错畸形患者未萌尖牙、前磨牙牙冠宽度的预测

目的通过对错畸形患者的尖牙、前磨牙与其他牙(组)牙冠宽度的相关性分析,为错畸形人群的尖牙、前磨牙的牙冠宽度的预测提供科学依据。方法选择南京医科大学附属口腔医院正畸科就诊的江苏籍错畸形患者模型382副,按照安氏Ⅰ、Ⅱ1、Ⅱ2、Ⅲ类分组,测量牙冠宽度,进行尖牙、前磨牙与其他牙(组)的相关性分析,并建立预测方程。结果建立错畸形人群的尖牙、前磨牙牙冠宽度之和的预测方程:男性U3U4U5=0.270X+3.504(r2=0.5821),L3L4L5=0.272X+2.390(r2=0.5977);女性U3U4U5=0.221X+6.884(r2=0.4951),L3L4L5=0.230X+5.173(r2=0.5000)。X为上、下颌中切上、下颌第一磨牙牙冠宽度之和。结论本研究所建立的回归预测方程要优于Moyers预测法,回归预测方程不因错畸形安氏分类的不同而有差别。     

一种新的预测法在替牙期牙列预测中的应用

目的 建立预测尖牙和前磨牙宽度和的多元回归方程。方法 测量180例青少年牙齿的近远中宽度,将替牙期已萌的牙齿分成5组,以上下颌的尖牙与前磨牙宽度之和为应变量(Y),进行多元回归分析,比较Moyers预测法(75%水平)、Tanaka&Johnston预测法和本预测法的相关系数及95%区间。结果 本预测法的相关系数高于其余2种方法,95%区间也最窄。结论 本预测法是一种较科学的预测替牙期未萌牙齿宽度的方法。?     

第一恒磨牙的牙根吸收

本文报告了1例未萌出的上颌第二前磨牙引起邻近的第一磨牙严重吸收的病例。患者,11岁,因Ⅱ类错(牙合)畸形伴双牙弓拥挤而进行矫正。全景X 线片上可见到第三磨牙、上颌左侧尖牙和右侧第二前磨牙未萌出。根周X 线片显示未萌出的前磨牙已明显地导致邻近磨牙的吸收。拔下的上颌右侧第一磨牙检查,发现其3个牙根     

使用45°倾斜头颅测量X线片预测未萌下颌尖牙与前磨牙的近远中径

混合牙列期的矫治,重要的是要知道未萌出牙的近远中径的大小,以便采用不同的矫治措施。以往的方法有:①直接从X线片上测量或再使用预测公式;②使用预测表;③前二种方法结合使用。本文作者研究了使用45°倾斜的头颅测量X线片来预测未萌下颌尖牙和前磨牙近远中宽度的可靠性,以便建立预测表。     

上颌中切牙内收与消耗牙弓间隙量的相关性研究

目的 探究上颌中切牙内收量与其消耗牙弓间隙量的比例关系。方法 选择拔除上颌第一前磨牙的前牙深覆盖成年正畸患者203例,对治疗前、后的锥形束CT进行三维重建,测量上颌中切牙内收量(X₁)、尖牙间宽度变化量(X₂)及尖牙远中移动量。数字化扫描仪扫描治疗前的上颌石膏模型,测量上颌前段牙弓拥挤度。将上颌中切牙内收量、尖牙间宽度变化量与消耗的总牙弓间隙量(Y)进行相关分析、线性回归分析。结果 上颌中切牙内收量与牙弓间隙的消耗量呈强正相关(r=0.726,P＜0.001),尖牙间宽度变化量与牙弓间隙消耗量呈负相关(r=-0.317,P<0.001),消耗的总牙弓间隙量(Y)与上颌中切牙内收量(X₁)、尖牙间宽度变化量(X₂)的回归方程为Y=1.25X₁-0.494X₂-2.299。结论 上颌中切牙每内收1 mm,消耗的牙弓间隙为1.250 mm;尖牙间宽度每缩减1 mm,消耗的牙弓间隙为0.494 mm。     

