長崎県五島住民の歯の形質人類学的研究
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概要
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A series of field surveys were undertaken among the inhabitants of Gotoo island in Nagasaki Prefecture to examine their teeth character. Investigations were conducted on 224 plaster models of upper and lower jaws taken from inhabitants of Gotoo island. Since the geographical situation of this island has suggested the existence of close communication with neighboring regions, data obtained from these regions were compared with those of Gotoo islanders for the possible manifestation of ethnological characteristics in their teeth. The results were as follows. 1) The data obtained show that the crown thickness of the Gotoo inhabitants was little different from that of other Japanese and inhabitants of neighboring regions, but the crown width of the Gotoo inhabitants was larger than that of the Japanese and inhabitants of neighboring regions. 2) The occurrence of the double-shovel shaped incisor was found in 20.6% in the upper central incisors, 4.5% in the upper lateral incisors. The frequency of the doubleshovel shaped incisor nearly equaled that found in the inhabitants of the Ishigaki island of Okinawa. The occurrence of the shovel-shaped incisors was very frequent, showing 71.6% in the upper central incisors and 72.5% in the upper lateral incisors. This trend was similar to that of the common Japanese, and the shovel-shaped incisors may be considered as a characteristic physical trait of mongoloid race. 3) The occlusal surface groove pattern in the upper first premolar was found most frequently, showing 48.4% in the type B. But in the inhabitants of Kyushu and Nansei island, frcquency of the type A was found over 50%, and this trend was different from Gotoo inhabitants. 4) As for the occlusal groove pattern in the lower first premolar, type E was found most frequently, with 61.8%. This trend was similar to that of the inhabitants of Kyushu and neighboring regions. The groove pattern of the occlusal surface found in the lower second premolar was found most frequently, with 55.7% in type C. The occurrence of type C was more frequent than in inhabitants of Kyushu and neighboring region. 5) With regard to the cuspal types in the lower first premolar, type 2- was found most frequently, with 52.8%, followed by 43.1% of the type 2. This suggested that development of the lingual cusp was very poor, But in the inhabitants of Kyusyu, type 2 was more frequent than type 2-. 6) With regard to the cuspal types in the upper molars, type 4 was found in 96.8% in the first molars, 21.0% in the second molars. Namely, no greater tendency toward retrogression of hypocone could be noticed in the first molar. The occurrence of type 4 in the first molars of the Gotoo islanders was more frequent than that of the inhabitants of Kyushu regions, Nansei island and other Japanese. 7) The occurrence of a mesiodistally compressed crown type in the second molar could be observed in 11.7% of the inhabitants of Gotoo. There was no noticeable difference between Gotoo islanders and the common Japanese. 8) The occurrence of Carabelli cusp in the first molar was 9.9%, which was almost the same rate as that of Japanese in other regions, and less frequent than that of the Caucasian race. 9) Dryopithecus pattern (Y5) in the lower molars was seen in 51.0% in the first molars and in 5.1% in the second molars. Occurrence of the Y5 in the first molars of Gotoo inhabitants was less frequent than that of Japanese in other regions and other races. Occurrence of the Y5 pattern in the second molars showed much lower frequency than that of the first molars. On the other hand, occurrence of the +5 pattern and +4 pattern was found most frequently. These trends were almost the same as those of the common Japanese. 10) The occurrence of protostylid was 12.3% in the lower first molar and 0.5% in the second molar. The 6th cusp was found in 27.3% of the lower first molar and 11.9% of the second molar. The 7th cusp was found in 8.2% of the lower first molar and 0.6% of the second molar. The deflecting wrinkle was seen only in the lower first molar, and the occurrence was 39.7%. These traits were more frequently encountered among Mongoloid race including Japanese.
- 九州歯科学会の論文
- 1984-06-25