Quality of Life in Orthodontic Patients Before and After Appliance Therapy: A Narrative Review

Background: Orthodontic treatment is increasingly recognised as a complex, patient-centred intervention whose impact extends beyond occlusal correction to include physical comfort, psychosocial well-being, and self-perceived esthetics. Oral health-related quality of life (OHRQoL) has therefore become a key outcome for evaluating orthodontic care across all treatment stages. Aim: This narrative review of 140 studies synthesises current evidence on OHRQoL changes in orthodontic patients before treatment, during active therapy, and after treatment completion, with particular emphasis on temporal patterns and appliance-related differences. Methods: A comprehensive narrative review of 140 studies was conducted using PubMed, Scopus, Web of Science, Cochrane Library, and Google Scholar (search period: inception to December 2025). Studies assessing OHRQoL or patient-reported outcomes in orthodontic patients of any age were included. Only studies employing validated instruments, such as OHIP, CPQ, OIDP, and PIDAQ, were considered. Dual-reviewer agreement was assessed using Cohen's kappa (κ = 0.82). Formal risk-of-bias assessment was conducted using ROBINS-I for non-randomised studies and the Cochrane Risk of Bias tool for RCTs. Sensitivity analyses were performed comparing high-quality studies (low risk of bias, n = 52) versus all included studies. Results: The reviewed evidence consistently demonstrates that malocclusion is associated with impaired baseline OHRQoL, particularly affecting psychosocial and esthetic domains. The early phase of orthodontic treatment is marked by a transient deterioration in OHRQoL due to pain, discomfort, speech disturbances, and functional limitations (87% of studies report pain peaks within 24-48 h; 79% report resolution by 4-7 days). These effects typically diminish as patients adapt to the appliance. Progressive improvement is observed during mid-treatment, while treatment completion is associated with substantial long-term gains in self-esteem, social functioning, and overall quality of life. Appliance type influences short-term outcomes, with clear aligners generally associated with better early OHRQoL than fixed and lingual systems (65-75% of studies favour aligners for early comfort; 78% favour lingual systems for esthetic satisfaction). Conclusions: Orthodontic treatment follows a dynamic, time-dependent OHRQoL trajectory characterised by short-term impairment and significant long-term psychosocial benefits. Systematic integration of validated OHRQoL measures into orthodontic care may enhance patient-centred decision-making and optimise clinical outcomes.