A microspectrophotometric analysis of the effect of fluoride on immature enamel matrix protein of rat molar teeth.

Over a 24-h period, Wistar rats from 4 litters, 6 to 9 days old, were given five intraperitoneal injections of a solution of 0.9% sodium chloride containing sodium fluoride (3 mg F/kg body weight). Within-litter controls were used. All rats were killed by decapitation 2 h after the final injection and the rat heads, cut sagittally, were processed for protein histochemistry. The intensity of staining of the protein in the enamel matrix of the upper jaw molar tooth buds was quantified using the two-wavelength method of microphotometry. A significant increase in the intensity of staining of fluoride-treated tissues over controls was observed with the histochemical methods specific for arginine (P less than 0.01), tyrosine (P less than 0.05), and cysteine (P less than 0.05). Other histochemical methods specific for amino acid groups failed to show any significant difference between fluoride and non-fluoride-treated enamel matrix.