Studies on the distribution of mineral elements in the tooth of zinc-deficient rats

Elemental analysis of plaque-like black deposits noted on the surface of teeth in zinc-deficient rats at necropsy was performed. Rats deficient in zinc show signs of abnormality in iron metabolism and increase or accumulation of iron in plasma and tissues. This study was designed, therefore, to examine the plasma and salivary levels of iron and other elements and to determine the distribution of mineral elements in the dental substances of zinc-deficient rats by contact microradiography, electron probe microanalysis (EPMA) and X-ray fluorescent element mapping spectrometry (XEMS) on ground sections of teeth. Rat tooth specimens were analyzed also for zinc, iron, copper and manganese using colorimetry and Inductively Coupled Plasma, ICP. EPMA and XEMS analyses revealed the presence of iron on the enamel surface of maxillary molars teeth of zinc-deficient rats. However, no such deposition was seen on those of controls. The zinc-deficient rats showed higher iron concentration in mixed saliva and in plasma, compared with the controls. Thus, the sign of abnormality in iron metabolism noted in the oral cavity of zinc-deficient rats was investigated by EPMA and XEMS analyses, with discussion on the origin of supradental iron deposits.