Pittayapat Pisha, Jacobs Reinhilde, Bornstein Michael M, Odri Guillaume A, Lambrichts Ivo, Willems Guy, Politis Constantinus, Olszewski Raphael
OIC, OMFS-IMPATH Research Group, Department of Imaging and Pathology, Faculty of Medicine, University of Leuven and Oral and Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium.
Department of Radiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Eur J Orthod. 2018 May 25;40(3):239-248. doi: 10.1093/ejo/cjx066.
To assess the reproducibility of landmarks in three dimensions that determine the Frankfort horizontal plane (FH) as well as two new landmarks, and to evaluate the angular differences of newly introduced planes to the FH.
Three-dimensional (3D) surface models were created from CBCT scans of 26 dry human skulls. Porion (Po), orbitale (Or), internal acoustic foramen (IAF), and zygomatico-maxillary suture (ZyMS) were indicated in the software by three observers twice with a 4-week interval. Angles between two FHs (FH 1: Or-R, Or-L, mid-Po; FH 2: Po-R, Po-L, mid-Or) and between FHs and new planes (Plane 1-6) were measured. Coordinates were exported to a spreadsheet. A statistical analysis was performed to define the landmark reproducibility and 3D angles.
Intra- and inter-observer landmark reproducibility showed mean difference more than 1 mm for x-coordinates of all landmarks except IAF. IAF showed significantly better reproducibility than other landmarks (P < 0.0018). The mean angular difference between FH 1 and FH 2 was 0.7 degrees. Plane 3, connecting Or-R, Or-L and mid-IAF, and Plane 4, connecting Po-R, Po-L and mid-ZyMS, both showed an angular difference of less than 1 degree when compared to FHs.
This study revealed poor reproducibility of the traditional FH landmarks on the x-axis and good reproducibility of a new landmark tested to replace Po, the IAF. Yet, Or showed superior results compared to ZyMS. The potential of using new horizontal planes was demonstrated. Future studies should focus on identification of a valid alternative for Or and ZyMS and on clinical implementation of the findings.
评估用于确定法兰克福水平面（FH）的三维标志点以及两个新标志点的可重复性，并评估新引入平面与FH之间的角度差异。
通过对26个干燥人类头骨的CBCT扫描创建三维（3D）表面模型。三位观察者在软件中两次标记出耳点（Po）、眶点（Or）、内耳门（IAF）和颧上颌缝（ZyMS），间隔4周。测量两个FH（FH 1：Or-R、Or-L、Po中点；FH 2：Po-R、Po-L、Or中点）之间以及FH与新平面（平面1-6）之间的角度。将坐标导出到电子表格中。进行统计分析以确定标志点的可重复性和三维角度。
除IAF外，所有标志点的x坐标在观察者内和观察者间的标志点可重复性显示平均差异超过1mm。IAF的可重复性明显优于其他标志点（P < 0.0018）。FH 1和FH 2之间的平均角度差异为0.7度。连接Or-R、Or-L和IAF中点的平面3以及连接Po-R、Po-L和ZyMS中点的平面4与FH相比，角度差异均小于1度。
本研究揭示了传统FH标志点在x轴上的可重复性较差，而测试用于替代Po的新标志点IAF具有良好的可重复性。然而，与ZyMS相比，Or显示出更好的结果。证明了使用新水平面的潜力。未来的研究应集中于确定Or和ZyMS的有效替代物以及这些发现的临床应用。
