The frequency of congenitally missing anterior teeth was studied by panoramic radiographic examination, inspection and question. One group of subjects consisted of 1, 433 students trained in radiology (1, 272 males and 161 females) at Fukuoka Dental College whose average age was 24.3 years. The other group of subjects consisted of 1, 209 patients (544 males and 665 females) from a dental office practice in Saseho city. Their ages ranged from 7-30 years. Since some cental incisors were difficult to discriminate from the lateral ones in the lower jaw, both of them were counted as incisors. 1. Two students (0.1%) had three anterior teeth missing : the maxillary bilateral incisors and one mandibular incisor (one student), and one maxillary lateral incisor and the mandibular bilateral incisors (one). 2. Seven students (0.5%) had two anterior teeth missing : the maxillary bilateral incisors (one student), one maxillary lateral incisor and one mandibular incisor (one), the mandibular bilateral incisors (four), and the mandibular ipsilateral incisor and canine (one). Twenty patients (1.7%) had the following two missing : the maxillary bilateral incisors (four patients), the mandibular bilateral incisors (nine), the maxillary contralateral incisor and canine (one), the mandibular ipsilateral incisor and canine (two), the maxillary bilateral canines (three), and the mandibular bilateral canines (one). 3. Twenty-four students (1.7%) had one anterior tooth missing : the maxillary lateral incisor (five students), the mandibular incisor (fifteen), and the maxillary canine (four). Thirty-four patients (2.8%) had a tooth missing : the maxillary lateral incisor (seven patients), the maxillary canine (seven), and the mandibular canine (twenty). 4. No missing central incisor was observed in either the students or the patients. 5. The rates of congenitally missing the anterior teeth for the students and the patients were as follows : the maxillary lateral incisor (0.6%, 1.0%), the mandibular incisor (1.5%, 2.6%), the maxillary canine (0.3%, 0.9%), and the mandibular canine (0.1%, 0.2%).
