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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 29  |  Issue : 4  |  Page : 292-294

Prevalence of Third Molar Agenesis between the Individuals of Kerala and Bhutan: A Comparative Study


Department of Oral Medicine and Radiology, Navodaya Dental College, Raichur, Karnataka, India

Date of Submission17-Sep-2016
Date of Acceptance05-Nov-2017
Date of Web Publication15-Feb-2018

Correspondence Address:
Dr. Prashant Patil
Department of Oral Medicine and Radiology, Navodaya Dental College, Raichur, Karnataka - 584 103
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.JIAOMR_120_16

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   Abstract 


Aim: The aim of the study was to evaluate the prevalence of the third molar agenesis in Keralites and Bhutanese groups of individuals. Materials and Methods: One hundred and seven panoramic radiographs retrieved from the department of oral medicine and radiology were analyzed, which included 55 individuals from Kerala and 52 individuals from Bhutan within the age range of 18–25 years. The prevalence of third molar agenesis between individual dentition quadrants, upper and lower jaw, and right and left side of the dentition were examined and compared between the two groups. The data was analyzed using student's un-paired t-test and Chi square test. Results: Prevalence of third molar agenesis among 107 participants was 28.9%. It was more in Bhutanese (35.29%) compared to Keralites (23.63%). The association of females with agenesis was found to be more than males in both the groups (61.1% females in Bhutanese and 69.2% females in Keralites). Third molar agenesis was found to be more prevalent in maxillary arch as compared to the mandibular arch. The association of third molar agenesis with age and sex in both the groups was statistically not significant (P > 0.05). Incidentally, we found 0.9% of second molar agenesis bilaterally in Bhutanese. Conclusion: Third molar agenesis was higher among Bhutanese as compared to Keralites.

Keywords: Agenesis, prevalence, third molar


How to cite this article:
Patil P, Nazeer S. Prevalence of Third Molar Agenesis between the Individuals of Kerala and Bhutan: A Comparative Study. J Indian Acad Oral Med Radiol 2017;29:292-4

How to cite this URL:
Patil P, Nazeer S. Prevalence of Third Molar Agenesis between the Individuals of Kerala and Bhutan: A Comparative Study. J Indian Acad Oral Med Radiol [serial online] 2017 [cited 2019 May 22];29:292-4. Available from: http://www.jiaomr.in/text.asp?2017/29/4/292/225466




   Introduction Top


When compared to all other teeth in the mouth, the third molar is a classic example of contradictions. There are many developmental anomalies which can be found in the third molars. Variability of the third molar development gives every group a unique character. It belongs to the essential characteristics of the dentition's status of the given population. It shows significance for dental developmental anomalies that can indicate the degree of genetic load of individuals and relatives. For dentists, anthropologists, and geneticists it belongs into the sphere of interest due to its nature.

The third molar during its formation is characterized by widely varying crown and root morphology as well as by its varying presence or absence in the oral cavity.[1] Agenesis of this tooth is frequent, although its frequency ranges widely, varying from zero among an unspecified sample of craniums in Tasmania to 49% in an unspecified sample of Hungarian craniums.[2] Third molar agenesis also varies according to various ethnic groups. Hence, in our study we compared the prevalence of third molar agenesis between Kerala and Bhutanese groups of individuals, whether there was any difference between both the genders or individual dental quadrants among both the groups.


   Materials and Methods Top


The study was conducted in the Department of Oral Medicine and Radiology, Navodaya Dental College, Raichur. There is a diversity of students studying in the Navodaya Education Trust campus, which made it easier to conduct a comparative study among two diverse groups of individuals from India and abroad. A total of 107 orthopantomograms of individuals between 18 and 25 years of age were retrieved from existing records of the patients who had visited for either orthodontic or surgical consultation. Individuals below 18 years and above 25 years of age were excluded from the study. Among the 107 participants, 55 were from Kerala and 52 were from Bhutan. The data was collected, put into separate folders for each group, and analyzed for prevalence of third molar agenesis among both the groups, age and sex distribution between the groups, and comparison between total number of third molar agenesis between maxillary and mandibular teeth in both groups.


