A comparative study on silicon nitride, titanium and polyether ether ketone on mouse pre-osteoblast cells

The current study provides more insights about the surface bioactivity of the silicon nitride (Si₃N₄) as a potential candidate for bone regeneration in craniofacial and orthopaedic applications compared with conventional implantation materials. Current skeletal reconstructive materials such as titanium and polyether ether ketone (PEEK) are limited by poor long-term stability, biocompatibility and prolonged healing. Si₃N₄ is an FDA-approved material for an intervertebral spacer in spinal fusion applications. It is biocompatible and has antimicrobial properties. Here, we hypothesize that Si₃N₄ was found to be an osteoconductive material and conducts the growth, differentiation of MC3T3-E1 cells for extracellular matrix deposition, mineralization and eventual bone regeneration for craniofacial and orthopaedic applications. MC3T3-E1 cells were used to study the osteoblastic differentiation and mineralization on sterile samples of Si₃N₄, titanium alloy and PEEK. The samples were then analysed for extracellular matrix deposition and mineralization by FTIR, Raman spectroscopy, SEM, EDX, Alizarin Red, qRT-PCR and ELISA. The in vitro study indicates the formation of collagen fibres and mineral deposition on all three sample surfaces. There was more profound and faster ECM deposition and mineralization on Si₃N₄ surface as compared to titanium and PEEK. The FTIR and Raman spectroscopy show formation of collagen and mineral deposition at 30 days for Si₃N₄ and titanium and not PEEK. The peaks shown by Raman for Si₃N₄ resemble closely to natural bone. Results also indicate the upregulation of osteogenic transcription factors such as RUNX2, SP7, collagen type I and osteocalcin. The authors concluded that Si₃N₄ rapidly conducts mineralized tissue formation via extracellular matrix deposition and biomarker expression in mouse calvarial pre-osteoblast cells. Thus, this study confirms that the bioactive Si₃N₄ could be a potential material for craniofacial and orthopaedic applications leading to rapid bone regeneration that resemble the natural bone structure.