A. BLUME*, E. LENZ, G. RASER, W. DIETZ (Dept. Prosthetic Dentistry and Dental Materials Research Erfurt, Friedrich-Schiller-University Jena)
The use of Titanium in restorative dentistry will continue to expand. A major problem is the bonding of Titanium with dental ceramics, which is affected by processing conditions (temperature, holding time). Therefore, in these studies the interface was especially investigated under practice-like conditions.
Three low fusing Titanium ceramics (DUCERATIN, TIBOND, VITA TITANKERAMIK) were fired on to Titanium samples according to instructions for use and, additionally, with varied holding times. Cross sections of these test pieces obtained by grinding were prepared for examination of the interfaces by light- and scanning electronmicroscopy as well as X-Ray-microanalysis (XRMA) and microhardness determination (MHV 0,02) as a measure of exchanging elements.
In all cases the microscopical investigations showed a rough-surfaced Titanium (up to a depths of 1 µm), which is mechanically more or less well-bonded with ceramics. A remaining Titanium alpha-case is visible (3 - 5 µm in thickness). By XRMA of ceramics part a maximum content of 3,5% of Titanium was found in a thin layer of up to 15 µm below the surface. Measurements on Titanium part established small but different amounts of foreign elements up to a depths of 20 µm. The microhardness determinations of Titanium yield an increasing hardness in nearly the same range of depths. An influence of different holding times of ceramic firing was not established.
The different investigations of the interface show bath a mechanically caused microretention and an exchange of Titanium and foreign elements between ceramic and metal. The findings support the effect of interface reactions on Titanium ceramic bonding.