混合牙列中下颌牙弓长度的分析

本文介绍一种利用修订后的Hixon-Oldfather预测图以及逐步填入法,对混合牙列的牙齿大小与牙弓长度关系进行了分析,预测牙齿大小与牙弓长度的不调,同时还讨论了在下颌牙弓间隙分析中需要考虑的一些因素。文章介绍的修订后的Hixon-Oldfather预测图见图。图中的横轴,表示下颌每侧已萌切牙的近远中宽度与根尖牙片上测得的未萌前磨牙宽度的总和。纵轴表示下颌未萌尖牙、前磨牙的预测宽度之和。斜线为回归直线。找出横轴上的下颌切牙及前磨牙测量总和的点,垂直向上与斜线相交,由交点向左     

58例自体牙齿再植术成败原因分析

1993～1996年4年间作者共进行牙再植术86例,现随访到58例72个牙齿,报告如下:1　临床资料随访到的58例患者,年龄9～51岁,男39例,女19例,35岁以下者47例,占81.3%。下颌牙24个,上颌牙48个。下颌中切牙9个,上颌中切牙15个;下颌侧切牙7个,上颌侧切牙13个;上颌尖牙11个,下颌前磨牙4个,上颌前磨牙8个;下颌磨牙4个,上颌磨牙1个。　　外伤脱位53个:其中中切牙20个,侧切牙16个,尖牙8个;前磨牙9个。错位阻生5个:其中尖牙2个,前磨牙3个。扭转畸形9个:其中中切牙4个,侧切牙4个,尖牙1个。慢性尖周炎2牙均为磨牙。智齿拔除致邻牙脱位3个,均为磨牙。2　操作…     

Tanaka-Johnston dentition analysis for northern Chinese

目的 分析北方汉族青少年下颌切牙总宽度与尖牙、双尖牙总宽度之间的相关性,探寻适合目标人群的Tanaka-Johnston预测方程.方法 从就诊于首都医科大学口腔医学院正畸科的病例中选取记存模型127副.研究下颌切牙总宽度与尖牙、双尖牙总宽度之间的相关性,建立北方汉族人的Tanaka-Johnston预测方程,并评价不同预测方程的准确性.结果 男性组下颌切牙总宽度与上、下颌尖牙双尖牙总宽度之间相关系数r为0.71、0.77,女性组r为0.50、0.56.除本研究得出的方程外,其他预测方程普遍存在低估倾向.男性组实测值与预测值之差小于1mm的以北方汉族人方程上颌84%、下颌88%为最高;女性组以成都汉族人方程上颌74%,下颌81%为最高.结论 与女性相比,男性下颌切牙总宽度与尖牙、双尖牙总宽度存在较强的正相关关系.预测准确度最高的方程分别为:男性上颌Y=11.8+0.5X,下颌Y=10.9+0.5X;女性上颌Y=11.1+0.5X,下颌Y=10.0+0.5X.     

北方汉族人Tanaka-Johnston预测方程研究

目的分析北方汉族青少年下颌切牙总宽度与尖牙、双尖牙总宽度之间的相关性,探寻适合目标人群的Tanaka-Johnston预测方程。方法从就诊于首都医科大学口腔医学院正畸科的病例中选取记存模型127副。研究下颌切牙总宽度与尖牙、双尖牙总宽度之间的相关性,建立北方汉族人的Tanaka-Johnston预测方程,并评价不同预测方程的准确性。结果男性组下颌切牙总宽度与上、下颌尖牙双尖牙总宽度之间相关系数r为0.71、0.77,女性组r为0.50、0.56。除本研究得出的方程外,其他预测方程普遍存在低估倾向。男性组实测值与预测值之差小于1mm的以北方汉族人方程上颌84%、下颌88%为最高;女性组以成都汉族人方程上颌74%,下颌81%为最高。结论与女性相比,男性下颌切牙总宽度与尖牙、双尖牙总宽度存在较强的正相关关系。预测准确度最高的方程分别为:男性上颌Y=11.8+0.5X,下颌Y=10.9+0.5X;女性上颌Y=11.1+0.5X,下颌Y=10.0+0.5X。     

