Prolonged exposure to elevated temperatures exceeding 47°C,which can occur during root canal obturation,can cause damage ofboth dental and bonetissues. In orderto study the temperature distribution on the surfaceof the tooth rootatemperature measuring device with cold-junction compensation is proposed. For in vitro measurement of the temperature distribution on the surface of the tooth, 8 thermocouples placed in direct contact with the cementum of the tooth were used.In order to eliminate thecold-junction temperature variations,the temperature equilibration device and RTD wereused. The suggested linear approximation for the thermocouples'conversionfunction providesa nonlinearity relativeerror of less than 0.05%for K-type thermocouples and 0.07% for J-type thermocouples over the temperature range from20 to 60°C.