Relationship between large tubules and dentin caries in human deciduous tooth.

The purpose of this study was to elucidate the relationship between large tubules and dentin caries by using human deciduous incisors that showed various levels of attrition but no macroscopical lesions resulting from caries. The teeth were cut longitudinally in the mesio-distal direction and the exposed surfaces observed with a high-resolution field emission scanning electron microscope. The inside of each large tubule showed dense collagen fibers running parallel to its long axis and small spherical bodies of aggregated crystals, but no marked attrition. In teeth where attrition had exposed dentin at the incisal edge, oral bacteria had infiltrated the large tubules. Furthermore, in teeth with advanced attrition, it was difficult to distinguish between the large tubules and the surrounding dentin matrix, and numerous bacteria were observed in both areas. These findings support the hypothesis that large tubules play a role in the pathway of caries formation in coronal dentin when incisal dentin is exposed by attrition. This suggests that early treatment of exposed dentin surfaces might be effective in preventing dental caries.