西安地区正常(牙合)牙冠宽度及上、下颌牙量相关性研究

目的:测量西安地区汉族人正常(牙合)牙冠宽度,并对上下颌牙量的相关性进行研究.方法:选取符合纳入标准的个别正常(牙合)共计107例(男52例女55例),测量各个牙齿的最大近远中径宽度,然后依据测量值进行上、下颌牙量的相关性研究.结果:得出了西安地区正常(牙合)各个牙牙冠宽度,其中上颌中切牙、侧切牙、尖牙、第一恒磨牙以及下颌的尖牙、前磨牙牙冠宽度男性明显大于女性,存在着显著的统计学差异.上、下颌前牙量之间及上下颌总牙量间均存在着显著的相关性(γ前牙=0.754,γ全牙=0.851),Bolton指数的正常值分布范围为78.32±3.01,全牙比正常值分布范围为91.10±2.27;根据这种上、下颌牙量间的相关性得出了用于计算牙量不调量的直线回归方程.结论:西安地区部分牙冠宽度男大于女,上下颌牙量间存在相关性.     

Mixed dentition space analysis in a Jordanian population: comparison of two methods

AIMS: To test the reliability of the Moyers charts and the Tanaka and Johnston equations in Jordanians and to derive coefficients of correlation between the combined mesiodistal widths of the four permanent mandibular incisors and the combined widths of the canine and premolars of the maxillary and mandibular quadrants. METHODS: The dental models of the dentition of 130 male and 96 female Jordanian subjects (age range is 14-16 years) with complete permanent dentition were randomly selected. The mesiodistal width of the four permanent mandibular incisors, maxillary and mandibular canines, and premolar teeth were measured using a vernier gauge caliper to the nearest 0.1 mm. The actual teeth measurements were then compared with the predicted values derived from the Tanaka and Johnston equations and Moyers probability tables. Correlation and linear regression analyses were performed between the predicted and actual tooth size for Jordanian children and standard regression equations were developed. RESULTS: Except for the maxillary arch in male subjects, Tanaka and Johnston regression equations underestimated the mesiodistal widths of permanent canines and premolars. On the other hand, there were no statistically significant differences between actual mesiodistal widths of canines and premolars and the predicted widths from Moyers charts at the 65% and 75% level for the lower and upper arches in male subjects and at the 85% level for the upper and lower arches in female subjects. For the newly developed regression equations, the correlation coefficients between the sum of the mandibular four incisors and the sum of the canine and premolars were 0.60 (for lower) and 0.51 (for upper) in male subjects and 0.59 and 0.64, respectively, in female subjects. CONCLUSIONS: (1) Tanaka and Johnston prediction method was not accurate when applied to a Jordanian population. (2) Moyers method for prediction can be used for Jordanian children at different probability levels for male and female subjects.     

A new, accurate and fast digital method to predict unerupted tooth size

The sum of the lower incisor tooth width has been proposed as the best predictor for calculating unerupted canine and premolar mesiodistal tooth sizes. The aims of this study were to develop a new, fast, and accurate computerized method to predict unerupted mesiodistal tooth sizes and to determine which reference tooth or combination of reference teeth was the best predictor for canines and premolars in a Spanish sample. The dental casts of 100 Spanish adolescents with permanent dentition were measured to the nearest 0.05 mm with a two-dimensional computerized system. The goal was to predict unerupted canine and premolar mesiodistal tooth sizes using the sizes of the upper central incisor, upper and lower first molar, or a combination of these as a reference and using a specific mesiodistal tooth-size table. The results showed that the Digital Method proposed was very accurate in predicting unerupted canine and premolar tooth size. The combination of the sums of the permanent upper central incisor and the lower first molar was the best predictor for canines and premolars in this sample. Upper arch teeth were better predicted than lower arch teeth. The upper lateral incisor provided the worst predictions.     

