Lee Shin-Jae, Lee Sungim, Lim Johan, Ahn Sug-Joon, Kim Tae-Woo
Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.
Am J Orthod Dentofacial Orthop. 2007 Dec;132(6):796-800. doi: 10.1016/j.ajodo.2005.12.037.
Tooth-size studies are important in orthodontics. Our aim in this study was to establish normative data on tooth size with a clustering method.
Dental casts of 307 subjects with normal occlusion were examined. In these subjects, the tooth-size data sets in the maxilla and the mandible were clustered for men and women by using multivariate normal mixture models. This analysis clustered the data sets into groups of observations that were cohesive and separate from the other groups. The parameters were estimated with expectation-maximization procedures, and the number of clusters was selected via the Bayesian information criterion.
Seven heterogeneous clusters in men and 4 clusters in women were identified. This study indicated that, in normal occlusion, tooth sizes are variable. These heterogeneities in the normal occlusion group seem to have contributed to the variability found in normative data.
The method used in this study seems to provide a more substantive design for artificial teeth and add an additional dimension in the process of diagnosis of patients. Further applications seem possible in dental anthropometry by simultaneously dealing with the full dentition as a data set.
牙齿大小研究在正畸学中很重要。本研究的目的是用聚类方法建立牙齿大小的规范数据。
检查了307名咬合正常受试者的牙模。在这些受试者中，使用多元正态混合模型对男性和女性上颌和下颌的牙齿大小数据集进行聚类。该分析将数据集聚类为具有凝聚力且与其他组分离的观察组。通过期望最大化程序估计参数，并通过贝叶斯信息准则选择聚类数。
确定男性有7个异质聚类，女性有4个聚类。本研究表明，在正常咬合中，牙齿大小是可变的。正常咬合组中的这些异质性似乎导致了规范数据中的变异性。
本研究中使用的方法似乎为人工牙提供了更实质性的设计，并在患者诊断过程中增加了一个维度。通过将全牙列作为一个数据集同时处理，在牙人类学中似乎可能有进一步的应用。
