The purpose of this study was to obtain basic data needed to clinical diagnosis and treatment by investigating the occlusal wear facets and those related factors. Sixty-six subjects, ranging from 24 to 26 years of age without symptoms of stomatognatic system, were selected from dental students in Chosun University. The area of occlusal wear facets was measured and twenty subjects were selected, and divided into two groups (Group I and Group II). The Group I had small facet areas, and the Group II had large facet areas. These two groups were investigated into right and left side wear facet areas, vertical overlaps, occlusion types of working side, masticatory muscle activities, and asymmetry of right and left side masticatory muscle function. The results were as follows: 1. The average wear facet areas of all subjects was $22.84{pm}88.95mm^2$, and Group I and Group II were $96.12{pm}32.00mm^2$ and $372.94{pm}65.63mm^2$ respectively. 2. The right and left wear facet areas of Group I were $46.72{pm}14.36mm^2$ and $49.40{pm}21.46mm^2$ respectively. The right and left wear facet areas of Group II were $175.27{pm}45.75mm^2$ and $185.69{pm}45.37mm^2$ repsectively. 3. The vertical overlap of Group I and Group II was $3.88{pm}0.81mm$ and $2.88{pm}1.14mm $ respectively. 4. Most of the Group I had Canine protection occlusion (80%), and most of the Group II had Group function occlusion (80%). 5. The masticatory muscle activities at rest position, maximum bite, habitual chewing, right and left unilateral chewing were greater in Group II than in Group I, especially in the masseter muscle of working side at right and left unilateral chewing. (P<0.01). 6. The asymmetry of right and left wear facets and masticatory muscle activities were greater in Group II than in Group I. (P<0.01).