Carabelli Trait Research Articles

Carabelli's trait and tooth size of human maxillary first molars

Carabelli's trait is a morphological feature that can occur on the protocone of human maxillary molars. This study tests the hypothesis that Carabelli's trait is correlated statistically with the dimensions of the crown's four principal cusps or whether, as a cingular feature, the trait truly accretes onto an otherwise unaffected crown. Computer-assisted image analysis was used to measure the 6 intercusp distances and 12 angular relationships among cusp tips on the permanent first molar of 300 young adult American whites. Carabelli's complex was scored using an 8-grade ordinal scheme. Crown size was quantified in three ways, namely as 1) maximum mesiodistal and buccolingual diameters, 2) the 6 intercusp distances, and 3) the 12 angular cusp arrangements. There was no sex difference in the morphological expression of Carabelli's trait in this sample. Overall crown size and intercusp distances were significantly and progressively larger in molars with larger Carabelli's trait expressions. There are graded size responses between crown size (mesiodistal and buccolingual diameters), sizes of the four principal cusps, and morphological stage of Carabelli's complex, though the statistical relationships are appreciably stronger in males than females. Carabelli's trait occurs preferentially in larger molars. In contrast, angular (shape) relationships among cusp tips are not discernibly affected by trait size in either sex. There is the situation, then, that Carabelli's trait is developmentally correlated with crown size, but with no apparent alteration of cusp arrangements, suggesting that the increases are isometric across the occlusal table. Why the association is much weaker in females remains speculative, but these data provide yet another line of evidence that, within a population, tooth size is associated in a positive fashion with crown complexity.

Carabelli Trait Viewed from Developmental Perspective

Carabelli Trait Viewed from Developmental Perspective

Associations between Carabelli trait and cusp areas in human permanent maxillary first molars

Few dental anthropological studies have investigated the associations between tooth crown size and crown traits in humans using quantitative methods. We tested several hypotheses about overall crown size, individual cusp areas, and expression of Carabelli cusps in human permanent first molars by obtaining data from standardized occlusal photographs of 308 Australians of European descent (171 males and 137 females). Specifically, we aimed to calculate the areas of the four main molar cusps, and also Carabelli cusp, and to compare the relative variability of cusp areas in relation to timing of development. We also aimed to compare cusp areas between males and females and to describe how Carabelli cusp interacted with other molar cusps. Measurements included maximum crown diameters (mesiodistal and buccolingual crown diameters), the areas of the four main cusps, and the area of Carabelli cusp. The pattern of relative variability in absolute areas of molar cusps corresponded with their order of formation, the first-forming paracone displaying the least variation, and the last-forming Carabelli cusp showing the greatest. Overall crown size and areas of individual cusps all showed sexual dimorphism, with values in males exceeding those in females. Sexual dimorphism was smallest for paracone area and greatest for Carabelli cusp area. Overall crown size and cusp areas were larger in individuals displaying a Carabelli cusp, especially the hypocone area. Although the combined area of the protocone and a Carabelli cusp was greater in cuspal forms than noncuspal forms, protocone area alone was significantly smaller in the former. Our findings lead us to propose that, in individuals with the genotype for Carabelli trait expression, larger molar crowns are more likely to display Carabelli cusps, whereas molars with smaller crowns are more likely to display reduced forms of expression of the trait. We suggest that the pattern of folding of the internal enamel epithelium in developing molar crowns, particularly in the protocone region, can be modified by a developing Carabelli cusp.

The prevalence and mode of inheritance of Carabelli trait in the Sinhalese

The Ceylon Journal of Medical Science (CJMS) since its re-launch in 2016 is the official journal of the Faculty of Medicine, University of Colombo. The focus of the CJMS is to provide a platform to those involved in diverse fields of medical science to publish high quality research. This will facilitate promotion of evidence based medicine and thereby improve health care. This platform is open to doctors, researchers, scientists in medical sciences and medical education and students in both medical and allied health sciences. The CJMS is an open access, peer-reviewed journal.

