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Table of Contents   
ORIGINAL RESEARCH  
Year : 2014  |  Volume : 25  |  Issue : 3  |  Page : 331-335
Determination of the biometric characteristics of palatine rugae patterns in Uttar Pradesh population: A cross-sectional study


1 Department of Oral Pathology and Microbiology, D. J. College of Dental Sciences and Research, Modinagar,Uttar Pradesh, India
2 Department of Oral Pathology and Microbiology, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India
3 Department of Pedodontics. D. J. College of Dental Sciences and Research, Modinagar,Uttar Pradesh, India

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Date of Submission04-Dec-2013
Date of Decision26-Dec-2013
Date of Acceptance20-May-2014
Date of Web Publication7-Aug-2014
 

   Abstract 

Background: Identification is the establishment of identity of an individual. The basis of dental identification is based on the observation that no two individuals can have same dentition. Palatal rugae are irregular, asymmetric ridges of the mucous membrane extending laterally from the incisive papilla and the anterior part of the palatal raphe. The location of palatal rugae inside the oral cavity confers them with stability even when exposed to high temperatures or trauma. Their resistance to trauma and their apparent unique appearance has suggested their use as a tool for forensic identification.
Aims: To record the biometric characteristics of shape, size, direction, number and position of palatal rugae and analyze whether palatal rugoscopy can be used as a tool for personal identification and for sex determination.
Settings and Design: A cross-sectional study.
Materials and Methods: The sample consisted of 100 subjects (50 males, 50 females) between 18 and 25 years. Maxillary impressions were made with elastomeric impression material and dental stone was used to make models. The palatal rugae patterns were traced and analyzed with a magnifying hand lens. The biometric characteristics of number, size, shape, and direction were analyzed using Thomaz and Kotz classification (1983). The casts were coded to blind the examiners about the identity of the subjects.
Statistical Analysis Used: Unpaired t-test and one-way ANOVA using SPSS 19.0 statistical program for Windows.
Results: The average number of rugae was slightly more in females. Wavy (44.9%) and curved (41.8%) shapes were more prevalent. Maximum number of rugae was found in E quadrant (40.73%). The average size was 9.221 mm. Most rugae were forwardly directed in both groups.
Conclusion: This study concluded that rugae pattern are highly individualistic and can be used as a supplementary method for personal identification and sex determination. Further inter-observer and intra-observer variability were not found to be significant, which further validates the use of rugoscopy as a forensic tool.

Keywords: Biometric characteristics, forensic odontology, individuality, rugoscopy

How to cite this article:
Sekhon HK, Sircar K, Singh S, Jawa D, Sharma P. Determination of the biometric characteristics of palatine rugae patterns in Uttar Pradesh population: A cross-sectional study. Indian J Dent Res 2014;25:331-5

How to cite this URL:
Sekhon HK, Sircar K, Singh S, Jawa D, Sharma P. Determination of the biometric characteristics of palatine rugae patterns in Uttar Pradesh population: A cross-sectional study. Indian J Dent Res [serial online] 2014 [cited 2020 Jul 6];25:331-5. Available from: http://www.ijdr.in/text.asp?2014/25/3/331/138331
Palatal rugae refer to the asymmetrical, irregular ridges on the anterior part of palatal mucosa on each side of the median palatine raphae and behind the incisive papillae. [1] Winslow was the first to describe them in 1732, and the earliest illustration was probably by Santorini in 1775. [2],[3] The pattern orientation is formed by about 12 th -14 th week of prenatal life and remains stable until the oral mucosa degenerates after death. [4] They are permanent and unique to each person and clinicians and scientists can use them to establish identity through discrimination (via casts, tracings or digitized rugae pattern). Once formed, they do not undergo any changes except in length, due to normal growth, remaining in the same position throughout the entire person's life. [5] The palatal rugae pattern remains are unchanged and are not altered by chemicals, heat, diseases, or trauma. The anatomical position of rugae inside the mouth, surrounded by cheeks, lips, tongue, buccal pad of fat, teeth and bone, keeps them well-protected from trauma and high temperature. Hence, they can be used as a reference landmark for forensic identification. [4] The form, layout, and characteristics of rugae are not affected by either eruption or loss of teeth. They are stable and resist decomposition for up to 7 days after death. [6] Even if palatal rugae are destroyed due to any trauma; they are reproduced exactly on the same site. [7] The use of palatal rugae was suggested as one of the method of identification in 1889 by Harrison Allen. Palatal rugae pattern are considered to be unique to an individual and hence hold the potential for identification. Their use in forensic identification is preferred because of the low utilization cost, simplicity and reliability. [6] Thus, with all the above characteristics palatal rugae acts as ideal post mortem evidence that is present in all victims. It is resistant to change with age or with trauma and thus palatoscopy has been used as an important tool in forensic odontology.

