FLUORIDE-INDUCED LESIONS IN THE TEETH OF THE SHORT-TAILED FIELD VOLE (MICROTUS-AGRESTIS) - A DESCRIPTION OF THE DENTAL PATHOLOGY

The effect of fluoride on the appearance of the teeth of the short-tai led held vole, Microtus agrestis, was investigated in both wild animal s collected from field sites affected by different levels of industria l fluoride contamination and laboratory-reared animals consuming exper imental grass diets of known fluoride concentration or with known fluo ride concentrations in drinking water. The extent and severity of lesi ons on the surface and structure of both incisors and molars are descr ibed as six lesion types and related to the amount of biologically ava ilable orally ingested fluoride. In the incisors of voles consuming re latively low fluoride diets, lesions are mainly confined to those resu lting from disruption of enamel pigmentation expressing itself as conc entric bands of pigmentation-free areas on incisor surfaces. The visib le effects on molars at low fluoride levels are confined to minor alte rations in surface appearance. At higher levels of available dietary f luoride, effects on enamel pigmentation are superseded by alterations in the formation, composition, and strength of both enamel and dentine . The incisors exhibit a marked to severe increase in the cutting tip erosion rates with comparable increases in the extent of abnormal surf ace changes (enamel hypoplasia) and loss of enamel pigmentation. The g rinding surfaces of molars from animals exposed to high levels of diet ary fluoride exhibit increasingly severe erosion of outer enamel regio ns, combined with cavitation and staining of the exposed central denti ne. The mechanisms through which fluoride elicits increasingly visible and pathological alterations to the surface and subsurfaces of rodent teeth are discussed. (C) 1997 Wiley-Liss, Inc.