中国ナシ(納西)族の歯冠形態の特徴 : 東アジア民族集団との比較

The purpose of this study is to assess what might be diagnostic of the Naxi dental characteristics and to demonstrate the ethnic relationships of the Naxi among Asian populations. Plaster models were taken from 80 male and 80 female students, 16 to 19 years of age, of the Naxi tribe middle high school in Lijiang, Yunann, China. Nineteen nonmetrical traits of tooth crown were classified using the Arizona State University Dental Anthropological System and counted with the individual count method. The frequencies of 19 traits in the Naxi were compared with those of 24 East Asian populations. Nine crown traits that indicated high frequencies were UI1 Shoveling, UI1 Double-shovel, UC Canine medical ridge, LP2 Premolar lingual cusp variation, U and L1,2 Odontome, LM1 Deflecting wrinkle, LM1 Protostylid, LM1 Cusp5 and LM2 4-Cusp. Those showing low frequencies were UI1^2 Winging, UI2 Interruption groove, UC Tuberculum dentale, UC Canine distal accessory ridge, UM1 Cusp 5, UM1 Carabelli's trait, LM1 Distal trigonid crest, LM1 Cusp 6 and LM2 Y groove pattern. On comparing the eight crown traits that indicated significant differences between Sinodonts which is typical of Northeast Asia, and Sundadonts which is typical of Southeast Asia, the Naxi tribe had three Sinodont-like traits: Double-shovel, Cusp 5 and Y groove pattern, and four Sundadont-like traits: Winging, Shoveling, Deflecting wrinkle and 4-Cusp. Two major clusters were found by cluster analysis on Ward method among the 25 East Asia populations including the Naxi tribe, based on the 19 crown traits. The one macro-cluster contains all northern peoples and Naxi (Sinodonts), and the other all Southeast Asia and Jomon (Sundadonts). The Sinodonty cluster was divided into two subclusters, one was the Han, Japanese and the south China group, and the other the Chaoxian, the Man and the Da furs group including the Naxi. The multidimentional scaling analysis showed that the Naxi tribe was distant from the Sundadonts and closed to the Dufurs, the Chaoxian, the Man and the Yami. The Naxi tribe showed affinities, in terms of nonmetric crown traits, with Northeast Asians rather than with Southeast Asians. The Naxi tribe was the closest to the Da furs among the populations compared here.

中国ダフル族の歯の形質人類学的研究

Tooth crown traits of the Dafurs of Inner Mongoria province, China, were examined and compared with 23 East Asian populations in order to clarify the anthropological position of the Dafurs based on Mongoloid dental variation. Plaster models were taken from 92 male and 98 female students, 16 to 19 years of age, of the Dafurs tribe middle high school in Hailaer. Nineteen non-metric traits of tooth crown were classified using the Arizona State University dental anthropological system and counted with the individual count method.The frequencies of 19 traits in the Dafurs were compared with those of 23 East Asian populations. Ten crown traits that indicated high frequencies were Shoveling (UI1), Double shovel (UI1), Canine medial ridge (UC), Cannine distal accessory ridge (UC), Premolar lingual cusp variation (LP2), Protosylid (LM1), Deflecting wrinkle (LM1), Cusp 6 (LM1), Cusp 7 (LM1) and 4 cusp (LM2). Those showing low frequencies were Winging (UI12), Interruption groove (UI2), Tuberculum dentale (UI2), Odontome (UandL 1, 2), Hypocone (UM2), Cusp 5 (UM1), Carabelli's trait (UM1), Distal trigonid crest (UM1) and Y-groove pattern (LM2).On comparing the eight crown traits that indicated significant differences between Sinodonty which is typical of Northeast Asia, and Sundadonty which is typical of Southeast Asia, the Dafurs had six Sinodont-like traits: Shoveling, Double-shovel, Carabelli's trait, Cusp 5, Deflective wrinkle and Y-groove pattern, and two Sundadont-like traits: Winging and 4 Cusp.Two major clusters were obtained from a cluster analysis on the Ward method among 23 East Asian populations and the Dafurs, based 19 crown traits. One was Sinodonty cluster, and the other Sundodonty cluster. The Dafurs was included in the Sinodonty cluster. The Sinodonty cluster was divided into two subclusters, one was the Han and Japanese group, and the other the Chaoxian and the Man group. The Dafurs was included in the latter.Furthermore, the multidimensional scaling analysis showed that the Dafurs was closest to the Chaoxian and the Man, and nearest to Sundadonty as contrasted with typical Sinodonty.Judging from the above analyses, it was proved that the dentition of the Dafurs was charasteristic of both Sinodonty and Sunndadonty, and the Dafurs was the closest to the Chaoxian and the Man in the East Asian Mongoloid populations.

