THE STATISTICAL STUDY OF INTERDENTAL SPACE IN THE PRIMARY DENTITION

유치열(乳齒列)의 치간공극(齒間空隙)에 관(關)한 통계학적(統計學的) 연구(硏究)

The purpose of this study was to statistically evaluate the spacing of primary dentition according to whether or not a space existed and measurement of amount of space in 205 children (male 114, female 91) from 2 to 6 years of age. The results were as follows; 1. In the incidence of interdental space on each region, spacing between the primary lateral incisors and primary canine in maxilla and between the primary canine and 1st primary molar in mandible showed the highest percentage, on the other hand, spacing between the 1st and 2nd primary molars in both jaw showed the lowest percentage. 2. In the kinds of interdental space, the state of primate space and other space together showed the highest percentage, and in the degree of spacing, $S_2$ showed the highest percentage in both jaw. 3. In the incidence of primate space, maxillary primate space showed higher percentage than mandibular primate space in bilateral case. 4. In the type of arch form, spaced arch showed higher percentage than closed arch and about the half of closed arch showed crowding. 5. In both Jaw, available space showed incisor segments, canine segments, and premolar segments in order of amount, and there were not statistically significant differences of sex or jaws in the amount of available space.