Impaction of maxillary canines and its effect on the position of adjacent teeth and canine development: A cone-beam computed tomography study

Introduction: The purposes of this study were to characterize the 3-dimensional position of teeth adjacent to impacted canines and examine whether impaction affects canine development using cone-beam computed tomography. Methods: Cone-beam computed tomography images of 34 unilateral maxillary impacted canines (12 males, 22 females; mean age, 16.5 years) were collected. Twenty-one canines were palatally impacted (PIC), and 13 were buccally impacted (BIC). Angular measurements of lateral incisors (LIs), first premolars, and the impacted canines positions relative to a 3-dimensional coordinate system and canines' volume, length, and shape of the roots, were compared between the affected and contralateral control sides. The influence of canine position and severity of impaction was examined. Statistics included the paired t test, Wilcoxon signed rank test, and McNemar test. Results: In the PIC group, LIs showed significant mesiobuccal rotation (-17.1 degrees), mesial angulation (8.4 degrees), and buccal root torque (5 degrees) and first premolars mesiobuccal rotation (6.1 degrees). In the BIC group, LIs displayed mesiobuccal rotation (-18 degrees) and significant palatal root torque (-5 degrees). The canine volumes were similar in BICs and slightly smaller in PICs. The lengths were shorter in both, but root hooks were more prevalent in BICs. The severity of impaction affected the measured variables. Conclusions: The differential position of the adjacent teeth is pathognomonic for PIC vs BIC, and impaction seems to affect canine development. The findings provide evidence-based clinical and radiographical clues for early diagnosis of canine displacement and planning the most efficient treatment strategy. In addition, they support timely orthodontic eruption before the development of the apical third of the root.