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目的比较不同错牙合类型同名牙牙冠大小,为建立未萌恒牙宽度预测方程提供指导依据。方法选取2012—2013年就诊于吉林大学口腔医院正畸科就诊的12~18岁男、女患者初诊记存模型各150副,按照安氏错牙合分类法将其分为Ⅰ、Ⅱ、Ⅲ组。测量各组模型同名牙牙冠的近远中宽度,比较分析其大小及其性别差异。结果各组内大多数研究样本左右两侧同名牙的牙冠宽度差异无统计学意义(P>0.05),而不同性别同名牙的牙冠宽度差异存在统计学意义(P<0.05)。结论应分别建立不同性别的未萌恒牙宽度预测方程,并取两侧同名牙牙冠宽度的平均值,以提高预测方程的准确性。     

不同错牙合类型同名牙牙冠大小比较分析

目的    比较不同错牙合类型同名牙牙冠大小,为建立未萌恒牙宽度预测方程提供指导依据。方法    选取2012—2013年就诊于吉林大学口腔医院正畸科就诊的12 ~ 18岁男、女患者初诊记存模型各150副,按照安氏错牙合分类法将其分为Ⅰ、Ⅱ、Ⅲ组。测量各组模型同名牙牙冠的近远中宽度,比较分析其大小及其性别差异。结果      各组内大多数研究样本左右两侧同名牙的牙冠宽度差异无统计学意义（P＞0.05）,而不同性别同名牙的牙冠宽度差异存在统计学意义（P＜0.05）。结论    应分别建立不同性别的未萌恒牙宽度预测方程,并取两侧同名牙牙冠宽度的平均值,以提高预测方程的准确性。     

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。     

安氏Ⅱ类错(牙合)的牙冠宽度与Bolton指数的测量分析

目的:通过对安氏Ⅱ1类及安氏Ⅱ2类错(牙合)与正常(牙合)模型比较,分析上下颌牙冠宽度、Bolton指数差异,为安氏Ⅱ类错(牙合)矫治设计提供参考.方法:以正常(牙合),安氏Ⅱ1及安氏Ⅱ2错(牙合)各40例为研究对象,分别进行牙冠宽度测量并计算Bolton指数.结果:①安氏Ⅱ1错(牙合)的上下颌侧切牙及第二前磨牙的牙冠宽度比正常(牙合)大,并有显著性差异.②Bolton指数前牙比及全牙比:正常(牙合)＞安氏Ⅱ2错(牙合)>安氏Ⅱ1错(牙合).③正常(牙合)上下颌前牙牙量的直线回归方程:Y=X 10.45;全牙列的直线回归方程:Y=1.13X-2.57.结论:上下颌牙量不调是造成安氏Ⅱ类错(牙合)深覆盖、深覆(牙合)的因素之一;前牙量及全牙量的线性回归方程具有较高的临床应用价值.     

牙列拥挤与牙弓、牙槽弓、基骨弓形态相关性的多元回归分析

目的:分析错(牙合)畸形人群的牙列拥挤程度与牙弓、牙槽弓及基骨弓的长度和宽度相关性,探讨牙列拥挤的病因机制.方法:选择错(牙合)畸形患者382 例,测量初始记存模型的牙冠宽度,牙弓弧形长度,牙弓、牙槽弓、基骨弓宽度和长度,对拥挤度与牙弓、牙槽弓、基骨弓的宽度和长度进行回归分析.结果:牙列拥挤与牙弓、牙槽弓、基骨弓的宽度、长度相关,有统计学意义,且长度对牙列拥挤的影响大于宽度.牙弓、牙槽弓、基骨弓与牙列拥挤的相关性依次减少.结论:牙弓、牙槽弓、基骨弓形态与牙列拥挤密切相关,且长度对牙列拥挤的影响大于宽度,提示在临床处理拥挤病例时扩弓的重要性.     

