Peretz B, Shapira J, Farbstein H, Arieli E, Smith P
Department of Pediatric Dentistry, Hadassah Faculty of Dental Medicine Jerusalem, Israel.
J Anat. 1996 Feb;188 ( Pt 1)(Pt 1):167-72.
Individuals with Down's syndrome (DS) tend to display a reduction in size of permanent teeth, and reduced intercuspal distances in molars. A total of 51 permanent maxillary 1st molars of 26 DS children were examined from dental casts, 65 permanent maxillary 1st molars of normal children were examined from dental casts of 33 individuals. The following measurements were performed on both right and left molars (teeth 16 and 26 respectively): (1) all intercusp distance (distobuccal, db; distolingual, dl; mesiobuccal, mb; mesiolingual, ml); (2) the db-mb-ml, mb-db-ml, db-ml-mb, dl-mb-db, mb-dl-db, and dl-db-mb angles; (3) the area of the quadrangle shaped by connecting the cusp tips. All the intercusp distances were significantly smaller in the DS group. Stepwise logistic regression, applied to all the intercusp distances, was used to build a multivariate probability model for DS and normals. The mb-dl and mb-ml distances of the upper right molar (tooth 16) were sufficient to discriminate between DS and normal teeth: [table: see text] The probability for DS is higher when mb-ml is relatively higher in the mb-ml/mb-dl ratio. Another logistic analysis based on groups of angles revealed a combination of 3 angles which gave highly statistically significant discrimination between both groups: the mb-db-dl angle was higher in DS, the mb-dl-db angle was slightly smaller in DS, and the mb-ml-db angle was slightly smaller in DS. The dl cusp was located closer to the centre of the tooth. The change in size occurs at an early stage, while the change in shape occurs in a later stage of tooth formation in DS population. Our probability model for DS teeth is simple and practical because it requires only 2 intercusp distances to be put into the formula.
唐氏综合征（DS）患者的恒牙往往尺寸减小，磨牙的牙尖间距离也减小。从26名唐氏综合征儿童的牙模中检查了总共51颗上颌第一恒磨牙，从33名个体的牙模中检查了65颗正常儿童的上颌第一恒磨牙。对左右两侧磨牙（分别为牙齿16和26）进行了以下测量：（1）所有牙尖间距离（远中颊尖，db；远中舌尖，dl；近中颊尖，mb；近中舌尖，ml）；（2）db-mb-ml、mb-db-ml、db-ml-mb、dl-mb-db、mb-dl-db和dl-db-mb角度；（3）连接牙尖顶端形成的四边形面积。唐氏综合征组的所有牙尖间距离均显著更小。将逐步逻辑回归应用于所有牙尖间距离，用于建立唐氏综合征患者和正常人的多变量概率模型。右上颌磨牙（牙齿16）的mb-dl和mb-ml距离足以区分唐氏综合征患者和正常牙齿：[表格：见原文]当mb-ml在mb-ml/mb-dl比值中相对较高时，唐氏综合征的概率更高。基于角度组的另一项逻辑分析显示，有3个角度的组合在两组之间具有高度统计学意义的区分：唐氏综合征患者的mb-db-dl角度更高，唐氏综合征患者的mb-dl-db角度略小，唐氏综合征患者的mb-ml-db角度略小。dl尖更靠近牙齿中心。尺寸变化发生在早期阶段，而形状变化发生在唐氏综合征人群牙齿形成的后期阶段。我们的唐氏综合征牙齿概率模型简单实用，因为只需将2个牙尖间距离代入公式即可。
