错(牙合)畸形尖牙、双尖牙组与其它组牙的相关分析

目的：研究错牙合、正常牙合的尖牙、双尖牙组与其它组牙的相关性，为尖牙、双尖牙组的预测提供科学依据。方法：选用５组不同类型错牙合和正常牙合，每组男女各３０人，共３６０人，应用ＹＭ－２１１５三维测量仪测量牙齿最大近远中径，进行有关的相关性统计分析。结果：正常牙合的尖牙、双尖牙组与下切牙组高度相关，符合Ｍｏｙｅｒｓ预测机理，但错牙合的尖牙、双尖牙组一般与同牙列的切牙加第一磨牙组高度正相关。结论：临床上对错牙合尖牙、双尖牙组的预测不能简单等同于正常牙合。     

尖牙、双尖牙、磨牙的合关系研究

调查武汉市２７３１个恒牙猎人群，年龄１２～１７岁，男性１４６８人，女性１２６３人，按正常标准从中筛选出８５人，占调查人数的３％。对正常模型进行测量，探讨其尖与沟，尖与隙，尖与窝的对位关系特点，通过究得出以下结论：①磨牙中性，尖牙双尖牙跨骑关系和磨牙中性偏近中，尖牙双尖牙交错关系是正常的两种基本关系类型，分别占７６％和２４％；尖牙双尖牙的跨骑和磨牙偏近中的程度约为１ｍｍ。②两种型的形成机理主要是由于上下牙冠近远中径比例的差异及牙位补偿调整的结果。     

上颌第一双尖牙牙冠周径测量及其影响因素

目的探讨上颌第一双尖牙牙冠的周径与其颊舌径、近远中径、对角距离等解剖标志间的关系,为制作和选择带环提供参考依据.方法收集12～25岁患者拔除的100只离体上颌第一双尖牙,利用游标卡尺对上颌第一双尖牙进行测量,分析、观察牙冠周径与颊舌径、近远中径、对角距离的关系,列表总结并作统计学处理.结果上颌第一双尖牙牙冠周径与其颊舌径、近远中径关系最为密切(P<0.01).结论可通过测量上颌第一双尖牙颊舌径来推算牙冠周径.     

待萌尖牙、双尖牙近远中宽度的预测

<正>近年来,在混合牙列早期进行正畸治疗有一个逐渐增加的趋势。对于正畸医生来说,要想做出正确的诊断和合理的治疗计划,必须对待萌尖牙、双尖牙近远中径进行准确的预测,对牙齿大小与牙弓长度的关系进行精确的分析。 早在1897年,Black已就此问题进行探讨,提出根据牙齿平均近远中宽度来预测待萌尖牙和双尖牙的宽度。由于     

曲面断层片测量牙根角度的可靠性评价

目的：参照相对于水平弓丝平面的实际牙体长轴．检验曲面断层片测量牙齿近远中倾斜度的可靠性。方法：选择一个解剖标志清晰，牙齿可拆卸的透明模拟殆架，将直径08mm的铬钢球粘在牙切缘／耠面和根尖／根分叉处，作为牙长轴在牙片和相片上的参考标志。用特定技术拍摄每一颗牙的照片来测量牙齿的实际近远中向倾斜度。结果：只有所有上颌牙的倾斜角度与实际的近远中倾斜度显著相关。X线片中，下颔相邻两牙长轴的聚合与离散情况和上颌的一样，同真实情况没有显著相关，特别是呈现离散表现的上尖牙到双尖牙区和呈现聚合表现的下颌切牙到尖牙区．与真实情况无相关。结论：曲面断层片上无法显示真实的牙齿近远中倾斜度，需要谨慎使用于临床判断中。     

