Carabelli Trait Research Articles

The Patterning Cascade Model and Carabelli's trait expression in metameres of the mixed human dentition: exploring a morphogenetic model.

The Patterning Cascade Model (PCM) provides an evolutionary developmental framework for exploring diversity in tooth crown form. According to the model, proximity of secondary enamel knots and tooth germ size track underlying developmental processes that dictate ultimate crown morphology (i.e., cusp number, accessory cusp presence/size). Previous research has shown the model to successfully predict variation in Carabelli's trait expression between antimeric and metameric pairs of human permanent molars. In this study, we quantify Carabelli's trait expression for metameres of the mixed dentition (dm2 and M1) and assess the PCM's potential for explaining differences in expression between the two elements. Crown dimensions, intercusp distances, and Carabelli's trait expression were collected from 49 subadults possessing observable dm2/M1 pairs. Wilcoxon signed-rank tests and paired t-tests were performed to assess whether metameres differ significantly in morphometric variables. We explored the relationships between relative intercusp distances (RICDs) and Carabelli's trait expression using proportional odds logistic regression. Intra-individual dm2/M1 pairs differed significantly in Carabelli's trait expression (p = 0.01), with dm2 exhibiting higher grades of expression more commonly despite its smaller crown size. Paired molars differed in only one statistically significant RICD: metacone-hypocone (p < 0.01). Most RICDs shared the predicted negative relationship with Carabelli's trait expression, but this relationship was only statistically significant for three RICDs in the dm2 (mean, protocone-paracone, metacone-hypocone). We found mixed support for the PCM's ability to explain differences in Carabelli's trait expression between metameres of the mixed molar row. Results suggest that protocone-paracone enamel knot spacing has the greatest influence on Carabelli's trait expression. Lack of statistical significance for many of the relationships explored may reflect limitations related to sample composition and sample size.

Ethnic Association of Cusp of Carabelli Trait and Shoveling Trait in an Indian Population.

Variations in the structure of teeth have always been of great interest to the dentist from the scientific as well as practical point of view. Additionally, ever since decades inter trait relationships have been a useful means to categorize populations to which an individual belongs. To determine the association between Cusp of Carabelli and Shoveling Trait in a selected Indian population native of Bangalore city, Karnataka, India. A cross-sectional study was carried out in 1885 children aged between 7-10 years. Casts of the study subjects were made to study the presence of Cusp of Carabelli of right maxillary permanent molar and shoveling trait of right maxillary permanent central incisor using the Dahlberg's classification and Hrdliucka's classification respectively. Linear regression was used to assess the association of cusp of carabelli trait with the tooth dimensions and logistic regression was used to evaluate the association of the carabelli trait with gender and presence/absence of shoveling. A 40.5% of subjects had Cusp of Carabelli on first molar and 68.2% had shoveling on upper central incisor. The study revealed positive association between the two traits studied in the population. A significant difference was also found with presence of Cusp of Carabelli and the buccolingual tooth dimension of the maxillary molar (p<0.05). There is an association between the Cusp of Carabelli and the shoveling trait in the present study population, and this will be valuable in the determination of ethnic origin of an individual.

Mild hypodontia is associated with smaller tooth dimensions and cusp numbers than in controls

ObjectiveThe associations seen clinically between variations in tooth number, size and shape reflect the repetitive genetic interactions occurring between the epithelium and mesenchyme during the initiation and morphogenetic stages of the Complex Adaptive System that is dental development. The aim of this study was to investigate the clinical relationship further by comparing multiple crown parameters, including cusp numbers, between patients with mild hypodontia and controls in a Romanian sample. DesignDigital images of dental casts of the permanent dentition from 28 patients with mild hypodontia and 28 controls were used. Measurements from the vestibular and occlusal surfaces were performed using a 2D image analysis method and cusps, including the Carabelli trait, were counted. Two-way analysis of variance was performed. ResultsThe dimensions of the mild hypodontia group had smaller values than the controls, with many measurements being significantly different (significance values varied from p=0.049 to p=0.001). The most affected regions were the upper and lower anterior region in both sexes. Mesio-distal, bucco-lingual and occlusal area and perimeter dimensions were affected. Females from the hypodontia group had significantly less tricuspidated lower premolars when compared with the control group. Carabelli cusps were present in the hypodontia group less frequently, the difference being highly significant (p=0.0002) in women. ConclusionsThe hypodontia patients presented with reduced crown dimensions and shape compared with controls. This is the first published study to demonstrate smaller cusp numbers in patients with hypodontia than in controls. The findings are compatible with a model of dental development as a Complex Adaptive System incorporating associations between tooth number, size and shape.

