title: The effect of UV-photofunctionalization on the time-related bioactivity of titanium and chromium-cobalt alloys.
abstract: This study examined the possible changes in the bioactivity of titanium surfaces during their aging and investigated the effect of ultraviolet (UV) light treatment during the age-related change of titanium bioactivity. Rat bone marrow-derived osteoblastic cells were cultured on new titanium disks (immediately after either acid-etching, machining, or sandblasting), 4-week-old disks (stored after processing for 4 weeks in dark ambient conditions), and 4-week-old disks treated with UVA (peak wavelength of 365 nm) or UVC (peak wavelength of 250 nm). During incubation for 24 h, only 50% of the cells were attached to the 4-week-old surfaces as compared to the new surface. UVC treatment of the aged surface increased its cell attachment capacity to a level 50% higher than the new surfaces, whereas UVA treatment had no effect. Proliferation, alkaline phosphatase activity, and mineralization of cells were substantially lower on the 4-week-old surfaces than on the new surfaces, while they were higher on the UVC-treated 4-week-old surfaces as compared to the new surfaces. The age-related impaired bioactivity was found on all titanium topographies as well as on a chromium-cobalt alloy, and was associated with an increased percentage of surface carbon. Although both UVA and UVC treatment converted the 4-week-old titanium surfaces from hydrophobic to superhydrophilic, only UVC treatment effectively reduced the surface carbon to a level equivalent to the new surface. Thus, this study uncovered a time-dependent biological degradation of titanium and chromium-cobalt alloy, and its restoration enabled by UVC phototreatment, which surmounts the innate bioactivity of new surfaces, which is more closely linked to hydrocarbon removal than the induced superhydrophilicity.
authors.affiliation: Laboratory for Bone and Implant Sciences, The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA 90095-1668, USA.
authors.forename: Wael
authors.initials: W
authors.lastname: Att
authors.forename: Norio
authors.initials: N
authors.lastname: Hori
authors.forename: Fuminori
authors.initials: F
authors.lastname: Iwasa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamada
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ueno
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ogawa
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D002448:Cell Adhesion / Q000187:drug effects / Q000528:radiation effects; D002465:Cell Movement / Q000187:drug effects / Q000528:radiation effects; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002858:Chromium Alloys / Q000494:pharmacology*; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D008855:Microscopy, Electron, Scanning; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D010641:Phenotype; D051381:Rats; D017207:Rats, Sprague-Dawley; D013499:Surface Properties / Q000187:drug effects / Q000528:radiation effects; D013997:Time Factors; D014025:Titanium / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D001672:Biocompatible Materials; D002858:Chromium Alloys; D014025:Titanium