Masseteric post-stimulus EMG complex following mechanical stimulation of osseointegrated oral implants

Periodontal receptors can be located in the periodontal ligament itself, the alveolar bone, the periosteum and the gingiva. The aim of the present study was to quantify the contribution of the periodontal ligament receptors in eliciting a reflex response in human masseter muscles. Surface EMG recordings were made in 17 human subjects, fully or partially edentulous, and all provided with osseointegrated oral implants ad modum Brånemark. They maintained a constant clenching level. Mechanical stimulation of an oral implant in the upper central incisor region failed to elicit a reflex in fully edentulous subjects with oral implants in both jaws. The absence of a reflex response strongly suggests that the receptors in the periodontal ligament itself are mainly responsible for the reflex. Stimulation of the same area in subjects with oral implants in the upper jaw and natural teeth in the lower jaw elicited a reflex response in most subjects. Since they were instructed to clench in full habitual occlusion, transmission from the stimulated area to periodontal receptors of natural teeth is very probable.