对500名要求正畸的青少年作了先天性恒牙缺失流行病学的调查,每个病例都采取了曲面断层x线摄影,发现先失恒牙缺失发病率为6.8％,并对缺牙数目及缺牙顺序进行统计。 500 orthodontic adolescents were asked to do a survey on the epidemiology of congenital loss of permanent dentition. Curvature tomography was taken in each case and the incidence of loss of first loss permanent tooth was found to be 6.8%. The number of missing teeth And missing teeth order statistics.