A study of Korean norm about tooth size and ratio in Korean adults with normal occlusion

Kim, Dae Sik; Kim, Young Jun; Choi, Jae Hoon; Han, Jong Hoon

Abstract

The purpose of this study was to measure the average tooth size of Korean with normal occlusion. According to the study, the average tooth ratios between the upper and lower teeth which could assure the proper ovebite, overjet and good interdigitation were calculated. The normal occluson sample of this study consisted of 43 Korean male adults and 51 Korean female adults. Among them, 22 Korean male adults and 51 Korean female adults were from KAO(Korean Association of Orthodontists), 21 Korean male adults were from Department of Orthodontics, College of Dentistry, Yonsei University. The results from this study were as follows : 1. The average tooth size of Korean Norm classified by male and female was measured. 2. The average tooth size of Korean male adults with normal occlusion was significantly larger than that of Korean female adults except upper and lower first molars.(p<0.05) 3. The tooth ratio which could predict the proper overbite and overjet in anterior teeth and proper occlusion in posterior teeth was calculated. 1) Sum of inciosrs = 4 : 2.97 2) Neff's anterior coefficient = 1.22 3) Bolton's anterior ratio = 78.29%, overall ratio = 91.14% 4. A positive correlation was observed between the sum of lower anterior incisors and the sum of unilateral canine and premolars in each jaw. Based this correlation, the regression equation was made which could predict the sum of unerupted unilateral canine and premolars in mixed dentition. 1) Sum of unilateral unerupted upper canine and premolars' width = 10.435018 + 0.513346x(sum of lower 4 incisors' width) 2) Sum of unilateral unerupted lower canine and premolars' width = 9.654002 + 0.502565x(sum of lower 4 incisors' width)