Ryosuke Shiba

Increased pain sensitivity of the upper extremities of TMD patients with myalgia to experimentally-evoked noxious stimulation: possibility of worsened endogenous opioid systems.

The purpose of this study was to examine whether or not temporomandibular disorder (TMD) patients with chronic masticatory myalgia have increased pain sensitivity at remote sites outside of the head and neck region, and to evaluate whether the endogenous pain inhibitory systems triggered ischemic pain functions favorably in those patients. Twenty female TMD patients with chronic myalgia and 20 controls participated in this study. Ischemic pain was produced to activate endogenous opioids. The pain threshold time, pain tolerance time, pain intensity and pain unpleasantness were compared between the TMD patients and controls. The pressure pain thresholds in the hand were also compared before, between, and immediately after the ischemic pain. The TMD patients showed higher severe pain intensity and unpleasantness values and had lower pressure pain thresholds in the hand. Although both groups showed an increase in the pressure pain threshold, there was less of an increase in the pressure pain threshold in the TMD patients than in the controls. These findings indicate that TMD patients have increased pain sensitivity at remote sites, and also indicate additional evidence that the endogenous opioid systems may become impaired in TMD patients with chronic masticatory myalgia.

Histochemical and electron microscopical studies on the effect of duct ligation of rat salivary glands

Abstract The effects of duct ligation on the submandibular and sublingual salivary glands were studied by histological, histochemical and electron microscopical methods. Ligation of the main excretory duct led to acute atrophy of both glands within a few days, showing disappearance of mucous secretory granules from acini and luminal dilatation of ducts in which the activity of oxidative enzymes decreased. After prolonged duct ligation, duct and acinar cells of both glands showed extreme atrophy histologically; however, individual cells still contained cellular organelles and low activity of oxidative enzymes for essential vital functions. Moreover, some acinar cells after prolonged ligation revealed regeneration at the periphery of each lobule. Myoepithelial cells showed no reduction of alkaline phosphatase activity throughout the period of ligation.

Differential effects of NMDA and AMPA/KA receptor antagonists on c-Fos or Zif/268 expression in the rat spinal dorsal horn induced by noxious thermal or mechanical stimulation, or formalin injection.

The involvement of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate (KA) receptors in the induction of c-Fos and Zif/268 expression in spinal dorsal horn neurons following noxious thermal or mechanical stimulation, or formalin injection into the rat hind paw was examined by intrathecal administration of a competitive NMDA receptor antagonist, 2-amino-5-phosphonopentanoic acid (APV) or an AMPA/KA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), or both, 30 min prior to noxious stimulation. APV caused a significant reduction in the level of c-Fos expression in the superficial layer induced by each of these three noxious stimuli. The effects of APV on Zif/268 expression or of CNQX on c-Fos or Zif/268 expression in the superficial layer induced by these three noxious stimuli were dependent on the type of stimulus applied to the rat hind paw. The noxious thermal stimulus-evoked c-Fos expression level was reduced by APV and/or CNQX, while Zif/268 expression was hardly changed. Both c-Fos and Zif/268 expressions following formalin injection were reduced by APV alone and APV+CNQX, but not by CNQX alone. Zif/268 expression following noxious mechanical stimulation was significantly reduced only by APV+CNQX although APV or CNQX alone did not affect the expression, while c-Fos expression was reduced by APV and APV+CNQX but not by CNQX alone. These findings suggest that NMDA and AMPA/KA receptors are differentially involved in c-Fos and Zif/268 expression in the spinal dorsal horn following noxious thermal, formalin and mechanical stimulation.

Traumatic myositis ossificans in the masseter muscle

Traumatic myositis ossificans in the left masseter muscle of a 25-year-old man is described. The lesion, which extended intramuscularly from the lateral surface of the zygomatic bone to the mandibular angle, was resected by an intraoral approach. The specimen was composed of mature cortical bone in the outer portion and spongy bone, including degenerated muscle fibers and marrow spaces, in the inner portion. At the lower end of the specimen was a sequence of bone formation involving fibrous connective tissue, cartilage, woven bone, and mature lamellar bone with many osteoblasts. Clinicopathologic features of 26 reported cases of traumatic myositis ossificans of the maxillofacial region are reviewed, and the pathogenesis of the disease is discussed.

Morphological evaluation of changes in velopharyngeal function following maxillary distraction in patients with repaired cleft palate during mixed dentition.

Objective To describe the morphological changes of nasopharyngeal components after maxillary distraction and clarify whether the morphological characteristics are related to velopharyngeal function (VPF). Design Perceptual judgments of hypernasality and nasendoscopy were performed before and after treatment. Lateral cephalograms were obtained to describe the morphological changes. Setting Department of Oral and Maxillofacial Surgery, Miyazaki Medical College, Miyazaki, Japan. Participants Nine patients with repaired cleft palate in the mixed dentition stage underwent maxillary distraction using a face mask and an intraoral fixed appliance system. Outcome Measures The severity of hypernasality, velopharyngeal insufficiency, and measurements such as pharyngeal depth, velar length, and the rotation of the palatal plane were evaluated. Results Increase in pharyngeal depth was not always proportional to the amount of advancement. It depended on the posture of the posterior pharyngeal wall and the rotation of palatal plane. Conclusion Cephalometric measurements of the nasopharynx before and after surgery confirmed subsequent changes in VPF. These were suggested to be useful in predicting future VPF. When performing maxillary distraction in patients with cleft palate in the mixed dentition stage, and when velopharyngeal closure is found to occur by velar contact against the hypertrophied adenoid, patients should be counseled about risks of subsequent deterioration in their speech before surgery.

