Effects of micro/nano strontium-loaded surface implants on osseointegration in ovariectomized sheep

Background Poor osseointegration of dental implants often occurs in osteoporotic patients and processed implant surfaces could help to improve the dilemma. Purpose This study aimed to compare the effects of different titanium (Ti) surfaces on bone-implant osseointegration in ovariectomized (OVX) sheep. Materials and Methods Four groups were included: smooth titanium (ST) was merely polished Ti; micro titanium (MT) was treated with hydrofluoric acid (HF) for 30 minutes; strontium-loaded nano titanium (NT-Sr) was formed by magnetron sputtering; strontium-loaded micro/nano titanium (MNT-Sr) was fabricated by HF etching combined with magnetron sputtering. The biological responses were evaluated by human bone marrow-derived mesenchymal stem cells (hBMMSCs) experiments in vitro. Osseointegration was evaluated in vivo after each surface implant was inserted into OVX sheep' mandibles. Results The numbers of adhered and mineralized hBMMSCs increased significantly in the MNT-Sr group. The bone-implant contact and the maximal pull-out force increased significantly with MNT-Sr surface. The bone volume ratio and trabecular number of the MNT-Sr group were significantly higher than others, whereas trabecular separation decreased. Conclusions These results indicated that an MNT-Sr surface promotes the differentiation of hBMMSCs in vitro and enhances bone-implant osseointegration in vivo, which may be a promising option for clinical implants in osteoporotic patients.