Osteoclastic Response on Titanium Surfaces in Modified Simulated Body Fluid

Purpose: It was hypothesized that calcium phosphate (CaP) deposition onto Ti surfaces using biomimetic deposition contributed to not only improving osteogenesis but also suppressing osteoclastogenesis in terms of high surface hydrophilicity. Materials and Methods: Ti discs with two different surfaces were prepared: machined and anodic oxidized surfaces. The specimens of two different surfaces were soaked in modified simulated body fluid solution for 14 days at physiologic condition. Murine RAW 264.7 cells were utilized as osteoclast precursor cells. To evaluate osteoclast differentiation activity on Ti surfaces, tartrate-resistant acid phosphatase activity assay was conducted, and cells on Ti discs were investigated with a field emissionscanning electron microscope (FE-SEM). The expression of nuclear factor of activated T cells 1 (NFATc1) and c-Fos, two critical transcriptional factors involved in osteoclastogenesis, were also assessed in terms of mRNA and protein levels by real-time reverse transcriptase-polymerase chain reaction and western blot, respectively. Results: Tartrate-resistant acid phosphatase activities on both machined and anodic oxidized Ti surfaces soaked in modified simulated body fluid were significantly lower compared with nonimmersed ones. FE-SEM observation showed that the number of differentiated osteoclasts was lower on anodic oxidized surfaces immersed in modified simulated body fluid compared with nonimmersed Ti surfaces. Protein and mRNA expression of NFATc1 and c-Fos were significantly decreased on anodic oxidized Ti surfaces immersed in modified simulated body fluid compared with those on nonimmersed ones. The effects of immersion of Ti discs in modified simulated body fluid on osteoclastogenesis were higher on anodic oxidized surfaces than on machined surfaces. Conclusion: It can be concluded that osteoclastogenesis was inhibited by biomimetic deposition using modified simulated body fluid, especially on anodic oxidized Ti surfaces. Keywords: anodic oxidation, biomimetic deposition, osteoclast, simulated body fluid, surface energy