Influence of impacted maxillary canine orthodontic traction complexity on root resorption of incisors: A retrospective longitudinal study

Introduction: The orthodontic traction of impacted canines is a procedure of variable complexity. The objective of this study was to determine the influence of this complexity on the root resorption (RR) of adjacent incisors, using cone-beam computed tomography. Methods: This longitudinal retrospective study included 45 patients (19 female, 11 male; ages, 18.16 ± 7.3 years) with maxillary impacted canines, classified into 2 groups according to the level of orthodontic traction complexity: low complexity group (n = 20) and high complexity group (n = 25). The amounts of RR of 45 maxillary central and 45 lateral incisors were evaluated before and after treatment. Complexity was defined considering impaction sector, eruption inclination angle, and canine position (palatal, buccal, or bicortical). Three orthodontists measured RR in each maxillary incisor. Independent t tests or Mann-Whitney U tests were used to compare resorption between groups depending on the normality of the data. A multiple linear regression was calculated to evaluate the influence of all variables on RR (α = 0.05). Results: RR of maxillary incisors in the sagittal, coronal, and axial sections showed no significant differences between groups (P > 0.05). Independently of the groups, RR ranged approximately from 1 to 1.5 mm and from 3 to 4 mm². RR was less than 2 mm² in the axial sections. Multiple linear regression indicated no significant influence of orthodontic treatment complexity on RR. Male patients had more RR, specifically in the maxillary central incisors than female patients (P < 0.05). Conclusions: The complexity of orthodontic traction of impacted maxillary canines is not a risk factor for greater RR of maxillary incisors close to the impaction area.