Influence of maxillary canine impaction characteristics and factors associated with orthodontic treatment on the duration of active orthodontic traction

Introduction: Orthodontic traction of a maxillary impacted canine (MIC) increases the orthodontic treatment time. Therefore, the objective of this study was to evaluate the influence of MIC characteristics and factors associated with orthodontic treatment on the duration of active orthodontic traction. Methods: This follow-up and retrospective study included 45 MICs orthodontically tractioned into the occlusal plane with the use of a standardized protocol. MIC characteristics, including type, sector, side, location, height, and complexity of impaction, as well as α and β angles and canine root length and area were measured. Likewise, factors associated with orthodontic treatment, including sex, age, malocclusion, premolar extractions, previous incisor root resorption, ANB, APDI, and SNA angles, and PNS-ANS distance were also evaluated. The statistical analysis included multiple linear regressions to estimate the influence of all variables on the duration of traction (α = 0.05). Results: Sex had significant influence (P = 0.027) on the time of traction; in female patients, the time was 2.05 months more than in male patients. Bilateral impaction treatment increased the time by 2.74 months compared with unilateral cases (P = 0.001). Traction of bicortically centered impacted canines increased the duration of traction by 2.85 months (P = 0.001). Finally, the traction time increased in 2.35 months (P = 0.046) when the impaction sectors were 4 or 5 (close to the midline). Conclusions: The duration of active orthodontic traction of MIC is mainly influenced by sex, bilateral type, bicortically centered location, or when MIC is located in sector 4 or 5 close to midline, increasing the traction time by some months.