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ORIGINAL ARTICLE
Year : 2020  |  Volume : 23  |  Issue : 2  |  Page : 179-188

Profound approach to check legitimacy of an old technique used to gauge palatal rugae


1 Department of Maxillofacial Surgery and Diagnostic Sciences, Division of Oral Pathology, College of Dentistry, Jazan University, Jazan, Saudi Arabia
2 Department of Prosthetic Dental Science, College of Dentistry, Jazan University, Jazan, Saudi Arabia
3 Department of Preventive Dental Science, College of Dentistry, Jazan University, Jazan, Saudi Arabia
4 Department of Oral Pathology and Microbiology, Sri Venkateswara Dental College and Hospital, Chennai, Tamil Nadu, India

Date of Submission04-Jun-2019
Date of Acceptance15-Sep-2019
Date of Web Publication7-Feb-2020

Correspondence Address:
Dr. S Patil
Department of Maxillofacial Surgery and Diagnostic Sciences, Division of Oral Pathology, College of Dentistry, Jazan University, Jazan - 45412
Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_303_19

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   Abstract 


Aims: The present study aimed at assessing two fixed points of reference from where the mesial and distal point of all rugae can be measured so that the exact movement of particular rugae in any direction can be evaluated and assessing the changes in the palatal rugae after orthodontic treatment. Methods: A longitudinal study conducted among a sample of 20 (8 male and 12 female) adult patients. Pre- and post-orthodontic treatment casts of patients were obtained from the Department of Orthodontics College of Dentistry Jazan University. Antero-posterior linear distances (Technique I) between medial and lateral points of primary, secondary and tertiary rugae were measured. Also, the transverse linear distance (Technique II) between medial and lateral points of right and left rugae were measured. Technique III involved marking two fixed points and using these two points a third point is located on the medial or lateral end of rugae of right and left side in pre and post-treatment orthodontic casts. The independent sample t-test was employed to compare gender. Difference between the pre- and post-treatment mean values were checked by the paired t-test. Results: Technique III successfully showed the statistically significant difference (P ≤ 0.05, 95% CI) in the overall pre and post-treatment values on the patients' cast (N = 20) which was not observed with a technique I and technique II. Conclusion: The triangle created by the three reference points in the technique III was able to identify the changes in the palatine rugae more precisely than the technique I and Technique II.

Keywords: Forensic odontology, orthodontic treatment, rugoscopy, stability


How to cite this article:
Gupta B, Gupta S, Jafer M, Quadri F, Raj A T, Patil S. Profound approach to check legitimacy of an old technique used to gauge palatal rugae. Niger J Clin Pract 2020;23:179-88

How to cite this URL:
Gupta B, Gupta S, Jafer M, Quadri F, Raj A T, Patil S. Profound approach to check legitimacy of an old technique used to gauge palatal rugae. Niger J Clin Pract [serial online] 2020 [cited 2020 Oct 1];23:179-88. Available from: http://www.njcponline.com/text.asp?2020/23/2/179/277861




   Introduction Top


Forensic odontology, or forensic dentistry, was defined by Keiser-Neilsen in 1970 as “that branch of forensic medicine, which in the interest of justice deals with the proper handling and examination of dental evidence and with the proper evaluation and presentation of the dental findings.”[1] Subsequently, any dental substantiation if submitted in the court of law has to be researched methodically for each characteristic concerning its immovability and reproducibility.[2]

It has been long debated by investigators that palatine rugae are unique to each individual and hence, can be used effectively as an adjunct in forensic odontology. The lifelong stability of the rugae shape, direction and unification has been comprehensively documented.[2] Several authors have noted that the distinctive pattern of the palatal rugae did not transform as a result of growth, but remain constant from the time of growth until the degeneration of the oral mucosa after death.[2],[3]

However, researchers have argued as to whether legal identification based merely on palatal rugae is acceptable or not. Many studies stated against it and have advocated that changes in the length of rugae are seen with age as a result of underlying palatal growth.[4],[5],[6],[7] Moreover, numerous researchers have determined that movement of teeth due to orthodontic treatment or otherwise can also change the position of the rugae points.[8],[9],[10]

Furthermore, some orthodontic stimuli like extraction of first premolars can lead to variation in length[4] or direction of palatal rugae, as reported by Peavy and Kendrick.[3] Even trauma, extreme finger sucking, infancy and persistent pressure with orthodontic treatment and dentures may also contribute to changes in rugae pattern.[11] Very few studies have been accepted to establish the reliability of palatal rugae pattern in individual identification which could play a crucial role in forensic sciences. Furthermore, rugoscopy can be effectively utilized for forensic identification only when there is information such as dental casts, tracings or digitized rugae patterns available for comparisons.

