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A discrepância de tamanho dentário, de Bolton, na oclusão normal e nos diferentes tipos de más oclusões, bem como sua relação com a forma de arco e o posicionamento dentário

Carreiro, Luiz Sérgio; Santos-Pinto, Ary; Raveli, Dirceu Barnabé; Martins, Lídia Parsekian
Fonte: Dental Press Editora Publicador: Dental Press Editora
Tipo: Artigo de Revista Científica Formato: 97-117
POR
Relevância na Pesquisa
46.26%
Esta pesquisa teve como objetivo geral avaliar a discrepância de tamanho dentário, na oclusão normal e nos diferentes tipos de más oclusões e a sua relação com as medidas que determinam a forma de arco e o posicionamento dentário na região anterior. Para tanto, foram estudados 185 pares de modelos de gesso, divididos em 4 grupos: Grupo 1 (composto por 41 pares com Oclusão Normal, sendo 20 do gênero masculino e 21 do gênero feminino); Grupo 2 (composto por 44 pares com má oclusão de Classe I, divisão 1, sendo 22 do gênero masculino e 22 do gênero feminino); Grupo 3 (composto por 54 pares com má oclusão de Classe II, sendo 28 do gênero masculino e 26 do gênero feminino) e Grupo 4 (composto por 46 pares com Classe III, sendo 23 do gênero masculino e 23 do gênero feminino). Observou-se que não ocorreu dimorfismo sexual entre as discrepâncias de tamanho dentário e os diferentes tipos de oclusão dentária; as proporções estabelecidas por Bolton não se aplicaram ao grupo com Oclusão Normal; na Oclusão Normal, Classe I, Classe II e Classe III, houve um predomínio de excesso dentário total (RAZ12) no arco inferior; na Classe I houve uma igualdade na distribuição de excesso dentário anterior (RAZ6) nos arcos superior e inferior; na Oclusão Normal...

Maxillary canine - First premolar transposition: Restoring normal tooth order with segmented mechanics

Capelozza Filho, Leopoldino; Cardoso, Mauricio de Almeida; Tien, Li An; Bertoz, Francisco Antonio
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 167-175
ENG
Relevância na Pesquisa
46.15%
Tooth transpositions present at a relatively low incidence in the world population and primarily affect maxillary canines and premolars. Treatment of this disturbance should take into account aspects such as facial pattern, age, malocclusion, tooth-size discrepancy, stage of eruption, and magnitude of the transposition. Mechanics for correction should be entirely individualized, reducing the risks and adverse effects. Practitioners often select simpler options, indicating extraction of permanent teeth, which is an irreversible procedure that may bring about damages to the patient. This study presents a case report and treatment of unilateral transposition of maxillary canine and premolar with repositioning of affected teeth to their respective normal positions. © 2006 by The EH Angle Education and Research Foundation, Inc.

Tooth-size discrepancy: A comparison between manual and digital methods

Correia,Gabriele Dória Cabral; Habib,Fernando Antonio Lima; Vogel,Carlos Jorge
Fonte: Dental Press International Publicador: Dental Press International
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2014 EN
Relevância na Pesquisa
46.25%
INTRODUCTION: Technological advances in Dentistry have emerged primarily in the area of diagnostic tools. One example is the 3D scanner, which can transform plaster models into three-dimensional digital models. OBJECTIVE: This study aimed to assess the reliability of tooth size-arch length discrepancy analysis measurements performed on three-dimensional digital models, and compare these measurements with those obtained from plaster models. MATERIAL AND METHODS: To this end, plaster models of lower dental arches and their corresponding three-dimensional digital models acquired with a 3Shape R700T scanner were used. All of them had lower permanent dentition. Four different tooth size-arch length discrepancy calculations were performed on each model, two of which by manual methods using calipers and brass wire, and two by digital methods using linear measurements and parabolas. RESULTS: Data were statistically assessed using Friedman test and no statistically significant differences were found between the two methods (P > 0.05), except for values found by the linear digital method which revealed a slight, non-significant statistical difference. CONCLUSIONS: Based on the results, it is reasonable to assert that any of these resources used by orthodontists to clinically assess tooth size-arch length discrepancy can be considered reliable.