With this background, this study was undertaken to study and record the rugae pattern with respect to biometric characteristics of shape, size, direction, number and position in a cross section of the population in Uttar Pradesh. The individuality of the rugae pattern and their correlation with sex of the individual was also evaluated.


   Materials AND METHODS Top


A total of 100 subjects, 50 males and 50 females who were healthy and free of congenital abnormalities, inflammation or trauma related to palate, within the age group of

18-25 years of the student population belonging to Uttar Pradesh were randomly selected for this pilot study. Written informed consent was obtained from the subjects, after explaining the purpose and objective of the study. The study was conducted after obtaining approval from the Institutional Ethics Committee (Reference No

DJC/NOT./2012/1104B).

A maxillary impression was made for each individual using rubber base impression material to record the fine details of the palatal rugae patterns. Dental casts were prepared with dental stone for analysis, the rugae was traced on these casts using a superfine black marker (calcorrugoscopy) [Figure 1]. The casts were coded by a dental intern. The principal investigator who was blinded about the identity of the casts, used a magnifying hand lens to visualize and analyze the biometric characteristics of the palatal rugae using Thomas and Kotz classification (1983). [8]
Figure 1: Calcorrugoscopy on the dental cast model

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Rugae length was recorded under magnification using digital vernier calliper. [8] The palatal rugae traced by the principal investigator using a superfine black marker. The rugae number was calculated separately on the left side and right side. The direction of each primary rugae was determined by measuring the angle between the line joining its origin and termination and a line perpendicular to median raphe. Forward-directed rugae (a) were associated with positive angles, backward directed rugae (b) with negative angles, and the perpendicular rugae (c) with angles of zero degrees. The palatine rugae were classified into four major types:

  • Straight type: The rugae patterns which ran directly from their origin to termination
  • Curved type: The rugae pattern which has a simple crescent shape, slightest bend at the termination origin of rugae
  • Wavy type: The basic shape of wavy was serpentine, however, if there was a slight curve at the origin or termination of the curved rugae, it was classified as wavy
  • Circular type: A rugae needed to display a definite continuous ring formation.


To analyze the position of palatal rugae, the principal investigator obtained standardized photographs of models and used the Adobe Photoshop software 7.0 for windows to divide the palate into quadrants, with the aim of obtaining the co-ordinates position of palatal rugae. The co-ordinate position of the palatal rugae pattern were determined as described in [Table 1]. Based on these lines between the areas they were named as A, B, C, D and E. The information obtained was recorded in a rugoscopy record or rugogram by the principal investigator.
Table 1: Co-ordinate position of the palatal rugae patterns


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To assess intra-observer variability, the principal investigator analyzed the same dental casts once again after 1 month without any reference to the previous analysis.

To assess the inter-observer variability, four dental surgeons of similar experience were selected as evaluators. These evaluators were provided the dental casts and they were asked to independently analyze the rugae pattern using exactly the same method used by the principal investigator. The results were compared to check the inter-observer variability. The data collected were statistically analyzed using the SPSS (Statistical Package for Social Sciences) 19.0 statistical program for Windows.


   Results Top


The total number of rugae was determined on right and left side and the total number of rugae in males and females were compared. The largest number of rugae was 16 and the least was 6. The average number of rugae was slightly more in females than in males, but it was statistically insignificant.

The most prevalent shapes were wavy (44.9%) and curved (41.8%), followed by straight (10.5%) and circular (2.7%) in the total population. In males, curved shape (50.7%) was most common, while in females, the wavy rugae pattern (46.2%) was predominant. The details of the gender-wise distribution of the rugae pattern are in Graph 1.

The maximum number of rugae was found in E quadrant (40.73%) of the total population. In females, 40.16% and in males 41.31% rugae were found in E quadrant [Graph 2]. The maximum number of rugae in E quadrant in females was 9, while the maximum number of rugae in the E quadrant was 6 in males. In both males and females, the least number of rugae were seen in the A quadrant [Table 2].
Table 2: Position analysis in males and females


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In males, the mean average size was 9.55 mm, while in females the mean average size was 8.97 mm.

