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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 11  |  Issue : 1  |  Page : 11-15

Carabelli's trait: Frequency and expression in primary and permanent dentition


1 Commanding Officer & Corps Dental Adviser, 1 Corps Dental Unit, Kolkata, West Bengal, India
2 Department of Pedodontics and Preventive Dentistry, Dr. R. Ahmed Dental College and Hospital, Kolkata, West Bengal, India

Date of Submission19-Oct-2019
Date of Acceptance10-Dec-2019
Date of Web Publication11-Mar-2020

Correspondence Address:
Dr. Santanu Mukhopadhyay
2/1D, Merlin Uttara, 94/7K GT Road, Kotrung (Hindmotor), Hooghly - 712 233, West Bengal
India
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DOI: 10.4103/srmjrds.srmjrds_73_19

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  Abstract 

Aim: Carabelli's trait (CT) is a cusp or groove seen on the palatal surface of the mesiopalatal cusp of primary maxillary second molars and permanent maxillary first molars. The purpose of this study was to determine the frequency and degree of expression of CT in the primary maxillary second molars and permanent first molars in Bengali population. Methods: In this descriptive study, 377 children (193 males and 184 females) of both sexes were examined clinically for the presence of CT. Intraoral examinations were carried out to determine the incidence and degree of expression of a CT for the primary maxillary second molars and permanent first molars. When present, CT was recorded as cusp or pit. Results: The frequency of CT was 45.6% with no significant sex difference (P > 0.05). The prevalence of the trait was more in primary maxillary second molars (38.7%) than in permanent first molars (23.1%). Bilateralism of CT was observed in 79.1% of the cases. Negative expression or pit form of the trait was more common than cuspal configuration. There was a positive association (P = 0.00) between the occurrence of CT in the primary second molars and permanent first molars. Conclusion: The prevalence of CT was more in primary maxillary second molars than in permanent maxillary first molars. The presence of CT in the primary maxillary second molars was positively associated with CT in the maxillary permanent first molars.

Keywords: Bengali population, Carabelli's trait, prevalence


How to cite this article:
Mukhopadhyay P, Mukhopadhyay S. Carabelli's trait: Frequency and expression in primary and permanent dentition. SRM J Res Dent Sci 2020;11:11-5

How to cite this URL:
Mukhopadhyay P, Mukhopadhyay S. Carabelli's trait: Frequency and expression in primary and permanent dentition. SRM J Res Dent Sci [serial online] 2020 [cited 2020 Aug 7];11:11-5. Available from: http://www.srmjrds.in/text.asp?2020/11/1/11/280375


  Introduction Top


Carabelli's trait (CT) is a dental morphological trait located on the palatal surface of the mesiopalatal cusp of the maxillary permanent molars and the maxillary primary second molars. The condition is rarely present on the maxillary first primary molars or on the maxillary second permanent molars.[1],[2],[3],[4],[5],[6],[7] The condition was first described in 1842 by Carabelli (Mitchell, 1892), and since then, it has been identified as a significant trait in forensic, anthropological, and ethnic studies.[1]

The exact etiology of CT remains unclear. Biggerstaff proposed that the condition results from the interaction of genetic and environmental factors.[8] Moreover, variations in the prevalence of this trait among different ethnic groups also suggest genetic influence in its etiology.

The condition is known by many names which include fifth cusp, molar tubercle, enamel elevation, tubercle of Carabelli, and mesiopalatal prominence.[9]

If present, CT shows variable expressivity, ranging from a small pit to a well-developed cusp. Kondo and Townsend proposed that in individuals with the genotype for CT expression, larger molar crowns are more likely to display CT, whereas molars with smaller crowns are often associated with the reduced forms of expression of the trait.[10] Globally, many studies have been carried out to determine the prevalence of CT among different populations. To the best of our knowledge, no such studies were performed in Bengali population. The aim of the present study was to determine the incidence and degree of expression of CT in a group of Bengali population. In addition, we also evaluated the association of CT in the maxillary primary second molars and permanent first molars.