Molar morphology and the expression of Carabelli's trait in 45,X females.

The purpose of this study was to observe the expression of Carabelli's trait in maxillary first (M1) and second (M2) permanent molars in relation to tooth crown size and cusp number and to consider the role of the shortage of sex chromosome material in these features during tooth crown development. The data were derived from dental casts belonging to the KVANTTI Research Project on sex chromosome abnormalities headed by Professor Lassi Alvesalo in Finland. The subjects comprised 86 45,X females, 51 first-degree female relatives, and 150 population control females. Carabelli's trait was divided into three grades and cusp number was classified into two classes in Dahlberg's P12 and P9. The tooth crown diameters were measured with a sliding digital caliper. M1 in the 45,X females expressed a lower frequency of Carabelli's trait (19.8%) than in the female relatives (37.2%, P < 0.05). There was also a higher frequency of the three-cusp pattern (11.1%) than in the female relatives (2.4%, P = 0.055) or the control females (1.3%, P < 0.001). The expression of Carabelli's trait in M2 was of the same magnitude in the 45,X females and normal controls and was related to tooth crown size, whereas its expression in M1 of the 45,X females was associated with the cusp number rather than the tooth crown size. The shortage of one X chromosome in females has an influence on the morphology of the lingual cingulum region of the maxillary first permanent molar during tooth crown development.

The Prevalence of the Carabelli Trait in Selected Nepalese Population

The Prevalence of the Carabelli Trait in Selected Nepalese Population

Ethnic variation of selected dental traits in Coorg

Purpose:In a country like India, in addition to the great innate diversity, there are distinct migrant populations with unique dental traits.Aim:To assess the distribution and degree of expression of cusp of Carabelli of maxillary first permanent molars and shoveling trait of maxillary central incisors, between three ethnic groups of Coorg, namely Kodavas, Tibetans, and Malayalees.Materials and Methods:A cross-sectional, indirect, anthropometric, study was carried out among 15- to 30-year-old subjects belonging to three different ethnic origins. A random sample consisting of 91 subjects were recruited for the study. The shovel trait of incisors and the Carabelli trait of molars were recorded according to the classification given by Hrdliƈka and Sousa et al., respectively.Statistical Analysis:The Kruskal-Wallis test was employed to determine the difference in three populations for shoveling and Carabelli traits. Mann-Whitney Test was used for pair-wise comparisons of three populations.Result:Of the total 91 subjects, 31 were Kodavas, 30 Malayalees and 30 Tibetans. There was a statistically significant difference in shoveling trait among the three ethnic groups. For Carabelli traits, there was no statistically significant difference among three ethnic groups.Conclusion:The present study findings showed that Tibetans have a higher degree of shoveling trait than the selected South Indian ethnic groups.

Frequency and variability of dental morphology in deciduous and permanent dentition of a Nasa indigenous group in the municipality of Morales, Cauca, Colombia