大分県耶馬渓住民の歯の形質人類学的研究

In order to clarify an anthropological position of the Japanese of Yabakei based on Mongoloid dental variations, 6 tooth crown traits of the Japanese of Yabakei were examined and compared with 6 East Asia populations. In the six traits which show considerable difference between Sinodonty and Sundadonty, Double shoveling and 4-cusp in Yabakei were similar to those of Sinodonty, and Shoveling and Y-groove pattern were similar to those of Sundadonty. Carabelli's trait and Deflecting wrinkle lay between Sinodonty and Sundadonty. From a cluster analysis and multidimensional scaling analysis among 7 East Asian populations, the Yabakei was the nearest to the Chaoxian. Double shoveling and 4-cusp were approximate to those of Sinodonty than those of Taiwan. Shoveling and Y-groove pattern were approximate to those of Sundadonty than those of Taiwan. Carabelli's trait and deflecting wrinkle were most closely related to those of Taiwan. But the Yabakei was the closest to the Chaoxian.

Dental Size and Morphology of Precontact Marshall Islanders (Micronesia) Compared with Other Pacific Islanders.

The Marshall Island material is from five locations: the most southern Ebon Atoll; Kwajalein, Majuro, and Ujae atolls in the middle of the archipelago; and the southern Utrik Atoll. All but the Majuro skeletal and dental material was collected by MIW during archaeological excavations between 1993-1997. Crown dimensions and morphological observations were made of the teeth. Shoveling was present on the upper incisors ranging from trace to semi-shovel in 92% of I's and 90% of I's. This was a somewhat higher percentage than for Yap upper incisors, although it was not significant and the degree of shoveling was similar (Harris and others, 1975). The hypercone of the upper molars was always present on M but was absent 17% on M. Carabelli's trait had a low incidence in Oceania and cusps with free apices were rare. In precontact Marshallese, the cusps were present on M 39% which was about 10% higher than reported for Yap (Harris and others, 1975). There was a medium-sized cusp with an independent apex in 11% of M's. Of six dm's 33% had Carabelli's cusps. The Y occlusal groove pattern on M is fairly high in the Pacific (Swindler and others, 1998) and was present 90% of the time, the same figure reported for M in Yap (Harris and others, 1975). The presence of cusp six varied from 3% to 70% on M1 in the Pacific. The latter figure was for Yap which was significantly higher than the 55% found in the Marshallese. M (21%) and M (50%) were more variable. The metrical analysis revealed several significant differences in tooth size among the peoples of Micronesia. The teeth from Palau and Kiribati were usually larger than those from the Marshall Islands and Guam. The teeth of Native Australians are generally the largest in the Pacific The dental evidence suggested that the precontact people living on the small atolls and coral islands in the eastern areas of Micronesia were in many ways dentally similar to the modern day Yapese who were found to be dentally more closely affiliated with people to the east (Polynesia) than to the south (Melanesia) (Harris and others, 1975).

Ethnic dental analysis of shovel and Carabelli's traits in a Chinese population.

Chinese populations differ from Caucasoids by having a high prevalence of shovel trait and a low prevalence of Carabelli's trait. This study was conducted to investigate the association between the shovel and the Carabelli's traits in a Chinese population. The research design investigated a Chinese population that resides in southern Taiwan. The ancestors of this Chinese population migrated to Taiwan from mainland China, mainly from Fukien and Kwangtung. The effects of sex and age on Carabelli's trait were controlled in this investigation, as was the association between tooth size and Carabelli's trait. Results show that males were more likely to have Carabelli's trait expressed on teeth than females. The buccolingual diameter of Carabelli's trait teeth was larger than that of teeth without the trait. After controlling for sex, age, and tooth size, the existence of the shovel trait increased the likelihood of having Carabelli's trait by a factor of five and a half, which is a significant effect.