47,XXY males: sex chromosomes and tooth size.

Alvesalo, L; Portin, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1980 EN
Relevância na Pesquisa
46.16%
Permanent tooth crowns of 47,XXY males were found to be generally larger than those of control males and females and their first-degree male and female relatives. These results suggest that tooth-size increase in 47,XXY males is due to a direct genetic effect and support the concept of the presence of a specific growth gene (or genes) in the human X and Y chromosomes. The effect of this gene (or genes) seems to be the promotion of tooth growth, and the Y chromosome is more effective than the X chromosome in this respect.

Survey on Bolton’s Tooth Size Analysis as Applied to Artificial Teeth

Babu, C. L. Satish; Sunil, T.; Rani, M. S.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.07%
The presence of proportionate teeth size in either arch is a must to obtain an ideal occlusion with good alignment, ideal overjet, ideal overbite and Class I molar relationship. The above facts made us think and to know if this proportion between maxillary and mandibular teeth existed in artificial teeth also? Hence, a survey is undertaken to study the tooth size relation in commercially available artificial teeth. From the results of the present study it was concluded that the anterior and the overall ratios are slightly varied when compared to the standard Bolton’s ratios. On comparison the difference between the study ratios and the standard Bolton’s ratios were not statistically significant.

Tooth Size Variation Related to Age in Amboseli Baboons

Galbany, Jordi; Dotras, Laia; Alberts, Susan C.; Pérez-Pérez, Alejandro
Fonte: S. Karger AG Publicador: S. Karger AG
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.29%
We measured the molar size from a single population of wild baboons from Amboseli (Kenya), both females (n = 57) and males (n = 50). All the females were of known age; the males represented a mix of known-age individuals (n = 31) and individuals with ages estimated to within 2 years (n = 19). The results showed a significant reduction in the mesiodistal length of teeth in both sexes as a function of age. Overall patterns of age-related change in tooth size did not change whether we included or excluded the individuals of estimated age, but patterns of statistical significance changed as a result of changed sample sizes. Our results demonstrate that tooth length is directly related to age due to interproximal wearing caused by M2 and M3 compression loads. Dental studies in primates, including both fossil and extant species, are mostly based on specimens obtained from osteological collections of varying origins, for which the age at death of each individual in the sample is not known. Researchers should take into account the phenomenon of interproximal attrition leading to reduced tooth size when measuring tooth length for ondontometric purposes.

Mesiodistal crown diameters and tooth size discrepancy of permanent dentition in thalassemic patients

Hattab, Faiez N.
Fonte: Medicina Oral S.L. Publicador: Medicina Oral S.L.
Tipo: Artigo de Revista Científica
Publicado em 01/12/2013 EN
Relevância na Pesquisa
46.22%
Objectives: To provide a description of mesiodistal crown diameters (MD) and tooth-size discrepancy (TSD) of the permanent dentition in patients with thalassemia major (TM) and to compare the results with those of unaffected control group. Study design: The sample consisted of 46 thalassemic patients, 25 males and 21 females aged 7.3 to 23.7 years (mean ± SD = 11.2 ± 3.9 years) and control group matched by age and sex. Dental casts of the participants were measured for MD, using a digital sliding caliper. Descriptive statistics were computed for each individual tooth. Student t-test was used for comparison of mean values between males and females as well as between thalassemic and control groups. The differences between sets of data were evaluated by analysis of variance (ANOVA). Results: All means for MD of thalassemic males and females were smaller than their controls, with 20 of the 24 comparisons being statistically significant (ranged from P<0.05 to P<0.001). In both thalassemic and control groups, males exhibited significantly larger MD than females in most instances. Canines displayed the most sexual dimorphic teeth in the dentition. Lateral incisors showed the greatest variability indicated by the coefficient of variation...

