Angle Orthod. 2020 May 1;90(3):390-396. doi: 10.2319/071319-469.1.
To evaluate a new superimposition method compatible with computer-aided cephalometrics and to compare superimposition error to that of the conventional Sella-Nasion (SN) superimposition method.
A total of 283 lateral cephalometric radiographs were collected and cephalometric landmark identification was performed twice by the same examiner at a 3-month interval. The second tracing was superimposed on the first tracing by both the SN superimposition method and the new, proposed method. The proposed method not only relied on SN landmarks but also minimized the differences between four additional landmarks: Porion, Orbitale, Basion, and Pterygoid. The errors between the landmarks of the duplicate tracings oriented by the two superimposition methods were calculated at Anterior Nasal Spine, Point A, Point B, Pogonion, and Gonion. The paired t-test was used to find any statistical difference in the superimposition errors by the two superimposition methods and to investigate whether there existed clinically significant differences between the two methods.
The proposed method demonstrated smaller superimposition errors than did the conventional SN superimposition method. When comparisons between the two superimposition methods were made with a 1-mm error range, there were clinically significant differences between them.
The proposed method that was compatible with computer-aided cephalometrics might be a reliable superimposition method for superimposing serial cephalometric images.
评估一种与计算机辅助头影测量兼容的新叠加方法，并将其与传统 Sella-Nasion（SN）叠加方法的叠加误差进行比较。
共收集了 283 张侧位头颅侧位片，由同一位检查者在 3 个月的间隔内进行了两次头颅解剖标志识别。第二次描记通过 SN 叠加方法和新提出的方法分别叠加在第一次描记上。新方法不仅依赖于 SN 标志点，还最小化了另外四个标志点（Porion、Orbitale、Basion 和 Pterygoid）之间的差异。通过两种叠加方法将重复描记的标志点定向，计算出在前鼻棘、A 点、B 点、颏顶点和下颌角点的标志点之间的误差。采用配对 t 检验来比较两种叠加方法的叠加误差是否存在统计学差异，并探讨两种方法之间是否存在临床显著差异。
与传统 SN 叠加方法相比，新方法的叠加误差更小。当以 1mm 的误差范围对两种叠加方法进行比较时，它们之间存在临床显著差异。
与计算机辅助头影测量兼容的新方法可能是一种可靠的叠加方法，用于叠加连续的头颅侧位片。
