Biomechanical and Morphometric Evaluation of a Strontium-Incorporated Implant and Four Commercially Available Implants: A Study in Rabbits.

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.