In recent years, various kinds of sports populations of youths and elders are dramatically increasing. In order that these support population can participate in a sport more happily and more safely, we have to take the safety measures for preventing serious injury of the oral maxillofacial region. Especially, for contact sports, mouth-guards, shoulder pads, leg-guards, tapings are need to be equipped as a protector for traumatic injury, It was reported that mouth-guards were useful not only to prevent injury, but to improve sport capability, and a relationship between the physiological function of the oral maxillofacial region and physical activity came to attract attention. In this paper, I will discuss the present status and the future view of sports dentistry, such as the efficacy of mouth-guards and occlusal relation on physical capability, based on the previous scientific reports and articles related to sports dentistry.

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The purpose of this study is to assess what might be diagnostic of the Naxi dental characteristics and to demonstrate the ethnic relationships of the Naxi among Asian populations. Plaster models were taken from 80 male and 80 female students, 16 to 19 years of age, of the Naxi tribe middle high school in Lijiang, Yunann, China. Nineteen nonmetrical traits of tooth crown were classified using the Arizona State University Dental Anthropological System and counted with the individual count method. The frequencies of 19 traits in the Naxi were compared with those of 24 East Asian populations. Nine crown traits that indicated high frequencies were UI1 Shoveling, UI1 Double-shovel, UC Canine medical ridge, LP2 Premolar lingual cusp variation, U and L1,2 Odontome, LM1 Deflecting wrinkle, LM1 Protostylid, LM1 Cusp5 and LM2 4-Cusp. Those showing low frequencies were UI1^2 Winging, UI2 Interruption groove, UC Tuberculum dentale, UC Canine distal accessory ridge, UM1 Cusp 5, UM1 Carabelli's trait, LM1 Distal trigonid crest, LM1 Cusp 6 and LM2 Y groove pattern. On comparing the eight crown traits that indicated significant differences between Sinodonts which is typical of Northeast Asia, and Sundadonts which is typical of Southeast Asia, the Naxi tribe had three Sinodont-like traits: Double-shovel, Cusp 5 and Y groove pattern, and four Sundadont-like traits: Winging, Shoveling, Deflecting wrinkle and 4-Cusp. Two major clusters were found by cluster analysis on Ward method among the 25 East Asia populations including the Naxi tribe, based on the 19 crown traits. The one macro-cluster contains all northern peoples and Naxi (Sinodonts), and the other all Southeast Asia and Jomon (Sundadonts). The Sinodonty cluster was divided into two subclusters, one was the Han, Japanese and the south China group, and the other the Chaoxian, the Man and the Da furs group including the Naxi. The multidimentional scaling analysis showed that the Naxi tribe was distant from the Sundadonts and closed to the Dufurs, the Chaoxian, the Man and the Yami. The Naxi tribe showed affinities, in terms of nonmetric crown traits, with Northeast Asians rather than with Southeast Asians. The Naxi tribe was the closest to the Da furs among the populations compared here.

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To examine the involvement of calcium channel in the regulation of uptake at synapse and retrograde axonal transport of exogenous materials, we measured the amount of retrograde transport of horseradish peroxidase (HRP) in the masseter motoneuron of the rat administered with calcium channel modulators. A mixture of HRP and one out of L-, P- or N-type calcium channel modulators was injected into the rat masseter muscle. After a survival period of 6 hours, 60μm serial cross cryosections of the brainstem were prepared and processed for the HRP reaction. The amount of HRP reaction products in the masseter motoneuron was quantitatively measured using an image processing system. In the animal administered with the P-type calcium channel antagonist, the amount of HRP reaction products was changed and significantly lower than that in the control one without administration of the antagonist. Other three modulators did not affect the amount of HRP reaction products. These results were discussed with the hypothesis that HRP uptake at the synapse of motoneuron is coupled to the recycling process of transmitter.

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The purpose of this study was to confirm the prognostic state of the patients with intermittent locking of the temporomandibular joint. After the treatment, we sent out the questionnaire to the 19 patients with the intermittent locking who were treated between October 2000 and September 2001. The subjects consisted of 12 individuals (3 males, 9 females) who completed the questionnaire form. We classified the subjects into the two groups. Comfortable group had a long period from the start of clicking before refering to our clinic. All patients had the TMJ pain. Uncomfortable group had the long treatment period and complained of sound and pain when the questionnaire was sent. But there were no statistical differences. We considered the possibility that the improvement of chief complaint was involved.

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