关键词: 三维重叠, 锥形束CT, 颅面部, 稳定结构, 正畸学

Abstract: With the development of cone beam CT，cephalometry in orthodontics steps into three-dimensional measurement，which makes up for the spatial distortion of X-ray image cephalometry and demonstrates craniofacial characteristics of patients more directly，especially under circumstances of asymmetric craniofacial structures of left and right sides. Three-dimensional superimposition uses specific software to superimpose three-dimensional digital images，giving a detailed comparison between particular parts before and after orthodontic treatment，in which stable structures of hard and soft tissues are commonly considered as superimposition landmarks. At present，many researches have focused on craniofacial stable structures，however，there has been no golden standard. Our review summarizes the recent researches and applications of the stable structures of three-dimensional superimposition. This article also poses questions demanding prompt solutions，and further gives outlooks of future advance in cephalometry. 

Key words: three-dimensional superimposition, cone beam CT, craniofacial region, stable structure, orthodontics