Professor, Faculty of Dentistry, Pedro de Valdivia Univerisity, Santiago, Chile.
Professor, Faculty of Dentistry, University of Chile, Santiago, Chile.
J Prosthet Dent. 2020 Apr;123(4):611-617. doi: 10.1016/j.prosdent.2019.05.009. Epub 2019 Aug 2.
Craniometry is a method of determining the occlusal vertical dimension (OVD); the current prediction models do not consider factors such as facial type and sex or normalizing the OVD by using 1 main variable.
The purpose of this clinical study was to determine whether sex, facial type, and age can influence the creation of a predictive model by using the right or left eye-to-ear distance to determine the OVD in dentate and edentate individuals.
Healthy individuals (N=385) (238 women, 147 men) aged between 18 and 50 years were classified according to sex, age, and facial type. A single operator recorded all distances in millimeters between the anatomic landmarks proposed by Knebleman (nose-to-chin and right and left eye-to-ear distances) by using a computer numerical control (CNC) machined aluminum anatomic gauge. Measurements were converted into z-scores to determine abnormal values (±3 standard deviations criteria). The Pearson correlation coefficient was calculated for each facial type and for the entire sample between nose-to-chin and the right and left eye-to-ear distances. Multiple regression analysis was performed to establish the dependence of the measured variables on the OVD and the development of a further predictive model (α=.05).
According to the z-scores of the measured distances, 4 participants were discarded, leaving a final sample of 381 participants (237 women, 144 men; 115 leptoprosopic, 164 mesoprosopic, 102 euryprosopic). The left eye-to-ear distance showed a better correlation with the nose-to-chin distance (leptoprosopic r=0.54, mesoprosopic r=0.60, euryprosopic r=0.55, total sample=0.56) than the right eye-to-ear distance (leptoprosopic r=0.48, mesoprosopic r=0.56, euryprosopic r=0.54, total sample=0.51). Multiple regression analysis revealed that age was not a predictive variable (P=.57), that OVD depended on sex (P<.001) and facial type (P<.01), and that women had shorter OVD than men, as well as more euryprosopic faces than leptoprosopic faces. Using these relationships, the following equation to determine OVD was constructed as a model: OVD=42.17+(0.46×left eye-to-ear distance)+sex (women=-3.38, men=0)+facial type (leptoprosopic=0, mesoprosopic=-1.19, euryprosopic=-2.19).
OVD depends on facial type and sex, both of which are craniometric variables. This study proposed a baseline method of determining OVD by using the left eye-to-ear distance as an initial reference that involves a straightforward mathematical calculation.
头测量学是一种确定咬合垂直距离（OVD）的方法；目前的预测模型没有考虑到面部类型和性别等因素，也没有使用单一变量对 OVD 进行标准化。
本临床研究的目的是确定性别、面部类型和年龄是否可以通过使用右眼到左耳的距离来影响预测模型的创建，以确定有牙和无牙个体的 OVD。
将 385 名（238 名女性，147 名男性）18 至 50 岁的健康个体按性别、年龄和面部类型进行分类。一名操作人员使用数控（CNC）加工的铝合金解剖量规记录了由 Knebleman 提出的解剖标志（鼻颏和右眼到左耳的距离）之间的所有距离（毫米）。测量值转换为 z 分数以确定异常值（±3 个标准差标准）。对每个面部类型和整个样本，计算了鼻颏与右眼到左耳的距离之间的 Pearson 相关系数。进行多元回归分析，以确定测量变量与 OVD 的依赖性，并建立进一步的预测模型（α=.05）。
根据测量距离的 z 分数，有 4 名参与者被排除，最终样本为 381 名参与者（237 名女性，144 名男性；115 名瘦长型，164 名中面型，102 名宽面型）。左眼到左耳的距离与鼻颏距离的相关性（瘦长型 r=0.54，中面型 r=0.60，宽面型 r=0.55，总样本 r=0.56）优于右眼到左耳的距离（瘦长型 r=0.48，中面型 r=0.56，宽面型 r=0.54，总样本 r=0.51）。多元回归分析表明，年龄不是一个预测变量（P=.57），OVD 取决于性别（P<.001）和面部类型（P<.01），女性的 OVD 比男性短，宽面型比瘦长型多。利用这些关系，构建了一个确定 OVD 的模型方程：OVD=42.17+（0.46×左眼到左耳的距离）+性别（女性=-3.38，男性=0）+面部类型（瘦长型=0，中面型=-1.19，宽面型=-2.19）。
OVD 取决于面部类型和性别，两者都是头测量学的变量。本研究提出了一种以左眼到左耳的距离作为初始参考来确定 OVD 的基线方法，该方法涉及到一个简单的数学计算。
