Accelerated osseointegration around light-induced super-amphiphilic titanium surface

Contact osteogenesis plays an important role on the establishment of osseointegration. The enhancement of both osteogenic cell proliferation and differentiation is crucial to accelerate the time required for osseointegration. However, these are competing biological events in osteoblastic function. We hypothesized that super-amphiphilic (both hydrophilic and oleophilic) titanium surface may accelerate cell proliferation without sacrificing the rate of osteogenic differentiation. Objectives: The objective of this study was to examine the effects of light-induced super-amphiphilic titanium surfaces on their osteoconductive capacity in vitro and in vivo. Methods: Super-amphiphilic titanium surfaces were created for both machined and acid-etched titanium surfaces by UV light treatment. Amphiphilic status was measured by contact angle of water, glycerol and blood. Rat bone marrow-derived osteoblastic cells were cultured on either machined or acid-etched surface with or without light treatment. The cell proliferation, differentiation and mineralization were evaluated by hematocytometer, reverse transcriptase-polymerase chain reaction (RT-PCR) and mineralized nodule assay, respectively. In vivo osseointegration was evaluated by biomechanical push-in test and histomorphometry. Results: The contact angles were 0 degree for the both machined and acid-etched surfaces after the light treatment, as opposed to the ones over 65 degree of the untreated surfaces. The cell proliferation was increased 100% on UV light-treated machined and acid-etched surfaces (p<0.01), while maintaining osteogenic gene expression levels and increasing the mineralization. The in vivo fixation of the light-treated acid-etched implants measured by day 14 push-in test was 3.1 times greater than the untreated ones (p<0.01). Histomorphometric analysis showed that nearly 100% bone-titanium contact was obtained in light-treated acid-etched surfaces at day 28 post-implantation. Conclusion: The UV light treatment of both machined and acid-etched titanium resulted in increased osteoblastic proliferation and mineralization. We have thus developed a novel titanium surface with remarkably improved osteoconductive capacity, enabling rapider and more complete establishment of bone-titanium integration.