THE STATISTICAL STUDY OF MAXILLARY MEDIAN DIASTEMA

상악(上顎) 중절치간(中切齒間) 정중리개(正中離開)에 관(關)한 통계학적(統計學的) 연구(硏究)

The author surveyed 2,082 schoolchildren (Male: 1,078, Female: 1,004) from 7 to 12 years old in "N" primary school in kwang Ju City, and studied on 304 schoolchildren (Male: 176, Female: 128) having maxillary median diastema. The results were as follows: 1. The prevalence of maxillary median diastema was 14.6%, and it showed the greater rate at the boys than at the girls and the highest rate at 8 years old in the both sexes. 2. The maxillary median diastema showed decreasing tendency with ageing. 3. The frenum distance in children without local factors showed no change and the divergent degree of maxillary median diastema showed decreasing tendency after the eruption of maxillary lateral incisors. 4. The rate of maxillary median diastema associated with local factors was 37.8% and it showed increasing tendency with ageing. 5. The prevalence of median diastema according to etiology was as follows; rotated tooth; 12.2%, supernumerary teeth; 10.9%, abnormal frenum; 9.5%, peg lateralis; 7.2%, open bite; 2.6%, abnormal pattern of interseptal alveolar bone; 2.6%, missing lateral incisor; 0.7%, tooth size discrepancy; 0.3%.