中国遼寧省満族の歯の形質人類学的研究

Tooth crown traits of 19 members of the Manchu tribe of Xin-Bin, China, were examined and compared with those of 7 Northeast Asia populations in order to clarify the anthropological position of the Manchu tribe based on Turner's Mongoloid dental variation theory. Plaster models were taken from 104 male and 109 female students, 14 to 18 years of age, of the Manchu tribe middle high school in Xin-Bin. They were examined using the Arizona State University Dental Anthropology System. In the eight traits, considerable differences were shown between Sinodonty which is typical of Northeast Asia and Sundadonty which is typical of Southeast Asia. Winging (UI1^2) and 4-cusp (LM2) of Manchu were similar to those of Sundadonty. Shoveling (UI1), Double shoveling (UI1), Carabelli's trait (UM1), Deflecting wrinkle (LM1) and Y-groove pattern (LM2) of Manchu were similar to those of Sinodonty. Cusp 5 (UM1) of Manchu lie midway between Sinodonty and Sundadonty. Appearance rate of Double shoveling (UI1), Lingual cusp variation (LP2), Protostylid (LM1) and 4-cusp (LM2) were high in 7 Northeast Asia populations. Canine medial ridge (UC), Hypocone (UM2), Cusp5 (UM1), Carabelli's trait (UM1), Deflecting wrinkle (LM1), Distal trigonid crest (LM1) and Cusp7 (LM1) were middle, Winging (UI1^2), Shovelling (UI1), Interruption groove (UI2), Tuberculum dentale (UI2), Canine distal accessory ridge (UC), Odontome (UP, LP), Cusp6 (LM1) and Y-groove pattern (LM2) were low. In the eight traits, considerable differences were shown between Han trib and Manchu tribe. Double shoveling (UI1), Lingual cusp variation (LP2), Cusp 5 (UM1), Carabelli's trait (UM1), Protostylid (LM1) and 4-cusp (LM2) of Manchu were higher those of than Han. Tuberculum dentale (UI2) and Canine distal accessory ridge (UC) of Manchu were lower than those of Han.

Enamel thickness and the topography of the enamel-dentine junction in South African Plio-Pleistocene hominids with special reference to the Carabelli trait.

This study explores the internal morphology of early hominid teeth using high-resolution computed tomography. Data on Carabelli feature size, enamel thickness, and the topography of the enamel-dentine junction are considered together in order to examine the relationship among these variables in the maxillary molars of gracile and robust australopithecines from South Africa. In particular, one aim is to investigate the degree to which Carabelli feature size influences enamel thickness in the plane of the mesial cusps. The results demonstrate that maxillary molars attributed to Australopithecus africanus from Sterkfontein, Taung and Makapansgat possess larger Carabelli features and thinner enamel along the lingual wall of the protocone than do specimens attributed to Paranthropus robustus from Swartkrans and Kromdraai. Distinct differences in the position of the Carabelli feature at the level of both the enamel-dentine junction and tooth crown surface between early hominid species may help explain the observed disparity in enamel thickness at that region of the tooth crown as well as offer clues to the functional role of Carabelli's cusp. As the size and position of the Carabelli feature affects the linear thickness of enamel at this one particular region of the tooth crown, future comparative studies focusing on taxa that possess moderate to strong development of the Carabelli complex should use the linear thickness of enamel taken close to the protoconal dentine horn or at the maximum projection of the Carabelli's cusp.

The Effect of Shovel Trait on Carabelli's Trait in Taiwan Chinese and Aboriginal Populations

Chinese and other Mongoloid populations differ from Caucasoids by having a high prevalence of shovel trait and a low prevalence of Carabelli's trait. This study was conducted to compare the association between the shovel and the Carabelli's traits between Chinese and aboriginal Mongoloid populations. The research is designed to sample randomly a Chinese population and an aboriginal population having low admixture with neighboring populations. The Mongoloid aboriginal group was from the Bunun tribe who resides in an isolated alpine area in Taiwan. The effects of sex and age on Carabelli's trait were controlled in this study, as was the association between tooth size and Carabelli's trait. Our results show that males had more Carabelli's trait expressed on teeth than females in both of these two Mongoloid populations. The buccolingual diameter of Carabelli's trait teeth was larger than that of teeth without the trait. After controlling for sex, age, and tooth size, the existence of the shovel trait significantly increased the likelihood of having Carabelli's trait, especially in Chinese, which implies another significant ethnic feature for Mongoloid identification.

