Difference in noncollagenous matrix composition between crown and root dentin of bovine incisor.

A comparative study of the organic matrix in crown dentin and root dentin of the bovine incisor has been performed utilizing biochemical analyses and histochemical stainings. Root dentin contained only half the amount of dentin phosphophoryn present in crown dentin. Composition of noncollagenous matrix other than phosphophoryn was also suggested to be different between crown and root dentin. These data indicate that odontoblasts forming root dentin may secrete a noncollagenous matrix having a composition different from that of crown dentin, and that crown and root dentin may be separate in nature. The distinct compositions of noncollagenous matrix may reflect the difference in the mineralization process between crown and root dentin.