This study presents the stress analysis of the mandibular first premolar tooth restored with an all-ceramic crown under thermal loading as a result of hot/cold liquid intake to the mouth using the three-dimensional (3D) finite element analysis (FEA). In the first step of the study, the temperature changes as a result of hot/cold liquid intake were calculated. The thermal stress distributions because of the temperature changes were then obtained. Thermal loads ranging from 60 to 15 degreesC were applied on all prepared models. The distribution of temperature and stress were plotted for some critical points which were the transition points of strain to tension or tension to strain when hot or cold liquids were consumed. The changes in oral temperature cause thermal fatigue and the material stability might be negatively affected. According to the thermal tension results in the present study, IPS Empress, Carrara press ceramic and Ceramco FAC all-ceramic materials exhibited different values while IPS Empress 2 material showed similar properties to that of enamel.