Fracture mechanisms of retrieved titanium screw thread in dental implant.
Titanium and its alloy are increasingly attracting attention for use as biomaterials. However, delayed fracture of titanium dental implants has been reported, and factors affecting the acceleration of corrosion and fatigue have to be determined. The fractured surface of a retrieved titanium screw and metallurgical structures of a dental implant system were analyzed. The outer surface of the retrieved screw had a structure different from that of the as-received screw. It was confirmed that a shear crack initiated at the root of the thread and propagated into the inner section of the screw. Gas chromatography revealed that the retrieved screw had absorbed a higher amount of hydrogen than the as-received sample. The grain structure of a titanium screw, immersed in a solution known to induce hydrogen absorption, showed features similar to those of the retrieved screw. It was concluded that titanium in a biological environment absorbs hydrogen and this may be the reason for delayed fracture of a titanium implant.
Yokoyama
Ken'ichi
K
Department of Dental Engineering, School of Dentistry, Tokushima University, Japan.
Ichikawa
Tetsuo
T
Murakami
Hiroki
H
Miyamoto
Youji
Y
Asaoka
Kenzo
K
D001672:Biocompatible Materials; D015921:Dental Implants; D019232:Dental Restoration Failure; D006801:Humans; D006859:Hydrogen / Q000378:metabolism; D033081:Shear Strength; D014025:Titanium
D001672:Biocompatible Materials; D015921:Dental Implants; D006859:Hydrogen; D014025:Titanium