基于遗传算法优化青少年下颌磨牙后区生长潜力预测方法研究

目的　探讨影响青少年下颌磨牙后区生长潜力的因素,并分析基于遗传算法（genetic algorithms,GAS）优化青少年下颌磨牙后区生长潜力非线性预测方程的准确性。方法　选取2017—2019年于吉林大学口腔医院正畸科就诊的符合纳入标准的初诊患者306例。通过头颅定位侧位片测量下颌磨牙后间隙及颈椎测量指标,采用多元线性回归分析下颌磨牙后间隙与年龄、下颌第三磨牙牙龄、颈椎骨龄等的相关性,选取最强相关因子构建线性回归方程和基于GAS优化的非线性方程,并比较两个预测方程的准确性。结果　（1）不同矢状骨面型患者下颌磨牙后间隙不同,骨性Ⅰ类错牙合畸形组［（9.99 ± 2.53）mm ］与骨性Ⅲ类错牙合畸形组［（10.53 ± 3.53）mm ］比较,差异无统计学意义（P > 0.05）;而骨性Ⅱ类错牙合畸形组患者下颌磨牙后间隙［（8.98 ± 2.71）mm］小于骨性Ⅰ类和Ⅲ类错牙合畸形组,差异均有统计学意义（均P < 0.05）。故将所有患者分为骨性Ⅰ+Ⅲ类错牙合畸形组和骨性Ⅱ类错牙合畸形组。（2）下颌磨牙后间隙（RMS）与下颌第三磨牙牙龄（YL）呈正相关关系,两组分别构建线性回归方程和基于GAS优化的非线性方程如下。骨性Ⅰ+Ⅲ类错牙合畸形组：RMS = 1.489YL + 3.891;RMS = 2.36YL0.81 + 2.686。骨性Ⅱ类错牙合畸形组：RMS = 1.464YL + 1.961;RMS = 2.36YL0.81 + 0.723。基于GAS优化的非线性方程误差值低于线性回归方程,但其差异无统计学意义（P > 0.05）。结论　临床正畸医生进行青少年患者正畸方案设计时,应着重结合患者第三磨牙牙龄及矢状骨面型。应用基于GAS优化的非线性方程预测下颌磨牙后区生长潜力具有较高的预测精度和准确性。     

基于遗传算法优化青少年下颌磨牙后区生长潜力预测方法研究

 目的　探讨影响青少年下颌磨牙后区生长潜力的因素，并分析基于遗传算法（genetic algorithms，GAS）优化青少年下颌磨牙后区生长潜力非线性预测方程的准确性。方法　选取2017-2019年于吉林大学口腔医院正畸科就诊的符合纳入标准的初诊患者306例。通过头颅定位侧位片测量下颌磨牙后间隙及颈椎测量指标，采用多元线性回归分析下颌磨牙后间隙与年龄、下颌第三磨牙牙龄、颈椎骨龄等的相关性，选取最强相关因子构建线性回归方程和基于GAS优化的非线性方程，并比较两个预测方程的准确性。结果　（1）不同矢状骨面型患者下颌磨牙后间隙不同，骨性Ⅰ类错牙合畸形组［（9.99 ± 2.53）mm ］与骨性Ⅲ类错牙合畸形组［（10.53 ± 3.53）mm ］比较，差异无统计学意义（P > 0.05）；而骨性Ⅱ类错牙合畸形组患者下颌磨牙后间隙［（8.98 ± 2.71）mm］小于骨性Ⅰ类和Ⅲ类错牙合畸形组，差异均有统计学意义（均P < 0.05）。故将所有患者分为骨性Ⅰ+Ⅲ类错牙合畸形组和骨性Ⅱ类错牙合畸形组。（2）下颌磨牙后间隙（RMS）与下颌第三磨牙牙龄（YL）呈正相关关系，两组分别构建线性回归方程和基于GAS优化的非线性方程如下。骨性Ⅰ+Ⅲ类错牙合畸形组：RMS = 1.489YL + 3.891；RMS = 2.36YL0.81 + 2.686。骨性Ⅱ类错牙合畸形组：RMS = 1.464YL + 1.961；RMS = 2.36YL0.81 + 0.723。基于GAS优化的非线性方程误差值低于线性回归方程，但其差异无统计学意义（P > 0.05）。结论　临床正畸医生进行青少年患者正畸方案设计时，应着重结合患者第三磨牙牙龄及矢状骨面型。应用基于GAS优化的非线性方程预测下颌磨牙后区生长潜力具有较高的预测精度和准确性。     

