The possible role of periodontal mechanoreceptors in the control of parotid secretion in man.

In man, parotid flow has been recorded bilaterally using modified Lashley cups in response to mechanical stimulation of the teeth. The stimulus was defined and controlled by monitoring the rectified and integrated masseter electromyographic activity (e.m.g.) during repeated clenching on closely fitting bite-blocks placed between the molar teeth. Unilateral clenching on a bite-block resulted in a greater flow from the ipsilateral than the contralateral gland, and both exceeded the control values. There was also a positive correlation between the masseter e.m.g. activity and ipsilateral parotid flow. Parotid flow was also recorded before and during local anaesthesia of various intra-oral branches of the trigeminal nerve. Anaesthesia of two to three inputs always produced significant reductions in ipsilateral flow, but anaesthesia of a single input was not always effective. These results provide evidence in support of the hypothesis that intra-oral mechanoreceptors, particularly periodontal mechanoreceptors, are involved in the masticatory-salivary reflex.