Abstract: BACKGROUND: In the preparation of injectable extracellular matrix materials, most of the materials require pepsin digestion followed by combination with other matrix components like hydrogels for pulp tissue regeneration, which also means the destruction of the microenvironment retained by natural extracellular matrix materials.
OBJECTIVE: To investigate the effect of injectable dental pulp extracellular matrix prepared by grinding treatment on the regeneration of dental pulp tissue.
METHODS: (1) The dental pulp tissue from pig teeth was prepared into acellular dental pulp matrix materials after acellular treatment. After freezing in liquid nitrogen and high-speed grinding, the injectable dental pulp extracellular matrix was prepared. Then, the differences in cell adhesion efficiency and microstructure between the injectable dental pulp extracellular matrix and natural dental pulp extracellular matrix were compared. Immunohistochemical analysis was used to analyze extracellular matrix protein components in injectable dental pulp extracellular matrix. (2) Injectable dental pulp extracellular matrix material inoculated with dental pulp stem cells was injected into the dental pulp cavity constructed from the dentin matrix material. The samples were obtained after 1, 3, and 5 weeks of subcutaneous implantation in nude mice to observe the in vivo conversion rate of injectable dental pulp extracellular matrix materials and the regeneration ability of ectopic dental pulp tissue under the skin of nude mice.
RESULTS AND CONCLUSION: (1) Compared with the dental pulp extracellular matrix, the injectable dental pulp extracellular matrix significantly improved the cell adhesion rate and retained the porous collagen structure similar to that of natural dental pulp extracellular matrix. (2) Compared with the natural dental pulp extracellular matrix, immunohistochemical staining showed that there was no significant difference in the expression of fibronectin, collagen type I, and integrin β1 in the injectable dental pulp extracellular matrix, while the expression of fibronectin was significantly decreased. (3) In vivo experiments show that the injectable dental pulp extracellular matrix has excellent angiogenesis ability and promotes the formation of pulp-like tissues. The results exhibit that the milled injectable dental pulp extracellular matrix can still be used as an effective scaffold for the regeneration of dental pulp.

Key words: grind, human dental pulp stem cell, extracellular matrix, injectable, pulp tissue regeneration, stent material