Development of Inks for Tissue Engineering of the Dentoalveolar Region through Bioprinting

Oral health issues in the dentoalveolar region are considered to have a significant impact on the individual’s quality of life. Consequently, a range of treatment options have been developed to address complications in this region. However, certain shortcomings of these treatments have resulted in the exploration of regenerative strategies and tissue engineering approaches aimed at reconstructing tissue structures in this region. Within the tissue engineering approaches, the emerging technique of bioprinting, capable of potentially addressing limitations of traditional tissue engineering strategies, has recently gained widespread attention. This is because bioprinting has an enhanced potential to fabricate tissue analogues in a robust manner and with a high degree of geometrical resemblance to natural tissue by incorporating multiple biomaterials, cell types and biological factors within the manufacturing process.

Still, the application of bioprinting in dentoalveolar tissue engineering is a relatively unexplored field of study. The limited, recent research performed on this topic focuses mainly on the development of biomaterials and solutions to address the inherent heterogeneity within the dentoalveolar tissues. The aim of the research presented here is to combine both and to develop biomaterial-based strategies capable of being utilized in bioprinting and addressing heterogeneities such as the localized differentiation in dental pulp, the gradient structure of periodontal ligament interfacing bone and cementum, as well as the layered structure of the alveolar bone.  In particular, this thesis focuses on the development of novel biomaterials which could be used as biomaterial inks, bioinks and drug delivery systems to bioprint constructs, and which are able to recapitulate the dentoalveolar structures.

To achieve this, first, an overview of the materials used for this application was made, highlighting the current demands in this field of research. Next, hydrogels based on chitosan and poly n-isopropylacrylamide were developed, and their ability to be used in the fabrication process, and to support viability of dental pulp stem cells was demonstrated. Being based on tunable chemistries, these biomaterials create a basis for the development of bioinks with variable physical and mechanical properties for different tissues in the dentoalveolar region.

Addressing the heterogeneity in the dentoalveolar region could, aside from the development of suitable bioinks, further benefit from delivery of biological cues such as growth factors. As a result, a part of this thesis was dedicated to the development of microgels capable of delivering molecules within tissue engineering strategies. It was demonstrated that these microgels are capable of loading and sustained release of small molecules, and that they could be integrated in bioinks without having any negative impact on their printability.

Overall, the biomaterials developed in this thesis provide a solid basis for the fabrication of constructs through bioprinting which would be able to address the physical, mechanical and biological heterogeneity of the inherently complex dentoalveolar region.