Objectives: To determine the frequency, variability, sexual dimorphism and bilateral symmetry of fourteen dental crown traits in the deciduous and permanent dentition of 60 dental models (35 women and 25 men) obtained from a native, indigenous group of Nasa school children of the Musse Ukue group in the municipality of Morales, Department of Cauca, Colombia. Methods: This is a quantitative descriptive, cross-sectional study that characterizes dental morphology by means of the systems for temporary dentition from Dahlberg (winging), and ASUDAS (crowding, reduction of hypocone, metaconule and cusp 6), Hanihara (central and lateral incisors in shovel-shape and cusp 7), Sciulli (double bit, layered fold protostylid, cusp pattern and cusp number) and Grine (Carabelli trait); and in permanent dentition from ASUDAS (Winging, crowding, central and lateral incisors in shovel-shape and double shovel-shape, Carabelli trait, hypocone reduction, metaconule, cusp pattern, cusp number, layered fold protostylid, cusp 6 and cusp 7). Results: The most frequent dental crown features were the shovel-shaped form, grooved and fossa forms of the Carabelli trait, metaconule, cusp pattern Y6, layered fold, protostylid (point P) and cusp 6. Sexual dimorphism was not observed and there was bilateral symmetry in the expression of these features. Conclusions: The sample studied presented a great affinity with ethnic groups belonging to the Mongoloid Dental Complex due to the frequency (expression) and variability (gradation) of the tooth crown traits, upper incisors, the Carabelli trait, the protostylid, cusp 6 and cusp 7. The influence of the Caucasoide Dental Complex associated with ethno-historical processes cannot be ruled out.

Expression of Carabelli trait in children from Southern India - A cross sectional study

Background:The distribution of the Carabelli trait is highly variable in different regions and races of the world.Objective:To determine the prevalence of Carabelli trait in a group of children from Nellore.Materials and Methods:Children who attended the department between October 2011 to March 2012 were selected and examined for the expression of Carabelli trait in the maxillary primary second molar, permanent first and permanent second molars on the basis of the classification developed by Kraus and standards developed by Dahlberg.Statistical Methods:Descriptive statistics was performed and the relative frequency of expression in each category, according to Kraus's and Dahlberg's classification was calculated. Sexual dimorphism was statistically analyzed using Mann-Whitney U-test.Results:A total of 89.8% of primary second molars, 63.7% of permanent first molars, and 8% of permanent second molars showed some form of expression of Carabelli trait in the target population.Conclusion:Though there was a high frequency of intermediate expressions of this trait, occurrence of a definite cusp of Carabelli on the primary maxillary second molar and permanent maxillary first molar was relatively infrequent. A high percentage of the permanent maxillary second molars showed complete absence of Carabelli trait and there was no sexual dimorphism. Bilateralism with varying degrees of asymmetry was noted and there was tendency for concordance between the two sides but not within individual sides.

Carabelli's trait in Croatian populations over 1800 years

Examination and comparison of the morphological features of tooth crown in archaeological and recent samples can be difficult due to the different levels of tooth wear seen both within and between populations. These differences make the comparison of frequency data for Carabelli trait problematic. The aim of the present study is to detect the frequency and degree of expression of Carabelli's trait in Croatian populations from late antiquity to recent times and to use these data as supplementary evidence of complex population migration.A total of 1287 individuals from the late antiquity, medieval, early modern and modern periods were examined. Correlation between the presence of Carabelli's trait and tooth crown size was tested.The results of our analyses show that the frequency of Carabelli's trait is significantly greater in the early modern period (51.3%) and in the 21st century (43.1%) than in the late antiquity (20.4%) and medieval periods (23.4%).These results are consistent with historical evidence of migration and population change in the territory of present-day Croatia throughout the almost 1800 years covered by this study. The results also provide additional evidence for the complex nature of population change in the transition from the late antiquity to the early medieval period.

Metamerism, morphogenesis, and the expression of carabelli and other dental traits in humans

The patterning cascade model of tooth morphogenesis has emerged as a useful tool in explaining how tooth shape develops and how tooth evolution may occur. Enamel knots, specialized areas of dental epithelium where cusps initiate, act as signaling centers that direct the growth of surrounding tissues. For a new cusp to form, an enamel knot must form beyond the inhibition fields of other enamel knots. The model predicts that the number and size of cusps depends on the spacing between enamel knots, reflected in the spacing between cusps. Recently, work by our group demonstrated that the model predicted Carabelli trait expression in human first molars. Here we test whether differences in Carabelli trait expression along the molar row can also be predicted by the model. Crown areas and intercusp distances were measured from dental casts of 316 individuals with a digital microscope. Although absolute cusp spacing is similar in first and second molars, the smaller size and more triangular shape of second molars results in larger cusp spacing relative to size and, likely, less opportunity for the Carabelli trait to form. The presence and size of the hypocone (HY) and a range of small accessory cusps in a larger sample of 340 individuals were also found to covary with the Carabelli trait in a complex way. The results of this study lend further support to the view that the dentition develops, varies, and evolves as a single functional complex.

