Differential chewing function with removable partial dentures (RPDs) and fixed prostheses supported by the single-crystal sapphire implant was evaluated in five subjects with Kennedy Class II partially edentulous mandibles by means of electromyography. Rehabilitation with the single-crystal sapphire implant resulted in regular chewing patterns with a low variation coefficient and higher activity of chewing-side masticatory muscles compared to RPD rehabilitation. This difference in chewing function between the two rehabilitation modalities could be the result of differences in stability of occlusion and neurophysiologic feedback systems.