A statistical and clinical investigation of the impacted maxillary canines at Hokkaido University Hospital Orthodontic clinic for the past 7 years

Abstract

Impacted maxillary canines (impacted canines) are observed at a relatively high frequency. It is important to understand the impaction condition as various treatment options are available. Therefore, the objectives of this study were to classify the impaction conditions and determine the frequency of impacted canines. 1,379 patients were selected from among 1,905 patients examined at Hokkaido University Hospital Orthodontic clinic between November 1, 2001 and October 30, 2008. Those who changed hospital or had systemic diseases were excluded. Impaction was detected from panoramic radiograph when (1) a distance of 5mm or more from the cusp to the occlusal plane and (2) a tipping angle of the tooth axis of 6.0° or more from the midline. Patients who complied with one or both of these conditions were included after excluding those with submerged teeth in the intraoral photos. The impacted canines were classified according to the vertical position, horizontal position and tipping angle. 46 patients with 79 impacted canines were examined. In the vertical position, the distance from the cusp to the occlusal plane was mostly less than 25.0mm. The cusps most often corresponded to the horizontal position of the deciduous canines. The most common tipping angles ranged from 10.0°to 20.0°. The classification and frequency of the impaction condition of impacted canines were determined in this study.