Defects in oral hard tissue caused by various factors have a negative impact on the functional and aesthetic results of prosthetic treatment. In recent years, the usage of bone tissue engineering for bone reconstruction has drawn widespread attention. Bone tissue engineering exhibits significant advantages, including the abundance of building materials and few side effects. In this paper, the composition and structure of dentin and its application in bone tissue engineering are reviewed, providing a new way to further optimize its performance. The results of a literature review show that the structure of dentin is very similar to that of autogenous bone. The inorganic component is mainly hydroxyapatite (HA), while the organic component is mainly collagen I, noncollagenous proteins (NCPs) and growth factors. Because of its unique composition, dentin can act as a scaffold and/or growth factor source through different processing methods. The deproteinization process removes most of the organic substances and creates a HA-based scaffold material with high porosity, which allows for vascularization and cellular infiltration. Demineralization increases dentin porosity by reducing the crystallinity of the mineralized components, so that part of HA, collagen fibers and growth factors are preserved. Demineralized dentin possesses various regulation functions ranging from differentiation, adhesion and proliferation of primitive cells and bone forming cell lineage. Extracted NCPs, as bioactive molecules, have been proved to play important roles that control cell differentiation, crystal nucleation and mineralization in bone formation. NCPs could be combined with variety of scaffold materials and modify their properties.

Bone is capable of regeneration after injury, but the process of properly restoring form and function is highly complex and prone to failure. The restoration process requires highly ordered and sequential interplay at the injury site between the host immune system and bone tissue. The dynamic process that occurs after bone injury includes the formation of a hematoma, the development of an inflammatory response and callus, and the remodeling of newly formed bone tissue. The inflammatory response at the injury site is essential for the onset of bone regeneration. This inflammatory response is tightly linked with the host immune system, in which various immune cells and molecules are involved. Recently, the relationship between T cells and bone regeneration has become a popular topic; however, currently, there are no summaries of the relationship between T cells and bone regeneration. Thus, this review aimed to elucidate the modulatory functions of T cells in bone regeneration.