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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 2  |  Issue : 1  |  Page : 15-19

Analysis of rugae pattern morphology and their comparative differences in a Jazan population sample


Department of Prosthodontics, College of Dentistry, Jazan University, Jazan 45142, KSA

Date of Submission18-Oct-2019
Date of Decision31-Oct-2019
Date of Acceptance07-Nov-2019
Date of Web Publication21-Jul-2020

Correspondence Address:
Khurshid Ahmed Mattoo
Departments of Prosthodontics, College of Dentistry, Jazan University, Jazan 45142
KSA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sjfms.sjfms_5_19

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  Abstract 


Background: Palatal rugoscopy offers an excellent, reliable, and economical method for forensic identification in natural disasters or any other case that involves unknown remains where the death toll is extremely high. Their protective location, early complete development, stability, and singularness for each individual make this analysis of forensic useful. Objectives: The objective is to study the predominant rugae pattern among the Jazan population sample and to analyze the morphological differences in the number, types, size, and contour of various palatal rugae both intraindividual (within an individual) and interindividual (between individuals). Materials and Methods: A total of 110 patients (55 males and 55 females) in the age group of 20–35 years representing a pure ethnic Saudi population were selected based on a criterion of having an ideal natural dentition. Maxillary study models for all subjects were made from maxillary impressions. The rugae pattern recorded on cast was compared with intraoral high-magnification photographs for consistency and verification. Different types and orientation (to mid-palatine raphe) of rugae were then evaluated for the number, size, type, and contour (direction). Mean, standard deviation, and frequencies were calculated as the percentages of each type of rugae. Statistical analysis was done by using two-sample t-test and Chi-square tests at a significance level of 5%. Results: No differences in rugae pattern and rugae orientation was found between sexes, however, both pattern and direction differed in Saudi population when compared with other studies done on other population. Conclusion: The study concludes that no sexual dimorphism exists in rugae pattern and their orientation between male and female patients among the Saudi population.

Keywords: Forensic dentistry, hard palate, mid-palatine raphe, oral mucosa, postmortem


How to cite this article:
Mattoo KA, Darraj A, Rasean DA, Majali R, Shagri S. Analysis of rugae pattern morphology and their comparative differences in a Jazan population sample. Saudi J Forensic Med Sci 2019;2:15-9

How to cite this URL:
Mattoo KA, Darraj A, Rasean DA, Majali R, Shagri S. Analysis of rugae pattern morphology and their comparative differences in a Jazan population sample. Saudi J Forensic Med Sci [serial online] 2019 [cited 2020 Oct 19];2:15-9. Available from: https://www.sjfms.org/text.asp?2019/2/1/15/290350




  Introduction Top


Palatine rugae (plicae palatinae transversae and palatal rugae) are elevations of the oral mucosa toward the anterior part of the hard palate which theoretically are as a result of a discrepancy between the surface area of the oral mucosa and the underlying bone. This results in asymmetric and irregular elevations of oral mucosa in that region. Developmentally, they are made from the lateral membrane of the incisive papilla which arranges themselves in more or less transverse direction from the median palatine raphe, a mid-sagittal plane landmark. Prenatally, the rugae make their appearance during the 3rd month of intrauterine life that is marked by growth from the covering connective tissue in the maxillary bone with growth controlled mainly by epithelial–mesenchymal interactions.[1] Palatine rugae are defined scientifically as anatomical folds, the irregular fibrous connective tissue located on the anterior third of palate behind the incisive papilla.[2] Their evolutionary significance is indicated by their size in lower animals where they assist in gripping of food before tearing the food down. The role of palatine rugae in human beings is limited to phonetics, swallowing, mastication, and sucking.[3] Forensic advances of recent times, such as chelioscopy and rugoscopy have generated interest in these inert soft-tissue landmarks. The need for determining the cause of the death of an individual is mandatory for ruling out any associated crime, remarriage (where a spouse is missing or dead), monetary dispensations, burial (or cremation), and other social issues.[4],[5] The requirements of a forensic parameter to be effective in forensic science includes characteristic such as individuality (uniqueness), stability, reliability, resistance to postmortem changes, duplication, and easily recordable.[6],[7] Human casualties in natural disasters such as tsunami, floods, earthquakes, and hurricanes have brought challenges in forensic identification, since the economic viability of a forensic test results in an unplanned health expenses to the government organizations.