Most of the palatal rugae were forwardly directed (FD) in both groups. In females, the backwardly directed rugae and perpendicular (P) directed rugae were less present when compared to males [Graph 3].



The application of one-way ANOVA revealed no significant difference among the four observers at 1% level of significance. However, consistency among the four observers was 95% for shape analysis, 92% for number analysis, 94.9% for size analysis.

The association between the first observation and second observation made by the principal investigator at 1 month interval on the same dental cast models using same analytical methods was tested using the unpaired t-test. The application of unpaired t-test reveals no significant difference between observations for directions, positions, shapes, and sizes at 1% level of significance respectively.


   Discussion Top


Palatoscopy, or palatal rugoscopy, is the name given to the study of palatal rugae to aid in establishing a person's identity. [7],[9] With the possible exception of few cases where a denture with a name is found, it is highly unlikely that an unknown body would be identified by dental means simply from examination of the corpse. In every other case the postmortem findings have to be compared with some existing data on the individual thought to be involved in order to establish identification. Unlike lip prints antemortem records of palatal rugae may be found in dental practice in many forms such as dental casts, old maxillary dentures, and intraoral photographs. Now-a-days, palatal rugae patterns may be considered as a useful adjunct for identification purposes. [10] Some investigators have assessed its feasibility with the aid of a computer and a software program. [10] It can be used as necroidentification technique. In fact, the Brazilian Aeronautic Ministry demands palatal rugoscopy of all its pilots in order to ensure their identification in case of accidents. [11] Thomas et al. have worked on the possible use of palatal rugae patterns in paternity determination. [12] This study was undertaken to establish the indivualality of palatal rugae patterns by their biometric characteristics that include the shape, size, direction, number and position analysis and to compare the rugae pattern among males and females to analyze its usefulness as an additional method in human identification and sex determination.

In our study, the rugae patterns were studied using Thomaz and Kotz classification. This method was found to be practical and easy to perform and less time consuming. According to our analysis, the palatal rugae patterns of all 100 individuals were different from each other. Thus the rugae patterns are highly individualistic. These findings were in agreement with the results obtained in the similar studies conducted earlier by Hermosilla et al., [8] Dhoke and Osato [13] and various other authors. [1],[14],[15] There was no significant difference in the total number of rugae on the right side and left side of the palate among males and females. However, the average number of rugae was slightly more in females than in males, though the difference was not statistically significant. Similar findings have been reported by Shetty et al., Bharath et al., and Saraf et al. [1] and several other studies carried out in samples of the Indian population. [1],[16],[17],[18]

Different racial groups may have different rugae patterns. In a study conducted by Elena Septa on Romanian population the maximum number of palatal rugae was 18 and minimum number of palatal rugae was 6. However in our study carried out on an Indian sample, the maximum number of rugae was 16, while the minimum was 6. [19] In our study, wavy and curved palatal rugae shape were predominant, followed by straight and circular in the total population. This was in accordance with the previous study by Saraf et al. [1] Paliwal et al., [20] Mustafa et al., [21] in Indian population and by Kapali et al. [22] in Australian and Caucasians. In males, the curved rugae were most common, while in females, the wavy pattern was predominant. Similar findings were reported in a study by Jacob et al. [23] However, in a study conducted among dental students of dental college, King Saudi University, Riyadh, the circular shape was found to be more common in females.

In our study, the position analysis of the palatal rugae, showed that the maximum number of rugae were present in E quadrant. The least number of rugae were found in a quadrant in both groups, which was found to be in accordance to the studies done by Hermosilla et al. [8] The size of each palatal rugae was measured and the average size observed was 9.221 mm. However, the mean average size in a previous study done by Hermosilla et al. [8] was 9.58 mm. Very few studies in the review of literature have investigated this parameter. In Indian population, investigators have mainly interpreted on the incidence of shape, number and direction of palatal rugae patterns. [17],[18]

According to our analysis, most of the palatal rugae were FD in both groups. The females had more FD rugae than males. Similar findings were observed in a study sample of 100 subjects of the student population belonging to Mangalore, India. [17] However, in a study conducted by Jibi et al. [18] diverging type were more common in females and converging type were more prevalent in males. This study was cross-sectional in nature and included the palatal rugae records within a narrow age group of

18-25 years selected among the students of the institute who belonged to Uttar Pradesh. Hence, further studies across a wider sample age group, larger sample size and with the method of longitudinal studies may be performed among the same group of populations to corroborate our results.

