To assess the craniofacial changes related to growth and/or to orthodontic and orthognathic treatments, it is necessary to superimpose serial radiographs on stable structures. However, conventional superimposition provides only a graphical illustration of these changes. To increase the precision of growth and treatment evaluations, it is desirable to quantitate these craniofacial changes. The aims of this study were to (1) evaluate a superimposition-based cephalometric method to process numerical data for craniofacial growth changes and (2) identify a valid, reliable, and feasible method for superimposition. Forty pairs of cephalograms were analyzed at T1 and T2 (mean age 9.9 and 15.0 years, respectively). The superimposition-based cephalometric method involved relating the sagittal and vertical measurements on the T2 radiographs to the nasion and sella landmarks on the T1 radiographs. Validity and reliability were evaluated for three superimposition methods: the sella-nasion (SN); the tuberculum sella-wing (TW); and Björk’s structural. Superimposition-based cephalometrics can be used to quantify craniofacial changes digitally. The numerical data from the superimposition-based cephalometrics reflected a graphical illustration of superimposition and differed significantly from the data acquired through conventional cephalometrics. Superimposition using the TW method is recommended as it is valid, reliable, and feasible.

中文翻译：

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基于叠加的头颅法定量颅面变化

为了评估与生长和/或正畸和正颌治疗相关的颅面变化，有必要在稳定的结构上叠加放射线照片。但是，常规叠加仅提供这些变化的图形说明。为了提高生长和治疗评估的准确性，需要对这些颅面变化进行量化。这项研究的目的是（1）评估基于叠加的头颅测量方法以处理颅面生长变化的数值数据，以及（2）确定一种有效，可靠且可行的叠加方法。在T1和T2（分别为9.9岁和15.0岁的平均年龄）分析了40对脑电图。基于叠加的头颅测量方法涉及将T2射线照片上的矢状和垂直测量值与T1射线照片上的鼻孔和蝶鞍标志相关联。对三种叠加方法进行了有效性和可靠性评估：蝶鞍（SN）; 结核菌蝶翅（TW）；和比约克的结构。基于叠加的头颅测量技术可用于以数字方式量化颅面变化。来自基于叠加的头颅测量的数字数据反映了叠加的图形说明，并且与通过常规头颅测量获得的数据有显着差异。建议使用TW方法进行叠加，因为它是有效，可靠和可行的。蝶鞍（SN）; 结核菌蝶翅（TW）；和比约克的结构。基于叠加的头颅测量技术可用于以数字方式量化颅面变化。来自基于叠加的头颅测量的数字数据反映了叠加的图形说明，并且与通过常规头颅测量获得的数据有显着差异。建议使用TW方法进行叠加，因为它是有效，可靠和可行的。蝶鞍（SN）; 结核菌蝶翅（TW）；和比约克的结构。基于叠加的头颅测量技术可用于以数字方式量化颅面变化。来自基于叠加的头颅测量的数字数据反映了叠加的图形说明，并且与通过常规头颅测量获得的数据有显着差异。建议使用TW方法进行叠加，因为它是有效，可靠和可行的。