[Thermal expansion of dental alloys and porcelains].

Thermal behaviour of metal and porcelain against heat is an important factor in metal-porcelain bonding. For this reason thermal compatibility and the thermal expansion of metal and porcelain are some of the important subjects to be studied carefully. In this study, by means of dilatometric measurements, we determined the thermal expansion coefficients of metal alloy (Ivotect P) and porcelain (ITS-HTE, Ivoclar) which we use in routine practice. As a result we found that the porcelain has a nonlinear expansion as oppose to metal alloy and also the firing conditions affect the thermal expansion. In addition we observed that the thermal expansion coefficient of metal alloy had changed very little in repeated castings.