Palatal rugae are not affected by age and remain constant throughout the life under normal conditions. The transient underlying systemic disease may alter their size, but rarely, they undergo morphological changes except in severe fibrotic growths or tumors. Their internal position within the mouth, protects them from trauma and high temperatures. Even victims who have been burned during fire accidents, rugae are not markedly affected. While decomposition of a body, rugae have demonstrated resistance up to a period of 7 days after death under ideal conditions of storage in the mortuary.[8] Patterning of rugae forms between 12th and 14th week of prenatal life, while maintaining the same pattern throughout life and remains till oral mucosa degenerates (7 days after death) which is why rugoscopy has been used for personal identification of dead bodies.[9],[10]

In recent times, the application of forensics in dentistry has faced challenges, especially where mass disasters have taken place. Natural disasters such as hurricane Katarina and the Indian Ocean tsunami have been forensic nightmares to identify the dead for legal purposes. In Thailand alone, around 1895 bodies waited for identification for 6 months.[11] On reviewing the scientific literature, we were unable to find studies on the rugae pattern in the Jazan population, which has been declared as one of the important economic cities of the Kingdom of Saudi Arabia due to which many people from within the kingdom and outside of the country are migrating for a better future. This motivated conductance of the present study, which was aimed to analyze predominant rugae patterns among Saudi population dwelling in Jazan region and analyze the differences in the number, types, size, and contour of various palatal rugae within an individual between the right and left side of the palate and then compare the same with the opposite gender (gender differences). The collected data were also compared with the results of other studies that describe the rugae pattern of non-Saudi population, who are presently living in the region.


  Materials and Methods Top


This study is an observational, quantitative, cross-sectional descriptive study. The null hypothesis for the study states that there are gender differences in the pattern and orientation of rugae among the Saudi population living in the Jazan region. Ethical approval for the study was obtained before conducting the actual study from the concerned ethical committees of the Jazan University, which conducts its scientific studies in accordance with the Helsinki Declaration on human and animal experimentation. Approval for protection of human subjects and their medical privacy was obtained from the Institutional Review Board at Jazan University. Patients selected for the study were briefed and educated about the study and its importance following which written consent was obtained from them. Optimum number of patients aged between ≥25 and 35 years fulfilling the requirement for representativeness, reliability, efficiency, and flexibility were calculated to be 100 (50 males and 50 females) for the concerned study. Selection of the sample was random sampling (probability sampling) with replacement and the patients were chosen from various colleges of the university which admits students from all of its 14 governorates (subdivision) of the province. Out of a total of 1365 patients, the final study sample included healthy individuals of pure Saudi ethnicity with no history of orthodontic/orthognathic/prosthetic/surgical treatment, no history of facial trauma, free of congenital or acquired deformities of oral cavity or other parts of the body, healthy natural dentition with normal occlusion (Class 1 molar and canine relation), and being potentially cooperative. The ethnicity was determined based on fulfilling the criteria of having three generations of parentage that belong to or resided in any part of the Jazan province. Selected participants were divided into two main groups (male and female). For each selected participant, a high-resolution intraoral photograph [Figure 1] was taken using Digital still camera (Canon PowerShot SX280 HS). This was followed by making maxillary full-arch impressions using irreversible hydrocolloid (Thixotropic, Italy). The primary requirement for impression approval was an appropriate recording of palatal rugae details which were evaluated by a team of four staff members having experience of dental impression making for >8 years. The impressions were then poured with Type III dental stone (Elite Model; Italy). The study models were trimmed and model treatment was done using Bard-Parker blade (Hu-Freidy) to remove any undesired spicule/extension. The study models were then observed under a self-supported magnifying glass (LM-20 DeskBrite 200, Carson optical, 2× LED) and individual rugae patterns were then observed, outlined [Figure 2], and recorded on a data collection form. The parameters that were recorded during the analysis were the type and number of the rugae on the left and right side of the casts across the mid-palatine raphe and direction or orientation of the rugae on the left and right side of the palate in relation to the mid-palatine raphe. The method employed for identifying rugae pattern and its relation to the median palatine raphe was based on the classification of Thomas and Kotze[12],[13] and Indira et al. (including furcated rugae).[7] Seven types of rugae were recorded [Figure 3]a, [Figure 3]b, [Figure 3]c, [Figure 3]d, [Figure 3]e, [Figure 3]f, [Figure 3]g which included the following: (a) curved (simple crescent shape with gentle curve), (b) converging (two rugae originating away from the center and tend to unite toward its end), (c) straight (running directly from origin to termination), (d) diverging (two rugae originating near the center and tend to separate towards its termination), (e) wavy (serpentine), (f) circular (ring formation), and (g) furcated (additional branches originating from the main body). Various types of rugae and their number of both sides (right and left) in both genders were noted separately followed by their pooling. The direction of each ruga was determined by observing the angle between the line that joins their origin and insertion and a line perpendicular to the mid-palatine raphe. Forward-directed (F) rugae were associated with <90° (acute), backward-directed (B) rugae were associated with >90° (obtuse), and perpendicular rugae (P) were those that fall in line with an angle of 90° between origin and insertion [Figure 4].
Figure 1: Intraoral photograph showing rugae pattern