维吾尔族正常(牙合)青年牙、牙弓、基骨的测量研究

由于不同民族,不同地区人群的颅面结构不同。进行模型测量分析时必须根据不同民族、地区正常[牙合]的测量分析指数来进行错[牙合]畸形的诊断。本研究选择新疆维吾尔族人正常[牙合]牙颌模型测量分析,以建立正常[牙合]牙冠宽度,牙弓大小,基骨弓大小,腭盖高度及牙列指数的正常值。     

严重深覆(牙合)型AngleⅡ2错(牙合)牙弓宽度的测量分析

目的 :分析严重深覆牙合型AngleⅡ2 错牙合的牙弓形态特点。方法 :严重深覆牙合型AngleⅡ2 错牙合 3 2副模型为实验组 ,对照组 64副模型中AngleI错 牙合和AngleⅡ1错牙合各 3 2副模型 ,分别测量上颌尖牙之间距离、上颌第一磨牙之间距离、下颌尖牙之间距离和下颌第一磨牙之间距离。结果 :采用两样本t检验 ,四项指标中只有实验组的下颌前段牙弓宽度明显窄于对照组 (P <0 .0 0 1)。结论 :除了下颌前部牙弓宽度变窄外 ,严重深覆牙合型AngleⅡ2 错牙合牙弓形态基本正常。     

错[牙合]畸形患者Bolton指数分析

目的：通过对错[牙合]畸形患者Bolton指数测量分析,探讨牙冠宽度与安氏各类错[牙合]畸形的关系。方法：错[牙合]畸形患者的初始记存模型382副,按照安氏Ⅰ、Ⅱ1、Ⅱ2、Ⅲ类分组。测量牙冠宽度并计算Bohon指数,测量结果采用Dunean’s检验。结果：382例错[牙合]畸形病例的前牙比、全牙比、后牙比均没有性别间的差异。安氏Ⅰ、Ⅱ1、Ⅱ2类错[牙合]畸形患者前牙比和全牙比与正常[牙合]人群基本一致,而Ⅲ类错[牙合]畸形患者前牙比和全牙比则与正常[牙合]人群间存在差异,安氏Ⅲ类错[牙合]畸形患者的前牙比及全牙比明显高于其他各组,有显著性差异。结论：上下颌间牙量关系不调是安氏Ⅲ类错[牙合]畸形的主要病因之一。     

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。     

The mesiodistal crown diameters of primary dentition in Indonesian Javanese children

Dentition analysis of primary teeth is necessary for recognising and correcting occlusal problems in every stage of dental development to enable normal adult occlusion. To do this, normative data of mesiodistal tooth crown diameters from the same ethnic population are needed. The aims of this study were to gather normative data of mesiodistal crown diameters of primary dentition in Indonesian Javanese children and to compare this normative data with published data of other ethnic populations. Dental casts of 160 males and 137 females with acceptable occlusion, aged 3.25-6.58 years, were taken in Yogyakarta, Indonesia. Mesiodistal diameter was measured as the distance between the anatomic contact points using calipers with accuracy to within 0.05 mm. Each measurement was taken twice on different occasions. The results indicated that the magnitude of asymmetry between right and left teeth was larger in distal teeth within a tooth field, larger in males than females, and larger in mandibular than maxillary teeth. The stability of mesiodistal tooth crown diameters was less in males than in females, and was most prominent in the mandibular central incisor. Sexual dimorphisms were found in, the lateral incisor and first molar in the maxilla, and the canine, first and second molars in the mandible. Compared with other ethnic populations, Indonesian Javanese falls between Hong Kong Chinese and Australian Aboriginal.     

