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。     

Comparison of mesiodistal tooth crown diameters and arch dimensions between modern Mongolians and Japanese

The purposes of this study were to establish normative data for mesiodistal tooth crown diameters and arch dimensions in Mongolian adults and to compare them with those of Japanese adults. The study materials comprised dental casts of 100 modern Mongolian and 100 Japanese subjects (50 males, 50 females for each) with Angle Class I normal occlusion. The mean ages were 20 years 8 months for the Mongolian subjects and 20 years 0 months for the Japanese subjects. On the dental casts, the mesiodistal tooth crown diameters (excluding wisdom teeth) and dental arch dimensions were measured. The following arch dimensions were measured: inter-canine lingual, inter-premolar lingual, inter-molar lingual, inter-molar central, coronal arch length, basal arch length, and basal arch width. In the Mongolian samples, significant sex differences were noted, and most of the items were significantly larger in males than in females. Significant differences between the Mongolian and Japanese samples were mainly noted in the premolar and molar regions, rather than in the anterior region, and were significantly smaller in the Mongolian samples. In the Mongolian samples, the molar section widths and basal arch width and length were significantly larger in males and females compared with the Japanese samples. These results suggest that the tooth crown size and arch dimensions in the Mongolian samples differed from those in the Japanese samples, and that establishment of the clinical norm for Mongolian adults might be helpful in formulating treatment plans for Mongolian patients, given that these parameters are the basic tools for diagnosis.     

Mixed dentition space analysis for Indonesian Javanese children

The purposes of this study were to determine the applicability of Moyers and Tanaka-Johnston prediction methods for Indonesian Javanese children, and to develop new regression equations for predicting the size of the canine-premolar segment based on the normative standard of mesio-distal crown diameters of the permanent teeth in Indonesian children. Two hundred and eighty five sets of dental casts of the permanent dentition were obtained from Indonesian Javanese children in Yogyakarta, Indonesia during 2000– 2001. There were 143 males and 142 females aged 11.1 to 14.9 years. The mesio-distal crown diameters were measured with calipers to an accuracy of 0.05 mm. The statistical analyses were performed using computer software (SPSS 9.0 for Windows). This study confirmed that the use of Moyers and Tanaka-Johnston prediction methods for mixed dentition analysis among Indonesian Javanese children were unsuitable. Both methods underestimated the size of canine-premolar segments, with exception of the Tanaka-Johnston method in females. The combination of maxillary first molars and mandibular lateral incisors (

) showed relatively higher correlation with the actual size of ∑3 4 5. The development of new linear regression equations with predictor

for predicting the size of the canine-premolar segment was based on the normative standard of mesio-distal crown diameters of permanent teeth in Indonesian Javanese children. The newly developed regression equations are more accurate than the regression equation that uses predictor

for mixed dentition analysis among Indonesian Javanese.     

Fluctuating asymmetry of the permanent mandibular molars in a Japanese population

The purpose of the present study is to investigate the pattern of fluctuating odontometric asymmetry of permanent mandibular first and second molars in a Japanese population. Dental plaster casts of 112 (57 males and 55 females) Japanese undergraduate dental students were used. The mesiodistal and buccolingual diameters of the whole crown and trigonid and talonid crown components were taken on the left and right sides of the mandibular permanent first and second molars. Crown areas were also calculated. The fluctuating asymmetry (FA) value was obtained by dividing the absolute side difference by the absolute mean size of the left and right teeth: FA = abs (R?L)/((R + L)/2). Fluctuating asymmetry between mandibular first and second molars was significantly different with the mandibular second molar showing higher asymmetry in both males and females. Meanwhile, fluctuating asymmetry between males and females in the first and second molars was not significantly different in all measured dimensions. With regard to trigonid and talonid components, fluctuating asymmetry of the distal talonid area was significantly larger than the mesial trigonid area in the mandibular permanent first molar of males (P < 0.01), and asymmetry of buccolingual diameter of the talonid was also larger than that of the trigonid in the mandibular permanent second molar of males (P < 0.05). In conclusion, these findings suggest that the crown dimensions of later developing teeth in the mandibular molar tooth class and crown component in the same molar tooth show more asymmetry and, therefore, are more affected by external factors.     

