The effect of chronic treatment with fluoride on salivary activity, tooth, and bone in spontaneously hypertensive rats (SHR)

The present study evaluated the effect of chronic treatment with sodium fluoride on salivary activity, tooth, and bone in spontaneously hypertensive rats (SHR). The treatment was made with a 20-ppm NaF solution added to the drinking water for 30 days. Systolic blood pressure values were obtained by plethysmography; fluoride concentration was determined by an ion-selective electrode; calcium concentration and amylase activity were determined by commercial kits; and enamel microhardness was verified by longitudinal section. Systolic blood pressure values and animals' weight were not changed by treatment. However, the salivary flow rate-which was lowered in SHR at baseline when compared to Wistar rats-was found to be increased with the treatment with NaF. The fluoride concentration was increased in the plasma of the treated groups, even though it remained lower for the treated SHR in relation to the treated Wistar rats. Calcium concentration was decreased in the saliva and plasma of SHR treated with NaF. A reduction in the plasmatic total protein concentration was observed in SHR treated with NaF. The fluoride concentration on bone surface was found to be increased in Wistar or SHR treated with NaF. In treated SHR's femurs, it was observed a significant reduction in fluoride concentrations. Enamel microhardness of the incisor teeth was not changed by the treatment with NaF in both groups. The distribution of fluoride to the salivary glands in SHR is poor, and treatment with NaF causes a decrease in the concentration of important biochemical parameters to the salivary physiology in SHR.