A case of supernumerary primary and permanent canines

抄録

A case of supernumerary primary and permanent canines is presented. A 9Y4M-old boy was referred to our clinic for consultation regarding a maxillary supernumerary primary canine. An oral examination showed 2 primary canines with a similar morphology between the maxillary left lateral incisor and first primary molar. The primary canine in the opposite quadrant had the appearance of a fused-tooth, with composite resin restoration seen in the border. Orthopantomography revealed that permanent successors were present for each primary tooth in the maxillary left region, whereas only a single permanent canine was developing in the opposite quadrant. The 2 primary canines in the maxillary left region were extracted at 9Y4M. The mesially located permanent canine emerged into the oral cavity at 10Y1M and was extracted at 10Y9M. At 12Y2M, the other permanent canine located in the distal position had nearly reached the occlusal plane and the maxillary right permanent canine had arrived at the occlusal plane. Dental age was evaluated by assessing the tooth formation stages in 4 orthopantomographs taken between 8Y5M and 12Y2M, and found to be nearly the same as chronological age. However, the dental ages of the maxillary left permanent canine that had erupted earlier than the one located distally and of the left permanent canine were approximately 1 year behind chronological age. In addition, the dental age of the left permanent canine located distally was 2.5 years behind until the patient reached the age of 10Y9M, after which tooth development was accelerated following extraction of the mesially located permanent tooth.