   Results Top


In the 107 participants of our study, the prevalence of third molars was found to be 31 (28.9%). Among 52 Bhutanese, 18 (35.29%) participants showed the prevalence of third molar agenesis; whereas among 55 Keralites, 13 participants (23.5%) had the prevalence of third molars agenesis. The prevalence of third molar agenesis was found to be more dominant in the age group of 21 years in Bhutanese and 22 years in Keralites. The mean age group among both the participant groups was found to be 20 years, where 20.72 ± 0.95 was the mean and standard deviation in Bhutanese group and 20.85 ± 1.34 in Keralites [Figure 1]. The sex-wise distribution of the study sample showed 61.1% females and 38.9% males in Bhutanese, whereas 69.2% females and 30.8% males in the Keralites [Figure 2].
Figure 1: Age-wise distribution of Bhutanese and Keralites

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Figure 2: Sex-wise distribution of Bhutanese and Keralites

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The comparison of third molar agenesis between individual dental quadrants in both the groups showed greater prevalence in the maxillary left quadrant – 28 (50%) followed by maxillary right quadrant – 18 (44.4%) in Bhutanese and maxillary right quadrant – 18 (61.5%) followed by maxillary left quadrant – 28 (41.6%) in Keralites [Table 1]. In both the groups, agenesis was prevalent in the maxillary arch, irrespective of being right or left. The prevalence of agenesis in the first to fourth quadrants was 19, 6, 4, and 3, respectively. The prevalence of third molar agenesis in individual dental quadrants in each group and comparison between maxillary and mandibular quadrants [Table 2] and [Table 3] was statistically not significant (P > 0.05).
Table 1: Frequency of third molar agenesis with respect to individual dental quadrants in Keralites and Bhutanese

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Table 2: Comparison of prevalence of maxillary third molar agenesis between Bhutanese and Keralites

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Table 3: Comparison of prevalence mandibular third molar agenesis between Bhutanese and Keralites

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   Discussion Top


Agenesis of one or more teeth is one of the most common human developmental anomalies. The variability of third molar agenesis should be considered between different groups as it can show unique character and differences among close groups of populations. Agenesis can cause a difference to the craniofacial morphology. Failure of one or more of the third molars occurs in 20% of the population.[3] The reported incidence of teeth other than third molars being missing varies 1.6–9.6%.[3] The prevalence of third molar agenesis in the present study was 28.9%. In a study on contemporary American adolescents, Harris [4] reported that 15% of the sample showed at least one missing third molar and approximately 2% for all four third molars. Sandhu and Kaur [5] reported a prevalence of 11.5%. Rozkovcova et al.[6] studied the prevalence of third molar agenesis in young Czech population and reported 22.5% of agenesis of 1–4 third molars. The prevalence of third molar agenesis was shown to be ranging from 23 to 28%.[6],[7]

Numerous studies have found the prevalence of third molar agenesis as well as hypodontia to be slightly predominant in females.[8],[9],[10],[11],[12] According to the recent literature, only three authors have found males to be more predominant with third molar agenesis, even though the results were insignificant.[13] The prevalence of third molar agenesis in our study was predominant among females as compared to the males among both the groups.

There was difference between the prevalence of agenesis among the individual dental arches as well as between the maxillary and mandibular arches. Third molar agenesis was more common in the maxillary left arch in Bhutanese and maxillary right arch in Keralites [Table 1], though it was statistically insignificant. Contrary to our finding, Rozkovcova et al.[6] reported third molar agenesis predominant in the mandibular arch in both the sexes.

In the present study, single third molar agenesis was more frequent followed by two and three third molar agenesis. All the four third molars were missing in only 2 participants. According to Banks,[14] the most frequent agenesis is of both third molars, followed by one, three, and all four third molars, whereas Nanda [15] reported the most frequent agenesis was of one, two, three, and four molars.

Although tooth agenesis is considered to be a normal variant, the absence of third molar is reported to be associated with the agenesis of the other teeth 13 times more often.[16] This implies a more general underlying genetic cause, and that agenesis is more than just a localized chance event. Agenesis of third molars is said to be associated with absence of lateral incisors (12%), second premolars (11%), central incisors and second permanent molars (3%), and canines and first premolars (1%) in a study population compared to a group with the presence of all four third molars.[17] In our study, we found 0.9% agenesis of the second permanent molars only in the Bhutanese group.