On the Relationships of Postcanine Tooth Size with Dietary Quality and Brain Volume in Primates: Implications for Hominin Evolution

Jiménez-Arenas, Juan Manuel; Pérez-Claros, Juan Antonio; Aledo, Juan Carlos; Palmqvist, Paul
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.29%
Brain volume and cheek-tooth size have traditionally been considered as two traits that show opposite evolutionary trends during the evolution of Homo. As a result, differences in encephalization and molarization among hominins tend to be interpreted in paleobiological grounds, because both traits were presumably linked to the dietary quality of extinct species. Here we show that there is an essential difference between the genus Homo and the living primate species, because postcanine tooth size and brain volume are related to negative allometry in primates and show an inverse relationship in Homo. However, when size effects are removed, the negative relationship between encephalization and molarization holds only for platyrrhines and the genus Homo. In addition, there is no general trend for the relationship between postcanine tooth size and dietary quality among the living primates. If size and phylogeny effects are both removed, this relationship vanishes in many taxonomic groups. As a result, the suggestion that the presence of well-developed postcanine teeth in extinct hominins should be indicative of a poor-quality diet cannot be generalized to all extant and extinct primates.

Tooth size discrepancy in a Libyan population, a cross-sectional study in schoolchildren

Bugaighis, Iman; Karanth, Divakar; Borzabadi-Farahani, Ali
Fonte: Medicina Oral S.L. Publicador: Medicina Oral S.L.
Tipo: Artigo de Revista Científica
Publicado em 01/02/2015 EN
Relevância na Pesquisa
46.16%
Objetives: The aim of this cross-sectional study was to investigate the tooth size discrepancy (TSD) in a group of Libyan schoolchildren, and to compare TSD between sexes. Material and Methods: The sample comprised 333 Libyan schoolchildren (162 males with a mean (SD) age of 14.4 (1.1) years, and 171 females with a mean age of 14.1 (1.1) years). Anterior and overall TSD ratios were computed using descriptive statistics. Sex differences were statistically assessed using an independent t-test (P<0.05). Results: Males showed significantly wider MD tooth width compared to females (P<0.05), except for the maxillary first premolars and mandibular central incisors. There were significant differences (P<0.05) between the paired (right and left sides) tooth measurements except for the maxillary and mandibular central and lateral incisors as well as mandibular canines. The mean (SD) for overall and anterior TSD ratios were 91.3% (2.1) and 78.2% (2.6), respectively, with no significant sex differences for both variables (P> 0.05). The percentages of participants showing more than 2 SD variation for the anterior and overall ratios comprised 3% and 4.2% of the total sample, respectively. Conclusions: The anterior and overall TSD ratios for the examined subjects were established and showed no significant sexual dimorphism.

Tooth Size Variation in Pinniped Dentitions

Wolsan, Mieczyslaw; Suzuki, Satoshi; Asahara, Masakazu; Motokawa, Masaharu
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 28/08/2015 EN
Relevância na Pesquisa
46.27%
It is contentious whether size variation among mammalian teeth is heterogeneous or homogeneous, whether the coefficient of variation is reliable, and whether the standard deviation of log-transformed data and the residual of standard deviation on mean variable size are useful replacements for the coefficient of variation. Most studies of tooth size variation have been on mammals with complex-crowned teeth, with relatively little attention paid to taxa with simple-crowned teeth, such as Pinnipedia. To fill this gap in knowledge and to resolve the existing controversies, we explored the variation of linear size variables (length and width) for all teeth from complete permanent dentitions of four pinniped species, two phocids (Histriophoca fasciata, Phoca largha) and two otariids (Callorhinus ursinus, Eumetopias jubatus). Size variation among these teeth was mostly heterogeneous both along the toothrow and among species. The incisors, canines, and mesial and distal postcanines were often relatively highly variable. The levels of overall dental size variation ranged from relatively low as in land carnivorans (Phoca largha and both otariids) to high (Histriophoca fasciata). Sexual size dimorphism varied among teeth and among species, with teeth being...

