in any language up to September 2009. They also hand searched the reference lists of retrieved articles. They did only consider literature published in regular journals. For inclusion, the studies had to meet the following criteria: be randomized controlled trials (RCTs); use functional appliances for treatment of Class II malocclusion; and compare with an untreated control group, among others. The authors considered only one time articles that reported interim outcomes or updates. Two independent reviewers attained consensus during study selection, data abstraction and quality assessment. The studied outcome was the increase in total mandibular length as measured from the condylion. Both annualized standardized mean differences (SMD) and data synthesis were calculated using the random-effects model in the meta-analyses. Statistical heterogeneity was assessed (I2) and sensitivity analyses were undertaken.

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 .

Source of Funding:



Importance and Context:

Mandibular retrusion is a major contributing factor of Class II malocclusion, occurring in one-third of the population1. Functional appliances are intended to treat Class II malocclusion by stimulating mandibular growth at the condylar cartilage.2 However, their effectiveness remains controversial2-3. Previous systematic reviews3-4 explored this controversy but this review does approach the issue differently.

Strengths and Weaknesses of the Systematic Review:

The authors conducted a thorough systematic review with defined inclusion and exclusion criteria. They provided a list of search terms as well as reasons for study exclusions. Two independent reviewers selected studies, abstracted data, and duplicated quality assessments using separate printed forms. They performed meta-analysis by standardizing the different values of mandibular growth in the selected studies. The authors did not report if reviewers were blinded, nor did they discuss risks of publication biases. Reporting could have been improved.

Strengths and Weaknesses of the Evidence:

Of the included studies, two were at low risk of bias, one was at high risk of bias, and one had an unclear risk of bias. The quality of the evidence was weakened by the small sample sizes of the studies, heterogeneity among their baseline characteristics, the different types of study interventions and their corresponding outcomes. Additionally recording of outcomes using two dimensional images introduces errors which may affect interpretation That the studies comprised many different cephalometric analyses, different variables and reference points also weakens the strength of the evidence.

Implications for Dental Practice:

Successful treatment of Class II malocclusion using FAs is related to increases in mandibular length and to restrictions in maxillary growth restriction5,6, to profile changes6 and to dentoalveolar compensations4,5. The authors' research question was too narrow for the purposes of this systematic review. There is limited evidence that, in the short-term, FAs enhance mandibular growth during mixed dentition. However, these results, when considered independently of other simultaneous changes, have little clinical significance. 1.McNamara JA Jr. Components of Class II malocclusions in children 8-10 years of age. Angle Orthod 1981; 51:177-202. 2. Croft RS, Buschang PH, English JD, Meyer R. A cephalometric and tomographic evaluation of Herbst treatment in the mixed dentition. Am J OrthodDentofacialOrthop 1999;116:435-43. 3. Cozza P, Baccetti T, Franchi L, De Toffol L, McNamara JA Jr. Mandibular changes produced by functional appliances in Class II malocclusion: a systematic review. Am J Orthod Dentofacial Orthop. 2006 May;129(5):599.e1-12; discussion e1-6. Review. 4. Barnett GA, Higgins DW, Major PW, Flores-Mir C. Immediate skeletal and dentoalveolar effects of the crown- or banded type Herbst appliance on Class II division 1 malocclusion. Angle Orthod. 2008;78:361-9. 5. Harrison JE, O'Brien KD, Worthington HV. Orthodontic treatment for prominent upper front teeth in children. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD003452. 6. Flores-Mir C, Major PW. A systematic review of cephalometric facial soft tissue changes with the Activator and Bionator appliances in Class II division 1 subjects.Eur J Orthod. 2006;28:586-93.

Critical Summary Publication Date:


These summaries are not intended to, and do not, express, imply, or summarize standards of care, but rather provide a concise reference for dentists to aid in understanding and applying evidence from the referenced systematic review in making clinically sound decisions as guided by their clinical judgment and by patient needs. American Dental Association © 2019

Functional appliances do not seem to affect jawbone growth

Nikolaos Pandis DDS, MS, dr. med. dent


Systematic Review Author(s)

Marsico, E., Gatto, E., Burrascano, M., Matarese, G., Cordasco, G.

Summary Title

The effects of functional appliances on mandibular growth during mixed dentition are unlikely to be of clinical importance



Key terms

Orthodontic treatment is used to make teeth line up correctly. Braces are a kind of orthodontic treatment.

Braces are a common type of orthodontic treatment, but other appliances can be used to change the way teeth line up. Functional appliances, for example, are thought to promote growth of the jawbones in a way that would improve the alignment of teeth.

The authors wanted to know if functional appliances affected the growth of the lower jawbone, more than no treatment, in children who had both primary and permanent teeth. To answer that question, they evaluated the results of four studies, which involved 338 patients.

Authors’ findings
The authors analyzed the test results mathematically. They found that, on paper, there was a difference between the children treated with the functional appliances and those who did not receive any treatment. However, in practical terms, the additional growth detected with the appliance was so small, it likely would not be noticeable.

Compared to no treatment, use of functional appliances does not seem to result in additional growth of the lower jawbone in children who have both primary and permanent teeth. 


In children with both primary and permanent teeth, do functional appliances—a type of orthodontic appliance—affect growth of the lower jawbone compared to no treatment?


Compared to no treatment, functional appliances do not seem to affect growth of the lower jawbone more than would normally occur in children with both primary and permanent teeth.