Dr. Adams' Alabama Headache Blog

The vertical dimension of occlusion (VDO) which achieves the highest isometric strength of sternocleidomastoid muscles (SCMs) has been determined in complete denture patients. The purpose of the present day study was to investigate the effect of this VDO on electromyographic (EMG) activity of the masseters in complete denture patients using the Davicon M44 Dual EMG. Seventeen complete denture patients with complete upper and lower dentures for at least one year, no history of physical trauma to the head and neck, no untreated chronic illness and no cervical symptoms require treatment in the past 5 years were selected for this study. Patients were seated in an upright position and instructed to resist a horizontally transmitted force applied until resistance failed. The load was recorded under five conditions: rest position, biting on existing denture, bting on wooden blocks (2, 6 &10 mm) increasing the VDO 2mm) increasing the VDO 2 mm, 6mm and 10 mm respectively. On the second visit, bilateral electrodes were applied to the masseter muscles with 2 active electrodes in parallel with the muscle fibers. The subjects were instructed to bite as hard as possible on the existing denture and peak EMG activity was recorded in microvolts. An acyrlic resin layer was then fitted over the lower denture of each subject to add height on the existing denture. This height was determined from the maximum isometric strenth of the SCM muscle. The data was analyzed using the student's t-test. The results showed a statistically significant difference in the mean EMG activity or the right masseter muscle between the maximum clench on existing denture and maximum possible clench on the increased VDO which achieved peak isometric of the SCM muscle. The mean EMG activity of the left masseter maximum clench on an increased which achieved peak isometric strength of the masseter muscle. In conclusion, the vertical dimension of the occlusion which achieved maximum isometirc strength of the SCM muscles has a significant effect on the electromyo-graphic activity of the masseter muscles in complete denture patients.