Factors affecting forced eruption duration of impacted and labially displaced canines

Abstract

Patients with impacted maxillary canines typically endure long treatment time, and reliable pretreatmentestimates of orthodontic treatment duration would be beneficial to patients and clinicians. The purpose of this study was to identify factors that affect the duration of forced eruption for impacted maxillary canines. Data from treatment records and radiographic scans of 27 patients with 29 impacted and labially displacedmaxillary canines (25 unilateral, 2 bilateral) were collected. The patients underwent surgical and orthodonticinterventions to bring the canine into the dental arch. Linear and angular measurements between the cusp tip and various reference planes were made on 3-dimensional images. Measurements associated with dental follicle, bone density, and canine root length were also obtained. Data were analyzed using simple linear regression and stepwise regression analysis. A total of 29 treated canines moved into the arch over a period of 13.0±8.3months (range, 5-33months). Simple regression analysis showed that the only significant factor, with duration of traction as the dependent factor, was pretreatment inclination of the canines toward the midsagittal plane; stepwise regression analysis indicated a strong direct correlation betweenthe duration of traction and this factor. The other variables were not significantly associated with the duration of traction. The inclination of canines toward the midsagittal plane was found to be a reliablepredictor of the duration of forced eruption for impacted maxillary canines.