Dobai Adrienn, Vizkelety Tamás, Markella Zsolt, Rosta Adrienne, Kucsera Ágnes, Barabás József
Department of Oro-Maxillofacial Surgery and Stomatology, Semmelweis University, Mária Street 52, Budapest, 1085, Hungary.
Kandó Kálmán Faculty of Electrical Engineering, Óbuda University, Tavaszmező Street 15-17, Budapest, 1084, Hungary.
Oral Maxillofac Surg. 2017 Jun;21(2):207-218. doi: 10.1007/s10006-017-0620-7. Epub 2017 Mar 23.
As most orthognathic surgeries focus on the lower face, the aim of this study was to transfer previously developed two-dimensional cephalometry-which is useful for surgeons in the orthognathic surgery of the lower face-to three-dimensional (3D) cephalometry by using cone-beam computed tomography (CBCT). We selected the quadrilateral lower face analysis developed by the surgeon Di Paolo, who focused only for the lower face and mentioned that data in millimeters are more easy to use than angles for surgeons. Additionally, we wanted to create a 3D lower face analysis approach based on quadrilateral analysis and establish a reference table for surgical planning.
Three investigators assigned 16 landmarks on CBCT images from 30 patients with normocclusion. Intra-class correlation coefficients (ICCs) and standard deviations (SDs) were calculated according to each landmark. The maxillary and mandibular lengths and widths and the anterior and posterior lower facial heights (ALFH and PLFH) are presented as means and SDs. The asymmetry of the face was calculated with paired t test, and the coherence of the lower face was assessed with correlation coefficients (r) and regression models.
The ICCs were ≥0.90, and the SDs of the landmarks were lower than 1.00 mm, except for the J-point, which was located at the junction of the anterior border of the ramus and the corpus of the mandible. The SDs of linear measurements were 3.06-5.20 mm, and there was no significant facial asymmetry. The r among the structures was greater than 0.3 in 13 of 15 assessments. Based on these values, we could establish a floating norm of the lower face using the following five regressions: one linear regression for the mandibular length, two quadratic models for the ALFH and PLFH, and two multivariate regressions for the posterior widths of the maxillae and mandible.
The adaptation of quadrilateral analysis can provide accurate 3D characterization of the morphology of the lower face and the floating norm based on millimeter values, which is practical for surgeons. As the 3D extension of quadrilateral analysis could provide references of the lower face, which might be an accurate 3D approach for presurgical planning, the further investigation in bigger sample would be relevant in the practice.
由于大多数正颌手术集中于下脸部，本研究的目的是通过使用锥形束计算机断层扫描（CBCT），将先前开发的二维头影测量法（该方法对下脸部正颌手术的外科医生有用）转换为三维（3D）头影测量法。我们选择了由外科医生迪·保罗开发的四边形下脸部分析方法，该方法仅专注于下脸部，并指出以毫米为单位的数据对外科医生而言比角度更易于使用。此外，我们希望基于四边形分析创建一种3D下脸部分析方法，并建立用于手术规划的参考表。
三名研究人员在30名咬合正常患者的CBCT图像上指定了16个标志点。根据每个标志点计算组内相关系数（ICC）和标准差（SD）。上颌骨和下颌骨的长度、宽度以及下脸部的前、后高度（ALFH和PLFH）以均值和标准差表示。使用配对t检验计算面部不对称性，并使用相关系数（r）和回归模型评估下脸部的一致性。
ICC≥0.90，除位于下颌支前缘与下颌体交界处的J点外，标志点的标准差低于1.00毫米。线性测量的标准差为3.06 - 5.20毫米，且面部无明显不对称。在15项评估中的13项中，各结构之间的r大于0.3。基于这些值，我们可以使用以下五个回归建立下脸部的浮动标准：一个用于下颌骨长度的线性回归，两个用于ALFH和PLFH的二次模型，以及两个用于上颌骨和下颌骨后宽度的多元回归。
四边形分析的应用可以提供基于毫米值的下脸部形态的准确3D特征以及浮动标准，这对外科医生来说是实用的。由于四边形分析的3D扩展可以提供下脸部的参考，这可能是一种用于术前规划的准确3D方法，因此在更大样本中进行进一步研究在实践中会很有意义。
