Objective: To elucidate the prevalence of developmental anomalies of permanent lateral incisors among young patients in Japan. Study deign: A total of 1375 patients were observed between 1990 and 2008 at the Department of Pediatric Dentistry in the Kyushu Dental College Hospital and four private pediatric dental clinics in Kitakyushu City. Panoramic and periapical radiographs were examined for all those patients aged 5 to 19 years. Results: The prevalence of agenesis of the lateral incisors was 7.3% (100 patients), with more girls than boys being affected. The prevalence rates of absent upper and lower lateral incisors were 2.7 and 4.8 % (34 and 63 patients), respectively. Nine (0.7 %) of the total patients had microdontia. Eruption disturbance was present in five patients (0.4 %). Two of five patients presented with a disturbed eruption owing to an odontoma or a supernumerary tooth. Conclusion: In our study, the prevalence of agenesis of the lateral incisors was higher in Japanese children than in other populations, and eruption disturbance occurred less frequently than agenesis and microdontia. Nevertheless, the early differential diagnosis of an eruption disturbance is important in order to begin appropriate treatment at the optimal time.
