An analysis of static occlusion including occlusal force and occlusal contact area in intercuspal position may be helpful but a dynamic analysis of occlusion should be regarded as more important for analyzing the stomatognathic system. Anthropological research has shown that the Japanese and the Mongolian populations share morphological and genetic similarities, although their dietary lives are not the same. The purpose of this study was to evaluate the relationship between environmental factors such as dietary life and stomatognathic function with a dynamic analysis of physiological tooth displacement. Ten clinically healthy subjects were recruited (mean age 24.8 +/- 1.0 years). The subjects were divided into two groups 1) Mongolian group: five Mongolians grown with a more or less natural texture diet and 2) Japanese group: five Japanese grown with a relatively soft diet. The displacement of the upper left first molar was measured during function using a three-dimensional tooth displacement transducer Type M-3. The tooth displacement in the Japanese group occurred mostly in an apicopalatal direction, but intruded basically parallel to the tooth axis in the Mongolian group. The stress-strain curve revealed that elastic socket deformation and viscous elements were more pronounced in the Japanese group. It was concluded that environmental factors such as dietary life could influence tooth displacement during function.