台湾原住民 Rukai 族の歯についての形質人類学的研究
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概要
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A series of field surveys as undertaken among the Rukai tribe of the Taiwan aborigines to investigate their teeth size and the crown characters. The Rukai tribe is one of the minority tribes among the Taiwan aborigines, and these investigated data were compared with those of other rases. The results were as follows. 1. Mesiodistal and buccolingual diameters of the tooth crown of the Rukai tribe were a little smaller than those of the other Taiwan aborigines and Japanese, and this tendency was quite marked especially in the upper lateral incisors and lower second molars. But the crown indexes were about the same as those of the other Taiwan aborigines and Japanese, and this suggested that there was almost no difference in the rates between the mesiodistal and buccolingual diameters. 2. The double shovel-shaped incisors were mostly seen in the upper central incisors, and the occurrence was found in 16.7%. The frequency of the double shovel-shaped incisors was almost equal to that found in the Paiwan tribe, and inhabitants of Tanegashima and Ishigakishima, but lower than those for the Japanese. The occurrence of the shovel-shaped incisors was very frequent, with 93.7% in the upper central incisors, and 81.7% in the upper lateral incisors. This trend was similar to that of the Ami, Atayal and Paiwan tribe and inhabitants of Ishigakishima, but the occurrence was higher than that of the Japanese. Correlation was not shown between the double shovel-shaped and shovel-shaped incisors. 3. The most frequently found occlusal surface groove pattern in the upper first premolar was the basic type A with 48.4% and in the seccond premolar the more retrogressive type C with 57.6%. The occurrence of type A in the first premolar was nearly equal to that found in the Paiwan tribe, followed by Ishigakishima, Tanegashima and Kyushu inhabitants in ascending order. 4. As for the occlusal surface morphology in the lower first premolar, type 2- was found most frequently with 75.1% at the cuspal type, and type E was found most frequently with 67.1% at the occlusal surface groove pattern. The cuspal type in the second premolar was found most frequently with 56.2% in type 2, and occlusal surface groove pattern was found most frequently with 38.4% in type C. The occurrence of the type 3- and type 3 in the Rukai tribe was less frequent than in the Paiwan tribe and Japanese in the second premolar, and the occurrence of the type 2- in the Rukai tribe was more frequent than in the other races. The correlation between the cuspal type and the occlusal surface groove pattern was not shown in the first premolar, and significant positive correlation was recognized between the cuspal type and the occlusal surface pattern in the second premolar. 5. The cuspal type of the upper first molar was mostly of the type 4 with 92.5%. The occurrence of type 4 was less frequent than that of the other Taiwan aborigines and was more frequent than that of the Japanese. However, when it came to the upper second molar, the number of the type 4 decreased, contrasted to the increase in the number of the type 4-, showing the retrogression of the hypocone. The occurrence of a mesiodistally compressed crown type in the upper second molar could be observed in 23.0% of the Rukei tribe. This was less frequent than in the Paiwan tribe and more frequent than in Japanese. Occurrence of the mesiodistally compressed crown type showed the significant correlation with the occurrence of cuspal type. 6. The occurrence of Carabelli cusp in the first molar was 6.4% in the Rukai tribe, which was almost the same rate as that of the Paiwan tribe and Japanese. 7. Driopithecus pattern (Y5) in the lower first molars was seen in 44.5% in the Rukai tribe, which was almost the same rate as that of other Taiwan aborigines, and was less frequent than in the Japanese. Occurrence of the Y5 pattern in the second molars could not be observed in many cases. On the other hand, occurrence of the +5 and +4 pattern of the retrogressive type was found most frequently. These trends were almost the same as those of Japanese and other Taiwan aborigines. 8. The occurrence of the protostylid was 6.9% in the lower first molar. The 6th cusp was found in 27.6% of the lower first molar and 18.3% of the second molar. The 7th cusp was found in 5.4%, and the deflecting wrinkle was found in 52.1% of the first molar. Occurrence of the protostylid was seen less frequently in the Rukai tribe than in the Japanese, and occurrence of the 6th cusp and 7th cusp was almost the same rate as that of Japanese. Occurrence of the deflecting wrinkle was seen more frequently in the Rukai tribe than in the Japanese.
- 九州歯科学会の論文
- 1984-12-25