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

摘要： 随着锥形束CT技术的发展，正畸学领域的头影测量由二维层面走向三维。三维头影测量能弥补二维X线片影像资料存在的空间失真缺陷，特别是左右结构不对称的情况下，可更直观地展现患者颅面部特征。三维影像重叠是借助软件将正畸治疗前后三维数字化影像进行叠加，以比较术前术后特征部位的变化，其重叠标记物一般采取稳定的软硬组织结构。目前，对于颅面部稳定结构的研究不在少数，但并未得出统一的测量方法标准。文章就近年来对于颅面部三维影像重叠稳定结构的研究进展和应用做一综述，提出目前亟待解决的问题，对三维头影测量的发展进行分析。

关键词: 三维重叠, 锥形束CT, 颅面部, 稳定结构, 正畸学