One-phase or two-phase orthodontic treatment?

Abstract

Data sourcesMedline, Embase, Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), LILACS, BBO, ClinicalTrials.gov, the National Research Register and Pro-Quest Dissertation Abstracts and Thesis database.Study selectionRandomised controlled trials (RCTs) and controlled trials (CCTs) in children under 11 years at the beginning of treatment for interventions including; interceptive extractions, space maintenance, crossbite correction and habit dissuasion were considered.Data extraction and synthesisTwo reviewers independently extracted data and assessed study quality using the Cochrane Risk of Bias tool. Meta-analysis was possible for 11 comparisons.ResultsTwenty-two studies (18 RCTs, three CCTs) were included with 20 being considered to be at low or unclear risk of bias. For Class II correction in the short-term, meta-analyses demonstrated a statistically significant reduction in ANB (-1.4 degrees, 95 CI: -2.17, -0.64) and overjet (-5.81mm, 95 CI: -6.37, -5.25) with both functional appliances and headgear versus control. For Class II correction in the long-term, however, statistical significance was not found for the same outcomes. Treatment duration was prolonged with both functional appliances (6.85 months, 95 CI: 3.24, 10.45) and headgear (12.47 months, 95 CI: 8.67, 16.26) compared to adolescent treatments. Meta-analyses were not possible for comparisons of other interceptive treatments due to heterogeneity and methodological limitations. The overall quality of the evidence based on the GRADE assessment suggested that the level of evidence was low to moderate.ConclusionsThe results suggest a lack of evidence to prove that early treatment carries additional benefit over and above that achieved with treatment commencing later; however, this does not imply that early treatment is ineffective. The additional cost and burden to the patient, parent and clinician may, therefore, generally negate early treatment. Further trials of high quality of evidence are required assessing the effectiveness of interceptive treatment for a range of occlusal problems, particularly those not known to hinge on growth potential, with long-term follow up to ascertain whether short-term effects are maintained once growth has ceased and to delineate the effects of intervention timing on the overall treatment duration.