A full upper stabilization splint divided into three pairs of occlusal bilateral blocks was made for eight healthy young adult subjects. The three pairs of blocks allowed the location of the centric occlusal contacts to vary and to be distributed over equivalent periodontal surfaces. The electromyographic activity of the masseter and temporal muscles was recorded with surface electrodes during maximum voluntary clenching over the centric occlusal blocks. The electromyographic activity from the elevator muscles with the anterior blocks was significantly less than with the intermediate and posterior occlusal blocks. With use of the intermediate blocks, the activity from the elevator muscles was significantly less than with the posterior blocks. The elevator activity with the posterior blocks was similar to that with the full coverage splint.