A novel characteristic of porous titanium oxide implants.
OBJECTIVE
The anatase form of titanium dioxide (TiO2) is one of the most common crystalline forms of TiO2 and is normally produced by oxidation of titanium via thermal oxidation or anodizing. This crystalline form exhibits photocatalytic activity when it is irradiated with ultraviolet A (UVA) light. The aim of the current study was to analyze the crystal structure of anodic-oxidized TiUnite implants and to confirm the photocatalytic properties in vitro and in vivo.


METHODS
Cross-sectional observations by transmission electron microscopy were used to determine the surface crystal structure on the TiUnite implant. Subsequently, photocatalytic activity was confirmed by degradation of methylene blue, and hydrophilicity was measured based on the water contact angle. Furthermore, the in vivo effects of the photocatalytic activity of this compound were investigated.


RESULTS
An amorphous layer that was about 10 microm thick was observed on the TiUnite implant surface. In the amorphous layer, the anatase form of the crystalline TiO2 was identified. Photocatalytic activity was clearly demonstrated by the bleaching effect of methylene blue under UVA illumination. The contact angle decreased from 44 degrees to 11 degrees after UVA illumination. Although these data suggest increased hydrophilicity for the TiUnite implant, the bone-to-metal contact at 4 weeks was not influenced.


CONCLUSIONS
The anodic-oxidized TiUnite implant has inherent photocatalytic activity. UVA illumination increases the surface hydrophilicity of the implant. However, this increase in hydrophilicity does not improve bone apposition to the implant surface at 4 weeks.
Sawase
Takashi
T
Division of Applied Prosthodontics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan. sawase@nagasaki-u.ac.jp
Jimbo
Ryo
R
Wennerberg
Ann
A
Suketa
Naoki
N
Tanaka
Yasuhiro
Y
Atsuta
Mitsuru
M
D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology / Q000528:radiation effects; D003460:Crystallization; D015921:Dental Implants; D005260:Female; D046529:Microscopy, Electron, Transmission; D016348:Osseointegration / Q000187:drug effects* / Q000502:physiology; D010084:Oxidation-Reduction; D010777:Photochemistry; D016062:Porosity; D011817:Rabbits; D013499:Surface Properties / Q000528:radiation effects; D014025:Titanium / Q000737:chemistry* / Q000494:pharmacology / Q000528:radiation effects; D014466:Ultraviolet Rays
D001672:Biocompatible Materials; D015921:Dental Implants; C009495:titanium dioxide; D014025:Titanium