Logistic analysis of shovel and Carabelli's tooth traits in a Caucasoid population

Caucasoid populations differ from Mongoloids by having a high prevalence of Carabelli's trait and a low prevalence of shovel trait. This study was conducted to investigate the association between the shovel and the Carabelli's traits in a Caucasoid population. The research design sought a Caucasoid population at Milwaukee of Wisconsin in United States. The Caucasoid group selected for study was the European descendant. The effects of sex and age on Carabelli's trait were controlled in this investigation, as was the association between tooth size and Carabelli's trait. Results show that males were more likely to have Carabelli's trait expressed on teeth than females. The buccolingual diameter of Carabelli's trait teeth was larger than that of teeth without the trait. After adjusting for sex, age, and tooth size, the existence of the shovel trait decreased the likelihood of having Carabelli's trait which shows an significant effect.

Characteristic high- and low-frequency dental traits in sub-Saharan African populations

In an earlier investigation (Irish [1993] Biological Affinities of Late Pleistocene Through Modern African Aboriginal Populations: The Dental Evidence [Ann Arbor: University Microfilms]), biological affinities of 32 sub-Saharan and North African dental samples were estimated using comparative analyses of 36 dental morphological traits. Marked dental homogeneity was revealed among samples within each of the two geographic regions, but significant interregional differences were noted. Assuming dental phenetic expression approximates or is an estimate of genetic variation, the present study of 976 sub-Saharan-affiliated Africans indicates they are not closely related to other world groups; they are characterized by numerous morphologically complex crown and root traits. Turner ([1984] Acta Anthropogenetica 8:23-78; [1985] in R Kirk and E Szathmary (eds.): Out of Asia: Peopling the Americas and the Pacific [Canberra: The Journal of Pacific History], pp. 31-78; [1990] Am. J. Phys. Anthropol. 82:295-318; [1992] Persp. Hum. Biol. 2/Archaeol. Oceania 27:120-127; [1992] in T Akaszawa, K Aoki, and T Kimura (eds.): The Evolution and Dispersal of Modern Humans in Asia [Tokyo: Hokusen-Sha Publishing Co-], pp. 415-438) reports that Northeast Asian/New World sinodonts also have complex teeth relative to Europeans, Southeast Asian sundadonts, Australian/Tasmanians, and Melanesians. However, sinodonty is characterized by UI1 winging, UI1 shoveling, UI1 double shoveling, one-rooted UP1, UM1 enamel extension, M3 agenesis, and three-rooted LM1. Sub-Saharan peoples exhibit very low frequencies of these features. It is proposed that the collection of dental traits which best differentiate sub-Saharan Africans from other worldwide samples includes high frequencies of the Bushman Canine, two-rooted UP1, UM1 Carabelli's trait, three-rooted UM2, LM2 Y-groove pattern, LM1 cusp 7, LP1 Tome's root, two-rooted LM2, UM3 presence, and very low incidences of UI1 double shoveling and UM1 enamel extension. This suite of diagnostic traits is termed the sub-Saharan African dental complex.

Logistic analysis of the effects of shovel trait on Carabelli's trait in a mongoloid population

Mongoloid populations differ from Caucasoids by having a high prevalence of shovel trait and a low prevalence of Carabelli's trait. This study was conducted to investigate the effects of the shovel trait on Carabelli's trait in a Mongoloid population. The research design sought a population that resides in an isolated area and exhibits low admixture with neighboring populations. The Mongoloid group selected for study was the Bunun tribe of aborigines who inhabit an alpine area in Taiwan. The effects of sex and age on Carabelli's trait were controlled in this investigation, as was the association between tooth size and Carabelli's trait. Results show that males were more likely to have Carabelli's trait expressed on teeth than females. The buccolingual diameter of Carabelli's trait teeth was larger than that of teeth without the trait. After adjusting for sex, age, and tooth size, the existence of the shovel trait increased the likelihood of having Carabelli's trait by a factor of three, an effect that is significant.

