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 Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 27  |  Issue : 1  |  Page : 9-12

Diversity of palatal rugae patterns and their reliability in sex discrimination in a South Indian population


1 Department of Oral Medicine and Radiology, Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinaoutapalli, India
2 Department of Oral Medicine and Radiology, Vishnu Dental College, Vishnupur, India
3 Department of Oral Medicine and Radiology, St. Joseph Dental College, Eluru, Andhra Pradesh, India

Date of Submission30-Oct-2014
Date of Acceptance14-Jul-2015
Date of Web Publication12-Oct-2015

Correspondence Address:
Sai Madhavi Nallamilli
Department of Oral Medicine and Radiology, Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinaoutapalli - 521 286, Gannavaram Mandalam, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-1363.167066

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   Abstract 

Introduction and Aims: Array of palatal rugae in the realm of forensic odontology has been constantly explored owing to their individual uniqueness and resistance to postmortem procedures, while their scope in sex determination and racial profiling remains understated. In this context, the present study aimed to record the diversity of palatal rugae patterns in a South Indian population. Materials and Methods: A descriptive cross-sectional study was conducted among people who reported to the outpatient department of a dental institution. Sample comprised a total of 200 subjects divided into two groups of 100 each, based upon gender. Impressions of anterior maxilla were made of all the study subjects and casts obtained subsequently. Outline of palatal rugae pattern was traced on these models and the data computed. Z test and unpaired t-test were used for statistical analysis and the probability value calculated. In addition, logistic regression analysis was performed to estimate the accuracy of sex allocation. Results: The shape of rugae exhibited highly significant sex difference in the curved type, which was found to be higher in males, and in the wavy type which was higher in females, enabling sex differentiation using palatal rugae patterns. Logistic regression analysis predicted high power of sex allocation for males rather than females in the study population. Conclusion: This study highlighted the uniqueness and greater sex discrimination potential of curved shape of palatal rugae in categorizing males of South Indian population, substantiating their use in the identification of deceased, by relating the antemortem and postmortem dental records.

Keywords: Forensic odontology, palatal rugae patterns, personal identification, sexual dimorphism


How to cite this article:
Nallamilli SM, Tatapudi R, Reddy SR, Chennoju SK, Kotha R, Kotha P. Diversity of palatal rugae patterns and their reliability in sex discrimination in a South Indian population. J Indian Acad Oral Med Radiol 2015;27:9-12

How to cite this URL:
Nallamilli SM, Tatapudi R, Reddy SR, Chennoju SK, Kotha R, Kotha P. Diversity of palatal rugae patterns and their reliability in sex discrimination in a South Indian population. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2019 Sep 18];27:9-12. Available from: http://www.jiaomr.in/text.asp?2015/27/1/9/167066


   Introduction Top


Palatal rugae refer to a series of transverse ridges on the anterior part of mammalian palatal mucosa, on either side of median palatal raphe behind the incisive papilla. Rugae pattern is established by the 12 th -14 th week of prenatal life and is known to be unique to an individual. [1],[2],[3],[4],[5],[6],[7] To date, many studies have addressed the potential of rugae in personal identification, [8],[9],[10],[11],[12],[13],[14],[15] but their utility in racial profiling and sexual discrimination continues to be neglected. Hence, a study was designed with the aim to record the diversity of palatal rugae patterns in a South Indian population.


   Materials and Methods Top


On obtaining ethical clearance from the institutional ethical committee, a descriptive cross-sectional study was conducted among people attending the outpatient department of a dental institution. Subjects within the age group of 15-55 years and with a full complement of maxillary teeth (excluding third molar) were included in the study. Subjects with palatal asymmetries, with a history of palatal surgery or orthodontic treatment, and with lesions causing mucosal or bony changes in the maxillary anterior region were excluded. Study sample comprised a total of 200 subjects, divided into two groups based upon gender; Group 1 consisted of 100 males and Group 2 consisted of 100 females. After obtaining consent, impressions of the anterior maxilla (premolar to premolar region) were taken from all the study subjects and casts were poured subsequently. Dental models were obtained and outline of the palatal rugae was traced using a magnifying lens and a sharp graphite pencil under adequate light [Figure 1]. Rugae patterns were then categorized according to Thomas classification [16] and recorded in a pre-designed proforma. The data obtained were subjected to analysis using Statistical Package for Social Sciences (SPSS) software developed by SPSS Inc., 233 South Wacker Drive, 11th Floor, Chicago. Z test for proportions was used for side-wise and intergroup comparisons of rugae shape. Unpaired t-test was used for side-wise comparisons of rugae number and Z test for means for intergroup comparisons. A significance level of 5% was considered as the critical value. In order to calculate the accuracy of sex allocation using rugae shapes, a logistic regression analysis (LRA) was performed with sex.
Figure 1: Different types of palatal rugae shape delineated in a maxillary dental cast