Variability and patterning in permanent tooth size of four human ethnic groups

AimsDental dimensions vary between different ethnic groups, providing insights into the factors controlling human dental development. This paper compares permanent mesiodistal crown diameters between four ethnic groups highlighting patterns of tooth size between these groups and considers the findings in relation to genetic and environmental influences.Methods and resultsMesiodistal crown dimensions were recorded using standardised manual measurements on dental casts derived from four different human populations: Southern Chinese, North Americans of European ancestry, Modern British of European ancestry and Romano-British. Analyses based on double determinations showed that measurements in all study samples were reliable to an accuracy of 0.1 mm. The Southern Chinese sample was found to have the largest teeth overall, whereas the Romano-British sample generally displayed the smallest mesiodistal crown dimensions (p < 0.001). However, the Modern British sample had the largest maxillary central incisors, mandibular central and lateral incisors, and mandibular canines, while the North American sample had the largest maxillary first and second molars. Comparisons of coefficients of variation for teeth within each class showed that the later-forming teeth displayed greater variation in mesiodistal size than the earlier-forming teeth.ConclusionThe different patterns of tooth size observed between the study samples are thought to reflect differences in the relative contributions of genetic, and environmental influences to dental development between the four populations. For example, it is proposed that major environmental insults during the early life of Romano-Britons, including recurrent illnesses, poor nutrition and excessive lead ingestion, contributed to the reduction in size and greater variability of their later-forming teeth. Using a standardised methodology, significant differences in mesiodistal crown diameters have been demonstrated between four human ethnic groups. There were also distinct differences in the patterns of crown size between the groups, with the later-forming teeth in each type generally showing greater size variation.     

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。     

EVALUATION OF THE NEED TO DISTINGUISH BETWEEN WHITE AND BLACK PATIENTS IN PREDICTING THE COMBINED MESIODISTAL CROWN WIDTH OF CANINES AND PREMOLARS

The aim of the present study was to evaluate the need to distinguish between white and black patients when predicting the combined mesiodistal crown width of canines and premolars in Recife. A sample of 120 dental casts (60 from black and 60 from white patients) was selected from the archives of dental clinics in Recife. The mesiodistal crown width of the maxillary and mandibular canines and premolars and of the mandibular incisors was measured in these casts using a caliper with an accuracy of 0.02mm. The combined mesiodistal crown width of these teeth in the black patients was compared with that found in the white patients, and also with the estimated values obtained by regression equations based on the sample of white patients and on a large sample of a population from the same city. The study demonstrated that there were no significant differences between whites and blacks in the combined mesiodistal crown width of any of the three analyzed teeth groups and also revealed that such equations were statistically accurate in estimating the mesiodistal crown width of canines and premolars in blacks. It was concluded that there is no need for specific tables or equations regarding the patient''s race in the analysis of mixed dentition in Recife.     

Spacing in the human deciduous dentition in relation to tooth size and dental arch size

Dental casts of 243 preschool children, 129 males and 114 females, aged 2.5-5.5 years, were analysed for the presence of interdental spaces, mesiodistal crown diameters, intercanine width, intermolar width and arch length (circumference). The prevalence of primate spaces (diastemata mesial to the upper canines and distal to the lowers) varied from 65 to 90% by arch and sex; it was lowest in the lower arch especially in females, and highest in the upper. These prevalences did not increase with age; however, other spaces which usually occur between incisors may develop towards the end of the deciduous dentition, commonly in arches with primate spaces. Generally, spacing of the deciduous anterior teeth was significantly related to mesiodistal crown diameter and intercanine arch width. The crowns were significantly broader and the arches significantly narrower in cases with no spaces than in those where spaces existed. As the genetic programming for tooth size also normally affects arch size, greater discrepancies between mesiodistal crown diameters of the deciduous anterior teeth and their permanent successors are probably associated with more deciduous arch spacing.     

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.     

Crown size of deciduous teeth in Icelanders

Mesiodistal and buccolingual crown diameters of deciduous teeth were measured from dental casts of 540 Icelandic children. Statistically significant sexual dimorphism was present in five of the buccolingual and in six of the mesiodistal diameters. The variability of the measurements followed the field concept but did not show systematic sexual dimorphism. In accordance with the permanent teeth, the size of the deciduous teeth also proved to be at the top of the range for populations of European origin.     

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.