Researchers have found that the subjective nature of observation and interpretation within and between observers poses a problem. [22] As the interpretation of a particular palatal rugae pattern may vary according to experience and expertise of the observer, we attempted to evaluate the intra-observer and inter-observer variability in our study. To evaluate intra-observer variability, the principal investigator recorded her analysis for each of the coded maxillary casts, on two instances at an interval of 1 month. At the time of the second observation, there was no access to the observations made earlier. The association between the two sets of observations was compared using unpaired t-test. There was no significant difference observed in the shape, number, and direction and position analysis. However, there was a significant difference observed in size analysis. The results were found to be in accordance with the study conducted by Saraf et al. who found intra-observer variability to be negligible as the concordance between repeat observations was found to be 95%. [1]

To ascertain the inter-observer variability in palatal rugae patterns, four examiners were selected to interpret the analysis. The application of one-way ANOVA revealed no significant difference among the four observers at 1% level of significance. The results were in accordance with English et al. [24] who examined the accuracy of identification using the same method. The percentage of correct matches was 100% based on four investigators and 2 teams exception being 88% for one investigator but in our study the correct matches ranged from 94% to 100% correct matches. Similar findings have been reported by various authors with different methods as Shukla et al. have reported 90% correct matches among 30 observers on matching pre-operative and postoperative casts. The percentage among few varied from 74% to 98%, respectively. [25] Ohtani et al. explored the accuracy using palatal rugae pattern for personal identification in edentulous cases and achieved accuracy of 94% correct matches. [26] Bansode and Kulkarni verified the accuracy rate of identification of 90% correct matches among 13 examiners. [27]

The findings of our study clearly indicated the individuality of palatal rugae pattern and thus, their potential as valuable evidence in forensic dentistry which is in accordance with the study done in Jordian population. [21] The ability to use this method as an additional method of identification is dependent on having an ante mortem record of palatal rugae. This could simply consist of existing dental casts. However, other methods of recording the rugae pattern are possible for identification purposes. The observations of our study seem to indicate that it may be possible to use the palatal rugae as an adjunct with other methods to determine the sex of an individual; however studies using larger sample size are needed to validate this observation. At present, palatal rugoscopy is not acceptable as evidence in a court of law to link suspects to a crime scene. However as palatal rugae are unique to an individual, their role in forensic evidence is promising and therefore deserves further investigation.


   Conclusion Top


Within the limitations of the present study it may be concluded that rugae pattern are highly individualistic and can be used as a supplementary method for personal identification and sex determination. Further inter-observer and intra-observer variability were not found to be significant, which further validates the use of rugoscopy as an additional method to narrow the field of identification and give results in conjunction with other forensic science methods. Further research with a large sample size and a wide age range may be indicated in order to substantiate the present study findings.

 
   References Top

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2.Bhullar A, Kaur RP, Kamat MS. Palatal rugae - An aid in clinical dentistry. J Forensic Res 2011;2:124.  Back to cited text no. 2
    
3.Winslow JB.Exposure of the anatomical structure of the human body.Fisher - University of Toronto. 1732.  Back to cited text no. 3
    
4.Patil MS, Patil SB, Acharya AB. Palatine rugae and their significance in clinical dentistry: A review of the literature. J Am Dent Assoc 2008;139:1471-8.  Back to cited text no. 4
    
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25.Shukla D, Chaudhary A, Bablani D, Jain P, Thaper R.Establishing the reliability of palatal rugae pattern in individual identification (following orthodontic treatment). J Forensic Odontostomatol 2011;29:20-29.  Back to cited text no. 25
    
26.Ohtani M, Nishida N, Chiba T, Fukuda M, Miyamoto Y, Yoshioka N. Indication and limitations of using palatal rugae for personal identification in edentulous cases. Forensic Sci Int 2008;176:178-82.  Back to cited text no. 26
    
27.Bansode SC, Kulkarni M. Importance of palatal rugae in individual identification. J Forensic Dent Sci 2009;1:77-81.  Back to cited text no. 27
  Medknow Journal  

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Correspondence Address:
Harjeet Kaur Sekhon
Department of Oral Pathology and Microbiology, D. J. College of Dental Sciences and Research, Modinagar,Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.138331

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