title: [Bioactivity of ultraviolet ray-treated titanium surface in nitrogen storing environment].
abstract: OBJECTIVE
  To evaluate the adhesion, proliferation and differentiation of osteoblast-like cells on the ultraviolet (UV)-treated titanium in different storing environment, and to find a way to enhance the bioactivity of titanium and to prevent its age-related degradation.
  
  
  METHODS
  Acid-etched titanium disks stored under ambient conditions for 4 weeks and treated with UV light for 48 h.Then disks were divided into three groups and placed in a sealed container for 0 h (no-stored,NO group) , 4 weeks (air-stored, AS group) or in a sealed container filled with nitrogen for 4 weeks (nitrogen-stored,NS group) respectively. A group of UV-untreated titanium served as negative control (NC group).The surface morphology was evaluated using scanning electron microscopy (SEM), and hydrophilicity of disks were measured using contact angle measuring device. Cell counting kit-8 was used to measure the cell adhesion and proliferation. Cell differentiation was evaluated by testing alkaline phosphatase (ALP) activity using ALP reagent kit.
  
  
  RESULTS
  There was no difference in surface topography among groups.Contact angels in NS group [(67.70 ± 3.59)°] and NO group [(0.70 ± 0.28)°] were smaller than the others (P < 0.05). Cell adhesion in NS group at 2 h and 4 h point was (0.237 ± 0.006) and (0.578 ± 0.039), respectively, and proliferation at 3 d and 5 d point was (0.743 ± 0.026) and (1.548 ± 0.046) respectively, which were significantly higher than those in AS group [(0.158 ± 0.036), (0.400 ± 0.010), (0.499 ± 0.019) and (1.174 ± 0.062)] and in NC group [(0.161 ± 0.024), (0.390 ± 0.011), (0.508 ± 0.015) and (1.209 ± 0.025)] at the same time point (P < 0.05). How ever the results mention above in the NS group were lower than those in the NO group (P < 0.05). No difference were found between data from the AS group and NS group (P > 0.05). Osteoblast-like cells had an abundant spread on NS and NO group during 2 h incubation, but did not exactly spread on AS and NC group after incubation for 4 h. No difference were found in ALP among groups.
  
  
  CONCLUSIONS
  UV treatment can enhance bioactivity of titanium, and nitrogen storage can slow down its biological aging.
authors.affiliation: Department of Prosthodontics, Sun Yat-sen University, Guangzhou, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Wang
authors.forename: Ren
authors.initials: R
authors.lastname: Shang
authors.forename: Yun
authors.initials: Y
authors.lastname: Guan
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Teng
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D002448:Cell Adhesion / Q000528:radiation effects; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D051379:Mice; D008855:Microscopy, Electron, Scanning; D009584:Nitrogen / Q000737:chemistry*; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D001672:Biocompatible Materials; D014025:Titanium; D000469:Alkaline Phosphatase; D009584:Nitrogen