The purpose of this study was to calculate the temperature and thermal stress distribution as a result of hot/cold liquid in the mouth. This numerical study was carried out using three-dimensional finite element models and the tooth model was crowned with Au-Pd alloy, Ni-Cr alloy and porcelain. In the first part of the study, temperature changes as a result of hot/cold liquid in the mouth were calculated. In the second part, the thermal stresses caused by temperature changes were obtained. The tooth was assumed isotropic, homogenous, elastic and unsymmetrical. The authors using fortran 77 prepared all calculation programs. The distribution of temperature and thermal stress were plotted for some critical points.