Skip to main content
Log in

Kinetics of dissolution of calcium hydroxyapatite powder. III: pH and sample conditioning effects

  • Laboratory Investigations
  • Published:
Calcified Tissue International Aims and scope Submit manuscript

Summary

The kinetics of dissolution of synthetic hydroxyapatite powder (HAP) were studied at 37°C and constant pH in the pH range 3.7–6.9 by continuously recording proton uptake and calcium release. The effect of sample conditioning was carefully investigated. The powder previously equilibrated in saturated solutions shows an initial dissolution rate higher than the one obtained when dry powder directly added to the dissolution solution is used. This effect is interpreted by considering surface state differences. As previously shown, dry powder contains important amounts of calcium and phosphate ions adsorbed onto apatite surface, ions which are desorbed during equilibration. It is assumed that the initial presence of these ions slows the dissolution rate during the first stage of the process by the formation of a permselective layer. Except for these adsorption phenomena which are less important for human enamel powder (HEP) having a lower specific surface area, it is shown that in spite of structural, morphological, and purity differences, the general dissolution behavior of HAP is quite similar to that of HEP, previously studied, and for which a quantitative model has been proposed. The dissolution rates are stirring dependent in a large range of stirring speeds and are proportional to [H+]0.64. Moreover, it is shown that in the whole range of studied pH, a calcium accumulation process occurs at the interface during the first minutes of the acidic attack. It is concluded that in our experimental conditions, the dissolution process is limited by the diffusion of calcium and/or phosphate ions in the interface. The calcium-rich interface constitutes a layer of low permeability in which strong interactions considerably reduce the diffusion of calcium and/or phosphate ions released during the attack and thus considerably slows the dissolution process.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Gray JA (1962) Kinetics of the dissolution of human dental enamel in acid. J Dent Res 41:353–359

    Google Scholar 

  2. Chen WC, Nancollas H (1986) The kinetics of dissolution of tooth enamel. A constant composition study. J Dent Res 65:663–668

    PubMed  CAS  Google Scholar 

  3. Higuchi W, Mir NA, Patel PR, Becker JW, Hefferen JJ (1969) Quantitation of enamel dimineralization mechanisms. III. A critical examination of the hydroxyapatite model. J Dent Res 48:396–409

    PubMed  CAS  Google Scholar 

  4. Linge HG, Nancollas GH (1973) A rotating disc study of the dissolution of dental enamel. Calcif Tissue Res 12:193–208

    Article  PubMed  CAS  Google Scholar 

  5. Fawzi MD, Fox JL, Dedhiya MG, Higuchi WI, Hefferen JJ (1978) A possible second site for hydroxyapatite dissolution in acidic media. J Colloid Interface Sci 67:304–311

    Article  CAS  Google Scholar 

  6. Fox JL, Higuchi WI, Fawzi MB, Wu MS (1978) A new two-site model for hydroxyapatite dissolution in acidic media. J Colloid Interface Sci 67:312–330

    Article  CAS  Google Scholar 

  7. Christoffersen J, Christoffersen MR, Kjaergaard N (1978) The kinetics of dissolution of calcium hydroxyapatite in water at constant pH. J Cryst Growth 43:501–511

    Article  CAS  Google Scholar 

  8. Christoffersen J, Christoffersen MR (1979) Kinetics of dissolution of calcium hydroxyapatite. II. Dissolution in nonstoichiometric solution at constant pH. J Cryst Growth 47:671–679

    Article  CAS  Google Scholar 

  9. Christoffersen J (1980) Kinetics of dissolution of calcium hydroxyapatite. III. Nucleation-controlled dissolution of a polydisperse sample of crystals. J Cryst Growth 49:29–44

    Article  CAS  Google Scholar 

  10. Christoffersen J, Christoffersen MR (1982) Kinetics of dissolution of calcium hydroxyapatite. V. The acidity constant for the hydrogen surface complex. J Cryst Growth 57:21–26

    Article  CAS  Google Scholar 

  11. Patel MV, Fox JL, Higuchi WI (1987) Effect of acid type on kinetics and mechanism of dental enamel demineralization. J Dent Res 66:1418–1424, 1425–1430

    PubMed  CAS  Google Scholar 

  12. Margolis HC, Moreno EC (1985) Kinetic and thermodynamic aspects of enamel demineralization. Caries Res 19:22–35

    PubMed  CAS  Google Scholar 

  13. Christoffersen J, Arends J (1982) Progress of artificial carious lesions in enamel. Caries Res 16:433–439

    Article  PubMed  CAS  Google Scholar 

  14. Vogel GL, Carey CM, Chow LC, Gregory TM, Brown WE (1987) Ultramicro analysis of the fluid in human enamel during in vitro caries attack by hydrochloric acid. Caries Res 21:310–325

    PubMed  CAS  Google Scholar 

  15. Gramain Ph., Thomann JM, Gumpper M, Voegel JC (1988) Dissolution kinetics of human enamel powder. I. Stirring effects and surface calcium accumulation. J Colloid Interface Sci 128:370–381

    Article  Google Scholar 

  16. Thomann JM, Voegel JC, Gumpper M, Gramain Ph. (in press) Dissolution kinetics of human enamel powder. II. A model based on the formation of a self-inhibiting surface layer. J Colloid Interface Sci

  17. Frank RM (1973) Microscopie électronique de la carie des sillons chez l'homme. Arch Oral Biol 18:9–25

    Article  PubMed  CAS  Google Scholar 

  18. Gumpper M (1987) Etude cinétique de la dissolution des cristaux d'hydroxyapatite. Thesis ULP Strasbourg

  19. Voegel JC, Gramain Ph., Gumpper M, Thomann JM (1987) Ionic adsorption properties and equilibration kinetics of biological enamel powder near thermodynamic equilibrium. J Cryst Growth 83:89–95

    Article  CAS  Google Scholar 

  20. Gramain Ph., Voegel JC, Gumpper M, Thomann JM (1987) Surface properties and equilibrium kinetics of hydroxyapatite powder near the solubility equilibrium. J Colloid Interface Sci 118:148–157

    Article  CAS  Google Scholar 

  21. Tiselius A, Hjerten S, Levin O (1956) Protein chromatography on calcium phosphate columns. Arch Biochem Biophys 65:132–139

    Article  PubMed  Google Scholar 

  22. Wu MS, Higuchi WI, Fox JL, Friedman M (1976) Kinetics and mechanism of hydroxyapatite crystal dissolution in weak acid buffers using the rotating disk method. J Dent Res 55:496–505

    PubMed  CAS  Google Scholar 

  23. Bates RG, Acree SF (1943) H values of certain phosphatechloride mixtures, and the second dissociation constant of phosphoric acid from 1 to 60°C. J Res Natl Bur Stnds 30:129–155

    CAS  Google Scholar 

  24. Nims LF (1934) The first dissociation constant of phosphoric acid from 0 to 50°. J Am Chem Soc 56:1110–1112

    Article  CAS  Google Scholar 

  25. Tung MS (1976) Characterization and modification of permselective properties of apatite membranes. J Dent Res (Special Issue) 55:77–85

    Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Thomann, J.M., Voegel, J.C. & Gramain, P. Kinetics of dissolution of calcium hydroxyapatite powder. III: pH and sample conditioning effects. Calcif Tissue Int 46, 121–129 (1990). https://doi.org/10.1007/BF02556096

Download citation

  • Received:

  • Revised:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF02556096

Key words

Navigation