Oral survey of second-grade elementary school students in Hokkaido, Japan: Adjunct study in Sapporo Study Area of the Japan Environment and Children’s Study （JECS）

Abstract

Recently, the percentage of children visiting a dental clinic with malocclusion as the main complaint has increased in Japan. This finding may be due to the oral effects of environmental changes, such as the increasing trend in the size of permanent tooth crowns, in children. As there was a lack of surveys on malocclusion in recent years, we performed a fact-finding survey to understand malocclusion and the eruption of permanent teeth in children today. The study subjects were 82 children（46 boys and 36 girls）in the second grade of elementary school who agreed to an additional dental survey in the Sapporo regional center of the Japan Environment and Children’s Study（JECS）from July 2021 to March 2022. The survey included the total number of erupted permanent teeth, first molars, permanent premolars, the incidence and classification of the malocclusion, and the orthodontic treatment experience. At least one or more first molars had erupted in all children. The eruption of the upper and lower central incisors and mandibular lateral incisors was complete, while more than half of the maxillary lateral incisors had not erupted. More than half of the elementary children had malocclusion, with crowding being the most common malocclusion（59.5％）. This study elucidated the actual conditions of permanent tooth eruption and malocclusion in second-grade elementary school children in Sapporo, Hokkaido, Japan.