Medical or dental instruments, preferably handpieces, can have different temperature-measuring devices for measuring the temperature in the instrument or of at least a part of the instrument. The temperature-measuring devices can be designed, for example, to measure the temperature contactlessly by detection of electromagnetic radiation or to measure the temperature of an interior of the instrument that can be heated by a heat source. The temperature-measuring devices may be designed, for example, as electrical temperature measuring devices or may have a magnetic material whose magnetic property is a function of temperature and/or has a temperature-dependent course. The temperature-measuring device may have, for example, an electrical switching device and a signal device wherein the signal device is switched at least between a first signal condition and a second signal condition when a temperature limit value is reached or exceeded or is underrun.