Chorion type, birthweight discordance and tooth-size variability in Australian monozygotic twins

Race, J.; Townsend, G.; Hughes, T.
Fonte: Australian Academic Press Pty. Ltd. Publicador: Australian Academic Press Pty. Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
56.39%
Chorion type is an important variable that can affect the prenatal environment of monozygotic (MZ) twin pairs, leading to differences in growth and development. In particular, vascular anastomoses between monochorionic (MC) MZ twin pairs can lead to an imbalance in nutrition between co-twins. One objective of this study was to determine whether maternal reports, hospital records or birthweight discordances found in MZ co-twins provide reliable indications of monochorionicity. The other objective was to test the hypotheses that in MZ twin pairs of known chorion type, MC twin pairs would show greater birthweight differences and greater within-pair variability in permanent tooth size than dichorionic (DC) twin pairs, reflecting greater differences in intrauterine environment between MC MZ pairs. Birthweights and tooth size data were recorded for 170 pairs of MZ Australian twins enrolled in an ongoing study of dentofacial growth and development. Chorion type based on maternal reports was compared with that based on hospital records for a subsample of 68 pairs of these MZ twins. Maternal reports were found to be unreliable for determining chorion type and hospital records often did not provide enough information to be certain about chorionicity. For 27 twin pairs with confirmed chorion type...

Increased tooth size in females with twin brothers: evidence for hormonal diffusion between human twins in utero

Dempsey, P.; Townsend, G.; Richards, L.
Fonte: WILEY-LISS Publicador: WILEY-LISS
Tipo: Artigo de Revista Científica
Publicado em //1999 EN
Relevância na Pesquisa
46.07%
In rodents, the position of a fetus in utero is associated with the expression of sexually dimorphic traits. This phenomenon has been explained by prenatal diffusion of sex hormones among litter mates. To test for such effects in humans, female-male twin pairs provide a natural experiment. The size of dental crowns is a sexually dimorphic trait which can be measured with a high degree of reliability. Thus, two crown diameters of 28 permanent teeth were recorded for 56 opposite-sexed (OS) and 242 same-sexed (SS) twin pairs, and 150 singletons. Comparisons of OS twins with SS twins and singletons within each sex reveal that OS females have consistently larger teeth (on average) than other females, while there is no consistent difference between OS and SS twin males. It is proposed that diffusion of sex hormones from male to female co-twins in utero may account for the increased tooth size in OS females. This study is one of the first to report such an effect on a morphological variable in humans. The finding that the maxillary canine, one of the most sexually dimorphic teeth, exhibits the least effect in OS female twins, suggests that prenatal sex hormone levels may have less impact on sexual dimorphism in the maxillary canines than in other permanent teeth. Am. J. Hum. Biol. 11:577-586...

Tooth size patterns in patients with hypodontia and supernumerary teeth

Brook, A.; Griffin, R.; Smith, R.; Townsend, G.; Kaur, G.; Davis, G.; Fearne, J.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
56.41%
AIMS: Anomalies of tooth number may not be isolated conditions but may have wider associations in the development of the dentition including tooth size. This study aimed to examine links between hypodontia, supernumerary teeth and crown size, considering the effect on the development of the whole dentition and so increase understanding of the aetiology of these conditions. METHODS AND RESULTS: The patients, who were all of European ancestry, were 60 young adults (30 males and 30 females) with hypodontia and 60 age and sex matched controls together with 60 young adults (39 males and 21 females) with supernumerary teeth and 60 age and sex matched controls. Hand measurements of mesiodistal and buccolingual dimensions were made of the teeth on dental study models using Mitutoyo electric callipers. The mean value of two measurements was used and intra-operator and inter-operator reliability determined. Patients with hypodontia had smaller teeth than the control group and this difference was statistically significant (p<0.05) for all teeth except the MD dimensions of 13, 23, 24 and 44. The difference in size was greatest for the BL dimensions in hypodontia patients. Further, the greater the number of missing teeth the smaller the tooth size. The hypodontia patients also showed higher variability in tooth dimensions than the control group. Patients with supernumerary teeth had larger teeth than the controls...

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

Brook, A.; Griffin, R.; Townsend, G.; Levisianos, Y.; Russell, G.; Smith, R.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
66.31%
AIMS: Dental 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 RESULTS: Mesiodistal 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 0.1mm. 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. CONCLUSION: The different patterns of tooth size observed between the study samples are thought to reflect differences in the relative contributions of genetic...

