Protein loss of bovine dental enamel during in-vitro subsurface demineralization.

A chemical system based on the dialysis principle was used to study protein loss of dental enamel during demineralization with an acetic-acid buffer solution containing calcium and phosphate, in which the fluoride-ion activity was kept constant. This resulted in a subsurface lesion, with a depth of about 130 microns. After demineralization, protein material was isolated from the demineralization solution. u.v. Spectra of the protein showed strong absorbance between 240 and 300 nm. Amino-acid composition showed high glycine, glutamic acid, proline, serine and aspartic acid contents. After 10 days demineralization, the total protein loss was 3 micrograms cm-2; the mineral loss was 16 mg cm-2. Compared with the total enamel-protein content (0.06-0.09 wt per cent) protein loss (0.018 per cent of total lost material) was not proportional to the mineral loss, when a subsurface lesion was formed.