Studies on the caries susceptibility of prematurely exposed rat molars

Abstract

The purpose of this study was to examine the carious development on prematurely exposed rat molars. In this study, the first and second molars in the left side of the maxilla were artificially exposed before the normal eruption time. The normally erupted molars on the right side of the same animal served as controls.
The results obtained were as follows.
1) There were more carious fissures on the prematurely exposed molars than on the normally erupted molars. The earlier the molar was exposed, the more carious cavities it developed. (Fig. 1, 2)
2) When the rats were fed a cariogenic diet (Diet #2000) after weaning, the number of carious cavities and fissures of the prematurely exposed molars increased remarkably before that of the normally erupted molars. (Fig. 3, 4)
3) Even in the rats fed on the conventional diet after weaning, a considerable number of carious cavities and fissures were observed on the prematurely exposed molars. (Fig. 6, 8)
4) The plaque score of the prematurely exposed molars of the rats fed on the various experi-mental diet increased significantly more than that of the normally erupted molars. (Fig. 10)
5) The development of pre-eruptive maturation in the prematurely exposed molars was more irregular than in the normally erupted molars. (Photo. 4)
From these results, it was concluded that the prematurely exposed rat molars were more sus-ceptible to caries, and pre-eruptive maturation decreased the caries susceptibility in the pre-eruptive period.