The term of psychosomatic disorder in dentistry implies a variety of medically unexplained, functional symptoms related to the orofacial region. While most of these symptoms may be closely related to somatization of mental illness such as depression, anxiety disorder and somatoform disorder, excessive and inappropriate dental treatments are likely to be given to psychosomatic patients in a dental clinic. In particular, oral cenestopathy (bizarre, unpleasant sensation in the oral cavity) is a refractory, chronic syndrome that may be attributed to a hallucinatory symptomatology of psychotic disorder. Dentists are required to be aware of somatization symptoms in the orofacial region and consider informed consent of patients lacking organic etiology in regard to risks of dental treatments and consultation to psychiatrists.

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The purpose of this experiment was to develop a brain blood flow analysis system using a near infrared spectroscopy (NIRO300^®) in order to clarify the effect of masticatory movement and other bodily movements on the brain blood flow.
Three healthy males (26, 32, 36 years old) were asked to perform masticatory movement, finger tapping movement and opening and closing of the hand movement for 30 seconds each, and the masseter muscular activity and brain blood flow were simultaneously recorded by EMG and near infrared spectroscopy respectively. A computer program able to detect changes in masseter muscular activity and brain blood flow was developed. The measuring probe for blood flow, with the distance between irradiating part and detecting part of 4cm, was placed on the scalp over the cortical masticatory area where the responses to both the opening and closing movement of jaw and the finger movement were maximum. After these preparations, in order to confirm the setting position of the probe, a plastic capsule was placed at the mid-point between the irradiating part and the detecting part and MRI was performed. From the MRI it was confirmed that the midpoint between the irradiating part and the detecting part was set on the scalp of the area related to the movement. Also, it was possible to record and observe the masseter muscular activity and the changes in the blood flow for all subjects. The brain blood flow increased for all movements and the amount of increase was the greatest for the masticatory movement, followed by the finger tapping movement and by the opening and closing of the hand movement. Furthermore, it was found that the increase of blood flow could be quantitatively measured.
The brain blood flow analysis system developed in this experiment was able to evaluate both visually and quantitatively the changes in the brain blood flow related to masticatory movement and other bodily movements.

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There are two types of adjustable articulators, the Arcon and Condylar. The guiding systems are located on the upper member of the Arcon type articulator and on the lower of the Condylar type articulator. The movement of the articulators are different when the articulator settings on the adjustable mechanisms of both articulators are the same in the reproduction of lateral movements. In addition, when the movements of both articulators are the same, the articulator settings are different.
In the present study, we have focused on the effects of the guiding systems on the movement of the articulators. In order to evaluate the difference between type I and type VIII articulators (type I: which has the Arcon type guiding system on the upper member, type VIII: which has the Condylar type guiding system on the lower member), we calculated the lateral movements of both articulators by using a mathematical formulae.
The results are as follows:
When we apply the same articulator settings of the average lateral movement to both articulators, the largest difference takes place on the horizontal projective angle of the non-working side condylar guidance at 2.8°, whereas the smallest difference is observable on the sagittal projective angle of the non-working side condylar guidance at 0.6°. The three-dimensional discrepancies between both articulators are almost the same on the condylar and tooth pathways at about 0.15mm. This difference is explained by the three-dimensional rotation occurring during the lateral movement. Therefore, the difference between both articulators is affected by the articulator settings of the adjustable mechanisms.

