Jaw Reflexes Originating from the Periodontal and Muscle Spindle Receptors to the Jaw Muscles

We investigated the jaw reflexes using both the probability- and the discharge rate-based analysis methods. While recording the masseter muscle activity, computer controlled slow-rate “push” and rapid rate “tap” stimuli were delivered to the upper right central incisor before and during local anesthetic block. While preceding local anesthesia, the tap stimuli induced inhibitory reflex responses; during local anesthetic block, the same stimulus induced excitatory and inhibitory reflex responses. The push stimuli generated a combination of inhibitory and excitatory responses that disappeared during the local anesthetic block. We found that the discharge rate-based method was better for indicating the duration of earlier responses and the existence, sign, and duration of later responses.