All techniques till date are used to perceive the changes in orientation, length, displacement of the lateral and mesial end of rugae in the anterior/posterior or mesial/lateral direction.[12] The identified techniques by which all measurements were done to appraise changes or stability about the movement of palatal rugae till date do not mention about any fixed point of reference, which is stable and remains constant during all measurements in pre- and post-treatment cases. All these techniques have measured the distance between the primary rugae of the left and right side in linear transverse or distance between primary and secondary rugae in the anterior-posterior direction.[8] In all these methodologies, they measure the distance between one rugae to others, though both are not a stable landmark. There are chances of equal bodily movement of rugae on both halves of the maxillary arch as invariably the same amount of force is applied in orthodontic treatment. Hence no technique to date precisely explains the movement of individual rugae.

The present study aimed at assessing two fixed points of reference from where the mesial and distal point of all rugae can be measured so that the exact movement of particular rugae in any direction can be evaluated and evaluating the changes in the palatal rugae after orthodontic treatment.


   Methods Top


Study sample

A longitudinal study conducted among a sample of 20 (8 male and 12 female) adult patients. Pre- and post-orthodontic treatment casts of patients were obtained from the Department of Orthodontics College of dentistry Jazan University. Ethical approval was obtained from the Institutional Review Board of Jazan University, Jazan. All patients were adult (18-32 years old) Saudi Arabian nationals (homogenized sample) and their casts were selected randomly. Medical history revealed that all patients were healthy individuals, free of congenital abnormalities. They were indicated for orthodontic treatment without extraction with fixed edgewise technique with fully developed jaws with matured dentition at the beginning of treatment. None of the patients had palatal trauma, cysts or tumors or history of surgery on the palate.

Cast analysis

A 0.3 mm graphite pencil under adequate light and magnification was used to identify the landmarks on the palatal raphe and palatal rugae on the maxillary casts. Pre- and post-treatment casts were traced simultaneously as the rugae points showed a different pattern of shape, size, and position between patients. One operator marked and other operator checked the location of landmarks. Primary, secondary and tertiary rugae were traced according to the classification method of Lysell.[6] Mesial and lateral points were marked on primary, secondary and tertiary rugae on the right and left side of pre- and post-treatment casts. Antero-posterior linear distances (Technique I) between medial and lateral points of primary, secondary and tertiary rugae were measured. Also, the transverse linear distance (Technique II) between medial and lateral points of right and left rugae were measured.[8] Points for measurement were written in a short form (e.g. MLR1) where the first alphabet stands for point to be measured (medial or lateral), the second alphabet stands for side (left or right), the third alphabet stands for rugae, and the last digit stands for the number of rugae. It is noted that the two existing techniques do not have any fixed landmark. To overcome this shortcoming, we need to find two fixed reference points which are stable, valid and reliable.

Technique III is newly framed method in which we marked two fixed points and using these two points a third point is located on the mesial or lateral end of rugae of right and left side in pre and post-treatment orthodontic casts. In this technique, incisive papilla on both pre and post treatment casts is outlined. The primary, secondary and tertiary rugae were marked according to the classification method of Lysell.[6] Point A is marked on the posterior-most point of incisive papilla because the posterior part is more stable, as it undergoes the least change even after the teeth have been extracted.[13] However, only non-extraction cases were selected for the present study. Point B is marked on mid-palatal raphe parallel to a mesial point on tertiary rugae. Out of two tertiary rugae (right and left), the one which is more posterior is considered. This is done for standardization of this point. Both point A and point B are selected on mid-palatal raphe in such a way that they are not potentially affected by growth and/or treatment even in rapid maxillary expansion cases.

With the points A and B marked on pre-treatment cast, the distance between points A and B is measured using Vernier caliper with an accuracy of 0.1 mm. Vernier caliper is locked after recording distance between Point A and Point B on pre-treatment cast, then with locked Vernier caliper for the same distance between point A and Point B post-treatment cast was scratched/marked to minimize errors. This transfer of measurements is done by two individuals at a different time. This distance is marked irrespective of the movement of tertiary rugae in post-treatment cast.

So, there are two fixed points, point A and point B on pre- and post-treatment casts. From these two fixed points, a third point that is most mesial or lateral on primary, secondary and tertiary rugae on the right and left side is measured. Using these three points, a triangle (point A, point B and point to be measured) is constructed. Of these three points two points are fixed and stable, so any movement in the third point is seen as a change in arm length of a triangle.