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The purpose of this experiment was to clarify the most suitable chewing time for evaluating the masticatory efficiency of gumi jelly chewing.
Twenty healthy subjects in their twenties, 10 males and 10 females, average age 25.2, who were aware of their habitual chewing side and had neither systemic nor masticatory abnormalities, were selected. Informed consent was obtained after the general nature of the study had been explained to the subjects. The test bolus was a cylinder shaped gumi-jelly, 1.5cm in diameter and 0.8cm in height, weighing approximately 2g. The amount of glucose extraction while chewing gumi-jelly for each of 5, 10, 15, 20 and 25 seconds (5 sessions) was calculated by using a glucosemeasuring device. First, the relation between the chewing time and the amount of glucose extraction was investigated. Next, the amount of glucose extraction for each session was converted to the amount that would be released in 25 seconds of chewing, and was standardized to the average of the five sessions, and the results were compared among each other.
The amount of glucose extraction of each session increased as the chewing time increased and a highly significant correlation was found (r=0.873, p<0.01) . The average value of the amount of glucose extraction after standardization was close to one for every session, and the standard deviation was also small. The coefficient of variation of the amount of glucose extraction for each session was smallest for the 15-second session, and increased in the order of 20 sec, 10 sec, 25 sec, and 5 sec. The value for the 20-second session was very close to that of the 15-second session.
From these results it was suggested that the amount of glucose extraction during gumi jelly chewing increased in relation to the amount of masticatory work done, and that the suitable chewing time for evaluating the masticatory efficiency in gumi jelly chewing was 15 or 20 seconds.

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This study was conducted to investigate the functional change of auditory path way stemming from jaw position. Therefore, we measured tympanogram and distortion product otoacoustic emission in closed position and canine apical position (lateral position) of 11 healthy subjects, and reviewed a functional change of auditory pathway by mandibular lateral move.
1. The incisal point moved 0.8 (1.1) mm in sagittal direction (X), 3.8 (0.9) mm in lateral direction (Y), 2.8 (1.3) mm in vertical direction (Z) . In the condyle point, working side (WS) moves 0.2 (0.3) mm in front direction, 0.3 (0.3) mm in outside direction, 0.3 (0.5) mm in a downward course. The inclination of sagittal condyle path was 23.7 (59.3) °, lateral condyle path was -4.7 (63.1) °. The non-working side (NWS) moved 2.9 (1.2) mm in front direction, 0.5 (0.4) mm in an inside direction, 3.3 (1.3) mm in a downward course. The inclination of sagittal condyle path was 49.6 (6.8) °, lateral condyle path was 9.6 (7.0) °.
2. In tympanogram, WS showed significant decline in IMP, but the difference was not recognized in PRS and EAC. The difference was recognized in neither in NWS for this.
3. A DP level of lateral position showed significant degradation at 2000Hz and elevation at 5031Hz in WS. On the other hand, it recognized a significant rise at 1250Hz and 5031Hz, degradation at 2000Hz in NWS. The change was not accepted with other frequency.
4. Correlation with quantity of displacement to lateral position and quantity of DP level change is accepted. In incisal point, positive correlation was accepted between Z and 1250Hz, between Y and 2000Hz, negative correlation was accepted between Z and 2531Hz, 5031Hz in WS. However, the significance was not recognized in all measured value in NWS. At condyle point, positive correlation was accepted between inclination of lateral condyle path and 2531Hz in WS, but the reference was recognized in neither between other measured value.
From these results, it was suggested that mandibular position had an influence on auditory pathway, the change on auditory pathway was recognized in the response threshold of a DP level.

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Swallowing function was investigated in 5 oral cancer patients who underwent secondary unilateral radical neck dissection. The test food consisted of 10 ml liquid. Evaluation of the swallowing function was examined at preoperatively and 1 month and 6 months postoperatively. The evaluation was examined about the position of the hyoid at rest, the most elevated position of the hyoid, pharynx passage time and the degree of maximal opening of the esophageal entrance during swallowing with the picture analysis equipment.
1. There was no postoperative change in the position of the hyoid at rest.
2. There was no postoperative change in the most elevated position of the hyoid during swallowing.
3. There was no postoperative delay in pharynx passage during swallowing.
4. There was no postoperative reduction in the degree of maximal opening of the esophageal entrance during swallowing.
Our findings suggested that after unilateral resection of the anterior and posterior bellies of the digastricus and omohyoideus muscles, there was no deterioration of the movement of the hyoid and the opening of the esophageal entrance during swallowing.

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