Aim: To investigate the effect of chewing on body sway in patients wearing a dento-maxillary prosthesis.
Materials and Methods: The subjects were 17 patients who wore a dento-maxillary prosthesis after head and neck tumor resection. They were divided into two groups: maxillary prosthesis wearers （Group 1, 11 subjects） and mandibular prosthesis wearers （Group 2, 6 subjects）. Body sway while standing with eyes closed was measured by a computerized footboard in a static jaw position （habitual occlusal position with prosthesis） and a dynamic jaw position （gum chewing with prosthesis）. The environmental area, right-left distance, anterior-posterior distance, and total length of body sway were calculated and compared between the two jaw positions in each group by the Wilcoxon signed-rank test.
Results: The environmental area of body sway was significantly smaller in the dynamic jaw position than in the static jaw position in Group 1 （P＜0.033）. There was no significant difference in any of the body sway indices between the two jaw positions in Group 2.
Conclusions: Body sway tended to decrease during gum chewing in patients wearing a dento-maxillary prosthesis attached to the maxilla but not attached to the mandible.