The aforementioned two fixed points were used to measure all mesial and lateral points on primary, secondary and tertiary rugae on the right and left sides. [Figure 1] provides a schematic summary of technique III.
Figure 1: Schematic diagram for technique III

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A-B fixed distance for pre- and post-treatment casts

A- MRR1

B- MRR1

Now any change in length from A-MRR1 or B-MRR1 between pre-treatment and post-treatment will show the movement of a mesial point on right rugae 1.

Statistical analysis

The data were entered in Microsoft Office, Excel worksheets and analyzed using software IBM SPSS v. 20.0 (IBM Statistics, SPSS, Chicago, USA). The normality of the data was assessed using the Shapiro Wilk test while Levene's test for equality of error variances was used to analyze the homogeneity of error variances. Descriptive statistics were calculated. Intra-operator and an inter-operator agreement were analyzed by Kappa statistics. The independent sample t-test was employed to compare gender. Difference between the pre- and post-treatment mean values using all the three techniques was checked by observing the paired t-test values. Results obtained using all three techniques were compared with each other. As Ttechnique 3 was not similar to Techniques 1 and 2 the quality of the result obtained was defined by observing the length of the confidence intervals.[14]


   Results Top


Technique I

Pre-treatment and post-treatment values of twenty (N = 20) patients were recorded by using two previously used techniques and one newly formulated technique. On analyzing the gender difference, Technique I showed no statistical difference in both pre-treatment and post-treatment values in any of the prescribed measurements [Table 1].
Table 1: Gender wise comparison of the pre and post values for technique 1

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Combined value (male and female) difference between the pre- and post-treatment with 95% CI (confidence interval) showed no statistical difference [Table 2].
Table 2: Comparison of the pre and post values for technique 1 (n=20)

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Technique II

The gender analysis by technique II showed a significant difference (male vs. female) only with LRR3-LLR3 in both pre-treatment (P < 0.001) and post-treatment (P < 0.001) values, respectively [Table 3]. On overall comparison, it was observed that there was no significant difference between pre and post-treatment values [Table 4].
Table 3: Gender wise comparison of the pre and post values for technique 2

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Table 4: Comparison of the pre and post values for technique 2 (n=20)

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Technique III

With technique III [Table 5] it was seen that there was significant gender (Male vs. Female) difference in regard to pre-treatment values of LRR1-B and LRR3-B (P < 0.05). Also, significant gender difference was observerd for the post-treatment values of LRR1-B, LRR2-B, LRR3-B and LLR3-B. On the calculation of overall (male and female) comparison between pre and post-treatment values, it was observed that there was a statistically significant difference in MRR1-B, MRR2-B, A-MRR3, MRR3-B, MLR1-B, MLR2-B and A-LLR2 (P < 0.05) [Table 6].
Table 5: Gender wise comparison of the pre and post values for technique 3

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Table 6: Comparison of the pre and post values for technique 3 (n=20)

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Thus, the results interpret that Technique III showed the statistically significant difference (P ≤ 0.05, 95% CI) in the several overall pre- and post-treatment values on the patients' cast (N = 20) which was not observed with Technique I and Technique II.


   Discussion Top


The present study was conducted to test a new technique of rugae measurement against two techniques previously used in the literature. In this study, we demonstrated two points of reference that are fixed and from where the mesial and distal points of all the rugae could be measured. The focus was not on developing a substantially new technique which could report more accurate measurements; instead, it is to add to the fact that a fixed point of measurement will avoid the chances of possible bias and this will further contribute to forensic evidence as rugae patterns among different individuals are unique.[2] The direct comparison of all three techniques cannot be applied here as the parameters used are different. But it was made sure that all three techniques underwent the same statistical tests, and Technique III successfully showed the difference between pre- and post-treatment values and also the gender variation better than Technique I and II. Due to a dissimilar approach of technique III, the confidence intervals (CI) of the techniques were carefully studied, whereby the wider CI suggested the uncertainty of the obtained results.[14],[15],[16],[17] The contradiction in the result of previous studies can be attributed to the fact that earlier studies did not consider any fixed landmarks for measurements.