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Figure 2: Study model with marked rugae

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Figure 3: Class of rugae used for the study (a) curved (b) converging (c) straight (d) diverging (e) wavy (f) circular (g) furcated

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Figure 4: Orientation of rugae F – Forward, directing, B – Backward, directing,P– Perpendicular

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Statistical analysis included calculating the mean and standard deviation for total rugae numbers. The frequency was calculated as percentages of each type of rugae in different categories. Two sample t-test and Chi-square tests were performed to a significance level of 5% to be considered as statistically significant. The tests were done using Statistical Package for the Social Sciences (SPSS version 25, Institute Inc., Cary, NC, USA).


  Results Top


The results obtained are compiled from [Table 1], [Table 2], [Table 3], [Table 4]. The null hypothesis was rejected for number, pattern, and orientation (direction) of the rugae pattern. The mean value of total number of rugae (pooled) was 10.07 in males and 9.44 in females, with no significant difference. Mean number of rugae were more on the left side as compared to the right side in males, whereas they were more on the right side than left in females [Table 1]. Among various types of rugae, it was found that the curved and wavy were predominant in both sexes; however, they varied in distribution between the right and left side. The order in ascendance between various types was wavy rugae followed by curved, furcated, straight, diverging, and converging with the circular being least [Table 1] in both the sexes. Wavy rugae (28.6% males and 28.3% in females) were predominant in both sexes. Statistically, there was no significant difference between males and females between types of rugae pattern ([Chi-square = 4.68; P = 0.586, DF = 6, critical value = 12.592; nonsignificant [males vs. females]) [Table 2]. In regard to the rugae distribution between right and left sides within individual sexes, it was seen that curved rugae were more common on the left side (30.7%), while wavy rugae were more common on the right side (32.1%) of the palate in males. Furcated were almost equally distributed on both sides in both sexes. In females, there was no difference between the distributions of predominant waves on either side of the plate and showed very minute differences in other types of rugae. Statistically, there was no difference regarding the type of rugae pattern in males and females when compared for the left and right side within the same sex or when compared with the same side of the opposite sex [Table 3]. The analysis of rugae orientation reveals that forward-directed rugae were more predominant in overall participants (61.3%) followed by backward (28%) as well as in both sexes individually [Table 4]. Statistically, no significant difference was found among the genders regarding the orientation/direction of rugae among all possible comparisons [Table 5].
Table 1: Distribution of rugae based on individual types, sides (right and left), and pooled data in both genders (number, percentage, mean, and standard deviation)

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Table 2: Pooled rugae in both genders and significance of the differences

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Table 3: Comparison of differences in rugae distribution pattern between two sides of observed gender

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Table 4: Distribution and significance of differences in the orientation pattern of rugae between male and female subjects

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Table 5: Comparison of differences in rugae orientation in relation to the mid-palatal raphe

