In order to measure head posture of the working dentists, we have developed a remote measuring device. The purpose of this study is to examine the performance of the device and the availability for the actual daily works. One 2-axes accelerometer was used for the sensor of head movement. The output of the sensor was transported wirelessly with the Bluetooth protocol. The sensor was put on the left ear of a subject by a headphone type attachment. The receiver was connected to a computer and the data was stored directly. The data of the accelerometer was converted to the angle of the head rotation in the computer. The range of the sensor was ±90°with resolution of 0.18°. The axes of the sensor was set as that can measure the front-back bending and side bending movement of the head with sampling rate of 100 Hz. The subject instructed to make a desk work and a dental treatment. The device could be ready for measure within five minutes. The measurable period by one battery was more than two hours. The confirmed effective distance of the transmitter was a range of six meters. By this device we could measure enough period of the dental works and cover the movement range and detect the characteristic head movement of the jobs. With the easiness of preparation and the accuracy, we concluded that this device is available for our purpose.

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Purpose: Methods for analysis of occlusal contacts in the intercuspal position(IP) must be certified their levels of reliability, because the use of them without the knowledge is dangerous for implant patients when their teeth might be changed of their shapes based on false data. In this study, reliability of Add-picture was evaluated from intra- and inter-examiner agreements for detection of occluding teeth in comparison with articulating film, shimstock and silicone-black.
Methods: Subjects were 20 dental students that 278 antagonistic occlusal pairs without clinical mobility and malocclusions and the patient subjects were 10 implant patients. One of two examiners well trained for all methods examined with articulating film and shimstock, and made registrations of silicone-black for five subjects successively. Then the other examiner followed in the same manner. For intra-examiner agreement, whole procedures were repeated once more. Examinations with silicone-black and Add-picture were performed by the same examiners who made registrations.
The data in this study was clearly classified to positive(contact) or negative(no-contact), percent agreement and Kappa statistic were used to analyze inter- and intra-examiner agreements.
Result: In intra-examiner agreements of examiner A and B, silicone-black and Add-picture showed higher levels of agreements than shimstock in Percent agreement and Kappa statistic. Articulating film showed the lowest levels of agreements. In inter-examiner agreements of session 1 and 2, there were not clear differences among the methods in Percent agreement and Kappa statistic, except that articulating film showed the lowest levels of agreements. Proportions of positive agreements were greater than those of negative agreements in all methods and examinations.
Conclusion: Results that shimstock showed higher levels of agreements than articulating film consisted with those of Anderson¹ et al.(1993). Silicone-black and Add-picture showed almost same or little higher levels of agreements with or than shimstock. These results supported that silicone-black and Add-picture could be used as reliably as shimstock for clinical decisions.

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Purpose: There has been a significant number of malocclusion patients who suffer from the osteoarthritis associated with TMJ, and acquired anterior open bites were reported as a representative example. Treatments for patients with malocclusion often prove difficult, as the condyle position is not stable. It remains unknown as to whether this is due to the disease or the condyle position. This case report documents a clinical application of a Digital Gothic Arch Tracer for occlusal diagnosis and subsequent management and treatment of malocclusion with osteoarthritis.
Materials and methods: This case report presents the treatment process of a female patient (51 years, 6 months of age) with an acquired dual-bite malocclusion with severe osteoarthritis in the temporomandibular joint (TMJ). The occlusal condition of the patient was examined by a Digital Gothic Arch Tracer (DGAT, Gothic Display: Shofu Inc.). The GDAT was used as it provides an extra-oral tracing of jaw movements. While it is simple and easy to use, the accuracy remains impressively high, as several jaw motions are included into the final calculation.
Results: The ensuing treatment plan was as follows: Upon the first examination, the occlusal position was recorded with DGAT. The DGAT data was then evaluated for correlations between the terminal points of the rapid habitual opening-closing movements (tapping points), apex point and speaking position. The gothic arch figure revealed that when approaching the terminal points of the tapping points and the speaking position, there was a separation at the apex point. From this, we reached a conclusion on the new occlusal position for tapping points and the speaking position. Based on the DGAT results, via the occlusal adjustment method, we set the new occlusal position. On their final visit the patient received Prosthodontics treatment. The DGAT was able to provide an avenue of examination that maintained the original occlusal position without raising the vertical dimension. Therefore, it was rather simple and exact to compare the Tapping points and Apex points.
Conclusion: Using a Digital Gothic Arch Tracer, we successfully carried out the occlusal examination and treatment of a patient with osteoarthritis and malocclusion.

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The purpose of this experiment was to correspond for the voice security system when the patients wore the dentures. Because the phonetic disorder by the dentures some troubles in the biometric security system with sound recognition, for example, the cash cards, the credit cards and the lock of the doors. But there was few report about the individual recognition by the palatal plates. So we observed the changes of the rates of individual recognition by the palatal plates. The voices of 5 subjects were recorded without the experimental palatal plates and with them. The voice samples were analyzed with the soft for judging the individual recognition rates by the voices. And the rates of individual recognition, the time durations and the pitch curves for every word were observed. By the palatal plates, the rates of individual recognition decreased, the time durations increased, the pitch curves changed little. And by the palatal plates, there were significance (p<0.05) about the rates of individual recognition and the time durations, but there were not significance (p<0.05) about the pitch curves by the two-way layout ANOVA. The frequencies of the pitch curve changed by the vocal chords vibration and affected to the height of the voice. So they did not change by the labial and buccal plates. Therefore they will be able to use for the individual recognition system.

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The aims of this study were to measure the three-dimensional (3-D) loads exerted on the implants supporting an overdenture during function in vivo and to clarify the effect of the number of the implants on the loads. The load-measuring devices were mounted on the implants inserted in the mandible of a 62 aged female subject. Either two or four implants connected with a bar were used for supporting her overdenture. The loads on the implants were expressed three dimensionally as load vectors and were analyzed in the coordinates based on the Frankfort horizontal plane and sagittal plane. The tasks examined were maximum voluntary clenching (MVC) and gum chewing (GC). The total load exerted on the implants with a four-implant supported overdenture (4I-Od) was larger than that with a two-implants supported overdenture (2I-Od) at MVC. The maximum occlusal force on the overdenture showed the same manner (p<0.01). The directions of the loads were posterior and lateral at MVC. The total load exerted on the implants located on the working side, was larger than that on the implants located on the non-working side during GC in the case of 4I-Od. The similar manner was also observed in the 2I-Od. The tensile loads were registered during GC. The functional loads exerted on the individual implants in the case of 4I-Od were smaller than those in the 2I-Od. The loads on the implants during function are thus affected by the number of implants supporting the overdenture.

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