Oromandibular dystonia is characterized by sustained muscle contractions of the face, jaw, and/or tongue that cause difficulty in opening and closing the mouth, and often affects chewing, swallowing and speech, possibly leading to trismus and clenching. The etiology of oromandibular dystonia is varied and includes genetic predisposition, central nervous system injury, peripheral trauma, medication, metabolic or toxic state, and neurodegenerative disease. First-line treatment for oromandibular dystonia is botulinum toxin, and approximately 60% of treated patients experience improvements in chewing and speech after injection into the masseter, temporalis, or lateral pterygoid muscles. Furthermore, other medications are used, such as anticholinergic drugs, benzodiazepine, and anticonvulsants. Oromandibular dystonia may respond to sensory tricks to temporarily reduce symptoms, such as gently touching the lips or chin, chewing gum, talking, biting on a toothpick, or placing a finger underneath the chin may cause symptoms to temporarily subside, and which is accompanied by the modulation of sensorimotor cortex activities, as well as application of botulinum toxin. Affected patients with oromandibular dystonia may present psychiatric symptoms, such as depression, anxiety, obsessive-compulsive disorder, schizoid personality, space phobia, and other psychological abnormalities, and the psychological profile may further confuse the clinician and confound the diagnosis. Our recent findings show that treatment by injection of botulinum toxin into persistently contracted oromandibular and maxillofacial muscles in patients with idiopathic oromandibular dystonia is valid to alleviate not only the dystonic muscle activities, but also pain awareness and psychiatric mood states. The purpose of this review is to provide a basis for a comprehensive understanding of oromandibular dystonia.

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Silicone materials are generally considered clinically useful for occlusal contact examinations. Recently, Blue Silicone^® (BS) made from addition cure silicone rubber for occlusal contact examinations and BiteEye BE-I^® (BE-I) as a dental occlusion analyzer designed for use with BS, have been developed and make simple quantitative evaluations of occlusal contact possible. To elucidate the reliability of occlusal contact examinations by using BS, occlusal contacts were recorded using BS for 12 individuals (7 men and 5 women) on five different days and the day-to-day reliability was calculated by the results analyzed with BE-I. All 12 subjects were free of pain in the head and neck region (suggestive of temporomandibular disorders) and of abnormalities in the oral cavity with complete dentition. We obtained the following conclusions: 1. While gradually increasing the visual levels using BE-1 resulted in reductions of the occlusal contact area, the number of occlusal contact points tended to remain constant up to 30 μm, and increased those over 30 μm. 2. For anterior teeth, when comparing occlusal contact analysis from the maxillary side and from the mandibular side, the latter showed significantly greater occlusal contact areas. 3. The coefficients of reliability for occlusal contact areas obtained with lower bite force were 0.7 or better for anterior teeth and 0.8 or better for other teeth areas, indicating that this material presents sufficient stability for use in clinical settings. However, the coefficients of reliability for the number of occlusal contact points varied significantly and were lower than the coefficients of reliability for occlusal contact areas. The latter result suggests the need for further consideration when interpreting the examination results.

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Tumor necrosis factor-α (TNF-α) is a key inflammatory mediator in the temporomandibular joint (TMJ) exhibiting internal derangement. In this study, an antibody array was used to study the TNF-α-stimulated protein production profile of synovial fibroblasts. Synovial fibroblasts were prepared using the outgrowth method from the tissues of patients suffering from internal derangement of the TMJ. The synovial cells were stimulated by TNF-α for 4 hours, and the release of chemokines into the supernatant was determined using a human chemokine antibody array. The result of the antibody array indicated that TNF-α had a net stimulatory effect on chemokine levels. A total of seven chemokines were significantly upregulated, and the expression of these genes was analysed by a real-time polymerase chain reaction. Following stimulation with TNF-α for 2, 4, or 8 hours, expression of the seven chemokine genes was upregulated compared with untreated controls. These results suggest that TNF-α-induced chemokine production may be responsible for the inflammation associated with internal derangement of the TMJ.

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The clinical status of patients with masticatory muscle tendon-aponeurosis hyperplasia has not been fully elucidated and there is no established treatment for the disease. In this study, we examined treatment procedures used for such patients who underwent surgery in our department. From 2008 to 2013, we performed operations for 7 affected patients (3 males, 4 females; 17-35 years old) and measured the range of mouth opening before, during, and after the operation. All of the cases showed a significant increase in the range of mouth opening as compared to the pre-surgery measurement. In addition, the range of mouth opening was maintained for 6 months after the operation in patients who received training, whereas that was reduced in patients who did not undergo training. Our findings suggest that post-operation mouth opening training is important to maintain the increased range gained from surgery.

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To treat temporomandibular joint ankylosis, temporomandibular joint mobilization is generally performed, adopting an extraoral approach. In this study, we performed right coronoidectomy and lower temporomandibular joint mobilization, adopting an intraoral approach, to treat temporomandibular joint ankylosis due to malunion after a condylar process fracture, and achieved a favorable postoperative course; 1 year and 6 months after surgery, the range of mouth opening was 38 mm with the absence of pain. A panoramic X-ray and 3-dimensional CT images confirmed bone resorption and pseudarthrosis formation at the osteotomy stump, and there was no bone interference when opening the mouth. The results of this study suggest that temporomandibular joint mobilization adopting an intraoral approach may be an appropriate treatment choice in cases of extensive osseous ankylosis and coronoid process elongation in the medial part of the mandibular condyle. Furthermore, in order to prevent readhesion, it may be necessary to actively provide mouth-opening training after surgery.

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