상악유(上顎乳) 영구중절치(永久中切齒)의 상호(相互) 발육관계(發育關係)에 관(關)한 방사선학적(放射線學的) 연구(硏究)

A CEPHALOMETIC STUDY OF THE DEVELOPMENTAL RELATIONSHIP BETWEEN PRIMARY AND PERMANENT MAXILLARY CENTRAL INCISOR TEETH.

The purpose of this study is to determine the developmental relationship between the maxillary primary central incisors and their permanent successor. The auther took 315 cases of lateral cephalogram of the children (males were 171, females were 141) Angular change of the teeth and horizontal and vertical linear change were observed. The obtained results were as follows: 1. The inclination of the long axes of both incisor teeth was relatively stable and labio-version of both incisore was significant at 7 years of age. 2. The distance between the incisal edge of the permanent central insisor and the resorbing apex of the primary maxillary central incisor remained within 2mm of each other, 3. Vertical growth of the maxillary anterior portion was greater than horizontal growth from 6 to 7 years of age. 4. There was not a significant sexual difference.