Ultraviolet Photofunctionalization of Titanium Implants
Takahiro Ogawa, DDS, PhD
In the face of growing demands and challenges in implant therapy, implant surfaces with improved biologic capabilities are required. This review paper summarizes the findings of recent in vitro and in vivo studies related to ultraviolet (UV) photofunctionalization of titanium. UV photofunctionalization is defined as an overall phenomenon of modification of titanium surfaces occuring after UV treatment, including the alteration of physicochemical properties and the enhancement of biologic capabilities. Bone morphogenesis around UV-treated titanium implants is distinctly improved compared with that seen around untreated control implants, leading to rapid and complete establishment of osseointegration with nearly 100% bone-to-implant contact in an animal model, as opposed to less than 55% for untreated implants. A series of in vitro studies demonstrated considerable enhancement of attachment, retention, and subsequent functional cascades of osteogenic cells derived from animals and humans after UV treatment. UV treatment converts titanium surfaces from hydrophobic to superhydrophilic and removes unavoidably contaminated hydrocarbons. UV-treated titanium surfaces also manifest a unique electrostatic status and act as direct cell attractants without the aid of ionic and organic bridges, which imparts a novel physicochemical functionality to titanium, which has long been understood as a bioinert material. UV treatment is simple and low in cost, and it has been proven effective for all types of titanium surfaces tested. These data suggest that UV photofunctionalization can be a novel, effective measure to improve implant therapy in the dental and orthopedic fields. Future research will focus on validating these findings in clinical studies.