Letter | Published:

Surface Phenomena in Dental Caries

Naturevolume 214pages203204 (1967) | Download Citation



ONE of the important characteristics of early carious decay of human dental enamel is that it occurs below the surface and remains covered by a surface layer which is relatively unaffected by the attack. Human tooth enamel is highly calcified, containing 97 per cent mineral hydroxyapatite (which is negatively birefringent) and 3 per cent organic material and water. During carious decay there is an increase in the total pore volume in the tissue and this “mixed body” system1 produces positive form birefringence. When an early lesion of enamel caries is examined between crossed polars after imbibition with a medium having a refractive index remote from that of the enamel—water, for example—the surface zone is seen to retain its negative birefringence while the porous subsurface enamel becomes positively birefringent.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Wiener, O., Abh. Sachs Ges. Wiss., 32, 6 (1912).

  2. 2

    Thewlis, J., M.R.C. Spec. Rep. Series, No. 238 (1940).

  3. 3

    Brudevold, F., J. Dent. Res., 27, 320 (1948).

  4. 4

    Hals, B., Morch, T., and Sand, H. F., Acta Odont. Scand., 13, 85 (1955).

  5. 5

    Isaac, S., Brudevold, F., Smith, F. A., and Gardner, D. E., J. Dent. Res., 37, 254 (1958).

  6. 6

    Darling, A. I., Brit. Dent. J., 105, 119 (1958).

  7. 7

    Gray, J. A., and Francis, M. D., in Destruction of Hard Tissues (edit. by Sognnaes, R. F.) (Amer. Assoc. Adv. SeL, Washington, 1963).

  8. 8

    Poole, D. F. G., Mortimer, K. V., Darling, A. I., and Ollis, W. D., Nature, 189, 998 (1961).

  9. 9

    Silverstone, L. M., Brit. Dent. J., 120, 461 (1966).

Download references

Author information


  1. Medical Research Council Dental Research Unit, The Dental School, Bristol



  1. Search for LEON M. SILVERSTONE in:

About this article

Publication history

Issue Date



Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.