Patient-Reported Outcomes of Functional Orthodontic Treatment for Skeletal Class II and III Malocclusions in Growing Patients: A Systematic Review.

Functional orthopedic appliances are widely used to manage skeletal Class II and Class III malocclusions in growing patients due to their well-established dentoskeletal effects. However, their impact on patient-reported outcome measures (PROMs) remains insufficiently investigated. PROMs, including pain, functional impairment, swallowing difficulties, and oral health-related quality of life (OHRQoL), are essential components of patient-centered care and are increasingly emphasized in contemporary orthodontic research. This systematic review aimed to critically evaluate the available evidence regarding PROMs associated with functional appliance therapy in growing individuals. A comprehensive electronic search was conducted in June 2025 across eight major databases without language restrictions. This was supplemented by manual screening of reference lists to ensure the comprehensive identification of studies. Eligible studies included randomized controlled trials and controlled clinical studies assessing PROMs in growing patients treated with fixed or removable functional appliances. The outcomes of interest included pain, functional limitations, swallowing difficulties, and OHRQoL, assessed using validated instruments such as Oral Health Impact Profile (OHIP-14), Child Perceptions Questionnaire (CPQ 11-14), and Child Oral Health Impact Profile (COHIP-19), as well as structured questionnaires. Risk of bias was evaluated using Cochrane Collaboration tools, and the certainty of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Eight studies met the inclusion criteria: seven randomized controlled trials (RCTs) and one prospective cohort study, totaling 447 participants. The findings suggest that functional appliance therapy is generally associated with mild-to-moderate pain, primarily during the initial adaptation phase, which resolves over time. Short-term functional disturbances, such as difficulties in mastication and speech, were also commonly reported but tended to diminish as patients adapted to the appliance. Swallowing difficulties were temporary and improved with continued use. The overall impact on OHRQoL was minimal, with no clinically significant deterioration reported across the included studies. However, the certainty of evidence ranged from low to very low, mainly due to methodological limitations, small sample sizes, heterogeneity in study designs, variability in appliance types, differences in outcome measures, and imprecision in results. Considerable clinical and methodological heterogeneity precluded a meta-analysis. In conclusion, functional appliance therapy for skeletal Class II and Class III malocclusions in growing patients appears to be well tolerated, with predominantly mild, transient, and self-limiting PROMs and no significant adverse impact on OHRQoL. Nevertheless, the limited certainty of evidence underscores the need for high-quality, adequately powered multicenter RCTs using standardized PROMs and longer follow-up periods. This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database during the early stages of its conduct (registration number: CRD420251166637).