|Year : 2016 | Volume
| Issue : 1 | Page : 44-48
Analysis of palatal rugae patterns among two ethnic populations of Andhra Pradesh
Kommalapati Radhika Kalyani1, Kattappagari Kiran Kumar1, Poosarla Chandra Sekhar1, Gontu Sridhar Reddy1, Lingamineni Krishna Prasad2, Badam V Ramana Reddy1
1 Department of Oral and Maxillofacial Pathology and Microbiology, SIBAR Institute of Dental Sciences, Guntur, Andhra Pradesh, India
2 Department of Oral and Maxillofacial Surgery, SIBAR Institute of Dental Sciences, Guntur, Andhra Pradesh, India
|Date of Web Publication||18-Mar-2016|
Kattappagari Kiran Kumar
Department of Oral Pathology, SIBAR Institute of Dental Sciences, Guntur, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Background of the study: Human identification is a challenging aspect in forensic odontology. There are different methods for identification of an individual, such as finger prints, dental records and lip prints. The palatal rugae may also be considered an alternative method for identification as once formed in the embryo, their shape and consistency will be maintained throughout the life of an individual.
Aims and Objectives: The present study is conducted to analyze the difference in shape and number of palatal rugae and compare the gender dissimilarities in the major rugae pattern prevalent in Costal Andhra and Telangana populations.
Materials and Methods: A total of 100 persons in the age range of 17-25 years (Costal Andhra 50 and Telangana 50) were selected for the study and casts were prepared. Rugae were recorded based on the shape as wavy, curved, straight, circular, divergent and convergent. The results were analyzed using Statistical Package for Social Sciences (SPSS) version 16.01 statistical package.
Results: Average number of rugae pattern in males was slightly more when compared with females. Curved rugae pattern were more in Costal Andhra and statistically significant (P ≤ 0.001). There was no significant association between the rugae shape and population group studied. Divergent and wavy rugae patterns were more in males compared to females in both groups.
Conclusion: Rugae were more in number in Costal Andhra when compared to Telangana population. Wavy pattern were more in Telangana population when compared with Costal Andhra population. This is only preliminary study using geographically similar population and requires further studies on a larger sample.
Keywords: Curved, forensic odontology, palatal rugae, population
|How to cite this article:|
Kalyani KR, Kumar KK, Sekhar PC, Reddy GS, Prasad LK, Ramana Reddy BV. Analysis of palatal rugae patterns among two ethnic populations of Andhra Pradesh. J NTR Univ Health Sci 2016;5:44-8
|How to cite this URL:|
Kalyani KR, Kumar KK, Sekhar PC, Reddy GS, Prasad LK, Ramana Reddy BV. Analysis of palatal rugae patterns among two ethnic populations of Andhra Pradesh. J NTR Univ Health Sci [serial online] 2016 [cited 2020 Apr 9];5:44-8. Available from: http://www.jdrntruhs.org/text.asp?2016/5/1/44/178978
| Introduction|| |
Palatal rugae are also called as plica palatine transverse or rugae palatine. These are anatomically transverse, irregular, asymmetrical soft-tissue ridges on the anterior part of the palatal mucosa, located posterior to the incisive papilla on each side of the mid palatine raphae.  The study of palatal rugae patterns is known as palatoscopy or palatal rugoscopy.
Palatal rugoscopy plays a very important role in forensic odontology because these rugae remain protected from trauma and high temperature, owing to their location in the oral cavity, protected by the lips, cheeks, tongue, teeth and alveolar ridges.  Previous studies have shown that palatal rugae patterns are unique to an individual  and that these rugae can be equated to finger prints. 
Palatal rugae are observed prominently in the 3 rd month of intrauterine life and occupy most of the palatal shelves during the embryonic development.  The growth of palatal rugae is controlled by epithelial - mesenchymal interaction. In this interaction, specific extra cellular matrix molecules are spatiotemporally expressed during development.  Palatal rugae are considered to be one of the most stable structures throughout life and they do not change or alter their shape and size under any circumstances.  However with regard to palatal rugoscopy, some controversies still exist pertaining to the constancy, quantity and quality during development and the extent of differences between ethnic groups and sexes. 
