The low degradation of commercially pure titanium or titanium alloy in tissues is one of its assets for use in restorative procedures (Craig, Power and Wataha, 2004, 316). Trace amounts of elements have been shown to be released from these alloys into bone, the levels released are less than one part per billion in most cases, and their effects appear to minimal. Trace amounts have also been found in lung, liver, spleen, and kidney, with no ill effects noted. Titanium alloy may be coated with ceramic films to combine the high strength of the alloy with the favorable integrative characteristics of the ceramics (318). The thickness of the ceramic coating varies from 50 ¦m to 100 ¦m and is sprayed on to the metal alloy. It has several characteristics that influence its porosity, crystallinity, composition, strength, and thickness. Studies suggest that these layers promote a strong bone-implant bond more quickly, and promote biointegration rather than osseointegration, but the ceramic coats degrade over time, and this effect on the integration of the implant with the bone is not yet known.
As the aging population increases because of better health care and the ability to extend the lifespan, there is more and more call for replacement parts, particularly of hard tissues such as bones and teeth. Pure titanium and titanium alloys are ideally suited for such purposes because of their strength, resistance to corrosion, non-allergic nature, and good biocompatibility (Niimomi, 2003, 445-454). They are being used increasingly in Japan for dental fillings as an alternative to Ag-Pd-Au-Cu-alloy because of the increasing cost of Pd, as well as for implants in the form of pure titanium and Ti-6Al-4V alloys.
For dental implants to be successful, good functional properties are essential. Gaggl and Schultes (2001, 3061-3966)reported on a new kind of implant which has a maintenance free shock absorbing system so that there is no need to ...