Senior Resident, Department of Orthodontics and Dentofacial Orthopaedics, Maulana Azad Institute of Dental Sciences , New Delhi, India .
J Clin Diagn Res. 2015 Jan;9(1):ZC21-6. doi: 10.7860/JCDR/2015/8971.5458. Epub 2015 Jan 1.
One of the most fundamental limitations associated with the conventional cephalometrics is its inability to delineate size from shape as it depends mainly on linear and angular measurements. However, the biological structures warrant greater description in terms of shape and form for better comparison of variation in a particular population. To overcome these shortcomings, morphometrics are now being employed for describing the biological structures in terms of quantifying the shape and form. Also, statistical analysis is being applied to find the variability of this form in the population. The present paper assesses the use of the Procuste superimposition technique and the subsequent form analysis by the principal component analysis (PCA).
The lateral cephalograms of 10 adult females were taken from existing records, traced & digitized & then superimposed by means of procuste superimposition. A comparison was made with the conventional superimposition methods based on arbitrary reference planes like cranial base, FHP, SN. The statistical analysis for assessment of shape variability of the structures seen on the lateral cephalogram was done by calculating the principal components for 3 out of these 10 samples.
The conventional superimposition methods do not provide realistic picture of variation in the biological structures as they themselves are prone to variability even in a particular population.
Concepts in Morphometrics can be applied for the purpose of orthodontic assessment of a particular patient with regards to his craniofacial morphology. With the help of morphometrics, norms for a population can be determined based on all the kinds of variations present naturally in that particular population & individuals can thus be compared more realistically regarding the morphological variations.
传统头影测量学最基本的局限性之一在于，由于其主要依赖线性和角度测量，无法区分大小和形状。然而，生物结构需要在形状和形态方面进行更深入的描述，以便更好地比较特定人群中的变异情况。为了克服这些缺点，现在采用形态测量学来描述生物结构的形状和形态，并进行量化。此外，还应用统计分析来找出该形态在人群中的变异性。本文评估了普洛透斯叠加技术的应用以及随后通过主成分分析（PCA）进行的形态分析。
从现有记录中获取10名成年女性的头颅侧位片，进行描图、数字化处理，然后通过普洛透斯叠加法进行叠加。与基于颅底、FHP、SN等任意参考平面的传统叠加方法进行比较。通过计算这10个样本中3个样本的主成分，对头颅侧位片上所见结构的形状变异性进行统计分析。
传统叠加方法无法提供生物结构变异的真实情况，因为即使在特定人群中，它们自身也容易出现变异。
形态测量学的概念可用于对特定患者的颅面形态进行正畸评估。借助形态测量学，可以根据特定人群中自然存在的各种变异来确定该人群的标准，从而能够更真实地比较个体之间的形态变异。
