The effect of hydrofluoric acid treatment of TiO 2 grit blasted titanium implants on adherent osteoblast gene expression in vitro and in vivo

Abstract

It is widely accepted that implant surface factors affect the quality of the bone-to-implant interface. Recent additional treatments superimposed on moderately rough cpTitanium surface provide further enhancement of bone-to-implant contact. The aim of this study was to compare osteoinductive and bone-specific gene expression in cells adherent to titanium dioxide-grit blasted (TiO 2) versus TiO 2 grit blasted and HF treated (TiO 2/HF) cpTitanium implant surfaces. MC3T3-E1 cells were grown in osteogenic supplements on the titanium disk surfaces for 1–14 days. Real-time PCR was used to measure RUNX-2, Osterix, and bone sialoprotein (BSP) mRNA levels. Implants were placed in rat tibia and, following harvesting at 1–7 days after placement, real-time PCR was used to measure RUNX-2, alkaline phosphatase (ALP), and BSP mRNA levels in implant adherent cells. In cell culture, RUNX-2 and Osterix levels were significantly increased ( p<0.05) on the TiO 2/HF surfaces as compared to the TiO 2 and smooth surfaces through the cultural period, while BSP expression was elevated on both TiO 2 and TiO 2/HF surfaces when compared to a machined surface control. In cells adherent to implants retrieved from rat tibia, RUNX-2 mRNA levels were 2-fold and 8-fold greater on the TiO 2/HF surfaces at 1–3 and 7 days following implantation. This was paralleled by significantly greater levels of ALP at 3 and 7 days and BSP mRNA at 7 days following implantation. As a marker of osteoinduction, the increased levels of RUNX-2 in cells adherent to the TiO 2/HF surfaces suggest that the additional HF treatment of the TiO 2 grit blasted surface results in surface properties that support adherent cell osteoinduction. In vivo assessments of implant adherent cell phenotypes provide further insight into the mechanisms affecting alloplast–tissue interactions.