OPA-K平直弓丝矫治技术排齐阶段的临床研究

目的：研究平直弓丝矫治技术排齐阶段使用弹性链状圈远中移动尖牙的效果及其对前牙、尖牙、后牙的影响。方法：15例拔除4个第一双尖牙的正畸病例，使用日本TOMY公司生产的OPA-K平直弓丝矫治器进行矫治，排齐前后利用模型测量和X线头影测量进行统计学分析。结果：第一磨牙近中倾斜但前移不明显且牙冠近中舌向旋转；双尖牙及磨牙区牙弓缩窄；尖牙远中倾斜移动，牙尖间宽度增大；上下切牙舌向倾斜移动，前牙覆He加深。结论：平直弓丝矫治技术排齐阶段使用弹性链状圈远中移动尖牙配合弓丝末端回弯，可有效预防切牙唇倾，加快排齐的速度。应采取必要的增强支抗及控制前牙覆He的措施，预防此期中出现的不利变化。     

压低辅弓增加后牙支抗的临床应用研究

目的：研究压低辅弓在尖牙远移过程中增加后牙支抗的临床效果。方法：选择需要强支抗,上颌减数第一双尖牙的患者30例,随机分为研究组和对照组,每组15例,研究组采用上颌NANCE弓,配合0.017＂×0.025＂TMA压低辅弓,30°后倾弯,150g力远中牵引尖牙至第二双尖牙,对照组采用上颌NANCE弓,配合口外弓。将矫治前后的头颅侧位定位片和三维模型进行对比分析,其变化量进行独立t检验。结果：研究组在尖牙远中移动的过程中,右侧上颌第一磨牙近中移动0.77mm,近中腭向扭转8.9°;左侧上颌第一磨牙近中移动约0.72mm,近中腭向扭转8.8°;右侧上颌尖牙远中移动约5.5mm,远中腭向扭转10.3°;左侧上颌尖牙远中移动约5.71mm,远中腭向扭转15.1°。与对照组相比无显著性差异。且第一磨牙在前后向的位移与尖牙的位移和磨牙的扭转存在高度相关性。结论：30°后倾弯的压低辅弓在远中移动尖牙过程中,可以为后牙提供强支抗。     

改良滑动直丝弓托槽的竖沟设计对支抗的影响

目的研究改良滑动直丝弓托槽背板上的竖沟设计在拉尖牙向远中移动的过程中的作用,检验此设计在减小摩擦力节省支抗方面是否有效。方法选用Ⅱ°~Ⅲ°拥挤的AngleⅠ类错患者28例,年龄14~25岁,均拔除四个第一双尖牙,使用杭州西湖巴尔公司生产的改良滑动直丝弓矫治器进行矫治。在拉尖牙向远中移动的过程中,对尖牙采用竖结扎,在尖牙与第一磨牙之间挂弹性橡皮圈,力值为90~100g。在拉尖牙之前及尖牙与第二双尖牙并拢之后,分别进行模型测量和X线头影测量,并进行统计学分析。结果上颌尖牙远中移动的距离与上颌磨牙近中移动距离之比为11.161;下颌尖牙远中移动的距离与下颌磨牙近中移动距离之比为5.941。上下颌切牙均有明显内收。结论改良滑动直丝弓托槽的竖沟设计及尖牙的竖结扎,在拉尖牙向远中移动的过程中减小了尖牙托槽与主弓丝之间的摩擦力,节省了支抗,并符合差动力的原理。改良滑动直丝弓矫治器的使用可为错畸形的矫治提供强支抗,从而省去了使用口外弓等其它增强支抗的方法,使滑动直丝弓矫治器的使用更加简便。     

下切牙先天缺失与牙颌畸形关系的分析研究

目的：探讨下恒切牙先天缺失情况及其与牙颌畸形的关系以及下尖牙近远中径的变化。方法：从962名门诊正畸病人中选取下颌恒切牙缺失的病例27名，并测量下前牙牙冠的近远中径。结果：下颌恒切牙先天缺失96％是中切牙，92％伴有前牙深覆He，下尖牙无显著性增大。结论：下颌中切牙先天缺失与前牙深覆He的形成有密切关系，下尖牙无代偿性增大。     

一种下颌混合牙列的分析方法

在早期混合牙列中,准确地确定可利用的间隙非常重要。许多学者在早期混合牙列中对未萌出的恒尖牙及双尖牙的近远中径尺寸及其可利用的间隙进行估测得出多种方法。归类为两种途径,即各种X线摄片法和对已萌出的恒切牙近远中径的测定值来间接估计的方法。尽管间接估计法有多种不同的分析法,然统计学分析表明:X线摄片法的预测值更接近于实际的恒尖牙及双尖牙的联合宽度。本文提出了一种不用X线片的分析法称为侧切牙间距分析法     

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。     

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.     

