Heat changes cause thermal stresses in the restorations made of different materials. These stresses can become high in the vicinity of the contacts between different materials. The aforesaid thermal stresses can add up with stresses caused by mechanical loads, they can cause cracks in the dental structures and thus can lead much shorter life-span during use. The purpose of this research is the mathematical determination of the thermal stresses in the structure due to variable temperatures inside the mouth for the metal-supported porcelain restorations. It has been found that as the temperature increases, stress values increase at a fixed distance. The stress values in the ceramic and dentin regions reach higher magnitudes than those in metal and cement layers. At 55 degrees C, the stress value in the ceramic layer was calculated as 67.37 MPa. It has been concluded that there is a linear relationship between stress rising rate and temperature. (c) 2006 Elsevier Ltd. All rights reserved.