|Year : 2020 | Volume
| Issue : 1 | Page : 11-15
Carabelli's trait: Frequency and expression in primary and permanent dentition
Prasun Mukhopadhyay1, Santanu Mukhopadhyay2
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 Submission||19-Oct-2019|
|Date of Acceptance||10-Dec-2019|
|Date of Web Publication||11-Mar-2020|
Dr. Santanu Mukhopadhyay
2/1D, Merlin Uttara, 94/7K GT Road, Kotrung (Hindmotor), Hooghly - 712 233, West Bengal
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 May 31];11:11-5. Available from: http://www.srmjrds.in/text.asp?2020/11/1/11/280375
| Introduction|| |
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.,,,,,, 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.
The exact etiology of CT remains unclear. Biggerstaff proposed that the condition results from the interaction of genetic and environmental factors. 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.
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. 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|| |
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:
- All maxillary primary second molars and permanent first molars were present
- 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:
- Absence of the trait
- Pit or depression
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|| |
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 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.
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 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|| |
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. 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 (2014) observed a prevalence of CT in 96.6% of Iranian population. Mavrodisz reported a 65.34% frequency of this trait in Hungarian children. In Malaysian children, the frequency of CT was 54.2%. Among Indians, Joshi observed a prevalence of 88.2% and Kanappan and Swaminathan showed that the frequency of CT was 52.7%. In Africa, Barnes observed a low prevalence of this morphological trait in Negroids. 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.
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 (80%), Kannapan and Swaminathan (67.5%), Ferreira et al. (69.5%), and Kamatham et al. (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, Kannapan and Swaminathan, Ferreira et al. and Kamatham et al. also noted similar findings. This variation could probably be due to the interplay between environmental and genetic factors during odontogenesis.,,
Many studies have shown sexual dimorphism in the occurrence of this trait.,,, On the other hand, Rusmah, Falomo, Kieser, and Harris 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 but is in contrast with Salako andBello, 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, Rusmah, Alvesalo et al., and Falomo but contradicts the results of Biggerstaff, Salako andBello, and Kieser. 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.
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, but contradicts the results of Meredith et al. 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. but contradicts the findings of Shethri and Mosharraf 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 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. classified CT into a maximum of eight categories. Dahlberg's scale has seven types of cusps. Alvesalo et al. classified CT into five types. The present study is similar with the one described by Shethri 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., Kondo and Townsend examined standardized occlusal photographs for this purpose. Mosharraf 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|| |
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.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]