Effects of Fluoride on Protein Secretion and Removal During Enamel Development in the Rat

Abstract

Enamel maturation consists of a loss of the early secreted matrix proteins and an increase in mineralization. This study investigated the changes in enamel proteins of the rat incisor, caused by the ingestion of fluoride at various stages of enamel formation. Rats were given 0, 10, 25, 50, or 100 ppm fluoride in drinking water for five weeks. Changes in the protein composition of the secretory, early-maturation, and late-maturation enamel were investigated by means of gel filtration chromatography and polyacrylamide gel electrophoresis. No differences were found between fluorosed and control enamel proteins in secretory enamel. In fluorosed early-maturation enamel, amelogenins were retained in larger quantities than in control enamel in animals ingesting 25 ppm fluoride or greater. At the late-maturation stage of enamel formation, only enamel from animals ingesting 100 ppm fluoride in drinking water contained more protein, when compared with control enamel. This study suggests that fluoride ingestion levels resulting in enamel fluorosis inhibit the mechanisms involved in the removal of proteins during enamel maturation.

Get full access to this article

View all access options for this article.

References

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

Bhusshy, B.R. (1959): Chemical and Physical Studies of Enamel from Human Teeth: Density and Nitrogen Content of Mottled Enamel, J Dent Res 38:369-373.

Bronckers, A.L.J. J.; Jansen, L.L. ; and Woltgens, J.H.M. (1984): Long-term (8 Days) Effects of Exposure to Low Concentrations of Fluoride on Enamel Formation in Hamster Tooth-germs in Organ Culture in vitro, Arch Oral Biol 29:811-819.

Carter, J. ; Smillie, A.C. ; and Sheperd, M.G. (1984): Proteolytic Enzyme in Developing Porcine Enamel . In: Tooth Enamel IV, R.W. Fearnheard and S. Suga , Eds., Amsterdam: Elsevier Science Publishers , pp. 229-233.

Crenshaw, M.A. and Bawden, J.W. (1984): Proteolytic Activity in Embryonic Bovine Secretory Enamel. In: Tooth Enamel IV, R.W Fearnhead and S. Suga , Eds., Amsterdam: Elsevier Science Publishers , pp. 109-113.

Den Besten, P.K. and Crenshaw, M.A. (1984): The Effects of Chronic High Fluoride Levels on Forming Enamel in the Rat, Arch Oral Biol 29:675-679.

Den Besten, P.K. and Crenshaw, M.A. (1985): Changes in the Fluoride-induced Modulation of Maturation Stage Ameloblasts of Rats, J Dent Res 64:1365-1370.

Eastoe, J. (1984): Composition of Mature Enamel Proteins from Fluorosed Teeth. In: Tooth Enamel IV, R.W. Fearnhead and S. Suga , Eds., Amsterdam: Elsevier Science Publishers , pp. 326-330.

Fejerskov, 0.; Johnson, N.W. ; and Silverstone, L.M. (1974): The Ultrastructure of Fluorosed Human Dental Enamel, Scand J Dent Res 82:357-372.

10.

Fejerskov, 0.; Silverstone, L.M. ; Melson, B. ; and Moller, I.J. (1975): Histological Features of Fluorosed Human Dental Enamel, Caries Res 9:190-210.

11.

Fincham, A.G. ; Belcourt, A.B. ; Lyaruu, D.M. ; and Termine, J.D. (1982): Comparative Protein Biochemistry of Developing Dental Enamel Matrix from Five Mammalian Species, Calcif Tissue Int 34:182-189.

12.

Laemmli, U.K. (1970): Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4, Nature 227:680-685.

13.

Lyaruu, D.M. ; Belcourt, A. ; Fincham, A.G. ; and Termine, J.D. (1982): Neonatal Hamster Molar Tooth Development: Extraction and Characterization of Amelogenins, Enamelins, and Soluble Dentin Proteins, Calcif Tissue Int 34:86-96.

14.

O'Farrell, P.H. (1975): High Resolution Two-dimensional Electrophoresis of Proteins, J Biol Chem 250:4007-4021.

15.

Olsson, I. and Laas, T. (1981): Isoelectric Focusing in Agarose Under Denaturating Conditions, J Chromatogr 215:373-378.

16.

Patterson, C.M. ; Basford, K.E. ; and Kruger, B.J. (1976): The Effect of Fluoride on the Immature Enamel Matrix Protein of the Rat, Arch Oral Biol 21:131-132.

17.

Robinson, C. and Kirkham, J. (1984): Enamel Matrix Components, Alterations During Development and Possible Interactions with the Mineral Phase. In: Tooth Enamel IV, R. Feamhead and S. Suga , Eds., Amsterdam: Elsevier Science Publishers, pp. 216-265.

18.

Shimizu, T. ; Tanabe, T. ; and Fukae, M. (1979): Proteolytic Enzyme in Porcine Immature Enamel , J Dent Res 58(B):782-789.

19.

Shinoda, H. (1975): Effects of Long-term Administration of Fluoride on Physico-chemical Properties of the Rat Incisor Enamel, Calcif Tissue Res 18:91-100.

20.

Shinoda, H. (1983): Effects of Long-term Administration of Fluoride on the Enamel Formation in Rats. In: Mechanisms of Tooth Enamel Formation, S. Suga , Ed., Tokyo: Quintessence Publishing Co., Inc., pp. 273-284.

21.

Silness, J. and Gustavsen, F. (1970): Some Observations on the Fine Structure of Fluorosed Dental Enamel, Acta Odontol Scand 28:701-720.

22.

Suga, S. (1970): Histochemical Observation of Proteolytic Enzyme Activity in the Developing Dental Hard Tissue of the Rat, Arch Oral Biol 15:555-558.

23.

Termine, J.D. ; Belcourt, A.B. ; Christner, P.J. ; Conn, K.M. ; and Nylen, M.U. (1980): Properties of Dissociatively Extracted Fetal Tooth Matrix Proteins. 1. Principle Molecular Species in Developing Bovine Enamel , J Biol Chem 255:9760-9768.

24.

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