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   Results Top


Descriptive statistics of palatal rugae

The mean age of subjects in Group 1 was 29.06 years and in Group 2 was 29.99 years. Z test for proportions was used to describe the statistics of rugae shapes [Table 1]. Curved and wavy types were found to be the most common ones, while converging type was the least common. There was a highly significant sex difference in the curved type, which was found to be higher in males (Group 1) with a P value <0.001. There was also a highly significant sex difference in the wavy type, which was higher in females (Group 2) with a P value <0.001. However, side-wise comparisons of rugae shape remained statistically insignificant in both the groups [Table 1]. The mean number of rugae in Group 1 was 6.71 and in Group 2 was 7.09 [Table 2]. No significant difference was obtained on comparing the rugae number between the two sexes using Z test for means. Side-wise comparisons of rugae number were made using unpaired t-test, which also failed to reveal significant difference between the groups [Table 2].
Table 1: Descriptive statistics of the palatal rugae shape

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Table 2: Descriptive statistics of the palatal rugae number

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Logistic regression analysis

The accuracy of sex prediction by LRA is depicted in the classification table [Table 3]. Application of LRA to all the rugae types yielded a correct sex allocation rate of 77% in males and 57% in females.
Table 3: Classification table of logistic regression analysis

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   Discussion Top


Palatal rugae own the features of an ideal forensic parameter - uniqueness, postmortem resistance, and constancy, facilitating personal identification procedures. Winslow (1732) was the first to describe them, while Santorini (1775) provided a diagrammatic illustration of rugae, depicting three continuous wavy lines that cross the midline of the palate. Goria (1911) put forth the first system of palatal rugae classification, following which numerous classifications have come into existence. Palatoscopy, or palatal rugoscopy, first proposed in 1932 by a Spanish investigator Trobo Hermosa, is the study of palatal rugae in order to ascertain a person's identity. Literature states no two palates to be alike in their configuration and even between twins, rugae patterns are said to be similar but not identical. Few authors reported the diversity of rugae patterns and their sex discrimination potential among different ethnic groups with varied results. Due to this uncertainty, we attempted to study the distinctiveness of the palatal rugae patterns if any, to characterize this regional sample. [1],[2],[17],[18]

In the present study, curved and wavy types were more commonly found in both the sexes while converging type was the least common. These findings were in accordance with some previous studies [16],[19] and contradicting those of Paliwal et al. [20] and Kallianpur et al., [21] who reported the most predominant shape as wavy in their studies. Intergroup comparisons of rugae shape revealed highly significant sex difference in the curved type, which was found to be higher in males, and in the wavy type, which was higher in females [Table 1]. This finding is not in line with the findings of Chatterjee et al. [22] and Saraf et al., [23] who reported a significant difference in the converging type in females and circular type in males. Bharath et al. [24] reported the difference in unification pattern among (converging) males and (diverging) females to be statistically significant. On the other hand, Sharma et al. [25] and Nayak et al. [19] individually observed no gender-related variations in the palatal rugae patterns.

Side-wise comparisons of rugae shape revealed insignificant findings in both the groups, which is not in agreement with the findings of Paliwal et al. [20] who reported that straight rugae pattern on the right side of the palate was significantly predominant in the male subjects of Madhya Pradesh population, whereas wavy shape was predominant in the population of Kerala. The explanation for these differences may be attributed to the variations in the populations studied and their individual sample sizes. On analyzing the rugae number, irrespective of the sex, mean number of rugae was 7, comparable with the findings of Saraf et al. [23] and Fahmi et al., [26] while others like Bharath et al., [24] Paliwal et al., [20] and Kallianpur et al. [21] reported it to be 12, 9, and 8, respectively. These variations may be ascribed to the genetic factors of the population examined. Intergroup comparisons of the mean rugae number revealed no significant differences between the two groups [Table 2], analogous to the findings of Saraf et al., [23] Fahmi et al., [26] and Eboh. [27] Side-wise comparisons also failed to reveal significant results in both the groups, which is comparable with the results of previous studies. [20],[21],[23],[24],[25],[27],[28] In the current study, LRA enabled a sex prediction of 77% in males and 57% in females using rugae shapes. This may indicate a high power of sex allocation for males rather than females using palatal rugae patterns, which stands as a key observation in our study that will help categorize males of this region.


   Conclusion Top


Palatal rugae are among the best protected, morphologically distinct soft tissue structures in the body, which are conserved after death and also accessible during life. In the event of traffic accidents or mass disasters, when other identification procedures are not feasible, comparison of the antemortem and postmortem palatal rugae models can play a major role. This study successfully established the individuality of the rugae patterns and a greater sex discrimination potential of curved shape of palatal rugae in categorizing males of a South Indian population, substantiating their use in the identification of deceased. Reduced accuracy in females should be addressed in further studies using a larger sample. Conversely, multi-centered research among diverse ethnic groups is desirable for a more comprehensive understanding of the role of palatal rugae in the realm of forensic odontology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

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    Figures

  [Figure 1]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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