Isfahan University of Medical SciencesDental Research Journal1735-33271120080113Effect of Changes in Vertical Dimension of Occlusion on Electromyographic Activities of Masticatory Muscles in Denture Wearers88FarahnazNejatidanesh. drj@dnt.mui.ac.irOmidSavabi Esfahani20101106Introduction The occlusal vertical dimension changes influence activity and tonocity of orofacial and masticatory muscles. Thus, the function and esthetic of the edentulous patients are affected by these changes. In this study, the effects of changes in vertical dimension on electromyographic activities of masticatory muscles were evaluated. Methods & Materials Complete dentures were constructed for 10 edentulous patients. The mandibular dentures were duplicated to change the vertical dimension. Electromyographic activities of right masseter and temporal muscles were recorded in three vertical dimensions: (1) V DO, (2) VDO+4mm, and (3) VDO-4mm. The selected functions were maximum voluntary clenching, chewing, swallowing and phonetics. One way ANOVA was used for data analysis. Results Mean integrated electromyographic activity was more in proper occlusal vertical dimension in different functions. There was no significant difference between the three groups. Discussion The results showed that the immediate and few changes of vertical dimension is ineffective in electromyographic activities of masticatory mucsles. Key words Vertical dimension,Electromyography, Complete denture.