Development of 3D in vitro mineralized bone model to reproduce dental implants osseointegration process

Dental implant osseointegration is the process by which these medical devices integrate within bone. Because of the significant failure rate of dental implant osseointegration in the long term, specific models designed to better understand this process are needed. Current limitations related to in vivo models justify the development of in vitro substitutes. The aim of this study was to develop a 3D in vitro mineralized bone model to reproduce dental implant osseointegration. To achieve this, we started by fabricating a 3D mineralized hydrogel-based in vitro model and characterizing it for mineralization, osteogenic differentiation, cell-deposited extracellular matrix, and inflammatory markers. Immortalized human mesenchymal stem cells (MSCs) were embedded in a methacrylated collagen-hyaluronic acid gel matrix and cultured in osteogenic differentiation medium with elevated calcium concentration. The model exhibited early mineralization, deposition of minerals in a spherical form and expression of osteogenic differentiation markers. Proteomic profiling revealed a collagen-rich extracellular matrix with enrichment of type I collagen. Additionally, there was enrichment of signaling pathways involved in osteogenic differentiation. This hydrogel-based model was further integrated into a 3D-printed PLA scaffold with a dental implant as an in vitro platform to study dental implant osseointegration. We demonstrated cellular migration, matrix deposition, and initiation of mineralization on dental implants with two different surface roughnesses. Additionally, a sensitive pull-out test was specifically developed for the model to detect the attachments initiated by the cells. Therefore, the developed model has strong potential to revolutionize dental implant screening by bridging the gap between 2D in vitro models and in vivo models.