Different cellular response to UV-treated titanium between osteoblasts and fibroblasts

Deriving maximum osseointegration capacity of titanium is a challenge. We previously demonstrated that ultraviolet (UV) treatment of titanium may have a potential to increase its osteoconductive potential. Objectives: This study examined the effect of different time period of UV treatment on the behavior and response of osteoblastic and fibroblastic cells. Methods: Acid-etched titanium disks were treated with UV light at a level of 0.1 mW/cm2 UVA and 0.03 mW/cm2 UVB for various time periods up to 48 hours. Hydrophilicity and albumin adsorption of these disks were measured. Osteoblastic cells derived from the rat bone marrow and fibroblastic cells derived from the rat palatal tissue were cultured on these disks. Cell attachment was evaluated by the number of cells attached at 3 hour of culture, and cellular metabolic activity by WST1. Cell proliferation was evaluated by BrdU DNA incorporation assay. Results: Hydrophilicity of the titanium, as well as the albumin adsorption rate, increased with an increase of UV treatment time (p<0.01). The number of osteoblastic cells attached to titanium surfaces after 3 hour of incubation was 2 times greater for the 48 hour UV treated surface than the non-treated one. The 48 hour UV-treated surface also increased the osteoblastic WST1 value 5 times. Osteoblastic proliferation measured by BrdU incorporation at day 2 and 4 was 2 times greater on the 48 hour UV-treated surface than on the untreated control. In contras, the fibroblastic proliferation was 1.7 times greater on the untreated control surface than on the UV-treated surface. In vivo biomechanical push-in test in the rat femur revealed that UV-treated implant showed over 2.5 times stronger osseointegration than the untreated implants. Conclusion: The results suggest selective cell affinity of the UV-treated titanium surface, which may be a compelling reason why the UV-treated surface generates greater osseointegration capacity.