台湾原住民 Ami 族の歯冠形態について
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概要
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Aborigines of Formosa are of a minority race living on highland from the central to eastern regions of Formosa and are said to number about 250 thousand accounting for about 1.8% of the Formosan population. These aborigines are classified into ten tribes but they all belong to the Mongoloid race. For this paper, the Ami, one of the tribes of the aborigines, were investigated physical-anthropologically. Plaster casts of all teeth of the upper and lower jaws of 245 men and women combined were used and observations of crown morphology were made and measurements were taken. The results of the investigation were compared with those of each tribe of the Formosan aborigines and with those of Japanese of various locations mainly around Kyushu. The results were as follows : 1. The crown width was slightly smaller than that of the other Formosan aborigines and quite smaller than that of Japanese and the difference was considerable for the lower teeth in particular. The crown thickness of the Ami showed no great difference as compared with that of the other Formosan aborigines and was slightly smaller for the lower teeth as compared with that of the residents of Goto and Tanegashima islands. 2. Frequency of occurrence of double shovel-shaped incisors on the labial side of the incisor was high for both the upper and lower jaws in comparison with that of the other Formosan aborigines and Japanese around Kyushu. The frequency of occurrence for the upper jaw was much higher than for the lower jaw. 3. Frequency of occurrence of shovel-shaped incisors on the lingual side of the incisor was quite high for the upper jaw as was for the other Formosan aborigines and was higher than that of Japanese around Kyushu. The frequency for the lower jaw was markedly lower than that for the upper jaw. 4. Morphology of the grooves in the occlusal surface of the upper premolars showed a tendency similar to that for Bunun tribe. As compared with the other Formosan aborigines and Japanese, the Ami tended to show slightly regressive morphology. 5. In development of cusps of premolars in the lower jaw, the lingual cusp of the first premolar was poorly developed. This finding applied to the other Formosan aborigines and Japanese. Many Kyushu people however appeared to show good development of the lingual cusp. For the second premolar, development of the lingual cusp was marked and another cusp appeared on the linguodistal side, resulting in three cusps in quite many instances. The same applied to the other Formosan aborigines and Japanese. 6. Regression of hypocone at the upper molars was hardly seen for the first molar. For the second molar, considerable regression was seen. For the Ami, the tendency toward regression was slight as compared with Japanese. 7. Frequency of occurrence of mesiodistally compressed crown type for the Ami was about the same as that for the other Formosan aborigines but was higher than that for Japanese. Frequency of occurrence of carabelli's cusp for the Ami was the highest among the Formosan aborigines and was higher than that for Japanese. 8. Frequency of occurrence of the dryopithecus pattern at the lower first molar for the Ami was slightly higher than that for the other Formosan aborigines, but the difference was not so great. The frequency for the Ami was lower than for Japanese. At the second molar, the frequency was considerably low and types like regressed +5, +4, ×5, and ×4 increased, and about the same tendency as for the other Formosan aborigines and Japanese was seen. 9. Frequency of occurrence of protostylid, 6th cusp, and 7th cusp at the lower first molar was lower than that for the other Formosan aborigines and Japanese. Frequency of occurrence of deflecting wrinkles was higher than that for the other Formosan aborigines and Japanese.
- 九州歯科学会の論文
- 1987-08-25