MORPHOMETRY AND AUTORADIOGRAPHY OF ALTERED RAT ENAMEL PROTEIN PROCESSING DUE TO CHRONIC EXPOSURE TO FLUORIDE

Female Sprague-Dawley rats had 6 weeks of 0 (control), 75 or 100 parts /10(6) sodium fluoride in their drinking water. Whole mandibular incis ors were removed, fixed, demineralized and sections prepared for light -microscopic morphometric analysis of dose-related alterations in enam el protein retention. Other rats given 0 and 75 parts/10(6) only (cont rol and experimental groups) were used for autoradiographic evaluation of alterations in enamel protein removal. S-35-methionine was applied directly over secretory ameloblasts at the end of the fifth week of f luoride exposure. Incisors were removed either 5 or 7 days later and p rocessed for autoradiographic analysis. The results indicated: (1) ext ended retention of enamel proteins in fluoride-exposed maturation enam el as well as reduced enamel protein synthesis and/or secretion in the secretory stage; (2) negative linear correlation between extended ena mel protein retention and reduced enamel protein secretion among group s; and (3) repression of enamel protein removal. The data are also con sistent with the concept that the fluoride effect is multifactorial. C opyright (C) 1996 Published by Elsevier Science Ltd.