Dentin abnormalities in cheek teeth of wild red deer and roe deer from a fluoride-polluted area in Central Europe

This study analyses the severity and distribution of mineralization defects in the dentin of red and roe deer teeth (mandibular fourth premolars, first and third molars) obtained from individuals that had lived in a fluoride-polluted area along the Czech-German border. Mineralization defects presented as hypomineralized or interglobular dentin. In the P4s and M3s the entire dentin exhibited areas of defective mineralization, whereas in the M1s only the central and inner dentin portions were affected. This suggests that the early periods of dentin formation in the first molar, occurring during the late fetal and early postnatal (milk-feeding) periods of life, are protected against exposure to excess fluoride levels. Our findings are consistent with the hypothesis that certain protective mechanisms (partial placental diffusion barrier and blood-milk barrier to fluoride, clearance of fluoride from plasma by the rapidly growing skeleton) operate during these ontogenetic periods. Studying fluoride-induced dentin abnormalities in addition to enamel fluorosis broadens the time window during which fluoride effects on the developing dental hard tissues can be recorded. Including dentin in the analysis of dental fluorosis allows a more detailed reconstruction of lifetime fluoride exposure than would be possible by studying enamel fluorosis only, thereby adding to the significance of free-ranging deer as bioindicators of fluoride pollution.