Interrelation of tooth crown diameters

The purpose of this study was to clarify the interrelation of the tooth crown diameters using statistical methods. The material consisted of 414 dental casts from orthodontic patients in the Japanese female. The mesiodistal diameters of all permanent teeth on the left side were measured, excluding the third molars. These values were examined by correlation coefficient matrix and multivariate analyses such as multiple regression, principal component and canonical correlation, etc. The results were as follows: 1) The tooth crown diameters showed a strong intercorrelation within each jaw and between both jaws. 2) When the incisors and the canine were large in size, the premolars and the molars tended to be small. 3) When the incisors and the molars were large in size, the canine and the premolars tended to be small. 4) When the incisors and the premolars were large in size, the canine and the molars tended to be small. 5) All of the teeth except the upper lateral incisor were classified according to size into the four groups of incisors, canines, premolars and molars. 6) The dentition with small teeth tended to show a spaced arch.     

Tanaka-Johnston mixed dentition analysis for southern Chinese in Hong Kong

OBJECTIVE: To compare the prediction of unerupted permanent canine and premolar size of a comparable sample size of southern Chinese population with that of the study of Tanaka and Johnston. MATERIALS AND METHODS: Teeth on study casts of an unselected sample from a 12-year-old Hong Kong Oral Health Survey of 12-year-old children (n = 459; 295 males and 164 females) were measured in the mesiodistal dimension. A Chinese mixed dentition analysis based on the Tanaka and Johnston method was constructed with linear regression equations for prediction of the mesiodistal widths of unerupted canines and premolars. Results: Sexual dimorphism was evident between southern Chinese males and females in incisors, canines, and premolars in the mesiodistal dimension. CONCLUSIONS: To predict the space (in mm) required for alignment of unerupted canine and premolars in southern Chinese children, halve the sum of the mesiodistal dimensions of the four mandibular incisors and add the respective constants for males (upper, 11.5; lower, 10.5) or females (upper, 11.0; lower, 10.0).     

恒尖牙双尖牙近远中径预测方程

目的：为口腔正畸临床混合牙列间隙分析提供简捷,便利的诊断依据。方法：在模型上测量牙冠近远中径,对测量值进行直线回归与相关分析。结果：下切牙与尖牙,双尖牙近远中径存在直线相关关系。结论：建立了汉族人群上,下颌尖牙双尖牙近远中径观测方程。     

Prediction of breadth of permanent canines and premolars in the mixed dentition.

Multiple stepwise regression was used in the selection of mixed dentition variables capable of predicting the total breadth of the unerupted permanent canine and premolars. The material consisted of 77 children. Stone casts were made before and after eruption of the canine and premolars. At the first examination when the children were, on the average, 10 years old, intraoral roentgenograms were obtained of the canine and the premolars. To predict the total breadth of the upper canine and premolars the buccolingual breadth of the upper first permanent molar and measurements on roentgenograms of the breadths of the upper canine and premolars proved most useful. In the prediction of the total breadth of the lower canine and premolars the best results were obtained with measurement of the breadths of the teeth in the roentgenograms. The breadth of the incisors proved less useful as a predictor of the breadths of unerupted canines and premolars.     

Design and implementation of a hybrid genetic algorithm and artificial neural network system for predicting the sizes of unerupted canines and premolars

The aim of this study was to develop a novel hybrid genetic algorithm and artificial neural network (GA-ANN) system for predicting the sizes of unerupted canines and premolars during the mixed dentition period. This study was performed on 106 untreated subjects (52 girls, 54 boys, aged 13-15 years). Data were obtained from dental cast measurements. A hybrid GA-ANN algorithm was developed to find the best reference teeth and the most accurate mapping function. Based on a regression analysis, the strongest correlation was observed between the sum of the mesiodistal widths of the mandibular canines and premolars and the mesiodistal widths of the mandibular first molars and incisors (r = 0.697). In the maxilla, the highest correlation was observed between the sum of the mesiodistal widths of the canines and premolars and the mesiodistal widths of the mandibular first molars and maxillary central incisors (0.742). The hybrid GA-ANN algorithm selected the mandibular first molars and incisors and the maxillary central incisors as the reference teeth for predicting the sum of the mesiodistal widths of the canines and premolars. The prediction error rates and maximum rates of over/underestimation using the hybrid GA-ANN algorithm were smaller than those using linear regression analyses.     