Logistic analysis of the effects of shovel trait on Carabelli's trait in a mongoloid population

Mongoloid populations differ from Caucasoids by having a high prevalence of shovel trait and a low prevalence of Carabelli's trait. This study was conducted to investigate the effects of the shovel trait on Carabelli's trait in a Mongoloid population. The research design sought a population that resides in an isolated area and exhibits low admixture with neighboring populations. The Mongoloid group selected for study was the Bunun tribe of aborigines who inhabit an alpine area in Taiwan. The effects of sex and age on Carabelli's trait were controlled in this investigation, as was the association between tooth size and Carabelli's trait. Results show that males were more likely to have Carabelli's trait expressed on teeth than females. The buccolingual diameter of Carabelli's trait teeth was larger than that of teeth without the trait. After adjusting for sex, age, and tooth size, the existence of the shovel trait increased the likelihood of having Carabelli's trait by a factor of three, an effect that is significant. © 1996 Wiley-Liss, Inc.

Occurrence of the Carabelli trait in twins discordant or concordant for cleft lip and/or palate.

The frequency and expression of the Carabelli trait among 36 twin pairs discordant or concordant for cleft lip and/or palate were investigated. Four of 10 monozygotic (MZ) and 24 of 26 dizygotic (DZ) pairs of twins were discordant for clefts. The frequency of the trait on the first upper molars of the noncleft subjects was 79%. It varied from 54% to 61% in the subjects with clefts, and the frequency of the trait decreased with increasing extension of the cleft. The occurrence of the trait was bilateral in more than 90% of the MZ and the DZ subjects. MZ twins had a higher concordance rate for the corresponding molar comparisons and for cross-twin comparisons than did the DZ pairs. The corresponding polychoric correlations for MZ twin pairs were estimated to be 1.0, and for the DZ twin pairs estimates ranged from 0.4 to 0.5. Thus, genetic factors appear to control the Carabelli trait, and the heritability seems to be high even in our cleft lip and/or palate twins.

Fitting genetic models to Carabelli trait data in South Australian twins.

This study aimed to clarify genetic and environmental contributions to Carabelli trait variation on permanent first molar teeth in a large sample of South Australian twins. Estimates of polychoric correlations were obtained between pairs of monozygous (MZ) and dizygous (DZ) twins for Carabelli data and various gene-environment models fitted by a weighted least-squares approach. The favored model included additive genetic effects together with both a general environmental component and an environmental effect specific to each side. An estimate of heritability around 90% indicated a very strong genetic contribution to observed variation. The pattern of correlations for MZ and DZ data suggested that further studies involving other types of relatives would be worthwhile for detection of possible non-additive genetic effects of dominance or epistasis.

Tooth size and the Carabelli trait

The Carabelli trait and its association with maxillary molar crown base and cusp size was studied in a group of 128 Kwengo, a San-Negro hybrid community living in Western Caprivi, Namibia. The trait was classified according to a modification of the scheme put forward by Dahlberg and by Scott (In: Dental Anthropology, New York: Pergamon, 1963) (Hum. Biol. 52:63-78, 1980). Crown base areas were larger in trait-positive than in trait-negative molars, and this difference existed for all eight categories of the trait in the first molar and for most of the categories in the second and third molars. The degree of expressivity of the trait seems to be associated with molar size, but this is more apparent in the first than in the second and third molars.

歯冠形質に基づく台湾原住民ヤミ族の形質人類学的研究 : 東アジア諸集団における位置

Nineteen tooth crown traits of Yami tribe, Taiwan Aborigine, were examined and compared with 16 East Asian populations in order to clarify an anthropological position of Yami based on Mongoloid dental variations. In the eight traits which show considerable difference between Sinodonty which is typical of Northeast Asia, and Sundadonty which is typical of Southeast Asia, shoveling (UI1), Y-groove (LM2) and deflecting wrinkle (LM1) of Yami were similar to those of Sinodonty, while winging (UI1), cusp 5 (UM1) and Carabelli's trait (UM1) of Yami were similar to those of Sundadonty. Double shovel (UI1) and 4-cusp (LM2) of Yami lie midway between Sinodonty and Sundadonty. Two major clusters were obtained from a cluster analysis on Smith's MMD among 16 East Asian populations and Yami, based on 19 crown traits. One was a Sinodonty cluster, and the other was a Sundadonty cluster. Yami was included in the Sinodonty cluster. Furthermore, the principal co-ordinate anlysis showed that Yami, in Sinodonty, was nearest to Sundadonty, in contrast to typical Sinodonty. Judging from the above analyses, it was proved that the dentition of Yami was characteristic of both Sinodonty and Sundadonty, and had more resemblance, if anything, to Sinodonty rather than to Sundadonty.