Prevalence, expression, and dichotomous nature of Carabelli′s trait in permanent dentition of contemporary Jat Sikhs

Objective: The study determines distribution and forms of expression of Carabelli's trait in contemporary Jat Sikhs. It also ascertains the dichotomous nature of this trait. Study design: The study was conducted on 200 maxillary first molars (male: female ratio 50:50). The trait was scored either as present or absent. When present it was again assessed and categorized. All data was subjected to either chi-square analysis or Student t-test evaluation when indicated. The significance was noted at the 5% level. Results: Prevalence of trait came out to be 78.5%. The trait absent/present exhibits bilateral development. Groove form was the most common (35%) while pit form was least prevalent (2.5%). Each first molar and its antimere exhibit no statistical difference in the exhibition of trait. A definite statistically significant sexual dimorphism (P<0.05) exists in phenotypic expression of trait among sexes. Percentage frequency of pronounced tubercle was almost double in males while absence of tubercle was observed three times more in females. The ratio of nontubercular: Tubercular varieties is 1:1.5. Conclusion: The difference in this study was statistically significant at the 5% level, which was consistent with the greater crown reduction usually found in females. The present quantitative study in an endogamous group is of clinical, anthropologic, and forensic value and provides phylogenetic and ontogenic insights regarding the trait.

Prevalence of the carabelli trait in Iranian adolescents

Aim: The study of dental morphological features is important in anthropological researches, because it can provide information on the dental variations within a specific population. The aim of this study was to evaluate the prevalence of Carabelli trait in Iranian adolescents. Subjects and Methods: In this descriptive study, 500 individuals (aged 15-49 years) were examined. Direct intraoral examination was done, morphological details of the crown, and sex of the subjects were recorded and Dahlberg classification system was used. Hydrocolloid impressions were taken and the study was repeated on the dental casts. The resultant data were compared with the clinical data. Descriptive statistics and Chi-square tests were used for data analysis (α = 0.05). Results: The prevalence of the trait was 96.6%, with significantly different distribution between males and females. Class 6 was the most frequent configuration (28.4%) and Class 1 was the least frequent (6.2%). Conclusions: The frequency of the trait was higher than that in other reports, but nearly similar to that of European groups.

Brief communication: Two‐rooted lower Canines—A European trait and sensitive indicator of admixture across Eurasia

With the exception of Carabelli's trait, the European dentition is better known for the morphological traits that it does not exhibit rather than the ones that it does. One root trait, however, runs counter to the characterization of reduced and simplified European crowns and roots. Although a rare trait in general, two-rooted lower canines are much more common in Europeans than in any other regional grouping and, given adequate sample sizes, can be useful in evaluating gene flow between Europeans and neighboring groups. In European samples, two-rooted lower canines consistently exhibit frequencies of 5-8%. In our sample from northern Spain, the trait attains a frequency of almost 10%. In contrast, in Sub-Saharan Africans the trait is virtually unknown while in Asian and Asian-derived populations, it varies between 0.0 and 1.0%. Here we show that two-rooted canine frequencies for new migrants along the western frontiers of China and Mongolia ranged from 0-4%. These data suggest European-derived populations migrated into western China (Xinjiang Province) and Mongolia (Bayan Olgii Aimag) sometime during the late Bronze age (1000-400 BCE).