Studies done by Hauser et al. in 1989 have suggested that the mean recommended count changes fairly in adolescence, but the count increases markedly from the third to fourth decade onwards.  But, Lysell in 1955 concluded that the number of rugae decrease from the second decade onwards.  Peavy and Kendrick in their study identified that the palatal rugae do not change as a result of growth, but remain stable throughout life. 
Forensic odontology is a very important tool in racial profiling of the Indian population, which can be done by analyzing intra oral features such as teeth and palatal rugae. This study aims to analyze the difference in shape and number of palatine rugae and to compare the gender dissimilarities in the major rugae pattern prevalent in Costal Andhra and Telangana populations.
| Materials and Methods|| |
The samples obtained were from two same linguistic groups, but belonging to different areas, geographically from the state of Andhra Pradesh, India. Subjects in Group I were from coastal Andhra and Group II were from Telangana populations.
Native of the same geographic population. Free of any congenital abnormalities, inflammation, trauma or any orthodontic treatment and casts free of voids or air bubbles in anterior palatal region.
The study sample includes 50 plaster casts taken from the impressions of participants from the two equally distributed groups, age and sex matched, after obtaining informed consent. The age range was between 17-25 years. The study was given clearance by the Institutional Review Board. Maxillary arch impressions were taken with alginate impression material (Algitex Impression Material, Dental Products of India with Batch No. 31210) using stainless steel impression tray. Kalstone Class III green color (Kalabhai, India Batch No. 12531) was used to prepare the dental casts.
Casts free of air bubbles and other defects were selected for this study. The rugae were delineated using sharp tip 3B HB graphite pencil markings on the casts, under sufficient light. They were recorded based on the classification suggested by Kapali et al.,  as:
In addition to these patterns, if the rugae had two arms, it was categorized as "unification" or "branching." According to Thomas and Kotze,  rugae patterns are categorized as "branches and unification" depending upon the length of origin. Further, they are divided as being either converging or diverging depending upon their type of origin. The present study includes the shape and number of palatal rugae, irrespective of their length.
- Straight: Run directly from the origin to insertion.
- Curved: Single crescent shape with a gentle curve.
- Wavy: Serpentine shape.
- Circular: Showing definite continuous ring formation.
- Convergent: Same origin but immediately branched.
- Divergent: Different origin joined on their lateral portion [Figure 1].
The association between the numbers, patterns and ethnicity of rugae, compared with sex, was analyzed using Chi-square test and the two groups were compared for different parameters using Student t-test. All these tests were done using SPSS 16.01 statistical package (SPSS Inc., Chicago Illinois, USA).
| Results|| |
Out of the 100 cases, 50 each were age and sex matched and equally distributed in both the coastal Andhra (Group I) and Telangana (Group II) populations (n = 25 males and n = 25 females). Maximum study samples among males were in the 20-21 years age-bracket (40.0%) followed by 22-24 years (34.0%) and only 26.0% were 25 years. Whereas among females, 58.0% were between 20 and 21 years, 28.0% were 25 years old and only 14.0% were in the range of 22-31 years [Graph 1].
The mean age of Group I was 20-28 years whereas in Group II it was 20-26 years. The total number of rugae were more in Group I (604 [51%]) when compared with Group II (574 [49%]) [Graph 2]. In Group I, males have more number of rugae compared to females, whereas in Group II, females have more number of rugae, compared to males.
The average number of a specific rugae pattern in males were slightly more when compared with females, which was statistically insignificant
(P = 0.941). In Group I, curved rugae patterns were more frequently observed, which were statistically significant (P ≤ 0.001), whereas in Group II, wavy rugae pattern were more which were also statistically significant (P ≤ 0.001).
