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.     

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 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.     

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。     

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.     

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.     

Mixed dentition analysis in a Moroccan population.

The aims of this study were to produce odontometric data for a Moroccan population, to test Tanaka and Johnston and Moyers methods, to derive regression equations and elaborate a specific orthodontic prediction table for Moroccan children. 50 dental casts of Moroccan students (25 males, 25 females, mean age 22.6 years sd 1.35) were used to perform measurements of the greatest mesiodistal widths of all mandibular and maxillary canines and premolars and mandibular incisors with an orthodontic calliper. Significant sexual dimorphism was found in tooth sizes (p = .001). The study revealed close relationships between the total mesiodistal widths of the mandibular permanent incisors and that of the maxillary and mandibular canines and premolars. The correlation coefficients (r) and the coefficient of determination (R2) were better sexes combined for the maxilla (r = 0.60 ; R2 = 0.36 ) and for the mandible (r = 0.61 ; R2= 0.37). The regression equations elaborated for males and females were used as a basis for establishing an orthodontic prediction table for Moroccan children.     

Micro CT重建牙测量模型替代传统石膏测量模型的可行性研究

目的：探讨用Micro CT重建全牙列三维数字化模型替代传统石膏模型进行牙冠外形测量的可行性。方法：用游标卡尺测量上下颌7-7离体牙牙冠的冠宽、冠厚和冠高,作为基准数据;然后用离体牙翻制出上、下颌全牙列石膏模型,分别用游标卡尺和Micro CT自带软件测量牙冠的宽、厚、高;应用统计分析方法,评价各测量方法的可靠性和准确性。结果：利用Micro CT扫描石膏模型获得了精确的三维数字化模型;每项实验中各组数据间呈高度相关性且无明显差异（P〈0.001）;以离体牙测量结果为标准,Micro CT测量的误差范围为-0.338～0.338mm,石膏模型手工测量的误差范围为-0.408～0.408mm。结论：Micro CT可生成高精度的全牙列数字化模型,便于测量和储存,其牙冠外形的测量精度高于石膏模型。     

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.     

Development of a prediction equation for the estimation of mandibular canine and premolar widths from mandibular first permanent molar and incisor widths

The aim of this study was to develop a prediction equation for estimating the total widths of the mandibular permanent canines and premolars (TCPW) using the total widths of the mandibular first permanent molars and incisors (TWFMI). The sample comprised 288 mandibular dental casts of orthodontic patients (106 males and 182 females, average age 13.8 and 14.4 years, respectively). A digital vernier calliper was used to measure the mesiodistal tooth widths from the mandibular right to the left first permanent molar. An independent t-test was used to determine any gender difference and a multiple linear regression equation to predict TCPW using TWFMI. A paired t-test was used to compare the actual and predicted values of the canines and premolars. The results showed a statistically significant difference (P < 0.01) between the mesiodistal tooth widths of males and females. A moderate correlation and determination coefficient between TCPW and TWFMI was found (r = 0.64 to r = 0.67 and r(2) = 0.41 to r(2) = 0.44, respectively). There was no significant difference between actual and predicted values for males and females. The regression equations proposed are a good prediction method to determine TCPW.     

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.     

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 width predictions in a sample of Black South Africans.

Space analysis during the mixed dentition requires prediction of the mesiodistal widths of the unerupted permanent canines and premolars and prediction tables and equations may be used for this purpose. The Tanaka and Johnston prediction equations, which were derived from a North American White sample, is one example which is widely used. This prediction equation may be inapplicable to other race groups due to racial tooth size variability. Therefore the purpose of this study was to derive prediction equations that would be applicable to Black South African subjects. One hundred and ten pre-treatment study casts of Black South African subjects were analysed from the Department of Orthodontics' records at the University of Limpopo. The sample was equally divided by gender with all subjects having Class I molar relationship and relatively well aligned teeth. The mesiodistal widths of the maxillary and mandibular canines and premolars were measured with a digital vernier calliper and compared with the measurements predicted with the Tanaka and Johnston equations. The relationship between the measured and predicted values were analysed by correlation and regression analyses. The results indicated that the Tanaka and Johnston prediction equations were not fully applicable to the Black South African sample. The equations tended to underpredict the male sample, while slight overprediction was observed in the female sample. Therefore, new equations were formulated and proposed that would be accurate for Black subjects.     

唇挡对安氏Ⅱ类Ⅰ分类错畸形患者下颌牙列及骨骼影响的临床研究

目的　比较唇挡作用于下颌牙列前后的头颅侧位片及牙牙合模型 ,分析唇挡对下颌牙列及骨骼的影响。方法　选择 2 5例安氏Ⅱ类 1分类错牙合患者 ,戴用唇挡时间 1年 ,唇挡的位置位于距下前牙 2mm ,牙冠中点到牙龈缘 4mm处 ,唇挡的远中插入下颌第一磨牙颊面管的圆管中 ,治疗开始之前以及 1年后各拍头颅侧位片、下颌分析模型进行分析。结果　由于前牙唇倾以及牙合向的抬高 ,使下颌牙弓长度明显增加 ,双侧尖牙、第一双尖牙、第二双尖牙以及第一恒磨牙之间的宽度明显增加。结论　安氏Ⅱ类 1分类错牙合伴有下前牙轻度拥挤的患者 ,在第一阶段非常适合使用下颌唇挡 ,不但可以加大牙弓的宽度 ,而且可以整平Spee’s曲线以及打开咬合。     

Turner syndrome isochromosome karyotype correlates with decreased dental crown width

The aim of this project was to study possible influences of Turner syndrome (TS) karyotype and the number of X chromosomes with intact short arm (p-arm) on dental crown width. Primary and permanent mesio-distal crown width was measured on plaster casts from 112 TS females. The influence on crown width of four karyotypes: 1. monosomy (45,X), 2. mosaic (45,X/46,XX), 3. isochromosome, and 4. other, and the number of intact X chromosomal p-arms were investigated. In comparisons between karyotypes, statistically significant differences were found for isochromosome karyotype maxillary second premolars, canines, laterals, mandibular first premolars, and canines, indicating that this karyotype was the most divergent as shown by the most reduced crown width. When each karyotype group were compared versus controls, all teeth in the isochromosome group were significantly smaller than controls (P < 0.01-0.001). The 45,X/46,XX karyotype expressed fewer and smaller differences from controls, while 45,X individuals seemed to display an intermediate tooth width compared with 45,X/46,XX and isochromosomes. No significant difference in crown width was found comparing the groups with one or two intact X chromosomal p-arms. Both primary and permanent teeth proved to have a significantly smaller crown width in the entire group of TS females compared to healthy females. We conclude that the isochromosome group deviates most from other karyotypes and controls, exhibiting the smallest dental crown width, while individuals with 45,X/46,XX mosaicism seemed to have a less affected crown width. An influence of the number of intact p-arms on crown width could not be demonstrated in this study.     

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.     

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.     

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.     

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).