Abstract: A periodontal probe has a probe finger extending from a handle to an L-shaped distal end which includes a tip adapted for insertion into a periodontal pocket and formed of a thermally insulative material. A temperature sensing element is mounted at the extreme end of the tip. Conductive leads extend from the sensing element, through the probe tip to the handle. In a preferred embodiment, the temperature sensor is a thermocouple or thermistor, and the tip is sealed within an epoxy outer skin. The tip tapers so that the thermal mass of the probe in the vicinity of the sensing element quickly attains the temperature of surrounding tissue while minimally perturbing that temperature. The handle may contain signal processing or temperature display units, and the probe tip preferably includes graduations for indicating probe depth. Interchangeable sensor matching circuit elements adapt sensor elements having different characteristics to a common display driver.