Influence of periodontal receptors on the jaw-jerk reflex amplitude in man

To study the role of periodontal mechanoreceptors in the modulation of the human jaw-jerk reflex, 60 reflexes were elicited in each of six healthy ind ividuals under three different conditions: (a) with unilateral tooth suppor t on the ipsilateral side; (b) with support on the contralateral side; and (c) with support and local anesthesia of the periodontal tissues on the ips ilateral side. During all conditions, background muscle activity and mandib ular displacement were kept as constant as possible. Using on-surface EMG a nd the amplitude of the first peak of the biphasic jaw-jerk potential as th e outcome variable, a condition-dependent reflex amplitude was found for th e visually controlled right anterior temporalis muscle. Specifically, the ' ipsilateral support plus anesthesia' condition yielded higher amplitudes th an the 'ipsilateral support' condition. Highest amplitudes were found for t he 'contralateral support' condition. It was concluded that periodontal mec hanoreceptors on the ipsilateral side have an inhibitory effect on the jaw- jerk reflex amplitude in the anterior temporalis muscle.