台湾原住民の上顎側切歯の計測値について

概要

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Measurements of the maxillary incisors were taken in four tribes, Bunun, Ami, Paiwan, and Lukai among the Taiwan aborigines, and regressive phenomena and the relation of the lateral incisors to the central incisors were investigated. The results were as follows : 1. Both the central and lateral incisors were the smallest in Lukai tribe and no great differences were observed among the other three tribes, who showed about the same tooth size as Japanese. 2. The incidence rate of microtooth of the lateral incisors was the highest in Lukai tribe, with particular significance in females. 3. As compared with the central incisors, the reduction index of the lateral incisors showed low dimunition rates in the labiolingual diameter and no differences were observed among the four tribes. In the mesiodistal diameter, the dimunition rates were extremely high and Paiwan and Lukai tribes showed higher reduction rates than Ami and Bunun tribes. In the crown area, Lukai tribe showed the highest dimunition rates, followed by Paiwan tribe. 4. On the basis of the incidence rates for the group with an extensive degree of definite regression of the lateral incisors and for the group with a slight degree of regression, determined by the reduction indexes, regression in the labiolingual diameter was slight in most cases ; regression in the mesiodistal diameter was high in Lukai females ; and regression was slight in Ami females.
1983-12-25