Dentition and occlusion development in African American children: mesiodistal crown diameters and tooth-size ratios of primary teeth

PURPOSE: The aim of this study was to evaluate the mesiodistal primary tooth size diameter and posterior sagittal tooth-size ratio in an African American population and compare to existing African American and European American norms. METHODS: A sample of 1,124 African American children, 564 males and 560 females, was used to record crown size diameters employing indirect (cast) and direct (intraoral) measurement techniques. RESULTS: African American males showed larger crown diameters than African American females for each of the 5 classes of primary teeth (a=0.05 level). Sexual dimorphism averaged 3.5% in the maxilla and 3.2% in the mandible. When inter-racial primary crown size comparisons were made between African American and European American children, African American males showed larger mean crown diameters for each class of primary teeth compared to European American males. The inter-racial comparisons in crown diameters of females showed fewer statistically significant differences in primary teeth classes. When crown size comparisons of the primary dentition's posterior segments were made, African American males and females showed a larger primary posterior sagittal tooth-size-ratio compared to European American children. CONCLUSIONS: While intra- and inter-racial sex differences exist in the primary teeth of African American and European American children, with few exceptions, the mesiodistal crown size differences and sexual dimorphism appear to be larger for the African American population. African American children show a larger primary posterior sagittal tooth-size ratio (0.96) compared to European American children (0.94).     

Maxillary and mandibular mesiodistal tooth sizes among different malocclusions in a sample of the Turkish population

The purpose of this study was to establish normative data for mesiodistal tooth crown dimensions with respect to malocclusions and gender differences in Turkish sample. The subjects were randomly selected and assigned to three malocclusion groups according to Angle's classification. Each group consisted of 100 individuals between the ages of 13 and 18 years with the following distribution: Class I, 42 males and 58 females; Class II, 52 males and 48 females; and Class III, 51 males and 49 females. An electronic digital calliper was used to measure the mesiodistal tooth width from the right second permanent molar to the left second permanent molar on both upper and lower study casts. For statistical evaluation, one- and two-way analyses of variance and post hoc Tukey's honestly significant difference (HSD) tests were performed. There were statistically significant differences for the maxillary canine (P < 0.001), first premolar (P < 0.05), second molar (P < 0.05), and mandibular canine (P < 0.01) for males, and for all maxillary teeth and the mandibular central (P < 0.05), canine (P < 0.001), and first premolar (P < 0.05) teeth in females among the malocclusion groups. When Angle's classification was evaluated, significant differences were determined, except for the first and second mandibular molars. All mesiodistal widths were also found to be statistically different according to gender dimorphism. A significant relationship was found between mesiodistal tooth size, Angle's classification, and gender. Therefore, tooth dimensions may play a crucial role in treatment planning and in achieving satisfactory interdigitation of the upper and lower dentition following the completion of orthodontic treatment.     

Correlations among crown diameters of human teeth

Correlation coefficients were obtained for mesiodistal crown diameters of single teeth and tooth groups in the deciduous and permanent dentures. The degree of association between deciduous and permanent teeth was also determined for single teeth and tooth groups, and likewise between deciduous and permanent maxillary and mandibular teeth. Findings relate to the development of normal occlusion, and evolutionary aspects of man's dentition.     

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.     

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.     

Crown angulation measured by laser scanner

The aim of this study was to measure the crown angulation of Japanese subjects with normal occlusion using a laser scanner to minimize human error. Twenty study models with normal occlusion were scanned by laser scanner. Crown angulations of each tooth in scanned 3D dental images were measured according to Andrews’ procedure. In Andrews’ procedure, a plane was established along the mesiodistal contact points of each tooth. The crown angulations of each tooth were measured by projecting the facial axis of the clinical crown (FACC) and a vertical line from the occlusal plane, and the mean and standard deviation were calculated. In maxillary teeth, the canine crown angulation was highest at about 7°, thus indicating a mesial tip, which was seen in all teeth except the second molar. In mandibular teeth, the second molar crown angulation was highest at about 7°, thus indicating a mesial tip, and only the lateral incisor exhibited slight distal tip, while all the remaining teeth exhibited mesial tip. Standard deviations for the maxillary and mandibular teeth ranged from 2.5° to 8°. The standard deviation of the maxillary and mandibular second molars was particularly large.     

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.     

江苏地区正常的牙及牙弓测量研究

目的 测量125名江苏地区正常人群的模型,建立江苏地区正常牙及牙列指数的平均值。方法 选取正常模型125副(男61副,女64副),用电子游标卡尺测量牙冠宽度、牙弓宽度及长度、腭盖高度,对测量结果进行统计分析。结果 江苏地区正常人群的牙冠宽度、牙弓宽度及长度、腭盖高度均为男性大于女性,Bolton指数及Pont指数无性别差异。上下颌6个前牙牙冠宽度总和、全部牙冠宽度总和具有相关性,上颌中切牙与上颌前段牙弓宽度之间亦存在相关性,且建立了直线回归方程。结论 牙冠形态、牙列指数存在种族、地区和性别的差异,临床上应参照本民族、本地区的标准。     

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 biometric study of tooth size and dental crowding

