Human mastication modulated by experimental trigeminal and extra‐trigeminal painful stimuli

Abstract

This paper describes the modulation of human deliberately unilateral mastication by trigeminal and extra-trigeminal standardized painful stimuli. Series with 15 s of gum-chewing before induction of pain, during pain and after pain were quantitatively assessed by jaw-closing muscle electromyography (EMG) and kinematics of the lower jaw. Four different painful stimuli were used: cold stimulation of the frontal region, cold stimulation of the dominant hand, capsaicin stimulation of the hard palate, and pressure pain stimulation of the temporomandibular joint (TMJ). Intensity and quality of perceived pain were rated on visual analogue scales (VAS) and McGill's Pain Questionnaires (MPQ). Analysis of the data showed that frontal cold stimulation was the least painful test and was associated with the few^est changes in masticatory function. Cold stimulation of the hand and palatal capsaicin stimulation caused significant increases in peak amplitudes of EMG bursts from all jaw-closing muscles and faster jaw movements w^hereas TMJ pressure pain produced significantly lower peak EMG amplitudes. The present results suggest that nociceptive input from different tissues and even extra-trigeminal regions may modulate trigeminal motor function in selective ways. Thus, clinical observations of changes in masticatory function may not always be due to pain in the orofacial region and therefore do not necessitate orofacial treatment.

Effects of periodontal afferent inputs on corticomotor excitability in humans

“…It is well known that acute orofacial pain can modulate orofacial motor behaviour. For example, in humans, intra‐oral pain has been shown to modulate the EMG activity associated with the jaw‐closing muscles (28) and more recently, noxious stimulation with glutamate to the rat tongue, but not the masseter muscle, can modulate licking behaviour (29). Previously, our group has also shown that rapid changes in cortical excitability of the tongue MI, as measured by TMS, and the gains in motor performance that would otherwise occur in association with novel tongue‐task training were inhibited by capsaicin‐induced tongue pain (30).…”

Adjustment of Occlusal Splint with Synchronized T-Scan III Digital Occlusal Analysis System and Bio-EMG III in a Patient with Sleep Bruxism

“…Before the adjustment of the occlusal splint, the digital evaluation revealed that in the maximum intercuspal position the force of distribution was %40.8 for the right activity in the pain side and the increased EMG activity of the temporalis anterior muscle in the non-pain-side that could be related to the "pain adaptation model." Previously, it has been shown in several clinical studies and in experimental muscle pain studies 13 that a decrease of the EMG activity in the painful muscle and an increase in the EMG activity in nonpainful muscles was found during the dynamic contractions. 14 Lund et al 15 have described the interaction between the muscle pain and muscle coordination with the "pain-adaptation model" that lead to the increased activity of antagonistic muscle and the decreased activity of agonistic muscle during muscle pain.…”