Development of Bioactive Pulp Capping Agent

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The expression of developmental stage specific genes during pulp cell differentiation into preodontoblasts was examined in bovine adult pulp cell culture. When proliferation was down-regulated after 14 days, expression of fibronectin, type I and type III collagen mRNA was increased. Expression of alkaline phosphatase was gradually increased, and mRNA for osteocalcin, a marker of preodontoblast, appeared just before onset of mineralization. Expression of TGF-beta1 mRNA disappeared on day 21 when expression of alkaline phosphatase mRNA was increased. BMP-4 mRNA was expressed on day 14 when the expression of the extracellular matrix proteins was increased. BMP-2 mRNA was expressed on day 28 when osteocalcin appeared. Recombinant TGF-beta1 inhibited alkaline phosphatase activity, while BMP-2 and BMP-4 stimulated it. BMP-4 increased expression of alpha1(I) collagen mRNA, and BMP-2 increased osteocalcin synthesis. These results demonstrate the regulatory role of these TGF-beta superfamily members on the gene expression of extracellular matrix proteins and the differentiation of pulp cells into preodontoblasts.BMP-2 and -4 and TGF-beta1 were applied in the cavity on amputated pulp to examine their effects on pulp regeneration and reparative dentin formation. When BMP-2 and -4 were combined with type I collagen as a carrier, osteodentin was formed in the cavity 2 months postoperatively. While TGF-beta1 had no effect. In BMP-2 and -4 with inactivated dentin matrix applied teeth, tubular dentin was formed in the lower part of the cavity, although osteodentin was formed in the upper part, suggesting that some matrix component might be essential for differentiation into odontoblasts in addition to BMPs.We are going to develop an ideal carrier for the use of BMPs as a biologically active pulp capping agent.