The prevalence of the Carabelli cusp in selected Saudi population

The Carabelli cusp is a tubercle or cuspule, or a groove often seen on the palatal surface of the mesiopalatal cusp of maxillary permanent molars and maxillary second deciduous molars. The purpose of this study was to determine the prevalence, degree of expression of the Carabelli structure, and caries prevalence in the Carabelli structure in the permanent first and second maxillary molars in selected Saudi population. Two hundred and seventy six Saudi patients attending the college of dentistry clinics at King Saud University in Riyadh city were selected for examination. The patients’ age ranged from 11 to 55years old. Patients with severely carious, restored or missing upper first or second maxillary molars on any side were excluded. Both the first and the second upper molars were carefully examined for the occurrence of the Carabelli structure and the presence of caries. The prevalence of the Carabelli structure was 57.6% with a bilateralism of 91.2% in the first maxillary molars and 86.4% in the second molars. The Carabelli structure was found to be 29.7% as a groove expression, and 35.5% as a cusp expression. It was concluded that more than half of the Saudi population have a degree of expression of the Carabelli structure and the Carabelli trait is associated with increased caries incidence.Clinical relevance: Prominent pits and grooves can be foci for plaque retention and caries development, a large tubercle can pose some problems with orthodontic bands.

Non-metric Dental Characters in Papua New Guinea Highlanders with Special Reference to Other Asia-Pacific Populations

It has been suggested that the dental characteristics of Papua New Guinea (PNG) Highlanders are unique. For example, the frequency of shovel shaped incisor is relatively low, but that of tubercle-shaped incisors is high. Also their dental arches are shorter and broader compared with other Pacific populations. They are considered to be closely related to Aboriginal Australians on the basis of genetic and archaeological studies. However, their dental characters are distinctively different to those of Australians. The purpose of this study is to describe the frequencies of these dental characters and to compare them with other Asian and Pacific peoples. Materials were dental impressions of 111 young adults from Kasi village, Wabag, Enga Province, PNG. Characters used in this study comprised 17 dental traits that were recorded using Arizona State University Dental Anthropology System. Conspicuous characters in PNG include : low frequency of shoveling and double-shoveling of maxillary incisors ; Cusp 6 in mandibular first molar ; Carabelli's trait ; high frequencies of hypocone reduction in maxillary second molars ; Cusp 5 in maxillary first molars ; protostylid in mandibular first molars ; and 4-cusped mandibular second molars. It is suggested that this unique set of dental characters in PNG was acquired by morphological reduction from the original Australian type of dental characters and by admixture with south Asian and Pacific peoples. The principal coordinate plot for these 17 sets of scores, based on Smith's MMDs and standard deviations, showed that the PNG Highlanders belong to the Sundadont group and were located in an extreme position on the right of the first axis and in relatively lower position in the second axis.

Sexual dimorphism in deciduous crown traits of a European derived Australian sample

Sex determination of juvenile skeletal remains is a problematic area affecting physical anthropology, forensic science and archaeology. Sexual dimorphism in the morphometric crown traits of the deciduous dentition may be used to help resolve this issue. Dental stone casts from a European derived Australian sample ( n = 151) were used to investigate variation within crown traits of the deciduous canine and molars. The metric traits investigated were crown size, trigonid size and talonid size. The morphological features included Carabelli's trait and molar cusp number. Metric crown traits were significantly larger in males ( p < 0.05). The morphological crown traits were not significantly different between the sexes. The largest degree of sexual dimorphism was 11.11% in the trigonid mesiodistal diameter of the first deciduous molar. This is the first recording of the measurement in a European derived sample. Two multivariate statistics, linear functional discriminant analysis and binary logistic regression, were used to determine the success rate of sex classification from the crown traits. The most suitable was linear functional discriminant analysis, however similar results were found when using binary logistic regression. When using all variables investigated in this study, sex could be classified with accuracy of 70.2% from linear functional discriminant analysis (cross validated). The mandibular teeth had greater sexual dimorphism, classifying sex correctly 74.8% of the time compared to maxillary variables that had a success rate of 55.6%. Our results have shown that morphometric crown traits in the deciduous dentition can be used to classify sex of juvenile skeletons (11 months to 12 years) of European descent from linear functional discriminant analysis with accuracy between 70.2% and 74.8%.