Differential expression of Fos protein after transection of the rat infraorbital nerve in the trigeminal nucleus caudalis.

To determine the effects of nerve injury on Fos expression, temporal and spatial distributions of Fos-positive neurons in the trigeminal nucleus caudalis were examined after tissue injury for isolation of the infraorbital nerve as controls and transection of this nerve as well as noxious chemical stimulation by formalin injection in adult rats. Fos immunoreactivity was markedly elevated in laminae I and II of the only ipsilateral nucleus caudalis 2 h after these surgical procedures and noxious chemical stimulation. The distributions of Fos-positive neurons were restricted rostro-caudally following formalin injection and tissue injury compared to transection of the infraorbital nerve. One day after tissue injury and nerve transection, however, Fos-positive neurons were distributed bilaterally in laminae III and IV extending rostro-caudally and medio-laterally in this nucleus, and this persisted over the 2-week study period. The number of Fos-positive neurons in the side ipsilateral to nerve transection was markedly less than that in the contralateral side whereas positive neurons in the tissue injured rats were distributed symmetrically along the rostro-caudal axis. There was no difference in the contralateral sides between nerve transection and tissue injury groups. The rostro-caudal level showing reduction in Fos expression corresponded roughly to the sites of central termination of the injured nerve in this nucleus, suggesting a role for the primary afferents in the reduction of Fos expression in laminae III and IV neurons of the ipsilateral nucleus caudalis.

Primary neck management among patients with cancer of the oral cavity without clinical nodal metastases: A decision and sensitivity analysis.

A standardized neck management strategy for oral cancer patients without clinical nodal metastases remains to be established. Consequently, a decision and sensitivity analysis of two neck management protocols, involving either prophylactic neck dissection or careful observation, was conducted using the Oral Cancer Registry of Kyushu, Japan.

A cephalometric study by multivariate analysis of growth of the bony nasopharynx in patients with clefts and non-cleft controls

To clarify the characteristics of growth of the nasopharynx, comparison of the cephalometric growth of bones surrounding nasopharynx between 61 patients with complete unilateral cleft lip and palate (UCLP group) and 82 non-cleft controls (NCC group) was carried out. All of the subjects were divided into four developmental stages (i.e. stage 1 at 4 years of age, stage 2 at 8 years of age, stage 3 at 12 years of age and stage 4 at 17 years of age). Measurements on the antero-posterior and the vertical dimensions were derived from a coordinate system and points on bones surrounding the nasopharynx on lateral X-ray cephalograms, and results were analyzed by multivariate analysis and t-test. The results showed that (a) the posterior maxillary point (PMP) in the UCLP group was located more postero-superiorly than that in the NCC group, and this was the main factor that allows discrimination between the two groups and (b) the cranial base, posterior maxilla and the cervical vertebrae were found to be in independent in growth, however, the nasopharyngeal triangle connecting three points on these three bones (Ho: cranial base; PMP: posterior maxillary point; At: atlas) showed harmonious growth in both the UCLP and NCC groups.

Experimental and clinical studies of local application of solid and oil bleomycins for the treatment of oral cancer

Summary Local application of solid and oil bleomycins (BLMs) for the treatment of oral cancer was evaluated in experimental and clinical studies. Topical application of the BLMs resulted in high BLM levels in tumour tissues, especially, in metastatic lymph nodes. Clinically, the primary effects of the BLMs were good, and the 3-year end results were very favourable. It is most probable that the use of oil BLM will be included in the treatment plan for metastatic tumours in lymph nodes.

Measurement of Muscle Hardness Using a Hardness Meter: Application to the Masseter and Temporal Muscles and Reproducibility of Measurement

ABSTRACT This study was designed to evaluate the intra-examiner and inter-examiner reliability of measurements of masticatory muscle hardness and to confirm that the muscle hardness increases with contraction using a commercially available muscle meter. Twenty healthy asymptomatic female subjects participated in this study. Hardness was expressed as numerical relative values (0–100). First, muscle hardness was measured at a standardized point located in the masseter muscle and temporal muscle in a randomized order by two examiners, and again by one of the same examiners after ten minutes for the reproducibility study. Then the muscle hardness was measured at each point for 0 kgf, 3 kgf, 6 kgf, and 9 kgf levels of bite force. As a result, intradass correlation coefficient (ICC) analysis revealed good intra-examiner reliability in the masseter muscle (ICC = 0.711), good intra-examiner reliability in the temporal muscle (ICC = 0.643), good inter-examiner reliability in the masseter muscle (ICC=0.631), and unacceptable inter-examiner reliability in the temporal muscle (ICC = 0.008). Also, our results showed that muscle hardness increased with contraction, and relationships with a slope of 1.229, a y-intercept of 62.513, and a correlation coefficient of 0.448 were observed in the masseter muscle. However, no correlation was found between muscle hardness and bite force in the temporal muscle. The findings indicate that measurement of hardness provides reliable physiological information about the masseter muscle in this setting.