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.     

Mixed dentition analysis in a Jordanian population

OBJECTIVE: To examine the applicability of the Tanaka and Johnston method of prediction in a Jordanian population and to develop a new prediction method for this specific population if necessary. MATERIALS AND METHODS: Three-hundred and sixty-seven Jordanians (193 female, 174 male, mean age 15.5 years) were randomly selected to represent 0.1% of 10th grade schoolchildren from Amman, Jordan. The mesiodistal crown diameters of the permanent teeth were measured and compared with the predicted values derived from the Tanaka and Johnston equations. RESULTS: 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 0.60 and 0.66, respectively. There were significant differences between the actual measurements and measurements derived from the Tanaka and Johnston equations. New linear regression equations were derived for both genders to allow tooth size prediction in Jordanians. CONCLUSIONS: There is a limitation in the application of the Tanaka and Johnston's prediction method to a Jordanian population. It is important to use separate equations for male and female patients.     

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.     

替牙期未萌尖牙、前磨牙宽度和预测方程的建立

目的优化选择针对未萌尖牙、前磨牙宽度预测的基牙组合。方法取正畸科初诊患者的研究模型,按一定标准随机选出恒牙列模型180副,利用电子游标卡尺(精度0.01 mm)测量牙冠近远中径,并对测量值进行相关与回归分析。结果得到了与未萌尖牙、前磨牙宽度相关度较高的基牙组合,即,上颌第一磨牙和上、下颌中切牙联合;此组合与上、下颌预测牙的相关度分别为0.753和0.834,具有统计学意义(P≤0.001)。以此为基础进行回归分析,建立了预测上、下颌尖牙、前磨牙宽度之和的回归方程。结论建立了一组适合中国北方地区替牙期儿童未萌尖牙、前磨牙宽度的预测方程:男性Y=0.64X+6.89(上颌),Y=0.79X+2.45(下颌);女性Y=0.64X+6.86(上颌),Y=0.72X+3.90(下颌)(Y代表一侧未萌尖牙、前磨牙近远中宽度和,X代表双侧上颌第一磨牙及上、下颌中切牙的近远中宽度和的一半)。     

Tooth-size reduction associated with occurrence of palatal displacement of canines

This study investigates mesiodistal crown size of the maxillary and mandibular incisors of patients with palatally displaced canines (PDC). Pretreatment dental casts of orthodontic patients with PDC of 1 or both maxillary canines (N = 31; M10:F21) were collected. This PDC sample was matched according to age and sex with pretreatment dental casts from unaffected orthodontic patients. For the PDC and matched control samples, maximum mesiodistal crown diameters were recorded for the 4 incisors on the left side only. The results showed that, on average, the mesiodistal crown diameters for the maxillary and mandibular incisors measured smaller in the PDC sample than in the control sample. These findings of statistically significant tooth-size reductions associated with PDC occurrence indicate a generalized pattern of reduced tooth size as a characteristic associated with the PDC anomaly. Further, the presence of generalized tooth-size reduction in cases with palatally displaced canines helps explain why most orthodontic treatment plans for PDC patients are of the nonextraction type.     

Mixed dentition space analysis in Egyptian children

This study was done to examine the applicability of the Tanaka and Johnston and Moyers’ methods of prediction in Egyptian population and to develop a new prediction method for this specific population if necessary. A total of 325 Egyptian students 145 female, 180 male, mean age 14.4 years, SD±1.1 years were randomly selected from 10 preparatory and secondary schools in Mansoura city, Dakahlia governorate, Egypt during the academic year 2008–2009. The mesiodistal crown diameters of the permanent teeth were measured and compared with the predicted values derived from the Tanaka and Johnston's equations and from Moyers’ probability tables at 35%, 50% and 75%. Significant sexual dimorphism was found in tooth sizes. There were significant differences between the actual measurements and that derived from the Tanaka and Johnston's equation and Moyers’ tables. New linear regression equations were derived for both genders to allow accurate tooth size prediction in Egyptians. 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 0.78 and 0.89 in male and 0.63 and 0.87 in female, respectively. It can be concluded that there is a limitation in the application of the Tanaka and Johnston's and Moyers’ prediction methods to Egyptian population. The developed prediction equation is more accurate for predicting the mesiodistal widths of unerupted canine and premolars of Egyptian population.     