A study was conducted for the purpose of comparing mesiodistal tooth widths between a group of patients with good tooth alignment and a group of patients with crowded dental arches. Crowded arches were defined as those with more than 4 mm. of space deficiency. The hypothesis tested was whether the arches with more than 4 mm. of crowding consistently had larger teeth than the ones with lesser or no crowding. The difference in sizes between the groups (forty males and forty females) for all teeth measured was found to be statistically significant (p < 0.001). The multivariate data analysis indicated that the two groups were derived from two different populations and that the maxillary lateral incisors and second premolars and the mandibular canines and premolars were particularly different in these groups. It was also determined that the teeth in males were uniformly larger than in females, but not to a statistically significant level. There was less correlation, however, between the sex and the status of the tooth alignment in dental arches, so that both sexes had similar distribution of crowding versus noncrowding. On the basis of this study of eighty North American Caucasians, it is suggested that one should consider the sum of mesiodistal widths of teeth, in addition to the arch length analysis, in formulating an orthodontic treatment plan. When the cumulative tooth mass of the twenty permanent teeth is 140 mm. or more, the clinician may want to consider extraction therapy for such a case.     

Comparative Measurement of Mesiodistal Width of Six Anterior Maxillary and Mandibular Teeth in Rajasthan Population

The purpose of the study was to determine the mesiodistal width of six anterior teeth for better esthetics and good tooth arrangement in a cross section of Rajasthan population. The mesiodistal dimension of central, lateral incisor and canine on right and left sides was measured in 250 males and 250 females, these readings were used to determine the mean, minimum and maximum maxillary/mandibular teeth ‘anterior ratio’, difference in mesiodistal width, combined mean mesiodistal width, the number and percent of similar teeth of maxilla and mandible. It was observed from the present study that there is variation in mesiodistal width in right and left sides signifying that the anterior teeth are not mirror images of one another. Male subjects have greater mesiodistal width than female subjects and right side dominates in most of the readings indicating that mesiodistal width is greater on right side than on left side. Percentage variability and sexual dimorphism are also important findings of this study. This study can prove helpful in replacement of artificial teeth of prosthesis in this cross section of population.     

Crown components of mandibular molar teeth in 45,X females (Turner syndrome)

This study was designed to determine the possible effect of one X-chromosome constitution on components of the human permanent and primary molar teeth. Enamel, dentine, pulp and crown dimensions were measured on radiographs of first and second permanent and second primary mandibular molars of 49 Finnish 45,X females (Turner syndrome), their 46 first-degree male and female relatives and 50 non-related males and females. In permanent first and second molars of the 45,X females, crown width and the dimensions of tooth components were less than those of normal females and males. Reduction in size affected first more than second molars, and in both teeth the enamel was relatively as well as absolutely thinner than in the controls. No differences were found in tooth components between normal relatives and unrelated controls. These data agree with previous studies which have demonstrated that the X chromosome promotes enamel apposition and that both X chromosomes in normal females are active in amelogenesis, while the Y chromosome influences both dentine and enamel growth. The relative reduction in "dentine" or the estimated mesiodistal width of the tooth germ in the 45,X females indicates that their tooth development is affected at an early stage of morphogenesis. Taken together with the results already reported for anterior teeth, the present results suggest that there is an inverse correlation between the duration of crown formation and the severity of size reduction.     

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.     

Changes in the maxillary and mandibular tooth size-arch length relationship from early adolescence to early adulthood. A longitudinal study

The purpose of this study was to determine the association between the changes in maxillary and mandibular tooth size-arch length discrepancies (TSALD) and various dentofacial variables for 18 male and 14 female subjects with normal occlusion. All subjects were participants in the Iowa Longitudinal Growth Study and records were evaluated at two stages of dental development: stage I, when the permanent second molars initially erupted into occlusion (X age = 13.3 years); and stage II, at early adulthood (X age = 26.0 years). The following sets of variables were evaluated: mesiodistal crown diameters of single and groups of permanent teeth, dental arch widths and lengths, curve of Spee, maxillary and mandibular anterior and total crowding or spacing, anterior tooth rotations, and various cephalometric dentofacial parameters. Student's t test were used to compare subjects with the most and least changes. Regression analyses also were used to assess the relationships between these parameters and the changes in the maxillary and mandibular tooth size-arch length relationship. The most consistent finding from the t test comparisons is the significantly greater reduction in the available arch length in the group with the most TSALD at early adulthood. No other variables were found to be consistently different in the comparisons between the two groups. The results of the regression analysis indicated that a number of dentofacial variables are associated with the changes in the maxillary and mandibular TSALD--for example, the mesiodistal diameter of different teeth and the changes in anterior and posterior facial heights. The clinical implications of the present findings are discussed.