Dental Cephalometric Norms for the Chinese Population

Objective: The purpose of this study was to describe and analyse cephalometric floating norms to describe the individual incisors' position dependent on the sagittal and vertical skeletal pattern of Chinese people. As well, a soft tissue evaluation relating to the incisors' position and skeletal values was carried out. By using Chinese cephalometric data, these findings can give a prognosis in treatment planning for this population. Material and Methods: 139 cephalometric x-rays from Chinese people undergoing orthodontic treatment at the University of British Columbia, Canada, were landmarked. They were separated into females aged under and over 18 years as well as males under and over 18 years. Each picture was analysed with 40 landmarks, in which eight cephalometric values (ANB, H-angle, 1NA(°), 1NB(°), 1NA(mm), 1NB(mm), PgNB(mm), Index) were digitised. By using the linear and multiple regressions equation, a schema for the ideal incisors' position and nomograms were constructed. Results: The eight variables correlated significantly with each other. In imitation to STEINERs "acceptable compromises", a schema for ideal upper and lower incisors' position was constructed. By using the multiple regression equation, two different nomograms were drawn. Chinese people have more proclined incisors dependent on their sagittal and vertical skeletal pattern. A soft tissue evaluation was given with the H-angle. Conclusion: Different ethnic groups vary in their skeletal and dental values. Keywords: nomogram, floating norms, cepahlometrics, Chinese population, anterior border