Mixed dentition analysis in a Senegalese population: elaboration of prediction tables.

Estimating the size of unerupted teeth is an essential aspect of orthodontic diagnosis and treatment planning in the mixed dentition. Three main methods have been used to estimate the mesiodistal crown widths of unerupted canines and premolars: direct measurements on radiographs; calculations from prediction equations and tables; and a combination of radiographic measurements and prediction tables. Because there are clear racial differences in tooth sizes, the objectives of this study were to produce odontometric data, correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and the canine and premolars for each quadrant, and prediction tables with the regression equations, specifically for Senegalese children. Fifty black Senegalese students (25 women, 25 men, mean age 23.50 years) were selected from the University Cheikh Anta Diop in Dakar, Senegal. The mesiodistal crown diameters of the permanent teeth were measured with calipers. Significant sexual dimorphism was found in tooth sizes. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and that of the maxillary and mandibular canines and premolars were found to be 0.53 and 0.70, respectively. The standard error of the estimate was better (0.66) for women in the maxilla, and the r(2) values ranged from 0.46 to 0.57 for both sexes. Prediction tables were prepared. The accuracy of the prediction tables should be tested in a larger sample including more ethnic groups.     

Predicting the size of unerupted canines and premolars of the maxillary and mandibular quadrants in an Iranian population

The aim of this investigation was to examine the accuracy of Moyers probability tables and the Tanaka and Johnston prediction equations in predicting the size of unerupted canines and premolars of the maxillary and mandibular quadrants in an Iranian population and to derive a standard formula for it. METHODS: Out of a sample of 280 subjects, 50 (25 males and 25 females) were selected by specific inclusion criteria. An electronic digital caliper was used to read the nearest 0.01 mm. The teeth measurements derived were compared with those predicted from Tanaka Johnston equations and Moyers probability tables and then standard regression were developed. RESULTS: Tanaka and Johnston regression equations overestimate the mesiodistal width of permanent canines and premolars. There were no statistically significant differences between actual mesiodistal width of canines and premolars and the predicted width from Moyers charts at 65% for the lower and upper arches in male subjects and for the lower arch in females but none of the probabilities has good accuracy for the upper arch in females. For the newly developed regression equations, the correlation coefficients between the sum of the mandibular incisors and the sum of the canine and premolars were 0.709 (for lower) and 0.539 (for upper) in subjects. CONCLUSIONS: Tanaka and Johnston overestimate the actual size for Iranian teeth widths. Moyers method can be used at 65% probability level for male subjects and at the 75% and 85% level for upper arch and the 50% and 65% level for lower arch in female subjects.     

New regression equations for predicting the size of unerupted canines and premolars in a contemporary population

The determination of a tooth-size to arch-length discrepancy in the mixed dentition requires an accurate prediction of the mesiodistal widths of the unerupted permanent teeth. This is an essential factor in treatment planning. The aim of this study was to validate Tanaka and Johnston's analysis on 600 Syrian patients aged 14-22 years. Tanaka and Johnston's tables, equations, and approximations were modified in order to improve the accuracy of the prediction. The correlation coefficients found between the size of the permanent mandibular central incisors and maxillary first molars (31, 41, 16, and 26) and the maxillary and mandibular canines and premolars were high (r = .72 and .74, respectively). New, more accurate prediction tables applicable at earlier ages, and new regression equations were constructed. In addition, new easier approximations were developed to allow the prediction of the size of the unerupted maxillary canines and premolars by adding 6 mm to the half-widths of teeth 31, 41, 16, and 26. The analogous prediction of the size of the unerupted mandibular canines and premolars was obtained by adding 5.5 mm to the half-widths of same teeth, 31, 41, 16, and 26.