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  Discussion Top


The method used to evaluate palatine rugae in this study was direct observation of the study models and the intraoral photographs of the same individual, allowing one to verify the type of rugae if for some reason, it has not been recorded or duplicated on the study model. Selection of patients who had undergone orthodontic treatment in the past was avoided since some changes in orientation of rugae termination have been found,[14] and it would have given false rugae direction/orientation of the patient. The mean number of total rugae although differs in decimals between males (10.07) and females (9.44) but shows no statistical significance for the studied population. This finding is consistent with previous studies done on Saudi population[15] regarding the mean number of rugae and sexual dimorphism, but it conflicts with findings done on elsewhere population.[14] Although in this study, rugae of <5 mm were also included which were not included in the study done by Goyal and Goyal.[10] The present study showed that wavy rugae were commonly seen, whereas some studies have shown that curved form to be more common.[16],[17] This study also shows that although the mean number of rugae was found to be more on the left side than the right side in males, it was slightly more on the right side in females than males. In contrast to this study, a study done by Shetty et al.[18] shows that Indian and Tibetan male population showed more rugae on the right side than on the left side. Both sexes in this study, show wavy type of rugae as the dominant type, whereas other studies have shown converging type significantly higher in females and circular type in males.[15],[18]

Regarding the orientation/direction of rugae, the present study revealed that forwardly directed rugae were maximum (61%), followed by backward (28%) and then right angled (10%) in the pooled sample, and the same pattern was seen in both sexes. Goyal and Goyal in their study had forwardly directed rugae maximum followed by right angled (36.4%) and backward were the least (19.1%).[10] This could be another differentiating feature among the population. Between the right and left side, the forward, directing rugae were more in both sexes on the left side than the right side (169 on left versus 103 on right in males and 180 on left versus 113 on right in females). These results differ from a study by Goyal and Goyal[10] in which forward-directed rugae (48.3% in males and 40.8% in females) were more on the left side only in both genders, whereas their patients had right angled more on the right side in both genders.


  Conclusion Top


Within the limitations of this study, it can be concluded that the rugae patterns and orientations do differ among the Saudi population living in the Jazan province as compared to other populations, but they do not show any sexual differences between them. Although some mathematical differences have been noted in the rugae pattern of both genders, they cannot be inferred to the entire Saudi population, for which further exhaustive studies need to be conducted with larger samples.

Acknowledgment

The authors would like to acknowledge the efforts of all the participants, students, and other staff and nonstaff members of the institute who participated directly or indirectly during the course of the study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
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The Glossary of Prosthodontic Terms. Terms. J Prosthet Dent 1999:94;61.  Back to cited text no. 2
    
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Mattoo KA, Rahman S, Arora P. Duplicating palatine rugae in complete denture prosthesis to enhance the relationship between food and taste receptors. Med Res Chron 2014;1:150-5.  Back to cited text no. 3
    
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Muthusubramanian M, Limson KS, Julian R. Analysis of rugae in burn victims and cadavers to simulate rugae identification in cases of incineration and decomposition. J Forensic Odontostomatol 2005;23:26-9.  Back to cited text no. 8
    
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Goyal S, Goyal S. Study of palatal rugae pattern of Rwandan patients attending the dental department at King Faisal hospital, Rwanda: A preliminary study. Rwanda Med J 2013;70:19-25.  Back to cited text no. 10
    
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Thomas CJ, Kotze TJ. The palatal ruga pattern: A new classification. J Dent Assoc S Afr 1983;38:153-7.  Back to cited text no. 12
    
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Thomas CJ, Kotze TJ. The palatal ruga pattern in six southern african human populations, part I: A description of the populations and a method for its investigation. J Dent Assoc S Afr 1983;38:547-53.  Back to cited text no. 13
    
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Almeida MA, Phillips C, Kula K, Tulloch C. Stability of the palatal rugae as landmarks for analysis of dental casts. Angle Orthod 1995;65:43-8.  Back to cited text no. 14
    
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Fahmi FM, Al-Shamrani SM, Talic YF. Rugae pattern in a Saudi population sample of males and females. Saudi Dent J 2001;13:92-5.  Back to cited text no. 15
    
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Indira AP, Gupta M, David MP. Maria Priscilla David: Rugoscopy for Establishing Individuality. Indian J Dent Adv 2011;3:427-32.  Back to cited text no. 16
    
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Nayak P, Acharya AB, Padmini AT, Kaveri H. Differences in the palatal rugae shape in two populations of India. Arch Oral Biol 2007;52:977-82.  Back to cited text no. 17
    
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Shetty SK, Kalia S, Patil K, Mahima VG. Palatal rugae pattern in mysorean and tibetan populations. Indian J Dent Res 2005;16:51-5.  Back to cited text no. 18
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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