Congenital defects of the upper lateral incisors (ULI): Condition and measurements of the other teeth,measurements of the superior arch,head and face

We surveyed a French male population for the incidence of missing or reduced upper lateral incisors (ULI). In 5,738 subjects, we observed an incidence of 1.59% with one or two reduced ULI (the other normal) and 1.90% with one or two missing ULI (the other normal or reduced), altogether, 3.49% affected subjects. Furthermore, 250 random controls were observed. Agenesis of other teeth is more frequent in propositi. Missing third molars were 12.4% in controls, 24.0% in propositi with reduced ULI and 39.6% in propositi with two missing ULI. Furthermore, agenesis of incisors, canines and premolars ranges from 0.4% in controls to 1.3% in propositi having reduced ULI and 5.0% in propositi with two missing ULI. So, propositi with reduced ULI are intermediate between the controls and the propositi with missing ULI with respect to the frequency of agenesis of other teeth. On the other hand, a different ranking is observed with respect to the teeth measurements: reduction of tooth size is more marked in propositi with reduced ULI than in propositi with missing ULI. The reduction mainly affects canines, incisors and to a lesser degree, premolars. Arch length and interpremolar diameters are smaller in propositi with missing ULI, compared with controls.     

Congenital defects of the upper lateral incisors (ULI) and the morphology of other teeth in man

A sample of 192 male propositi with at least one ULI either missing or reduced has been compared with 197 male controls in terms of the morphology of the other teeth. Every class of propositi exhibits modifications in the following characters: Significant differences between propositi and controls were found for molar cusp number and groove pattern, particularly in the lower first molar and in propositi with reduced ULI. Significant differences between propositi and controls were also found with respect to caniniform pattern of the lower first premolar. The Carabelli's cusp is rarer in propositi. A hypothesis to account for these observations is proposed.     

The relationship of dental crowding to tooth size, dental arch width, and arch depth

This study was undertaken to answer the question, "Are there any differences in the mesiodistal tooth diameters, dental arch width and dental arch depth between the crowded and noncrowded dentitions?" The materials submitted for study consisted of the Orthoscan intraoral occlusograms of 89 subjects with well-aligned dentition and those of 74 subjects with gross dental crowding. The tooth size and arch dimensions were measured from these intraoral occlusograms. The data were subjected to statistical treatment for comparison of noncrowded and crowded groups. The findings in this study lead to the following conclusions: The mesiodistal tooth diameters of the crowded group were significantly larger than those of the noncrowded group. The dental arch widths of the crowded group were significantly smaller than those of the noncrowded group. No substantial or significant difference in dental arch depth between the crowded and noncrowded subjects could be noted. From these findings it seems that tooth size and dental arch width are determining factors in the formation of dental crowding. Clinically, these results suggest that in the treatment of dental crowding, extraction of teeth and/or expansion of dental arches should be considered depending on what is the main causative factor.     

Sex diagnosis of subadult specimens from Medieval Polish archaeological sites: metric analysis of deciduous dentition.

The subject of this work is the characterisation of the metric features of deciduous dentition in a Medieval population of central Poland with the use of the jackknife technique leave one out (LOO)-supporting multivariate methods, which are important for deriving discrimination equations that would result in sex determination of children's skeletal remains. The sex of the individuals was assessed through analysis of sex-specific DNA sequences (AMELY/AMELX, SRY and alpha satellite sequences). Discriminant analysis concerned only teeth of those individuals whose sex was confirmed by the primary structure of three DNA sequences. The deciduous tooth diameters of males were found to be significantly larger than those of females in four respects: MD diameter of the maxillary second molar, MD and BL diameters of the mandibular first molar and BL diameter of the mandibular second molar. A two-group discriminant analysis considered all those measurements as independent variables. A multiple regression procedure produced a linear equation predicting the sex of children's skeletons with a significant probability amounting to approximately 78%. The accuracy of the sex assessment of an individual, using dental measurements, was established at 69% in deciduous male and 88% in deciduous female teeth.     

