ABSTRACT
PURPOSE: Strontium has shown a positive effect on osseointegration in experiments. This study compared surface characterization and osseointegration of a strontium-incorporated implant with four commercial implants with different surface treatments. MATERIALS AND METHODS: A strontium-oxide layer was created by hydrothermal treatment on the surface of the implant (SLA-Sr). Surface characterizations were observed using a scanning electron microscope, three-dimensional (3D) optical microscope, and x-ray energy-dispersive spectrometry. Implants of different surface treatments including resorbable blasting media (RBM), sandblasting with large grit and acid etching (SLA-1, SLA-2), sandblasting and thermal acid etching (STA), and SLA-Sr were implanted into the proximal tibiae and femoral condyles of rabbits. Biologic effects were evaluated by removal torque testing and histomorphometric analysis after 3, 6, and 12 weeks of implantation. RESULTS: Nanostructures were observed on the surface of SLA-Sr and STA. Calcium (Ca) was detected on the surface of RBM. Sr was detected on the surface of SLA-Sr. SLA-1 and STA had greater surface roughness than SLA-2, SLA-Sr, and RBM (P < .05). In vivo, SLA-Sr achieved better removal torque value (RTV) than that of RBM and SLA-2 at 3 weeks (P < .05), as well as increased bone area ratio (BA%) in cortical bone compared with RBM at 3 weeks (P < .05). STA showed higher bone-to-implant contact ratio (BIC%) in cortical bone than RBM at 3 and 6 weeks (P < .05). Compared with RBM, SLA-1 had better RTV at 6 weeks and higher BIC% in cortical bone at 12 weeks (P < .05). CONCLUSION: In vivo, compared with SLA-2 and RBM, the implant with the strontium-oxide layer displayed slight advantages in new bone formation and osseointegration in the early healing stage. In the later osseointegration stage, the results of SLA-Sr were comparable with other implants.
Subject(s)
Dental Implants , Strontium , Animals , Osseointegration , Rabbits , Surface Properties , TitaniumABSTRACT
Recruitment of endogenous bone marrow-derived mesenchymal stem cells (BMSCs) has been widely discussed as an alternative strategy for bone regeneration. Strontium (Sr) is known to direct the BMSCs' commitment to the bone lineage and encourage bone formation; however, the underlying mechanisms remain elusive. In this study, an Sr-incorporated micro/nano rough titanium surface (MNT-Sr) was fabricated by hydrothermal treatment in an attempt to facilitate BMSCs' recruitment and their osteogenic differentiation to enhance rapid osseointegration. Micro rough titanium (MT) was set as the control biomaterial. In vitro, MNT-Sr and its extracts promoted the migration and osteogenic differentiation of BMSCs. In animal studies, green fluorescent protein (GFP)-labeled BMSCs were intravenously injected into wild-type rats for tracing before tibial implantation surgery. The GFP+BMSC recruitment to the implantation site was successfully triggered by MNT-Sr implantation. A trend for increased bone area (BA%), bone-implant contact (BIC%) and removal torque values (RTVs) was observed for the MNT-Sr implant compared to that observed for MT at 2 weeks. Advanced mechanism analysis indicated that Sr2+ enhanced the SDF-1α/CXCR4 signaling pathway both in vitro and in vivo. Taken together, these findings suggest that MNT-Sr has promising therapeutic potential for future use in dental implants by homing endogenous stem cells to stimulate bone regeneration.
