[Effect of broken black tea on the formation of dental enamel and the contents of twelve kinds of chemical elements].

The aim of this study was to investigate the effect of broken black tea with slightly hyper-normal fluoride content which was near the level of people tea-drinking habits on enamel morphological structure and its content of chemical elements. Thirty six rats were divided randomly into 3 groups: one was control group and another two groups fed with broken black tea infusion with F- content of 8.2 mg/l and 16.4 mg/l, respectively. After 360 days, collected 144 teeth, observed their morphological structure by electron micrograph, Scanning electron micrographs (SEM) and also analyzed concentrations of several chemical elements in tooth by x-ray fluorescence spectrometry (XRF). Chronic dental fluorosis in rats was induced by treatment with broken black tea with slightly hyper-normal fluoride content. Hyper-calcification and hypo-calcification appeared in enamel of those teeth from both broken black tea treated groups in dose-dependent manner. Twelve kinds of chemical elements, such as Ca, Mg, P, Al, Cl were examined. The contents of Ca, P, Mg were reduced and that of Al and Cl were increased significantly. Compared with control group, the levels of Si, S, Fe were lower in those teeth from treated group (broken black tea with the F- content of 8.2 mg/l), while higher in those teeth from treated group (broken black tea with the F- content of 16.4 mg/l). Long-term drinking broken black tea with hyper-normal fluoride content could cause chronic dental fluorosis, and its injury in enamel was related with Hyper-calcification and hypo-calcification mainly. Those changes of several chemical elements level in enamel, such as Ca, P, Al, Cl, were suggested that these chemical elements have influences on the development and mineralization of enamel.