2004 Volume 53 Issue 1 Pages 101-107
Metals are by far the oldest materials used in surgical procedures. Titanium alloys are hoped to be used much more for applications as implant materials in the orthopedic and dental medical fields because of their mechanical properties, such as biocompatibility, corrosion resistance and specific strength compared with other metallic implant materials. The performance of any biomedical material is controlled by two characteristics, biofunctionality and biocompatibility. Biofunctionality defines the ability of the device to perform the required function, whereas biocompatibility determines the compatibility of the material with the body. This biocompatibility is improved by coating the surface in contact with living tissues with calcium phosphates, specially hydroxyapatite. Some of the new implants utilize titanium alloys substructure coated with a thin layer of calcium phosphates ceramics, hydroxyapatite, or the plasma spray technique. Hydroxyapatite coating are designed to produce a bioactive surface promoting bone growth and inducing a direct bond between the implant and the hard tissues. The titanium metal also forms the bone like apatite layer on its surface in simulated body fluid, when it has been previously treated with NaOH aqueous solution to form a sodium titanium hydro gel layer on its surface. In the present study, surface structural changes of Ti-6Al-4V alloys with the alkali treatments and mechanical property in simulated body fluid were investigated. Thus it is expected that alkali treated titanium alloys could also form the bone like apatite layer on its surface in the living body and bond to living bone through the apatite layer. Studies have demonstrated that the bone bonding ability of titanium alloys could be evaluated by testing the titanium alloys in a simulated body fluid. In test results of with apatite coating specimens extremely higher fracture strength, compared with monolithic Ti-6Al-4V alloys whose fracture strength was 60MPa·m1/2. For apatite coating Ti-6Al-4V alloys the general tendencies in the fracture strength depending upon apatite coating were understood as follows. With apatite coating Ti-6Al-4V alloys it is recognized that speculated that this tight bond might be attributed to a graded interface structure between the apatite layer and the substrates.