Genetic and environmental influences on human dental variation: A critical evaluation of studies involving twins

Utilising data derived from twins and their families, different approaches can be applied to study genetic and environmental influences on human dental variation. The different methods have advantages and limitations and special features of the twinning process are important to consider. Model-fitting approaches have shown that different combinations of additive genetic variance (A), non-additive genetic variance (D), common environmental variance (C), and unique environmental variance (E) contribute to phenotypic variation within the dentition, reflecting different ontogenetic and phylogenetic influences. Epigenetic factors are also proposed as important in explaining differences in the dentitions of monozygotic co-twins. Heritability estimates are high for most tooth size variables, for Carabelli trait and for dental arch dimensions, moderate for intercuspal distances, and low for some occlusal traits. In addition to estimating the contributions of unmeasured genetic and environmental influences to phenotypic variation, structural equation models can also be used to test the effects of measured genetic and environmental factors. Whole-genome linkage analysis, association analysis of putative candidate genes, and whole genome association approaches, now offer exciting opportunities to locate key genes involved in human dental development.

Dental Anthropological Study of the Non-metric Traits of the Palauans

The frequency of the dental non-metric traits of school students in Koror, Palau was investigated. The parameters were recorded based on 22 crown traits classified by the Arizona State University Dental Anthropology System. In Palauans, the frequencies of shoveling and double shovel were not so high as in northeast Asians, but relatively high frequencies were found in tuberculum dentale in the maxillary second incisor and Cusp 5 in the maxillary first molar. Carabelli's trait and deflecting wrinkle were not found so frequently as in the Philippines and Bali populations. The frequency, 70.6%, of the 4-cusp type of the mandibular second molar was highest in the Asian populations cited in this study. The principal coordinate plot for these 17 sets of scores, based on Smith's MMDs and standard deviations showed that data from Sundadont and Sinodont populations were differently positioned on the first axis. The Palauans belonged to Sundadont group and located in an extreme position on the right of the first axis and in relatively lower position in the second axis, which represented the unique combination of dental characters of Palauans.

Frequency and variability of the dental morphology in African-Colombian children of a school institution of Puerto Tejada, Cauca, Colombia.

Objectives: To assess the frequency and variability of eleven non-metric dental crown traits (winging, shovel-shape, double shovel shape, Carabelli trait, deflecting wrinkle, protostylid, groove pattern, cusp number, sixth and seventh cusps) in permanent (UI1/UI2/UM1/LM1) teeth, in order to understanding the ethnic influence and the biological distance of the sample in study. Materials and methods: In this descriptive and quantitative study, frequency and variability of twelve non-metric dental crown traits were analyzed, through the ASUDAS System, in dental casts from 84 African-Colombian children of both sexes (42 females and 42 males), in mixed-dentition from Puerto Tejada, Cauca (Colombia) inhabitants. Results: High frequencies of Carabelli trait in grade 5; and +5 y +6 groove patterns, suggests Western dental complex influence. High frequencies of protostylid (P point or foramen secum) and deflecting wrinkle that suggest Mongoloid influence from the miscegenation with regional indigenous groups were observed. Winging, shovel-shape, double shovel, cusp number and cusp 6 showed low frequencies. Bilateral symmetry and absence of sexual dimorphism were demonstrated (except winging, shovel-shape and protostylid).

The Relationship between Carabelli's Trait and Tooth Crown Size in 45,X Females

The purpose of this research is to study the relationship between Carabelli's trait and tooth crown size in 45,X females and to clarify the effect of the shortage of X chromosome to the dental crown. The subjects comprised eighty-one 45,X females in the Kvantti research collection and Finnish female controls. Dahlberg's reference plaque (1956) was used to determine the score of the Carabelli's trait which was divided into three classes. The scores were compared with the maximum mesiodistal and buccolingual tooth crown diameters. The result showed that the mesiodistal diameters in 45,X females were significantly smaller than control females, while no association was found between Carabelli's trait and buccolingual tooth crown diameter in 45,X females. Mesiodistal tooth crown diameter was thought to be a key factor to develop the Carabelli's trait in 45,X females.