Fluoride Deposition in Different Segments of the Tibia of the Young Growing Rat

¹ From the National Institute of Dental Research and the National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland

By inserting a stainless steel pin into the tibiae of young rats, it was possible to determine the gain in length at each end of the diaphysis and to identify the bone that was deposited at the ends during the experimental period (20th–51st day of life). At the termination of the experiment, the tibiae were divided into four segments, three of which contained portions of the diaphysis. The oven-dry, fat-free weight, ash and fluoride content of these segments were determined. Intraperitoneal injections of 3.15 mg of fluoride (NaF) over a 30-day period, starting at 20 days of age, had no noticeable effect on the longitudinal growth rate and mass of the various tibial segments. The ash content of the various diaphyseal segments was similarly unaffected. The percentage of fluoride (ash basis) of the proximal diaphyseal segment (all new bone) was similar to that of the middle diaphyseal segment, but 35% lower than that of the proximal epiphysis. There appears to be no consistent relationship between the degree of calcification (% ash) and the deposition of fluoride in various tibial segments at the end of 30 days in the young growing rat.