Periodontal mechanoreceptors and bruxism at low bite forces.

OBJECTIVE: In this study, we examined if 6-9 Hz jaw tremor, an indirect indicator of Periodontal Mechanoreceptor (PMR) activity, is different in bruxists compared to healthy participants during production of a low-level constant bite force. METHODS: Bite force and surface EMG from the masseter muscle were recorded simultaneously as participants (13 patients, 15 controls) held a force transducer between the upper and lower incisors very gently. RESULTS: Tremor in 6-9 Hz band for bruxists was greater on average compared to controls, but the difference was not significant, both for force recordings and EMG activity. CONCLUSIONS: The low effect sizes measured with the current protocol contrast highly with those of our previous study, where larger, dynamic bite forces were used, and where jaw tremor was markedly different in bruxists compared with controls. SIGNIFICANCE: We have now gained important insight into the conditions under which abnormal jaw tremor can be elicited in bruxism. From a scientific standpoint, this is critical for understanding the 'abnormality' of PMR feedback in bruxism. From a clinical perspective, our results represent progress towards the development of an optimal protocol in which jaw tremor can serve as a biological marker of bruxism.