  Methods Top


The present study was undertaken as a part of school oral health survey conducted on primary schoolchildren of both sexes between August 2015 and July 2016. The ethical committee of our institute has approved the study, and informed consent was obtained from the parent of each participant. Bengali children of both sexes aged 6–11 years who met the following two criteria were included in this survey:

  1. All maxillary primary second molars and permanent first molars were present
  2. The maxillary primary second molars and permanent first molars did not have any dental caries or restoration.


Children with developmental anomalies were excluded from the study. Children who had a history of orthodontic treatment were also not included because of the possibility of grinding of CT during placement of molar bands. Oral examinations of children were carried out at their classrooms by one examiner (SM) under good illumination using disposable mirror. Before the study, 20 children were examined twice at an interval of 2 weeks to test the intra-examiner reliability. The kappa score for CT was 0.91.

A total of 377 children of both sexes were selected. The trait was recorded absent if the palatal aspect of the mesiopalatal cusp was smooth. The presence of any cusp, pit, or depression was considered as the presence of CT. The degree of expression of the trait was classified into:

  1. Absence of the trait
  2. Pit or depression
  3. Cusp.


Data were recorded in a preformed sheet and entered into an Excel file. Statistical analyses were carried out using Epi Info soft ware version 7 (CDC, Atlanta USA,2015). The level of significance was set at P < 0.05.


  Results Top


There were193 males (51.2%) and 184 females (48.8%) in this study population. Among the 377 children, 172 (45.6%) were diagnosed as having CT. The trait is more common in males (49.2%, 95/193 cases) than in females (41.8%, 77/184 cases). However, this difference was not statistically significant (P > 0.05). In both sexes, the expression of CT was higher in the primary dentition [Table 1]. The frequency of CT in the primary second molars was 42% (n = 81) in males and 35.3% (n = 65) in females, and overall, it was 38.7% (n = 146). The permanent first molars showed CT in 24.9% (n = 48) of cases in males, and in females, it was 21.2% (n = 39). The overall prevalence of CT in the permanent first molars was 23.1% (n = 87). The frequency of CT for the primary second molars was significantly higher (P = 0.000, Fisher's exact test).
Table 1: Prevalence of Carabelli's trait according to gender

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[Table 2] shows that bilateralism was more common than the unilateral expression of the trait. Among females, 83.1% (64 cases, n = 77) and, in males, 75.8% (72 cases, n = 95) had shown bilateralism regardless of the type of expression. Of the 172 children with CT, some kind of bilateral expression of the trait was seen in 79.1% (n = 136) of cases. Among 377 children examined, only 8.7% (n = 377) of cases showed simultaneous bilateralism in the primary second and permanent first molars. In addition, negative expression of the trait in the form of pit or depression was more commonly observed in all molars.
Table 2: Unilateral and bilateral distribution of Carabelli's trait

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Although there was no statistically significant difference in the occurrence of CT on the right and left primary second molars, we observed a significant association (P = 0.001) between the permanent left and right first molars [Table 3]. The frequency of cusp form in the primary second molars was 8.9% (n = 67), and in permanent first molars, it was 10.9% (n = 82). Negative expression or pit form was observed in 25.2% (n = 190) of the primary second molars and 15.5% (n = 117) in the permanent first molars. Regardless of the type of expression, CT shows no statistically significant difference between the right and left sides either in boys or in girls [Table 4].
Table 3: Expression of cusp and pit form of Carabelli's trait in primary and permanent molars

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Table 4: Comparison of Carabelli's trait according to sex

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[Table 5] shows that there was a positive association between the occurrence of CT in the primary second molars and permanent first molars.
Table 5: Association of Carabelli's trait in primary second molars and permanent first molars

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  Discussion Top


Dental morphological characteristics are useful in anthropological research since their incidence and degree of expression vary among populations. Bermúdez De Castro suggested that CT can provide a phylogenetic relationship between closely related populations.[11] Many studies have been carried out before and thereafter concerning the morphology of the CT, heritability, sexual dimorphism, and its influence on tooth size. The results of these studies have pointed out that the frequency of CT varies with ethnicity and geographic location. For example, Mosharraf[12] (2014) observed a prevalence of CT in 96.6% of Iranian population. Mavrodisz[1] reported a 65.34% frequency of this trait in Hungarian children. In Malaysian children, the frequency of CT was 54.2%.[13] Among Indians, Joshi[2] observed a prevalence of 88.2% and Kanappan and Swaminathan[3] showed that the frequency of CT was 52.7%. In Africa, Barnes observed a low prevalence of this morphological trait in Negroids.[14] In general, Caucasians show a high and the people of African origin have a low prevalence of this trait. Depending on the frequency of CT, Sadatullah et al. categorized populations groups into three types: high prevalence (2/3's frequency), moderate prevalence (between 1/3's and 2/3's frequency), and low prevalence (1/3's frequency) populations.[9]