Sexual dimorphism of tooth crown diameters. A contribution to the determination of the sex of subadult individuals from the early bronze age graveyard of Franzhausen I, lower Austria]

In this paper, the sexual differences between mesio-distal and bucco-lingual diameters of deciduous and permanent teeth of an Early Bronze Age population from Franzhausen are presented. Data from a total of 172 (85 male and 87 female) subadult individuals was collected. The presumptive sex determination needed for this investigation could be achieved because of specific burial rites that characterize the Unterw?lbling culture south of the Danube. The averages of both the deciduous and permanent teeth show that female individuals possess altogether teeth of smaller dimensions. The differences are, for a few permanent teeth, statistically highly significant. Using these to calculate discriminant analyses based on differing variable sets, a correct sex assignment was achieved in 81% to 75% of all cases. For the purposes of sexual diagnosis, a function combining only three measurements (MD and BL diameters of upper canine and BL diameter of the first upper molar) was 80% successful.     

Interspecific allometry of the mandible,dental arch,and molar area in anthropoid primates: Functional morphology of masticatory components

Allometric equations relating the lengths and widths of the mandible and dental arch, and of molar area, were obtained in a wide range of anthropoid primates grouped into four subsets, pongids, cercopithecids, nonmarmoset platyrrhines, and marmosets. Mandibular width is negatively allometric against length across anthropoids but cercopithecids had relatively wider mandibles than nonmarmosets of the same size class. Mandibular length relative to dental arch length was isometric within and between the four groups but dental arch width scaled negatively against all the other dimensions examined in this study, indicating a functional dissociation between the dental arcade and the bony mandible. Molar area showed various scaling patterns relative to mandibular length (isometry) and width (positive). There were no parameters that scaled positively against body weight across groups, except for molar area in cercopithecids (strongly) and nonmarmoset (moderately). Notable functional specializations include relatively long dental arches in cercopithecoids, related to large, elongate bilophodont molars, and the tendency to increase relative jaw length across the range of anthropoid sizes, reflecting negative allometry of the brain (cranial bicondylar width). We caution that various allometry and functional patterns may be masked by generalizing from broad taxonomic comparison involving a large sweep of adaptative patterns.     

Arch form,tooth size,and occlusomandibular kinesis in the Ceboidea

Correlations between dental morphology, arch configuration, and jaw movement patterns were quantitatively investigated in 23 ceboid species to elucidate integrative aspects of occlusal functional anatomy in an adaptive and evolutionary context. Differential maxillary-mandibular arch widths are primary in guiding lateral jaw movements. These movements are characterized according to their associated condylar shifts as either predominantly translatory or rotational. Predominantly translatory movements result from peripheral contact relationships between maxillary arches which are considerably wider posteriorly than their opposing mandibular arches. The greatest degree of mandibular movement is in the molar region in functional association with wide “primitive” maxillary molars, narrow mandibular molars, constricted maxillary intercanine widths, and narrow maxillary incisors. In contrast, predominantly rotational masticatory jaw movements result from differential arch widths which are greatest in the maxillary canine and incisor regions. Here most jaw movement is in the anterior segment and this is reflected in small maxillary-mandibular molar width differences, a high degree of premolarization, wide-set maxillary canine teeth, and wide maxillary incisors. Possible selectional factors in the putative evolution of rotational predominance in mastication from the more primitive translatory pattern are discussed.     

Birotundal diameter of the human sphenoid bone from age six years to early adulthood

Longitudinal data for a twenty-year period are presented for a dimension of the human sphenoid bone as seen on postero-anterior roentgenograms of 22 males and 18 females (healthy, American-born Caucasoids). Birotundal diameter measured as the distance between the centers of the right and left foramen rotundum averaged near 32.0 mm for each sex at age 6 years. Individual increase in size to age 26 years ranged between 3.2 mm and 8.3 mm. There is no correlation between size at age 6 years and change between this age and early adulthood. For 54 males and 50 females at age 9 years, intercorrelations were obtained among six variables: birotundal diameter, head breadth, bizygomatic diameter, bigonial diameter, upper and loweer dental arch widths at the permanent first molars. The r's were nonsignificant or low positive (with the exception of upper-lower dental arch, r = 0.76). The results of this study are aligned with three previous studies of human cranial base width.     

