Diabetes and salivary gland dysfunction are major factors that induce
dental caries in experimental animals, but there are no reports analyzing the association of
dental caries and salivary glands in an animal model of
diabetes mellitus (DM). To clarify the initial development of
dental caries and preceding salivary gland disorder, we performed a histopathological analysis on teeth and salivary glands in diabetic Wistar rats 7 weeks after
alloxan treatment (DM group) in comparison with nondiabetic rats (Non-DM group) and functional analysis on saliva secretion during the experimental period.
Pilocarpine-induced salivary fluid secretion in diabetic rats gradually decreased with continuous
hyperglycemia from immediately after
alloxan treatment to the time of autopsy. Histopathologically,
Oil Red O-positive lipid droplets accumulated in the acinar cells of the parotid gland. No tooth was stereoscopically defined as having
dental caries in any of the rats in either group; however, the external appearance remarkably changed owing to
occlusal wear in almost all molars in the DM group. The initial lesions of
dental caries, appearing as micro-defects in dentin with bacterial colonization on the molar surface, were identified using histopathological analysis, and the incidence in the DM group was more than twice that in the Non-DM group. In conclusion,
hyperglycemia simultaneously induces initial caries development and enhances spontaneous
occlusal wear in molar teeth of Wistar rats 7 weeks after
alloxan treatment. The parotid gland dysfunction caused by
hyperglycemia may be mostly involved in the pathogenesis of
occlusal wear as well as in
dental caries in this diabetic model.