[Changes of dentin matrices during carious process].

Abstract

Studies were made on the effects of demineralization with lactic acid or acetic acid on the organic matrices of human sound dentin, and on the changes of the matrices during carious process. When sound dentin was demineralized with 0.5 M lactic acid or 0.5M acetic acid, non-collagenous proteins and a small amount of collagen were extracted. A larger amount of protein containing phosphophoryn was extracted with lactic acid than with acetic acid, whereas when acetic acid was used for demineralization and then followed by an EDTA solution most of the phosphophoryn was removed. Since EDTA will remove phosphophoryn from sound dentin, low level of phosphophoryn in the extract obtained by treating carious dentin with EDTA, suggests that during the carious process a loss of phosphophoryn occurs. The analyses of carious dentin fractionated by the difference of its density showed that the lower density fraction of carious dentin contained a larger proportion of non-collagenous components to collagen. By the dansylation of sound and carious dentin nine dansyl amino acids, such as aspartic acid, glutamic acid, serine, glycine, alanine, proline, valine, leucine and tyrosine, were detected in the sound dentin, and in addition to these nine amino acids isoleucine was found in carious dentin. The amount of the respective dansyl amino acids in the fractionated carious dentin increased with the decrease of density.