Comparative study of mesiodistal crown diameters and arch dimensions between indigenous British and Pakistani immigrant populations

Over the last two decades, the United Kingdom has seen an increase in the number of immigrants from the Indian subcontinent, mainly Pakistan. The amount of information that is available regarding parameters such as mesiodistal crown diameters and dental arch dimensions is, however, somewhat limited for this population. An investigation was carried out to compare corresponding mesiodistal crown diameters and arch dimensions between samples of the indigenous British population in Leeds (England) and the Pakistani immigrant population living in Rochdale (England). Measurements were taken from dental casts. The results showed that there were no significant differences between the two ethnic groups in corresponding mesiodistal crown diameters or arch dimensions. Data are provided for the Pakistani immigrant population in Britain.     

A study of the taxonomic significance of the dental arch.

Sixteen dimensions were measured from the maxillary and mandibular dental arches of different ethnic groups of man, apes and monkeys. Multivariate analysis showed that discrimination was possible among the ethnic groups of man on the one hand and between the ape and monkey samples on the other. Nevertheless, the actual degree of discrimination between the primate samples depended upon whether the maxillary or mandibular arch dimensions were analysed. Furthermore, subsequent inclusion of the dental arch dimensions of fossil hominoid samples into the analysis confirmed the taxonomic significance of the dental arch, although its importance must await the acquisition of the more non-human primate data.     

Variation in dental occlusion and arches among Melanesians of Bougainville Island, Papua New Guinea. II. Clinical variation, geographic microdifferentiation and synthesis

Patterns of geographic microdifferentiation for dental occlusion and the size and shape of the dental arches are described for 14 villages on Bougainville Island, Papua New Guinea. Occlusal variables, such as overjet, overbite, molar relationships, crowding or spacing, and malalignment vary less among villages than do arch length and width. Arch length and width decrease in size from north to south. The pattern of biological distance among villages for occlusal variables and arch size correspond poorly to anthropometric, linguistic, geographic and migrational distances. The value of occlusal variables and arch size for discriminating among populations, the biological interpretation of multivariate data and the objectives of research on geographic microdifferentiation are discussed.     

金丝猴牙齿与体重间的相关性研究

对金丝猴牙齿与体重间关系的研究结果表明,在雄性中,无论是线性还是面积与颅长之间的相关关系均较雌性的更为紧密。而且,随着体重的增加,雄性牙齿的近中远中长(M/D)也比雌性的增长较快。在上、下颌中,上颌牙齿与颅长的关系表现出更强的相联性。与其他灵长类相比较,金丝猴在取食和咀嚼过程中主要利用颊齿;大的个体具有大的犬齿及一定比例的臼齿面积和齿弓(牙合)面面积;上齿弓(牙合)面面积大于下齿弓(牙合)面面积。也就是说上齿弓提供了比下齿弓更大的咀嚼面积。金丝猴牙齿与体重间的关系位于猴类和人猿类之间,更接近于大猩猩(Gorilla)、疣猴(Colobus)和猕猴。     

Dental morphology and odontometry of the Tibetan immigrants

Dental features such as size, shape, cusp number and groove pattern, deflecting wrinkle, protostylid, form and size of dental arch and occlusion pattern, as well as crown diameters of maxillary and mandibular dentition of the Tibetan immigrants in India are described. Sex differences in various measurements are also noted. Overall reduction in size, presence of hypodontia of the third molar, and absence of Carabelli's trait are a distinct progressive/evolutionary trend in the Tibetan dentition, while presence of a shovel-shaped lingual surface of central and lateral incisors is a retrogressive/primitive condition. In some of the dental features Tibetans resemble Caucasoid and modern populations, in certain others they resemble other Mongoloid populations, and in still other features they resemble aboriginal populations and fossil hominids.     

