Effect of fluoride on hypomineralized areas in the molars of rats fed a cariogenic diet

Abstract

Hypomineralized areas (HMA) were shown to exist in the molars of different types of young (22–24-day-old) rats, including germfree Sprague-Dawley rats. Under normal conditions these HMA undergo mineralization or maturation in conventional Sprague-Dawley rats fed a diet of laboratory chow. Concomitant with this mineralization an increase in resistance to decalcification occurred. Conversely, when young 22-day-old conventional rats were placed on a cariogenic diet, a great increase in HMA score during the first week on the diet was observed, but little or no increase during the following 2 weeks. When rats 21 days old were fed a cariogenic diet and treated topically with a solution containing 4500 μg/ml fluoride a decrease in HMA score was revealed (by silver nitrate staining) suggesting that mineralization had taken place under these conditions. Furthermore, this decrease in HMA score in the fluoride-treated group fed a cariogenic diet was even greater than that of littermate animals fed a chow diet. These data support the hypothesis that in rats fed a cariogenic diet an effective, topically applied agent might not only be cariostatic, but might even favour mineralization.