Teeth with vital pulp are those with an adequate vascular supply, so the circulatory status, and not sensitivity response of the pulp tissue, has been proposed to assess pulp vitality. Some experimental methods have been used to assess this; one of them is the measurement of tooth temperature, which may indicate the pulp vasculature. Some authors have found no differences between the temperatures of teeth with vital and nonvital pulp; however, others found that teeth with nonvital pulp have lower temperatures than teeth with vital pulp. Temperature measurement as a diagnostic procedure has been described with the use of thermocouple, thermistors, infrared thermography, and cholesteric liquid crystals. Many factors may influence the results of the temperature measurement procedure. For creating controlled conditions, each patient should be examined in a thermologic environment. Patients should be asked to refrain from smoking and eating/drinking for 60 minutes before the procedure. The room should be insulated and draft free, and the temperature should be maintained at 20°C. It is desirable to have them lie down or sit with adequate support for the head. The use of a rubber dam is also advocated. Tooth temperature measurement as a diagnostic procedure is reviewed to include description of devices for the test, associated factors, and value of the test.