In the present study, the frequency of CT was 38.7% for the primary second molars which is less compared to the results of Townsend and Martin[6] (80%), Kannapan and Swaminathan[3] (67.5%), Ferreira et al.[15] (69.5%), and Kamatham et al.[4] (89.8%). In our sample, the frequency of a CT on the permanent maxillary first molars was 23.1%. When we compared primary second molars and permanent first molars, primary second molars displayed significantly higher (P = 0.000) frequency of CT. Townsend and Martin,[6] Kannapan and Swaminathan,[3] Ferreira et al.[15] and Kamatham et al.[4] also noted similar findings. This variation could probably be due to the interplay between environmental and genetic factors during odontogenesis.[13],[15],[16]

Many studies have shown sexual dimorphism in the occurrence of this trait.[6],[10],[17],[18] On the other hand, Rusmah,[13] Falomo,[19] Kieser,[20] and Harris[21] observed no sex difference in the morphological expression of CT. In this study, males displayed a higher frequency of CT compared to females although this difference was not statistically significant. This is in agreement with the observations of Harris[21] but is in contrast with Salako andBello,[22] who reported a higher incidence of this trait in females than in males.

Bilateralism of the trait was observed in our study. This observation supports the findings of Joshi,[2] Rusmah,[13] Alvesalo et al.,[23] and Falomo[19] but contradicts the results of Biggerstaff,[8] Salako andBello,[22] and Kieser.[20] However, true bilateralism or simultaneous expression of CT in primary second and permanent first molars on both sides is low in our study which is in agreement with the findings of Flomo.[19]

We could not find a statistically significant difference between the right and left sides of primary second molars and permanent first molars, which is in accordance with some studies[4],[13] but contradicts the results of Meredith et al.[24] Furthermore, pit form or negative expression of the trait was more common in our study. This finding agrees with the observation of Kamatham et al.[4] but contradicts the findings of Shethri[25] and Mosharraf[12] who reported that cusps were more common than pit form of the trait.

The presence of CT on primary second molars was strongly associated with the presence of CT on the first permanent molars. Kieser[20] also noted a high degree of equivalence of this trait between primary second molars and permanent first molars.

Various investigators have studied the expression of this trait on different populations. However, the same criteria were not used. For example, Cox et al.[26] classified CT into a maximum of eight categories. Dahlberg's scale has seven types of cusps.[27] Alvesalo et al.[23] classified CT into five types. The present study is similar with the one described by Shethri[25] in which CT was classified into three types: smooth surface or absence of the trait, pit form or negative expression, and cusp form or positive expression of the trait. Moreover, several researchers performed intraoral examination while others used dental casts for examination of CT.[1],[9] Kondo and Townsend[10] examined standardized occlusal photographs for this purpose. Mosharraf[12] pointed out that clinical examination has the advantages of racial and sexual identification of an individual which is not possible with extracted teeth. Therefore, a comparison of results is not always possible.


  Conclusion Top


Nearly 40% of Bengali children showed CT, and the trait was more common in primary second molars than in permanent first molars. No statistically significant difference was observed in the frequency of males and females. Negative expression of the trait was more common than cuspal configuration. There was a positive association between the occurrence of CT in the primary second molars and permanent first molars.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Mavrodisz K, Rózsa N, Budai M, Soós A, Pap I, Tarján I. Prevalence of accessory tooth cusps in a contemporary and ancestral Hungarian population. Eur J Orthod 2007;29:166-9.  Back to cited text no. 1
    
