Traditional endodontic treatments replace damaged tissues with long-lasting materials but worsening long-term outcomes and co-morbidities due to lack of regeneration. In this work, a regenerative strategy using biomaterials and avoiding cell transplantation is investigated. These biomaterials include gelatine cryogels and odontogenic moieties. These included bioceramics (biphasic calcium phosphate, bredigite and ß-dicalcium silicate), typically used in endodontic treatments and known for their odontogenic potential, and mesoporous silica rods (MSR) with large size and high aspect ratio to load proteins without impeding cryogel formation. Thiol-ene resins were also designed as a biocompatible alternative to the cytotoxic composites used by dentists, and to seal the pulp chamber after cryogel implantation.
ALP activity of Dental Pulp Stem Cells (DPSC) cultured on bioceramic extracts was measured as a marker of odontogenic differentiation. In this configuration, cells may only have differentiated at the highest concentrations of bioceramics, which could not be incorporated in the cryogels. MSR were found to release proteins (lysozyme) for up to 44 days and did form cryogels with GelMA, but these gels were not able to maintain cell numbers after 7 days of culture. To avoid using toxic initiators, biorthogonal hydrogel crosslinking chemistry (using tetrazine and norbornene) was used for the cryogelation. The resulting click cryogels sustained cell numbers for 14 days, unlike GelMA cryogels, and swelled 80% more in mass than GelMA cryogels without compromising open porosity. Compressive Young’s modulus and pore size were also higher for click gels. Finally, after being loaded with SDF-1α-MSR, they could release SDF-1α for up to 15 days, increasing ALP activity of DPSC. Composites were also characterised via FTIR and rheology to find stable formulations that were curable by visible light. The resulting resins, synthesised using TPO as photoinitiator and mequinol as inhibitor, were cytocompatible depending on length of exposure to UV light.