Longitudinal Survey of Malocclusion during the Transitional Period of the Dentition: 6-12 Age Group

Abstract

The purpose of the present study was to disclose information on the course of malocclusion and the possible effect of the eruption sequency of lateral teeth on the formation of malocclusion of the permanent dentition.
A total 160 school children,88 boys and 72 girls who started their first year of primary school in Kagamihara city, Gifu Prefecture in 1980 were examined. The examination was subsequently carried out until 1986. Of these,48 children had to be excluded, because they had changed their school during the period of the present survey. Adhering to the registration method by Bjork et al, the Dental Stage (DS) which describes the steps in dental development, its chronological incidence, and the eruption rate of permanent teeth, the numbers and incidence of different types of malocclusion, and the sequence of eruption of lateral teeth were recorded.
The results obtained in the present study were as follows:
1) There was tendency towards a increase in maxillary protrusion, distocclusion of the first molar, deep overbite, inversion, scissors bite and crowding of the lower anterior teeth.
2) Lower anterior protrusion, open bite, scissors bite of molars and crowding of lower anterior teeth were declining.
3) Anterior protrusion is often observed in cases where the eruption sequece was 4→3→5,3·4→5 or 4→3→5 and an overbite in 4→3·5.
As far as the results obtained are concerned, it may be suggested that the eruption sequence of the lateral teeth may be related to the some types of malocclusion. Furthermore, the logitudinal survey provides the information pertinent to follow the course of the malocclusion.