Abstract
Inconsistent results have been reported on the chronological changes in the size of the permanent teeth crown and its actual condition is still not clear. The change in the tooth crown size was investigated between the present and twenty years past by measuring the mesio-distal and bucco-lingual width of central incisors and first permanent molars representing successor and predecessor respectively using plaster models of children with mixed dentition. The subjects were fifty-five children (twenty-eight males, twenty-seven females) and fifty-nine children (thirty males, twenty-nine females)who visited the pediatric dentistry clinic at Iwate Medical University from 1995 to 2000 and from 1975 to 1980, respectively. The following results were obtained.
1. The mesio-distal width of the first permanent molars of the present male children was significantly smaller than twenty years ago. As for the central incisor, the maxillary of the males was larger while mandible of the males, the maxillary and mandible of the females were smaller, although without statistically significant difference.
2. The bucco-lingual width of the first permanent molar showed no significant change when compared with twenty years ago in both male and female children. That of the male central incisor was significantly larger.
3. Although central incisors and first permanent molars were used for measuring typical permanent teeth, no consistent clear tendency was detected. Farther investigations on other kinds of permanent teeth are required.
