IADR Abstract Archives
Novel Antioxidant Role of Silicon Oxynitride Promote Rapid Bone Regeneration
Objectives: Current implants endure long healing times and loosening over time due to a lack of implant-bone bonding. To promote fracture healing, the reduction of reactive oxygen species combined with enhanced osteogenic stimulation must occur, and both of these processes are regulated by antioxidant enzymes such as superoxide dismutase. Here, we test the hypothesis of a novel implant coating biomaterial, silicon oxynitride (SiONx), to promote rapid healing through the sustained release of ionic Si and rapid formation of a carbonated hydroxyapatite layer.
Methods: SiONx samples were fabricated using plasma enhanced chemical vapor deposition, measured for ionic Si release using inductively coupled plasma mass spectrometry, and measured for hydroxyapatite formation using x-ray absorbance spectroscopy (XAS). Control groups (SiO2 glass cover slips) and SiONx samples were seeded with human osteoprogenitor cells for 30 days in vitro in wild type and SOD1-null (by siRNA) cells. Cell lysates were assayed for osteogenic gene expression using quantitative reverse transcriptase polymerase chain reaction. SiONx-coated implant materials were then implanted into rat critical sized calvarial defects to determine the effect of SiONx on bone density (micro-CT) and bone quality (XAS) after 5 weeks.
Results: Maximal osteogenic marker and SOD1 expression was observed for cells cultured on SiONx surfaces versus control surfaces. siRNA results revealed that ionic Si enhanced osteogenic gene expression through enhanced SOD1 expression. In vivo testing and micro-CT analysis showed full osteointegration of SiONx coated materials after 5 weeks as compared to uncoated surfaces. XANES analysis showed that the newly formed bone had a similar carbonate to phosphate ratio than the surrounding bone.
Conclusions: We conclude that SiONx films enhance critical sized bone defect healing by enhancing the expression of osteogenesis and reducing ROS activity by stimulating SOD1 expression, and, rapidly form an HA surface layer for rapid bone integration.
Methods: SiONx samples were fabricated using plasma enhanced chemical vapor deposition, measured for ionic Si release using inductively coupled plasma mass spectrometry, and measured for hydroxyapatite formation using x-ray absorbance spectroscopy (XAS). Control groups (SiO2 glass cover slips) and SiONx samples were seeded with human osteoprogenitor cells for 30 days in vitro in wild type and SOD1-null (by siRNA) cells. Cell lysates were assayed for osteogenic gene expression using quantitative reverse transcriptase polymerase chain reaction. SiONx-coated implant materials were then implanted into rat critical sized calvarial defects to determine the effect of SiONx on bone density (micro-CT) and bone quality (XAS) after 5 weeks.
Results: Maximal osteogenic marker and SOD1 expression was observed for cells cultured on SiONx surfaces versus control surfaces. siRNA results revealed that ionic Si enhanced osteogenic gene expression through enhanced SOD1 expression. In vivo testing and micro-CT analysis showed full osteointegration of SiONx coated materials after 5 weeks as compared to uncoated surfaces. XANES analysis showed that the newly formed bone had a similar carbonate to phosphate ratio than the surrounding bone.
Conclusions: We conclude that SiONx films enhance critical sized bone defect healing by enhancing the expression of osteogenesis and reducing ROS activity by stimulating SOD1 expression, and, rapidly form an HA surface layer for rapid bone integration.