Position and Distribution of Maxillary Displaced Canine in a Japanese Population: a Retrospective Study of 287 CBCT Scans

Objective: To assess the position, location, and distribution of maxillary displaced canines in a sample of Japanese population and to develop a classification for the maxillary displaced canine depending on the position in order to facilitate proper diagnosis of this frequently encountered clinical problem. Methods: Cone beam computed tomographic scans of 287 Japanese orthodontic patients (mean age 11.2 ± 1.8 years) with maxillary displaced canines were collected from private dental clinics in Himeji city, Japan. The maxillary displaced canines were evaluated and classified into ten different groups (Types A-J) according to their position and location. Results: Type B in which the canine is in a vertical position behind the lateral incisor causing root resorption in the apical one third of the lateral incisor was the most common (47%) followed by Types A and C in which the canine is either impacted in a mesioangular position behind the central incisor root causing root resorption in the apical one third of the central incisor or impacted in a vertical position between the lateral incisor and the first premolar without causing root resorption (17.1% and 16%) respectively. Types I and J were the rarest (0.4%). Conclusion: Maxillary displaced canines were classified into ten different groups according to their positions and locations because of the high variations. The development and standardization of a defined classification is essential for proper diagnostic and therapeutic considerations.