Comparative odontometric data between Moroccan and Senegalese]

INTRODUCTION: knowledge on the mesiodistal crown diameter of permanent teeth is relevant to clinical dentistry especially to orthodontics and prosthetic dentistry. Important variations have been reported in tooth crown size dimension between different populations. This seems to be related to complex interactions between genetic and environmental factors. The aim of this study was to compare the mesiodistal crown diameter of the permanent teeth in Moroccan and Senegalese populations. MATERIAL AND METHODS: the material for this study consisted of 104 pairs of study models of randomlyselected Moroccan (54 pairs) and Senegalese (50 pairs) children. The maximum mesiodistal dimensions were recorded for premolars, molars, canines and incisors in each study model using an electronic digital calliper (Mitutoyo, Japan) to the nearest 0.01 mm. The mesiodistal diameter of antimeric teeth was compared using paired sample t test. The independent sample t test was used to test for any difference between Moroccan and Senegalese regarding mesiodistal crown diameter of isomeric teeth. RESULTS: there were no significant differences in the mesiodistal diameter of antimeric teeth. The mesiodistal dimension of the canine was significantly larger in males than in females of both populations. The mesiodistal crown diameter of isomeric teeth was significantly larger in Senegalese in comparison to Moroccan. CONCLUSION: Further work with a larger number of non orthodontic subjects is needed to validate these findings.     

Anatomic crown width/length ratios of unworn and worn maxillary teeth in white subjects

STATEMENT OF PROBLEM: Dimensions of teeth have been available for a century. Some significant and clinically relevant aspects of dental esthetics, however, such as the crown width/length ratios, have not been presented in tooth morphology sources until recently. PURPOSE: The purpose of this study was to analyze the anatomic crowns of 4 tooth groups (central incisors, lateral incisors, canines, and first premolars) of the maxillary dentition with respect to width, length and width/length ratios and determine how these parameters are influenced by the incisal edge wear. MATERIAL AND METHODS: Standardized digital images of 146 extracted human maxillary anterior teeth from white subjects (44 central incisors, 41 lateral incisors, 38 canines, 23 first premolars) were used to measure the widest mesiodistal portion "W" (in millimeters) and the longest inciso-cervical/occluso-cervical distance "L" (in millimeters). The width/length ratio "R" (%) was calculated for each tooth. A 1-way analysis of variance was used to compare the mean values of W, L, and R for the different groups ("unworn" and "worn" subgroups, except for premolars). Multiple least significant difference range tests (confidence level 95%) were then applied to determine which means differed statistically from others. RESULTS: There was no influence of the incisal wear on the average value of W (width) within the same tooth group. The widest crowns were those of central incisors (9.10 to 9.24 mm) > canines (7.90 to 8.06 mm) > lateral incisors (7.07 to 7.38 mm). Premolars (7.84 mm) had similar width as canines and worn lateral incisors. The L-value was logically influenced by incisal wear (worn teeth were shorter than unworn teeth) except for lateral incisors. The longest crowns were those of unworn central incisors (11.69 mm) > unworn canines (10.83 mm) and worn central incisors (10.67 mm) > worn canines (9.90), worn and unworn lateral incisors (9.34 to 9.55 mm), and premolars (9.33 mm). Width/length ratios also showed significant differences. The highest values were found for worn central incisors (87%) and premolars (84%). The latter were also similar to worn canines (81%), which constituted a homogeneous group with worn lateral incisors (79%) and unworn central incisors (78%). The lowest ratios were found for unworn canines and unworn lateral incisors (both showing 73%). CONCLUSIONS: Along with other specific and objective parameters related to dental esthetics, average values for W (mesiodistal crown dimension), L (inciso-cervical crown dimension), and R (width/length ratio) given in this study for white subjects may serve as guidelines for treatment planning in restorative dentistry and periodontal surgery.