A Comparison of the Effects of Continuous and Periodic Fluoride Delivery on Fluoride Levels in Plasma,Enamel,and Bones of Nursing Rats

Abstract

The purpose of this study was to determine and compare the F levels in plasma, enamel, and bones of nursing rat pups that received the same daily dose of F by continuous or periodic delivery during enamel development. The hypothesis was that F delivered continuously would result in enamel F levels higher than those attained when F was delivered periodically. For continuous delivery, copolymer devices (Southern Research Institute) that provide slow release of F were implanted in the backs of four-day-old rat pups. For periodic delivery, rat pups received F by intraperitoneal injection or gastric intubation. The doses were 0.01, 0.02, or 0.04 mg Flday. The rats were killed at 13 days of age, 24 hours after the last periodic delivery. Plasma was collected, femur and calvaria bones were removed, and enamel was scraped from developing first molars. Fluoride assay was by the microdiffusion method of Taves, with a F electrode. For the 0.02 mg Flday dose, plasma levels in control, implanted, injected, and gastric-intubated rats were 0.004, 0.020, 0.011, and 0.009 ppm, respectively. Enamel F levels were 1.1, 61.9, 54.0, and 42.3 ppm, respectively. Femur F levels were 2.2, 81.2, 84.8, and 68.1 ppm, respectively. Calvaria F levels were 2.5, 79.3, 80.1, and 67.9 ppm, respectively. The results showed that there was no significant difference in the enamel F levels or in the bone F levels in rat pups that received continuous or periodic, by injection, delivery of F at the same daily dose. The significance is that similar levels of F can be attained in developing enamel if the same total dose of F is delivered continuously or periodically once a day. Previous studies have shown that there is less chance of producing disturbances in enamel mineralization with continuous F delivery when compared with periodic F delivery at a lower daily dose.

Get full access to this article

View all access options for this article.

References

Angmar-Mansson, B. ; Ericsson, Y. ; and Ekberg, O. (1976): Plasma Fluoride and Enamel Fluorosis, Calcif Tissue Res 22 :77-84.

Angmar-Månsson, B. and Whitford, G.M. (1982): Plasma Fluoride Levels and Enamel Fluorosis in the Rat, Caries Res 16 :334-339.

Angmar-Mansson, B. and Whitford, G.M. (1984): Enamel Fluorosis Related to Plasma F Levels in the Rat, Caries Res 18 :25-32.

Bawden, J.W. ; McLean, P. ; and Deaton, T.G. (1986): Fluoride Uptake and Retention at Various Stages of Rat Molar Enamel Development, J Dent Res 65:34-38.

Cowsar, D.R. ; Tarwater, O.R. ; and Tanquary, A.C. (1976): Controlled Release of Fluoride from Hydrogels for Dental Applications. In: Hydrogels for Medical and Related Applications, J.D. Andrade, Ed., ACS Symposium Series 31, Washington, DC: American Chemical Society, pp. 180-197.

Crenshaw, M.A. and Bawden, J.W. (1981): Fluoride-binding by Organic Matrix from Early and Late Developing Bovine Fetal Enamel Determined by Flow-rate Dialysis, Arch Oral Biol 26 :473-476.

Deaton, T.G. ; Bawden, J.W. ; and Crenshaw, M.A. (1986): F- Levels in Bone and Developing Enamel Following F-Injections, J Dent Res 65:306, Abst. No. 1229.

Drinkard, C.R. ; Deaton, T.G. ; and Bawden, J.W. (1985): Enamel Fluoride in Nursing Rats with Mothers Drinking Water with High Fluoride Concentrations, J Dent Res 64:877-880.

Ekstrand, J. ; Hardell, L.I. ; and Spak, C.J. (1984): Fluoride Balance Studies on Infants in a 1-ppm-Water-Fluoride Area, Caries Res 18:87-92.

10.

Forsman, B. (1977): Early Supply of Fluoride and Enamel Fluorosis , Scand J Dent Res 85:22-30.

11.

Gedalia, I. ; Mayer, I. ; Giron, J. ; and Deutsch, D. (1982): Fluoride Deposition in the Bones of Rats Determined by Fluoride and X-ray Diffraction Analysis, Arch Oral Biol 27:823-825.

12.

Gedalia, I. ; Goldhaber, P. ; and Golub, L. (1970): In vitro Uptake of Fluoride in Sodium-fluoride-treated Vital Mice Calvaria, J Dent Res 49:1553.

13.

Hodge, H.C. (1952): The Significance of the Skeletal Deposition of Fluoride. In: Metabolic Interrelations with Special Reference to Calcium, Trans, Fourth Conference, E.C. Reifenstein , Ed., Caldwell, NJ: Progress Associates, Inc., pp. 250-260.

14.

Mirth, D.B. (1980): A Review of Applications for the Control of Dental Caries, Pharmacol Therap Dent 5:59-67.

15.

Neely, J.H., Jr. ; Deaton, T.G. ; and Bawden, J.W. (1986): Enamel F Uptake From F Injections Given Throughout or Early or Late in Enamel Formation, J Dent Res 65:306, Abst. No. 1233.

16.

Neuman, W.F. and Neuman, M.W. (1958): The Chemical Dynamics of Bone Mineral, Chicago: The University of Chicago Press , pp. 81-100.

17.

Savchuck, W.B. and Armstrong, W.D. (1951): Metabolic Turnover of Fluoride by the Skeleton of the Rat, J Biol Chem 193:575-585.

18.

Speirs, R.L. (1986): The Relationship Between Fluoride Concentrations in Serum and in Mineralized Tissues in the Rat, Arch Oral Biol 31:373-381.

19.

Taves, D.R. (1968): Determination of Submicromolar Concentrations of Fluoride in Biological Samples, Talanta 15:1015-1023.

20.

Waterhouse, C. ; Taves, D. ; and Munzer, A. (1980): Serum Inorganic Fluoride: Changes Related to Previous Fluoride Intake, Renal Function and Bone Resorption, Clin Sci 58:145-152.

21.

Whitford, G.M. and Reynolds, K.E. (1979): Plasma and Developing Enamel Fluoride Concentration During Chronic Acid-Base Disturbances, J Dent Res 58:2058-2065.

22.

Zipkin, I. (1972): Mobilization of Fluoride from the Bones and Teeth of Growing and Mature Rats, Arch Oral Biol 17:479-494.