The Effect of Silicon Oxynitride on Antioxidant and Osteogenic Expression in Human Periosteum Cells

Objectives: Current craniofacial implants lack the needed stimulus to induce osteoprogenitor differentiation in calvarial fracture healing. In this study, we hypothesize that a novel material, silicon oxynitride, can stimulate the expression of osteogenic markers during osteoprogenitor differentiation
Methods: Silicon oxynitride films were prepared by plasma-enhanced chemical vapor deposition onto substrates made from Si-wafers with electron-beam physical vapor deposited Ti films. The films were evaluated for their interfacial adhesion to the underlying Ti layers, surface chemical structure and in vitro degradation behavior prior to in vitro cell culture testing. Human Periosteum cells (osteoprogenitors) were then cultured onto 1 square centimeter samples of silicon oxynitride, silicon dioxide, and silicon nitride.
Results: Transmission electron microscopy combined with x-ray photoelectron spectroscopy showed evidence of ionic bonding between the PECVD films and underlying Ti, evidenced by the presence of a Si-O-Ti interface with atomic concentration indicating stoichiometry of Six-Tix-O2x (x=0.33). Inductively coupled plasma mass spectrometry showed that PECVD films sustained the release Si over a 8 day period with nearly full dissolution of the silicon oxynitride layer. Quantitative polymerase chain reaction analysis showed evidence of elevated expression of antioxidant markers (superoxide dismutase) and osteogenic markers (collagen type 1, core binding factor a1) by 2-3 fold as compared to control samples (silica cover glass surface) with 3 days of testing.
Conclusions: These results indicate that silicon oxynitride films formed using PECVD can enhance the expression of osteogenic markers during osteoprogenitor differentiation.