Tooth size in individuals with congenitally missing teeth: a study of Japanese males

Yamada, H.; Kondo, S.; Hanamura, H.; Townsend, G.
Fonte: Univ Tokyo Publicador: Univ Tokyo
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
56.47%
There is evidence of a relationship between tooth size and tooth agenesis in human populations, with a tendency for reduced tooth size in individuals with missing teeth. The aim of this study was to analyze the size of remaining teeth (mesiodistal crown diameters) and their variability in individuals with varying degrees of severity of congenitally missing teeth. Tooth crown diameters were recorded from 100 dental plaster casts of Japanese males. Subjects were divided into three agenesis groups: group A had one missing tooth per individual, group B had two missing teeth per individual, and group C had three or more missing teeth per individual. For comparison, tooth size data were used from a previously studied sample of Japanese males who did not have any congenitally missing teeth. Group A displayed the largest mesiodistal crown size dimensions for all maxillary and mandibular teeth, followed by group B, and then group C. In comparison with the reference data, when only one or two teeth were missing, the remaining teeth tended to be larger, but when there were three or more missing teeth, the remaining teeth tended to be significantly smaller throughout the dentition. In terms of tooth size variability, dental dimensions in the agenesis groups were generally more variable compared with those in the reference sample. This tendency was most pronounced in the group with the greatest number of missing teeth. Although there was a tendency for the size of the remaining teeth to be more reduced as the number of missing teeth increased...

Tooth size and dental arch dimensions: a stereophotogrammetric study in Southeast Asian Malays

Al-Khatib, A.; Rajion, Z.; Masudi, S.; Hassan, R.; Anderson, P.; Townsend, G.
Fonte: Munksgaard Int Publ Ltd Publicador: Munksgaard Int Publ Ltd
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
66.35%
Objective – To investigate tooth size and dental arch dimensions in Malays using a stereophotogrammetric system. Setting and Sample Population – The sample consisted of 252 subjects with ages ranged from 13 to 30 years. Materials and Methods –  Images of dental casts were captured by stereophotogrammetry and selected variables were measured using a three-dimensional (3D) imaging system. Sex differences and changes associated with age were assessed, and interrelationships between different variables were explored within the study group. Results – Men had significantly larger mesio-distal crown widths and dental arch dimensions than women (p < 0.05). None of the dental arch dimensions or mesio-distal crown widths showed a significant change because of age except the widths of the upper canine, lower first molar and central incisor. Significant correlations of tooth size with dental arch dimensions were found, particularly with arch lengths and perimeters. A principal component analysis showed interrelationships between the majority of tooth size variables with inter-canine width, arch length and perimeter distances. Conclusion – This study has established new reference data for tooth size and arch dimensions in Malays and demonstrated patterns of variation that are relevant to anthropologists interested in making comparisons within and between different populations and also to clinicians developing treatment plans for their patients. The study confirmed the accuracy of the 3D photogrammetric method for measuring dental casts.; AR Al-Khatib...

Increased tooth crown size in females from opposite-sex dizygotic twins : a possible intrauterine hormonal influence on dental development.

Ribeiro, Daniela Cisoto
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2012
Relevância na Pesquisa
56.37%
Studies in rodents and humans have suggested that masculinisation of females and feminisation of males can occur between fetuses in utero due to hormonal diffusion. Opposite-sex twin pairs provide a useful model to study the effects of prenatal hormone diffusion on tooth size. This study aims to determine whether primary and permanent tooth sizes are altered in females and/or males from opposite-sex dizygotic (DZOS) twins compared with same-sex monozygotic (MZ) or dizygotic (DZSS) twins; to assess the sexual dimorphism between males and females from all zygosities; and to quantify the amount and magnitude of dental asymmetries, both directional and fluctuating asymmetries, in the different twin groups. Serial dental models of the primary, mixed and permanent dentitions of 122 males and 135 females, aged from 4 to 16 years of age from DZOS, MZ and DZSS twin pairs, were used. Mesiodistal (MD) and buccolingual (BL) crown dimensions, crown heights (CH) and intercuspal (IC) dimensions of all primary teeth and the permanent central incisors, lower lateral incisors, canines, second premolars, first and second molars were measured to an accuracy of 0.1mm using a 2D image analysis system. Dental crowns of DZOS females were consistently larger by approximately 1-3% in MD and BL dimensions...

