Early treatment of class III malocclusion is considered to reduce the need for later surgical intervention. However, the timing of early treatment is considered important with some studies suggesting this should be before 10 years of age. Although other studies suggest it has little influence. A wide range of appliances have been used e.g face- mask, chincup, FR-3 appliance of Frankel, bionator, reverse Twin-block, removable mandibular retractor, double-piece corrector, Class III elastics, and mandibular headgear .
The aim of this review was to evaluate the effectiveness of orthodontic methods used in the early treatment of Class III malocclusion in the short and long terms.
Methods
Searches were conducted in The Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, Medline and ClinicalTrials.gov databases. Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) of children aged 7-12 years with class III malocclusion undergoing fixed or removable orthodontic treatment for early correction were considered. The primary outcome was correction of reverse overjet. Data abstraction was carried out by two reviewers independently. The Cochrane risk of bias tool was used to assess RCTs and the Downs & Black Checklist for CCTs. The mean differences with 95% confidence intervals were expressed for the continuous data and random of fixed effects meta-analysis conducted.
Results
- 15 studies (9 RCTs, 6 CCTs) were included.
- 3 RCTs were considered to be at low risk of bias.
- 6 CCTs were all at high risk of bias.
- 3 RCTs (141) participants looked at the comparison between protraction facemask and untreated control. The results for:-
- reverse overjet mean difference = 2.5 mm (95% CI; 1.21-3.79; P = 0.0001) and
- ANB angle mean difference= 3.90° (95%CI; 3.54-4.25; P <0.0001)
- were statistically significant favouring the facemask group.
- All CCTs demonstrated a statistically significant benefit in favour of the use of each appliance. However, the studies had high risk of bias.
Conclusions
The authors concluded
There is a moderate amount of evidence to show that early treatment with a facemask results in positive improvement for both skeletal and dental effects in the short term. However, there was lack of evidence on long-term benefits. There is some evidence regarding the chincup, tandem traction bow appliance, and removable mandibular retractor, but the studies had a high risk of bias. Further high-quality, long-term studies are required to evaluate the early treatment effects for Class III malocclusion patients.
Comments
This detailed and well conducted and presented systematic review updates and extends the 2013 Cochrane review by Watkinson et al (Dental Elf – 18th Oct 2013). This review includes 3 year follow results from some the RCTs in the Cochrane review which have a positive effect on the outcomes. While the addition of CCTs to this review does provide some additional information because they are all at high risk of bias the additional work involving in including them can be queried when good RCTs are available. The review authors also highlight that a majority for the studies do not report on reverse overjet which is the main reason for a patient to seek treatment! Instead the focus is on cephalometric angles and concerns regarding their overuse in orthodontic research have raised (Kevin O’Brien’s blog June 18th 2014).
Links
Primary paper
Woon SC, Thiruvenkatachari B. Early orthodontic treatment for Class III malocclusion: A systematic review and meta-analysis. Am J Orthod Dentofacial Orthop. 2017 Jan;151(1):28-52. doi: 10.1016/j.ajodo.2016.07.017. Review. PubMed PMID: 28024779.
Other references
Original review protocol in PROSPERO
Downs SH, Black N. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health. 1998 Jun;52(6):377-84.PubMed PMID: 9764259; PubMed Central PMCID: PMC1756728.
Kevin O’Brien’s blog June 18th 2014
Dental Elf – 18th Oct 2013
Some evidence to support use of facemask appliance for class III malocclusions
Dental Elf – 5th Jun 2014
Second group of reviewers find some evidence for use of facemask for class III malocclusions
Dental Elf – 6th Aug 2014
