Thermal compatibility of titanium-porcelain system.
Porcelain-fused-to metal systems are popular in restorative dentistry. Residual stress caused by a mismatch of the thermal expansion coefficient of metal and porcelain induce clinical failure of the restoration. Titanium and its alloys have been gradually used in dentistry for their adequate strength, good corrosion resistance and excellent biocompatibility. Their oxidation characteristics and low thermal expansion coefficients capacitate for matching the low fusing porcelains. This investigation examined thermal compatibility of pure titanium with two low fusing porcelains and one high fusing porcelain. Thermal expansion coefficients (alpha) of pure titanium and porcelains were measured from room temperature to 600 degrees C at a mean heating rate of 5 degrees C/min. Difference in thermal expansion values (delta alpha) was also calculated to present the residual stress in each titanium-porcelain pairs. The bonding patterns of titanium to each opaque was demonstrated similar results from the predictions of alpha and delta alpha values.