Third molar agenesis influences the size of the remaining teeth and also delays the development of certain teeth; it has also been linked to diminished cuspal patterns. The reduction of the cusp of carrabelli has been associated with the third molar agenesis.[16],[18] It is also associated with crown size reduction, particularly crown size reduction of the lateral incisors, the second premolars, and inevitably with “peg-shaped” lateral incisors. This is true in the females than the males.[2]


   Conclusion Top


According to our study it was found that the incidence of third molar agenesis was higher in individuals from Bhutan as compared to those of Kerala. Comparison between both the genders in each group showed a higher prevalence of third molar agenesis in females and with higher probability in the maxilla as compared to mandible, irrespective of the gender. Because the sample size of our study is limited, further research is required with a larger sample size including diverse population in order to generalize our findings.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Gravely JF. A radiographic survey of third molar development. British Dent J 1965;119:397-401.  Back to cited text no. 1
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2.
Hellman M. Our third molar teeth; their eruption, presence and absence. Dent Cosmos 1936;78:750-62.  Back to cited text no. 2
    
3.
Vastardis H. The genetics of human tooth agenesis: New discoveries for understanding dental anomalies. Am J Orthod Dentofacial Orthop 2000;117:650-6.  Back to cited text no. 3
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4.
Harris EF. Patterns of hypodontia among third molars in contemporary American adolescents. Dent Anthropol 2009;22:8-17.  Back to cited text no. 4
    
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Sandhu S, Kaur T. Radiographic evaluation of the status of third molars in Asian-Indian students. J Oral Maxillofac Surg 2005;63:640-5.  Back to cited text no. 5
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Rozkovcova E, Markova M, Lanik J, Zvarova J. Development of third molar in the Czech population. Prague Med Rep 2004;105:391-422.  Back to cited text no. 6
    
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Mok YY, Ho KK. Congenitally absent third molars in 12 to 16 year old Singaporean Chinese patients: A retrospective radiographic study. Ann Acad Med Singapore 1996;25:828-30.  Back to cited text no. 7
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Grahnén H. Hypodontia in the permanent dentition. Odont Revy 1956;3.  Back to cited text no. 8
    
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Adler R, Adler-Hradecky C. Die Agenesie des Weisheitszahnes. Dtsch Zahnärztl Z 1963;23:1361-9.  Back to cited text no. 9
    
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Speckin J. Besteht ein Zusammenhang zwischen allgemeiner Hypodontie und der Nichtanlage der dritten Molaren? Med Diss, Hamburg; 1981.  Back to cited text no. 10
    
11.
Hölzl F. Zur Hypodontie des Weisheitszahnes. Med Diss, Bonn; 1972.  Back to cited text no. 11
    
12.
Suri S, Tompson BD, Atenafu E. Prevalence and patterns of permanent tooth agenesis in Down syndrome and their association with craniofacial morphology. Angle Orthod 2011;81:260-9.  Back to cited text no. 12
    
13.
Lynham A. Panoramic, radiographic survey of hypodontia of Australian defense forces recruits. Austral Dent J 1989;35:19-22.  Back to cited text no. 13
    
14.
Banks HV. Incidence of third molar development. Angle Orthod 1934;4:223-33.  Back to cited text no. 14
    
15.
Nanda RS. Agenesis of the third molar in man. Am J Orthodont 1954;40:698-706.  Back to cited text no. 15
    
16.
Garn S, Lewis A. The relationship between third molar agenesis and reduction in tooth number. Angle Orthodont 1962;32:14-8.  Back to cited text no. 16
    
17.
Nuvvula S, Kiranmayi M, Shilpa G, Nirmala SV. Hypohyperdontia: Agenesis of three third molars and mandibular centrals associated with midline supernumerary tooth in mandible. Contemp Clin Dent 2010;1:136-41.  Back to cited text no. 17
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18.
Garn SM, Lewis AB, Vicinus JH. Third molar polymorphism and its significance to dental genetics. J Dent Res 1963;42:1344-63.  Back to cited text no. 18
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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