Chi-square analysis for association between the rugae shape and population group showed no significance [Table 1]. Different rugae shapes contributed to the step wise discriminate analysis. Two rugae shapes: Divergent and wavy - were selected in eight steps. Divergent rugae entered the analysis first, indicating that they had the greatest ability to differentiate the population, followed by wavy rugae [Table 2]. When we compared the rugae patterns of divergent, wavy and constant, the structural matrix was seen to be different in males and females (−0.2527 and 0.2527 respectively).
|Table 1: Chi-square analysis for assessing different rugae patterns in guntur district Population (n=100)|
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|Table 2: Step-wise discriminate function analysis of the different rugae shapes|
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| Discussion|| |
Palatal rugae develop as a localized thickening of the epithelial proliferation. It mainly occurs on the hard palate on both sides of the mid palatal raphae. Palatoscopy or palatal rugoscopy is the term given to the study of the number and shape of rugaes. The structures remain unchanged throughout the life because of their location and these can be used effectively in forensic sciences for identification of an individual. 
There are other methods for identification of human remains, among which the most common methods of identification include visuals, finger prints and dental uniqueness. All visual methods are the best and most reliable, but these methods are not appropriate in case of mass disasters. Finger prints have long been a standard employed method. However in case of fire mishaps, disintegration of the body and other massive trauma, obtaining finger prints post-mortem, is difficult. Likewise, problematic dental records like missing teeth and fracture of teeth may cause problems for identification of persons in case of mass disasters.
To overcome all these problems the ideal post mortem identifier is one that is present in all victims and is resistant to changes. One such method that can be used for identification is hence, palatal rugae analysis. 
Thomas and van Wyk managed to identify a severely burnt edentulous body by comparing the rugae to those on the victim's denture and concluded that rugae are stable in adult life.  Thomas and Kotze have done studies on rugae dimensions in order to identify different rugae patterns in six South African populations to analyze the inter race differences. 
Hauser et al., in 1989 performed a study to compare the rugae patterns of Swazi and Greek population and they found definite differences in the patterns between the two populations. This could be because of development of rugae and growth of the palate.  In his study in 1988, English et al. demonstrated that palatal rugae patterns are sufficiently unique-enough traits for identification to be carried out based on their comparison. 
Despite the controversy about the stability of rugae shapes and patterns in different populations and between sexes, the uniqueness to individuals has been recognized in forensic science as providing potential sources of identification. 
The present study was carried out to assess the definite patterns in two different populations within the same geographic region. We observed that the mean number of rugae was greater in females when compared to males, which was similar to the observations of the study conducted by Kotrashetti et al.  We also noted significant differences in wavy rugae patterns followed by curved patterns in coastal Andhra males and this finding was similar to the findings of Indira et al. in 2012. In their study they observed that curved and sinuous forms were found to be higher in males when compared with females. 
Wavy patterns were distinctly noted in Telangana females in our study. This finding was almost analogous to the results observed by Shetty in 2007, when they observed wavy patterns mainly in Tibetan females. In their study they had selected two groups of populations - Mysorean and Tibetans. There observed that the wavy patterns were predominantly seen in females; this result matches accurately with our findings. 
In our study incidence of convergent and divergent pattern did not show any significance in both populations. This result is supported by Shetty and Premalatha 2011, in their study, where they observed that contrast of the unification of rugae - both convergent and divergent-did not show any specific trend.  Our study hence conclusively suggested that palatal rugae patterns are unique to each individual and rugae patterns with their different parameters can be used a high-quality tool for identification.
| Conclusion|| |
Rugoscopy is a technique that can be of very high interest in the identification of human remains. Palatal rugae are unique to individuals and these rugae can be used as population identification tools. In the present study, higher numbers of rugae were seen in coastal Andhra population when compared with Telangana population. Regarding the patterns of two different populations, compared with sex, curved patterns are more prevalent in persons from coastal Andhra and wavy patterns are seen more in Telangana populations. We did not observe any significant difference in divergent and convergent patterns between the two populations.
Further we would like to conclude that the sample size should consider determining the accuracy of palatal rugae being used in population identification. This was only a preliminary study using geographically and genetically similar populations; further studies can definitely be done with larger samples. Finally, we consider that rugae can be used as consistent tool in forensic identification.
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[Table 1], [Table 2]