Abstract
A stastical study was carried out to evaluate the circumstances of the oral habits of the children aged 3-15 yr. (423 boys and 379 girls,802 children in total) in a mountain village through psychological tests and investigation of the living environments of children and their parents. The following results were obtained:
1. The peak age of finger sucking was 3 years with girls (35.7%) and 4 years with boys (22.2%). After these ages a tendency to decrease in frequency was observed.
2. The peak age of the nail biting was 11 years in girls (26.5 %) and 10 years in boys (18.8%). However, the nail biting was observed in girls from infancy.
3. The peak age of bruxism was 7 years in boys (22.7%) and 4 years in girls (15.4%).
4. Based on sex, nail biting was found more with girls than with boys, on the other hand, bruxism was found more in boys than in girls. There was no difference in finger sucking.
5. Based on the analysis of the relationship between oral habits and personality characteristics, nail biting and bruxism showed a tendency twoards a low percentile in almost all of the items of personality characteristics, however, scarely any relationship was found in finger sucking.
6. Based on the analysis of quantification type III, the development of each oral habit showed a relationship to different personality characteristics.
7. In relation to the living environments, the nail biting occurred more in children whose mothers did not work than with those whose mothers worked, and bruxism occurred in the children who often play outdoors.
