Summary
The penetration of45Ca ions into whole bovine enamel from an aqueous solution was studied as a function of the Ca content in the solution. A sectioning technique was employed to measure the penetration of45Ca into the enamel.
Probably only Ca ions occupying surface positions in the hydroxyapatite crystallites participate in the exchange process at the solution-enamel interface. The fraction of Ca ions participating in the exchange was 2% of the total number of Ca ions. Two different diffusion processes occur; firstly, a process governed by a diffusion coefficient, D1 ranging from about 5×10−14 to 2×10−12 cm2/s and strongly dependent on the calcium concentration in the solutions; and secondly a process with a concentration-independent diffusion coefficient, D2, with a value of 2.8×10−12 cm2/s. It is assumed that the 2 diffusion types correspond to intra-and interprismatic transport, respectively. A model based on the pore structure of dental enamel and on surface charges on hydroxyapatite crystallites is discussed.
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References
Bell, L.C., Posner, A.M., Quirk, J.P.: The point of zero charge of hydroxyapatite and fluorapatite in aqueous solutions. J. Coll. Interf. Sc.42, 250–261 (1973)
Braden, M., Duckworth, R., Joystone-Bechal, S.: The uptake of24Na by human dental enamel. Arch. oral Biol.16, 367–374 (1971)
Brudevold, F., Söremark, R.: Chemistry of the mineral phase of enamel. In: Structural and chemical organization of teeth, II (A.E.W. Miles ed.), New York: Academic Press 1967
Crank, J.: The mathematics of diffusion. Oxford: Claredon Press 1970
Davidson, C.L.: Ontharding van tandglazuur. Thesis, University of Groningen (1973)
Den Hartog, H.W., Welch, D.O., Royce, B.S.H.: The diffusion of calcium, phosphorus and OD− ions in fluorapatite. Phys. Stat. Sol. (b)53, 201–212 (1972)
Fosdick, L.S., Hutchinson, A.C.W.: The mechanism of caries of dental enamel. Ann. N.Y. Ac. Sc.131, 758–770 (1965)
Groer, P.G., Marshall, J.H.: Mechanism of calcium exchange at bone surfaces. Calcif. Tiss. Res.12, 175–192 (1973)
Johnson, N.W.: Factors affecting the differential solution of human enamel in acid and EDTA. Arch. oral Biol.16, 385–396 (1971)
Jost, W.: Diffusion in solids. New York: Academic Press 1960
Joystone-Bechal, S., Duckworth, R., Braden, M.: Diffusion of radioactive ions into human dental enamel. Arch. oral Biol.16, 375–384 (1971)
Kibby, C.L., Hall, W.K.: Surface properties of calcium phosphates. In: The chemistry of biosurfaces (M.L. Hair, ed.), New York: Dekker 1972
Kukura, M., Bell, L.C., Posner, A.M., Quirk, J.P.: Radioisotope determination of the surface concentration of calcium and phosphorus on hydroxyapatite in aqueous solution. J. Phys. Chem.76, 900–904 (1972)
Leach, S.A.: Electrophoresis of synthetic hydroxyapatite. Arch. oral Biol.3, 48–56 (1960)
Meckel, A.H.: Structure of mature human enamel. Arch. oral Biol.10, 775–783 (1965)
Moreno, E.C., Zahradnik, R.T.: The pore structure of human dental enamel. Arch. oral Biol.18, 1063–1068 (1973)
N.B.S., Tables of error functions. N.B.S. Applied Math. Series41 (1954) Washington: Natl. Bureau of Standards
Neiders, N.E., Weiss, L., Cudney, T.L.: An electrokinetic characterization of human tooth surfaces. Arch. oral Biol.15, 135–151 (1970)
Poole, D.F.G.: The use of the microscope in dental research. Brit. Dent. J.121, 71–79 (1976)
Sheppard, C.W.: Basic principles of the tracer method. New York: Wiley (1962)
Shewmon, P.G.: Diffusion in solids. New York: McGraw-Hill 1963
Somasundaran, P.: Zeta potential of apatite in aqueous solutions and its change during equilibration. J. Coll. Interf. Sc.27, 659–666 (1968)
Swancar, J.R., Scott, D.B., Njemirovskij, Z.: Studies of the structure of human enamel. J. Dent. Res.49, 1025–1033 (1970)
Trautz, O.R.: Crystalline organization of dental mineral. In: Structural and chemical organization of teeth II (A.E.W. Miles ed.), New York: Academic Press 1967
Waters, N.E.: The selectivity of human dental enamel to ionic transport. Arch. oral Biol.16, 305–322 (1971)
Zwolinski, B.J., Eyring, H., Reese, C.E.: Diffusion and membrane permeability I. J. Phys. Chem.52, 1426–1453 (1949)