歯冠近遠心幅径値の分布型について 多数標本に基づく検討 第１報

Abstract

The purpose of this paper is to examine the data distribution of the tooth size in a large number of samples. The objective teeth were the upper central and lateral incisors, upper canine, lower second bicuspid and upper and lower first molars. Their mesiodistal crown diameters were measured from 1, 000 dental casts of the Japanese female orthodontic patients. On each of them, the histogram and a set of statistics, consisting of mean, standard deviation, coefficient of variance, skewness, kurtosis and Geary value were obtained in order to examine the distribution form. As the result, these teeth were classified into the three types of distribution. Type I: The normal distribution form was shown in the upper and lower first molars and upper central incisor. Type II: The distorted distribution form was shown in the upper lateral incisor. Type III: The leptokurtic distribution form was shown in the upper canine and lower second bicuspid. As a consequence, it was suggested that it is necessary to take the greatest care in data processing in case of carrying out various statistical researches on the tooth size dealing with such teeth as Type II or III.