The Effect of Ultraviolet-C Irradiation Via a Bactericidal Ultraviolet Sterilizer on an Anodized Titanium Implant: A Study in Rabbits

Purpose: After placement, titanium dental implants are conditioned by blood and tissue fluid. These initial processes are affected by the hydrophilicity of the implant. The hydrophilicity of titanium dioxide (TiO2) can be increased by ultraviolet (UV)-C irradiation. Anodic oxidation is an electrochemical treatment used to form TiO2 layers that are characterized by their thickness, roughness, and porosity on the surface of titanium implants. These oxide layers increase implant durability and performance. Therefore, the aim of this study was to investigate the effect of UV-C irradiation on the anodized titanium surface and the resultant tissue response. Materials and Methods: Twenty-five titanium disks and 56 screw-type implants were fabricated of commercially pure titanium and anodized. The samples were divided into a control group (anodized) and a test group (anodized and UV-C irradiated with a bactericidal UV sterilizer for 24 hours just prior to experimentation). The surface characteristics of the disks, including roughness, crystal phase of the oxide layer, chemical composition, and water contact angle, were then evaluated. Implants were placed into rabbit tibiae, and histomorphometric analysis was performed after healing periods of 4 and 12 weeks. The results were compared between groups. Results: The surface topography and phase of the oxide layer were not significantly different between test and control groups. Carbon surface impurities were noticeably decreased after UV-C irradiation, and water contact angle measurements were significantly lower (P .001). After a healing period of 4 weeks, test implants showed higher values for both bone-to-implant contact and the amount of bone in the thread area of the implant (P .01). No significant differences between groups were found for either histomorphometric measurement after 12 weeks. Conclusions: UV-C irradiation of an anodized titanium implant, accomplished via a bactericidal UV sterilizer, promoted an early bone response in rabbit tibiae. Keywords: anodic oxidation, histomorphometry, titanium irradiation, ultraviolet-C irradiation