In this study, changes in hemoglobin volumes and oxygen saturation level (StO₂) of human masseter muscles before and after hot pack and Myo-monitor^®application were investigated to clarify whether a Myo-monitor as well as a hot pack can improve blood flow of masticatory muscles. The subjects of this study were healthy volunteers with no history of muscle pain in the masticatory system. The hot pack group consisted of ten subjects who underwent hot pack application, and the Myo-monitor group consisted of ten subjects who underwent Myo-monitor. Hemoglobin volumes and StO₂were measured with a near-infrared spectroscope. The blood flow parameters were total hemoglobin volume (THb), oxygenated hemoglobin volume (OXHb), deoxygenated hemoglobin volume (deOXHb) and oxygen saturation level (StO₂) . Heart rate (HR) was simultaneously monitored using a plethysmograph.
The values of THb, OXHb, deOXHb, StO₂, and HR before and after Myo-monitor application were not significantly different, while THb, OXHb and StO₂after hot pack application were significantly larger than those before hot pack. Percentage of changes in THb, OXHb and StO₂after hot pack application in the hot pack group were significantly larger than those after Myo-monitor application in the Myo-monitor group.
The results suggest that hot pack application is more effective than Myo-monitor in improving masseteric blood flow.

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Although the posture and jaw function has been speculated to relate to each other, little scientific evidence is presented in humans due to lack of recording method. To clarify that, we designed and tested a standard noninvasive, accurate, and repeatable clinical method to record head and trunk posture for hours in freely behaving humans. The system was evaluated by measuring the following tasks successively conducted by five subjects: 1) reading a sheet of text (vertical and horizontal documents) while sitting on a chair, 2) sitting on a chair (in an upright position and freely), 3) walking slowly (in an upright position and freely) in a room, 4) tilting the head (anterior and posterior directions and right and left directions) and 5) turning the head (right and left) while sitting on a chair. Characteristic features were observed in the volunteers performing the reading and head movement tasks. While reading text of vertically lined letters, head movement was in the antero-posterior direction along with the direction of the letters, however, movement was limited when the volunteers read text of horizontally lined letters. During head tilting and turning, head and trunk movement was in the same direction for pitch but in the opposite direction for roll. In conclusion, this system accurately records head and trunk posture individually in human subjects; it is easily operated for clinical use and small enough to sit on the patient's trunk for hours of recording. A potential problem may be its battery consumption; however, current technology may overcome this.

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Evaluation of the function of the temporomandibular joint in healthy children is important. The purpose of this study was to investigate characteristics of condylar movement during lateral excursion in children in consideration of the differences of jaw length and jaw width between children and adults. Eighteen healthy subjects (thirty-six joints total) with normal occlusion were divided into two age groups: early mixed dentition group (4 boys, 5 girls, 8-10 years old, mean 8 years 11 months) and permanent dentition group (2 men, 7 women, 23-28 years old, mean 25 years 9 months) . Jaw movements were measured with 6 degrees of freedom jaw tracking device. Characteristics of condylar movement in children were investigated by three-dimensional condylar path distance during lateral excursion. The lateral excursion was done from the intercuspal position. The distance of condylar path was calculated at 1.0 mm interval from 1.0 to 5.0 mm of incisal path (D100%) . Furthermore, the distance of condylar path was calculated at 0.9 mm interval from 0.9 to 4.5 mm of incisal path (in children only, D90%) in consideration of the differences of jaw length and jaw width between children and adults. The distance between incisal point and anatomical center point of condyle (IP-CP) and the distance between left side anatomical center point of condyle and right side anatomical center point of condyle (LCP-RCP) were significantly smaller in children than in adults. IP-CP and LCP-RCP in children were about 90% of those in adults. The distance of working condylar path was significantly larger in children than in adults when the distance of incisal path was at D100% and D90%. The distance of working condylar path did not show significant correlation with both the jaw length and the jaw width in children. These results suggest that the working condylar movement during lateral excursion in children has higher mobility than that of adults without it is influenced by difference of jaw size between children and adults.

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