2.
Joshi MR. Carabelli's trait on maxillary second deciduous molars and first permanent molars in Hindus. Arch Oral Biol 1975;20:699-700.  Back to cited text no. 2
    
3.
Kannapan JG, Swaminathan S. A study on a dental morphological variation. Tubercle of Carabelli. Indian J Dent Res 2001;12:145-9.  Back to cited text no. 3
    
4.
Kamatham R, Nuvvula S. Expression of Carabelli trait in children from Southern India – A cross sectional study. J Forensic Dent Sci 2014;6:51-7.  Back to cited text no. 4
[PUBMED]  [Full text]  
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Kirthiga M, Manju M, Praveen R, Umesh W. Ethnic association of cusp of Carabelli trait and shoveling trait in an Indian population. J Clin Diagn Res 2016;10:ZC78-81.  Back to cited text no. 5
    
6.
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Lauc T. Influence of inbreeding on the Carabelli trait in a human isolate. Dent Anthropol 2003;16:65-72.  Back to cited text no. 7
    
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Sadatullah S, Odusanya SA, Mustafa A, Razak, AP, Wahab AM, Meer Z. The prevalence of fifth cusp (Cusp of Carabelli) in the upper molars in Saudi Arabian school students. Int J Morphol 2012;30:757-60.  Back to cited text no. 9
    
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Bermúdez De Castro JM. The Carabelli trait in human prehistoric populations of the Canary Islands. Hum Biol 1989;61:117-31.  Back to cited text no. 11
    
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Mosharraf R. Prevalence of the Carabelli trait in Iranian adolescents. SRM J Res Dent Sci 2013;4:12-5.  Back to cited text no. 12
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Rusmah M. The cusp of Carabelli in Malaysians. Odontostomatol Trop 1992;15:13-5.  Back to cited text no. 13
    
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Barnes DS. Tooth morphology and other aspects of the TESO dentition. Am J Phys Anthropol 1969;30:183-94.  Back to cited text no. 14
    
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Thomas CJ, Kotze TJ, Nash JM. The Carabelli trait in the mixed deciduous and permanent dentitions of five South African populations. Arch Oral Biol 1986;31:145-7.  Back to cited text no. 16
    
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Hsu JW, Tsai PL, Hsiao TH, Chang HP, Lin LM, Liu KM, et al. The effect of shovel trait on Carabelli's trait in Taiwan Chinese and aboriginal populations. J Forensic Sci 1997;42:802-6.  Back to cited text no. 17
    
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Noss JF, Scott GR, Potter RH, Dahlberg AA, Dahlberg T. The influence of crown size dimorphism on sex differences in the Carabelli trait and the canine distal accessory ridge in man. Arch Oral Biol 1983;28:527-30.  Back to cited text no. 18
    
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Falomo OO. The cusp of Carabelli: Frequency, distribution, size and clinical significance in Nigeria. West Afr J Med 2002;21:322-4.  Back to cited text no. 19
    
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Kieser JA. An analysis of the Carabelli trait in the mixed deciduous and permanent human dentition. Arch Oral Biol 1984;29:403-6.  Back to cited text no. 20
    
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Harris EF. Carabelli's trait and tooth size of human maxillary first molars. Am J Phys Anthropol 2007;132:238-46.  Back to cited text no. 21
    
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Salako NO, Bello LL. Prevalence of the Carabelli trait in Saudi Arabian children. Odontostomatol Trop 1998;21:11-4.  Back to cited text no. 22
    
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Alvesalo L, Nuutila M, Portin P. The cusp of Carabelli. Occurrence in first upper molars and evaluation of its heritability. Acta Odontol Scand 1975;33:191-7.  Back to cited text no. 23
    
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Meredith HV, Hixon EH. Frequency, size, and bilateralism of Carabelli's tubercle. J Dent Res 1954;33:435-40.  Back to cited text no. 24
    
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Shethri AS. The prevalence of the Carabelli cusp in selected Saudi population. King Saud Univ J Dent Sc 2011;2:13-6.  Back to cited text no. 25
    
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Cox GJ, Finn SB, Ast DB. Effect of fluoride ingestion on the size of the cusp of Carabelli during tooth formation. J Dent Res 1961;40:393-5.  Back to cited text no. 26
    
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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