Changes in facial skin temperature associated with chewing efforts in man: a thermographic evaluation.

Eleven healthy male adults chewed hard and soft chewing-gums for 5 min. A thermographic record of the face on the chewing side was made at the beginning of, during and after the effort. Facial temperature distributions during open/close cyclic unloaded jaw movements were recorded at a later date. The dimensions of the zones whose temperatures were 1.4 degrees C or more higher than the central temperature during the experiment were determined. There was a linear increase in the dimensions of these zones after the chewing. In contrast, the cyclic jaw movements did not result in significant increases. Chewing the hard gum produced significantly higher temperature rises than did the soft in the masseter area. After the chewing effort, the temperature fell gradually, but did not return to the initial state even after 30 min. The overall decreasing pattern of the temperature distribution for chewing the soft gum was similar to that for the hard gum. The facial temperature associated with chewing efforts rose in accordance with the resistance offered by the chewing-gums.