Functional orthopedic treatment in class II malocclusion over the past three decades: an overview of systematic reviews

Skeletal Class II malocclusion is a common and complex orthodontic condition frequently treated during growth with functional orthopedic appliances. Although these appliances are widely used, the relative skeletal and dentoalveolar effects of fixed versus removable appliances, and the evolution of reported outcomes over time, remain debated. This overview aimed to assess the effects of functional orthopedic appliances in growing Class II patients, describe and critically compare the evidence reported for fixed and removable appliances while distinguishing direct comparative evidence where available, assess review-level risk of bias and formally reported certainty of evidence, and examine changes in treatment modalities and reported outcomes over the last three decades. A comprehensive electronic search was performed in MEDLINE via PubMed, Embase (Embase.com), Scopus, Web of Science Core Collection, and the Cochrane Database of Systematic Reviews (CDSR), without date or language restrictions. The database searches were updated on August 19, 2026. The search strategy combined terms related to functional orthodontic appliances, Class II malocclusion, and systematic reviews or meta-analyses, and reporting followed the PRIOR statement. Eligible studies were systematic reviews or meta-analyses evaluating fixed or removable functional orthopedic appliances in growing Class II patients, with skeletal or dentoalveolar outcomes assessed by cephalometric analysis. Two reviewers independently screened, selected, and extracted data from eligible reviews. Risk of bias was assessed using ROBIS. Quantitative effect estimates reported in the included systematic reviews and meta-analyses were extracted and presented separately at the review level. No additional statistical pooling of review-level estimates was performed because overlap of primary studies could result in non-independence between systematic reviews. Findings that were unavailable quantitatively or were not directly comparable were synthesized narratively. Thirty-eight systematic reviews met the eligibility criteria and were included in the overview. Where available, quantitative effect estimates were presented individually for descriptive comparison without additional overview-level pooling. Both fixed and removable functional orthopedic appliances were associated with improvements in Class II-related skeletal and dentoalveolar parameters. Across reviews, removable appliances tended to report somewhat greater skeletal changes, whereas fixed appliances more often showed pronounced dentoalveolar effects, particularly lower-incisor proclination. However, these patterns were largely based on indirect comparisons across heterogeneous evidence bases. Direct comparative reviews showed variable findings and did not consistently demonstrate superiority of either appliance category. Statistical heterogeneity was frequently substantial where reported. Formal GRADE assessments were available in 10 of the 38 included reviews and varied across outcomes from very low to high; no de novo overview-level certainty rating was assigned. Both fixed and removable functional orthopedic appliances are associated with treatment-related improvements in Class II-related skeletal and dentoalveolar parameters in growing patients. However, the available evidence does not establish the overall superiority of either appliance category, as comparative findings are influenced by differences in appliance design, growth stage, patient compliance, treatment protocols, study design, and risk of bias. Appliance selection should therefore be individualized according to patient characteristics, growth considerations, treatment objectives, and appliance-specific biomechanics. PROSPERO CRD420251077796.