Factors Influencing the Duration of Orthodontic Traction of Impacted Maxillary Canines: A Systematic Review and Meta-Analysis

Background: The maxillary canine is the second-most frequently impacted tooth, affecting 1–3% of the population. It plays a crucial role in occlusion, facial esthetics, and arch development, making orthodontic traction the preferred approach over extraction or clinical monitoring without intervention. This systematic review aimed to identify the factors associated with the duration of orthodontic traction for impacted maxillary canines and to evaluate their influence. Methods: A systematic search was conducted in MEDLINE, Cochrane Library, Embase, Web of Science, and grey literature following PRISMA guidelines. Traction duration was defined as follows: (A) time from traction initiation to alignment; (B) time to cusp emergence; and (C) time to appliance removal. Risk of bias was assessed using RoB 2 and ROBINS-I v2. Results: Out of 1156 initial studies, 43 were included in qualitative analysis and 24 in quantitative analysis. The pooled mean treatment duration was 43.13 months (95% CI: 32.50–53.77; I2 = 99.6%) for definition A, 44.81 months (95% CI: 23.28–66.34; I2 = 99.8%) for definition B, and 87.48 months (95% CI: 69.80–106.07) for definition C. Alpha angle, vertical height, and sector were the most frequently reported factors, potentially influencing traction duration. Meta-regression showed a significant association between mean patient age and treatment duration for definition B (β = −8.168, 95% CI: −15.299 to −1.037; p = 0.025), whereas no significant associations were observed for definition A. Heterogeneity across studies was high, and most non-randomized studies showed moderate to serious risk of bias, while randomized trials presented some concerns. Conclusions: Patient- and treatment-related factors, including higher alpha angle, greater vertical height, and more midline positioning, appear to influence traction duration. Despite variability across studies, these findings provide valuable insights for clinical practice.