A longitudinal study of changes in tooth size and dental arch dimensions from the mixed to permanent dentitions in Australian aboriginals.

Tan, Wee Han
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013
Relevância na Pesquisa
66.44%
Objectives: (i) To investigate tooth size and dental arch dimensional changes from the mixed to permanent dentitions in Australian Aboriginals using a three-dimensional imaging system. (ii) To investigate the extent to which tooth size and dental arch dimensions contribute to dental crowding. Design: Longitudinal retrospective study. Participants/setting: Serial dental models of 49 Australian Aboriginals (28 males and 21 females) from the Yuendumu Study at ages 8, 12 and 15 years (or within a 1 year range). Main Outcome Measures: All the dental models were digitised using a 3D scanner (Optix 400S) and analysed with a 3D modeling software (Rhinoceros ® 3D 4.0). Study variables included mesiodistal tooth widths, arch widths, arch lengths, arch depths and tooth size arch length discrepancy (TSALD). Subjects at age 15 years were then subdivided into crowded (TSALD≤-1mm) and non-crowded (TSALD>-1mm) groups for analysis. Results: The changes in tooth size and dental arch dimensions from the mixed dentition to permanent dentitions are summarized as follows: 1) There was a mean reduction in mesiodistal widths of teeth ranging from 0.07mm to 0.24mm. 2) The intercanine and intermolar widths increased in males and females from the age of 8 to 15 years. 3) Arch length and arch depth showed a progressive reduction between 8 and 15 years of age. 4) Sexual dimorphism was observed whereby males had larger tooth size and dental arch dimensions than females. In crowded subjects...

On the Relationships of Postcanine Tooth Size with Dietary Quality and Brain Volume in Primates: Implications for Hominin Evolution

Jim??nez-Arenas, Juan Manuel; P??rez-Claros, Juan Antonio; Aledo, Juan Carlos; Palmqvist Barrena, Carlos Paul
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.33%
Brain volume and cheek-tooth size have traditionally been considered as two traits that show opposite evolutionary trends during the evolution of Homo. As a result, differences in encephalization and molarization among hominins tend to be interpreted in paleobiological grounds, because both traits were presumably linked to the dietary quality of extinct species. Here we show that there is an essential difference between the genus Homo and the living primate species, because postcanine tooth size and brain volume are related to negative allometry in primates and show an inverse relationship in Homo. However, when size effects are removed, the negative relationship between encephalization and molarization holds only for platyrrhines and the genus Homo. In addition, there is no general trend for the relationship between postcanine tooth size and dietary quality among the living primates. If size and phylogeny effects are both removed, this relationship vanishes in many taxonomic groups. As a result, the suggestion that the presence of well-developed postcanine teeth in extinct hominins should be indicative of a poor-quality diet cannot be generalized to all extant and extinct primates.

The effect of birthweight on tooth-size variability in twins

Apps, M.; Hughes, T.; Townsend, G.
Fonte: Australian Academic Press Pty. Ltd. Publicador: Australian Academic Press Pty. Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2004 EN
Relevância na Pesquisa
56.47%
Studies indicate that low birthweight (LBW) children display reduced deciduous tooth size but there is little information about permanent tooth size. It has also been shown that dental fluctuating asymmetry (FA) increases in response to various environmental influences, but the relationship between birthweight and FA remains unclear. The aim of this study was to compare tooth size and asymmetry, according to birthweight, in the deciduous and permanent dentitions of a sample of Australian twins. The study sample comprised 436 twins, classified into 2 groups: normal birthweight (NBW > 2500g) and low birthweight (LBW ≤ 2500g). For each individual it was generally possible to measure maximum mesiodistal crown diameters of both deciduous and permanent central incisors from serial dental models. Correlations were calculated between tooth-size variables and birthweight; subsequently comparisons of tooth size and FA were made between the LBW and NBW samples using Student's t tests. Small positive correlations (around .1) were noted between birthweight and tooth-size variables. There was no evidence of tooth-size reduction in the LBW male sample, but the LBW females displayed tooth-size reduction of approximately 2–3% for both deciduous and permanent incisors...