Nanostructured implant surfaces affect osteoblast gene expression and bone-to-implant contact

Purpose: Use of nanotechnology in developing new implant surfaces may expand the clinical influence of osteoblast biology. The aim of this study was to investigate the response of a nanostructured implant surface at the level of osteoblast differentiation and its effects in bone-to-implant contact (BIC) and removal-torque values (RTV). The hypothesis was that a nanostructured surface altered initial osteoinductive responses of cells to increase the accrual of interfacial bone mass. Methods: Commercially pure grade IV titanium implants (1.6x4.0 mm) were machined or machined and subsequently treated by acid etching or by dipping in an oxide resin solution. The surfaces were divided into six groups: machined (M), acid etched (Ac), and nanostructureds: titania-anatase (An), titania-rutile (Ru), alumina (Al), and zirconia (Zr). Surfaces were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), and by X-ray microanalysis (EDX). Implants for all the surfaces were inserted in rat tibia and harvested from 0-21 days for measurement of Alkaline Phosphatase (ALP), Bone Sialoprotein (BSP), Osteocalcin (OCN), Osteopontin (OPN), and RUNX-2 mRNA levels by real time PCR; from 0-56 days for RTV; and from 0–56 days for BIC. Results: mRNA levels on all nanostructured surfaces were increased compared to M and Ac. At 56 days, the mean RTV in Ncm was 13.9±1.3, 11.6±2.5, 11.3±2.4, 11.1±3.5, 10.4±3.9, 9.7±1.4 for Al, An, Ru, Zr, Ac, and M, respectively (n=6, p=0.02; Kruskall-Wallis test). Higher BIC (%) was measured for the all nanostructured surfaces versus Ac and M at 21 and 56 days. 65.77±6.49, 55.73±8.95, 51.81±7.20, 51.49±6.46, 37.48±15.16, 31.88±3.84, for Zr, Al, An, Ru, Ac, and M at 56 days, respectively (n=3, p=0.05; Kruskall-Wallis test). Conclusion: Nanostructured topographic features applied to machined cpTi implant promoted greater mesenchymal stem cell commitment to the osteoblast phenotype and associated increased BIC and physical association with bone. Support CAPES/CNPq