Santos Rodrigo Mologni Gonçalves Dos, De Martino José Mario, Haiter Neto Francisco, Passeri Luis Augusto
Department of Computer Engineering and Industrial Automation, School of Electrical and Computer Engineering, University of Campinas, Campinas, São Paulo, Brazil.
Department of Computer Engineering and Industrial Automation, School of Electrical and Computer Engineering, University of Campinas, Campinas, São Paulo, Brazil; Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação, Cidade Universitária "Zeferino Vaz", Campinas, São Paulo, Brazil.
Am J Orthod Dentofacial Orthop. 2017 Aug;152(2):242-249. doi: 10.1016/j.ajodo.2016.12.023.
The Frankfort horizontal (FH) is a plane that intersects both porions and the left orbitale. However, other combinations of points have also been used to define this plane in 3-dimensional cephalometry. These variations are based on the hypothesis that they do not affect the cephalometric analysis. We investigated the validity of this hypothesis.
The material included cone-beam computed tomography data sets of 82 adult subjects with Class I molar relationship. A third-party method of cone-beam computed tomography-based 3-dimensional cephalometry was performed using 7 setups of the FH plane. Six lateral cephalometric hard tissue measurements relative to the FH plane were carried out for each setup. Measurement differences were calculated for each pair of setups of the FH plane. The number of occurrences of differences greater than the limits of agreement was counted for each of the 6 measurements.
Only 3 of 21 pairs of setups had no occurrences for the 6 measurements. No measurement had no occurrences for the 21 pairs of setups. Setups based on left or right porion and both orbitales had the greatest number of occurrences for the 6 measurements.
This investigation showed that significant and undesirable measurement differences can be produced by varying the definition of the FH plane.
法兰克福平面（FH）是一个与双侧耳点和左侧眶下点相交的平面。然而，在三维头影测量中，也使用了其他点的组合来定义这个平面。这些变化基于这样的假设，即它们不会影响头影测量分析。我们研究了这一假设的有效性。
材料包括82名I类磨牙关系成年受试者的锥形束计算机断层扫描数据集。使用7种FH平面设置进行基于锥形束计算机断层扫描的三维头影测量的第三方方法。对每种设置进行6项相对于FH平面的侧位头影测量硬组织测量。计算FH平面各设置对之间的测量差异。计算6项测量中每一项差异大于一致性限度的出现次数。
21对设置中只有3对在6项测量中没有出现差异。21对设置中没有一项测量没有出现差异。基于左侧或右侧耳点以及双侧眶下点的设置在6项测量中出现差异的次数最多。
本研究表明，改变FH平面的定义会产生显著且不良的测量差异。
