Fixed or removable function appliances for Class II malocclusions

Abstract

Data sourcesEmbase, Cochrane Central Register of Controlled Trials, Medline (Pubmed), Web of Science, Google Scholar, Scopus, LILACS database and bibliographies of clinical trials encountered during search. There was no restriction on language or date during search.Study selectionRandomised Controlled Trials (RCTs) and Controlled Clinical Trials (CCT) in patients with Class II malocclusions that compared at least one fixed functional appliance with at least one removable functional appliance (RFA) in children below 16 years of age. Primary outcomes were clinical and lateral cephalometric measurements and the duration of treatment. Secondary outcomes included patient experiences of treatment, quality of life measures and harms arising during treatment as well as costs of both treatments.Data extraction and synthesisThe titles and abstracts of all studies identified through the search were assessed independently and in duplicate by two review authors. Disagreements about included studies were resolved through discussion with the third author. Heterogeneity was assessed using customised forms and risk of bias using a Cochrane Collaboration tool. A meta-analysis was planned for studies at low risk of bias with similar comparisons reporting the same outcome.ResultsTwo RCTs and two CCTs that met the inclusion/exclusion criteria were included in the final analysis. Risk of bias assessment indicated three trials were at high risk while one was unclear. Consequently, the included trials were deemed to be inappropriate for meta-analysis (MA).Two studies with 282 participants evaluated Twin Block with fixed Herbst appliance and reported significant improvements in anterior-posterior skeletal discrepancy, mandibular length and reduction of overjet with both appliances. While one study reported significantly shorter treatment duration in Herbst appliance, the other study did not find any difference. Herbst appliance had better compliance, less dropouts but more emergency visits.One trial that compared activator appliance with Twin Force Bite Corrector found significantly shorter time with the fixed appliance. However, effective length and sagittal positioning of the mandible was not different between the groups.One trial comparing activator with Forsus FRZ reported enhanced mandibular growth and restrained maxillary growth with both the appliances. While activator appliance was associated with increased posterior facial height, Forsus significantly rotated the occlusal plane.ConclusionsLimited available evidence indicates that both fixed and removable functional appliances are effective in reducing overjet in growing children. However, there is insufficient evidence to differentiate between the two types with respect to biological (skeletal and dental) effects or patient experiences.