C<scp>ells and</scp> E<scp>xtracellular</scp> M<scp>atrices of</scp> D<scp>entin and</scp> P<scp>ulp:</scp> A B<scp>iological</scp> B<scp>asis for</scp> R<scp>epair and</scp> T<scp>issue</scp> E<scp>ngineering</scp>

TLDR

Odontoblasts produce most dentin extracellular matrix, which contains both crystal nucleators and inhibitors; differences between dentin and pulp ECM explain why pulp remains non‑mineralized, yet after caries lesions odontoblasts and pulp cells can form reactionary or reparative dentin. Direct pulp‑capping induces a dentinal bridge by recruiting and proliferating undifferentiated cells that differentiate, synthesize matrix, and mineralize, and animal models evaluate bioactive molecules that promote this repair. ECM molecules can trigger dentinal bridge formation or extensive mineralization in coronal pulp, may close the pulp in the root canal, and thus hold promise as bioactive agents for pulp repair or tissue engineering.

Abstract

Odontoblasts produce most of the extracellular matrix (ECM) components found in dentin and implicated in dentin mineralization. Major differences in the pulp ECM explain why pulp is normally a non-mineralized tissue. In vitro or in vivo, some dentin ECM molecules act as crystal nucleators and contribute to crystal growth, whereas others are mineralization inhibitors. After treatment of caries lesions of moderate progression, odontoblasts and cells from the sub-odontoblastic Höhl's layer are implicated in the formation of reactionary dentin. Healing of deeper lesions in contact with the pulp results in the formation of reparative dentin by pulp cells. The response to direct pulp-capping with materials such as calcium hydroxide is the formation of a dentinal bridge, resulting from the recruitment and proliferation of undifferentiated cells, which may be either stem cells or dedifferentiated and transdifferentiated mature cells. Once differentiated, the cells synthesize a matrix that undergoes mineralization. Animal models have been used to test the capacity of potentially bioactive molecules to promote pulp repair following their implantation into the pulp. ECM molecules induce either the formation of dentinal bridges or large areas of mineralization in the coronal pulp. They may also stimulate the total closure of the pulp in the root canal. In conclusion, some molecules found in dentin extracellular matrix may have potential in dental therapy as bioactive agents for pulp repair or tissue engineering.