Relationship between vestibular lamina, dental lamina, and the developing oral vestibule in the upper jaw of the field vole (Microtus agrestis, Rodentia)

Formation of the oral vestibule is ignored in most studies on tooth development, although dental and vestibular lamina are closely related to each other. Knowledge about morphogenetic processes shaping the oral vestibule is missing almost completely. The aim of this study was to assess the developmental relationship between dental and vestibular lamina as well as formation of the oral vestibule in the upper jaw of the field vole (Microtus agrestis), a small rodent representing an attractive model species for comparative dental studies. Three-dimensional reconstruction revealed that the upper vestibular lamina of the vole joins the antemolar part of the diastemal dental lamina, similar to mouse. Later, this lamina complex regresses and the vestibular lamina is separated from the molar epithelium. Participation of the vestibular lamina in dental lamina formation, as hypothesized for mouse, therefore remains unclear. Except for increased apoptosis in the regressing diastemal dental lamina, spatial segregation of mitoses or apoptoses could be detected neither in the jaw arch epithelium nor in the adjacent mesenchyme. Therefore, in contrast to tooth primordia, apoptosis and mitosis seem to play a minor role in shaping of the upper oral vestibule. The buccal vestibule develops secondarily, probably in consequence of general growth of the head and localized differentiation of cells.     

Nasal shape,prognathism and adaptation in man

The association between nasal shape, prognathism and the shape of the maxillary dental arch has been examined within samples of Negro and European skulls. Prognathism tends to be accompanied by an increasingly broad and short nose. Particularly high correlations exist between nasal height and the length of the cranial base and between nasal breadth and the distance which separates the upper canine teeth. Regression analysis has yielded quantitative estimates of the effect on a given dimension of variation in one or more of the others. It seems probable that both nasal shape and the maxillary dental arch-prognathism complex may be subject to direct selection by environmental stress. The morphological association between these complexes suggests that a part of the interpopulation variation in prognathism may be a secondary effect of selection acting on the nose. Similarly, selection acting on the dental arch or maxilla could produce secondary changes in the nasal index (i.e. a non-adaptive component of nasal variation).     

Palatal dimensions in 45,X-females

Seventy-two females with 45,X-chromosome complement were examined for palatal dimensions, and the results of the measurements were compared to those of first-degree normal female relatives of the study subjects and population control females. Hard stone casts were prepared for measuring widths and lengths of the maxillary alveolar arch and palatal height between or at the level of the permanent canines, first and second premolars, and first molars with a palatometer and sharp-pointed vernier calipers (0.5 mm). According to the analyses of covariance (history of orthodontic treatment and loss of permanent teeth as cofactors and age as covariate), the differences in palatal dimensions between the groups were statistically significant or highly significant for all dimensions except for palatal height in the posterior segments. The group of the 45,X-females had the highest mean value for palatal height at the level of the canines and systematically the lowest mean values for palatal width in all segments, while no clear difference could be found in the length of the alveolar arch between the 45,X-females and the relatives, the population control group showing the lowest value in the posterior segments. The findings of this study indicate that the narrowed palate rather than the high palate is a frequent but not definite feature in 45,X-females. This may reflect the effect of sex-chromosomes on width but not other dimensions of the palate, resulting in deficiency of transversal growth of the palate possibly through decreased growth of the palatal shelves or through disturbances in the growth of the nasal septum, sutural growth, or--to which the exostosis on the palatal alveolar plates would refer--disturbances in apposition-resorption growth changes of the maxilla.     

The influence of tooth wear on root canal dimensions

The objective was to investigate the relations between tooth wear and root canal dimensions. The experimental group comprised 100 cuspids (canines), 50 of which had advanced abrasion and 50 were without it The dimensions of root canal were investigated at the light microscope level in order to define their vestibulo-oral and mesio-distal diameters in all three thirds. In the groups of teeth without abrasion the MD diameters of root canaliculi in their cervical thirds were greater than in the teeth with advanced abrasion. In the apical third the MD diameters of canaliculi were highly variable in teeth with no signs of abrasion. In the group of teeth with abrasion the MD and VO diameter values of the cervical thirds were significantly smaller than in the group of teeth without abrasion. In the mid-thirds the values of MD diameters were highly variable in the group of teeth with abrasion, whereas the VO diameter values were much greater than in the teeth without abrasion. As regards to the apical thirds, the VO diameter values were greater than in the control teeth. The data presented herewith contribute to better knowledge about tooth wear and are highly useful in restorative and reconstructive dental procedures.