Current pain classifications use 1.0-kg palpation of the masseter muscle to distinguish between “pain patients” and “healthy controls” but a thorough understanding of the normal physiological responses to various somatosensory stimuli is lacking. The aim of this study was to investigate somatosensory function of the skin over the masseter muscle in healthy participants that were divided into a masseter pain prone group (MPP) (n = 22) and non-MPP group (n = 22), according to the response to a 1.0-kg palpation. Quantitative sensory testing (QST) was performed at the skin above the right masseter muscle (homotopic). In an additional experiment, 13 individuals each from MPP and non-MPP received application of 60% topical lidocaine tape to the skin over the masseter muscle for 30 min. Immediately after, mechanical pain sensitivity (MPS), dynamic mechanical allodynia, and pressure pain threshold were tested. Homotopic MPS was significantly higher and PPTs significantly lower in MPP than in N-MPP (P < 0.05). Strikingly, no other differences in QST outcomes were observed between the groups (P > 0.05). After lidocaine application, no significant differences in homotopic MPS were observed between groups. The presence or absence of acute provoked pain in masseter muscle is exclusively associated with differences in homotopic MPS which is decreased following topical anesthesia.

Standardized palpation of the temporalis muscle evoke referred pain and sensations in individualswithout TMD.

Although the effects of sustained jawclosing activities on somatosensory sensitivity and fatigue have been investigated, the effects of sustained jawopening activities on somatosensory sensitivity in the masticatory muscles remain unclear. Therefore, this study aimed to investigate the effects of sustained jaw opening (e.g. during dental treatment) on fatigue, pressure pain sensations, and stiffness in the masticatory muscles.A total of 35 healthy volunteers performed 30 minutes each of two jaw motor tasks, with a 1week interval between tasks: unassisted jaw opening and jaw opening assisted by a mouth prop set at the right tooth. The pressure pain threshold (PPT) and muscle stiffness of the left masseter were measured before and after both jaw motor tasks (at 0 and 30 minutes) . Masticatory muscle fatigue was measured every 10 minutes (at 0, 10, 20, and 30 minutes) during each jaw motor task.No significant differences in the PPT were found between before and after the assisted jawopening task, but the PPT was significantly lower after compared with before unassisted jaw opening (P < 0.05) . No significant differences in left masseter muscle stiffness were found between any measurement point in either jaw motor task. Masticatory muscle fatigue was significantly higher after 10, 20, and 30 minutes of each jaw motor task compared with that at baseline (0 minutes) . However, no significant differences in masticatory muscle fatigue were found at any measurement point between both jaw motor tasks.The present results suggest that sustained jaw opening during dental treatment may affect pressure pain sensations in the masticatory muscles. In addition, masticatory muscle pain due to sustained jaw opening seems to be affected not only by jawopening but also jawclosing muscle (masseter muscle) .

Background Studies addressing the training‐induced neuroplasticity and interrelationships of the lip, masseter, and tongue motor representations in the human motor cortex using single syllable repetition are lacking. Objective This study investigated the impact of a repeated training in a novel PaTaKa diadochokinetic (DDK) orofacial motor task (OMT) on corticomotor control of the lips, masseter, and tongue muscles in young healthy participants. Methods A total of 22 young healthy volunteers performed 3 consecutive days of training in an OMT. Transcranial magnetic stimulation was applied to elicit motor evoked potentials (MEPs) from the lip, masseter, tongue, and first dorsal interosseous (FDI, internal control) muscles. MEPs were assessed by stimulus–response curves and corticomotor mapping at baseline and after OMT. The DDK rate from PaTaKa single syllable repetition and numeric rating scale (NRS) scores were also obtained at baseline and immediately after each OMT. Repeated‐measures analysis of variance was used to detect differences at a significance level of 5%. Results There was a significant effect of OMT and stimulus intensity on the lips, masseter, and tongue MEPs compared to baseline (p < .001), but not FDI MEPs (p > .05). OMT increased corticomotor topographic maps area (p < .001), and DDK rates (p < .01). Conclusion Our findings suggest that 3 consecutive days of a repeated PaTaKa training in an OMT can induce neuroplastic changes in the corticomotor pathways of orofacial muscles, and it may be related to mechanisms underlying the improvement of orofacial fine motor skills due to short‐term training. The clinical utility should now be investigated.