The Effects of Desalivation on the Fluoride Content of the Incisor and Femur of the Rat

¹ Alpha Omega Research and Postgraduate Center, Departments of Periodontics and Endodontics, Oncology and Radioisotopes, The Hebrew University-Hadassah Medical School and School of Dentistry, Jerusalem, and Hadassah Municipal Hospital, Tel-Aviv, Israel

The effect of interrupting the flow of saliva into the mouth by removal of salivary glands and parotid-duct ligation on fluoride uptake by the incisor tooth and femur was investigated in rats. The experiment was carried out with a low fluoride intake from drinking water or with daily intraperitoneal injections of NaF over a period of 5 weeks. Unoperated (control) rats were pair-fed with the desalinated parotid-ligated (DPL) rats. F¹⁸ was administered to additional groups of salivary-ligated and control rats. The mean weight gain of the experimental rats was less than the mean weight gain of the control rats. The mean fluoride and F¹⁸ contents of the incisor and femur were generally not significantly higher in the experimental group. The mean fluoride content of the femur in the desalivated parotid-ligated group was significantly higher than that found in the control rats. A significantly higher F¹⁸ content of the salivary glands and higher blood fluoride content in the experimental rats, accompanied by decreased F¹⁸ excretion in urine and feces, seemed to be the reason for the increased fluoride uptake by the hard tissues, especially in the femur. It appears that saliva plays a minor role in the incorporation of fluoride in the teeth of the rat; however, it has to be emphasized that these teeth have no counterpart in the human dentition.