Results of the current study demonstrated the effectiveness of the proposed technique in comparison to the previous two techniques. Although the earlier techniques showed a significant difference of value between the pre and post-treatment; the current technique demonstrated a more competent result based on a narrow confidence result obtained during the statistical analysis. The present study also demonstrated a difference in the pre- and post-treatment measurements of the palatine rugae. This finding is in accordance with previous studies.[8],[9],[10],[11],[12]

The is no dearth of literature that supports the argument regarding the stability in shape, direction and unification of palatal rugae throughout life.[3] Van der Linden states that the there is no change in the anterior palatine rugae after 10 years of age. However, numerous other authors report the contrary.[3],[4],[8] Also, the influence of orthodontic treatment on the length of rugae cannot be ignored and needs to be investigated thoroughly. Other factors like trauma, oral pernicious habits, infancy and persistent pressure with orthodontic treatment and prosthodontic appliances may also lead to alterations in the rugae.[3],[4],[5],[6],[7],[8] The qualitative and quantitative changes in the character trait of stability of palatine rugae, however small in magnitude, needs to be ascertained. This would aid in establishing guidelines for utilizing palatal rugae for identification in forensic investigations. This study has been able to depict changes in palatal rugae after orthodontic treatment in small sample size and a larger study in a different set of the population will add to the evidence. It is also to be noted that the triangle created by the three reference points in Technique 3 may have a three-dimensional change in the pre- and post-treatment casts. This can be observed, studied and reported in a more comprehensive approach.


   Conclusion Top


The new technique of rugae assessment was able to better identify the changes in the rugae after orthodontic treatment as compared to the previously employed techniques. The present study also reveals that orthodontic treatment can affect the dimensional stability of palatal rugae so investigator should be cautious when utilizing rugae for forensic purposes. However, as the prevalence of individuals undergoing orthodontic treatment is very low, the role and significance of palatal rugae patterns in individual identification cannot be ignored. The role of palatal rugae in individual identification remains a viable area of investigation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Keiser-Nielsen S. Person Identification by Means of the Teeth: A Practical Guide. Wright; Bristol, England 1980.  Back to cited text no. 1
    
2.
English WR, Robison SF, Summitt JB, Oesterle LJ, Brannon RB, Morlang WM. Individuality of human palatal rugae. J Forensic Sci 1988;33:718-26.  Back to cited text no. 2
    
3.
Peavy Jr DC, Kendrick GS. The effects of tooth movement on the palatine rugae. J Prosthet Dent 1967;18:536-42.  Back to cited text no. 3
    
4.
van der Linden FP. Changes in the position of posterior teeth in relation to ruga points. Am J Orthod 1978;74:142-61.  Back to cited text no. 4
    
5.
Hauser G, Daponte A, Roberts MJ. Palatal rugae. J Anat 1989;165:237-49.  Back to cited text no. 5
    
6.
Lysell L. Plicae palatinae transversae and papilla incisiva in man; a morphologic and genetic study. Acta Odontol Scand 1955;13(Suppl 18):5-137.  Back to cited text no. 6
    
7.
Simmons JD, Moore RN, Erickson LC. A longitudinal study of anteroposterior growth changes in the palatine rugae. J Dent Res 1987;66:1512-5.  Back to cited text no. 7
    
8.
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. 8
    
9.
Bailey LT, Esmailnejad A, Almeida MA. Stability of the palatal rugae as landmarks for analysis of dental casts in extraction and nonextraction cases. Angle Orthod 1996;66:73-8.  Back to cited text no. 9
    
10.
Abdel Aziz HM, Sabet NE. Palatal rugae area: A landmark for analysis of pre-and post-orthodontically treated adult Egyptian patients. East Mediterr Health J 2001;7:60-6.  Back to cited text no. 10
    
11.
Shukla D, Chowdhry A, Bablani D, Jain P, Thapar R. Establishing the reliability of palatal rugae pattern in individual identification (following orthodontic treatment). J Forensic Odontostomatol 2011;29:20-9.  Back to cited text no. 11
    
12.
Mustafa AG, Allouh MZ, Alshehab RM. Morphological changes in palatal rugae patterns following orthodontic treatment. J Forensic Leg Med 2015;31:19-22.  Back to cited text no. 12
    
13.
Ehrlich JA, Gazit ES. Relationship of the maxillary central incisors and canines to the incisive papilla. J Oral Rehabil 1975;2:309-12.  Back to cited text no. 13
    
14.
Cochrane, General method for cochrane reviews-Confidence Interval. London: Cochrane; 2014.  Back to cited text no. 14
    
15.
Feise RJ. Do multiple outcome measures require P value adjustment? BMC Med Res Methodol 2002;2:8.  Back to cited text no. 15
    
16.
McCormack J, Vandermeer B, Allan GM. How confidence intervals become confusion intervals. BMC Med Res Methodol 2013;13:134.  Back to cited text no. 16
    
17.
Panichkitkosolkul W. Confidence intervals for the coefficient of variation in a normal distribution with a known population mean. J Probab Stat 2013;324940.  Back to cited text no. 17
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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