"" A Study of Palatal Rugae Patterns in the Populations of Mongoloid and Tharu Ethnic Groups of Eastern Nepal

Research Article

Austin J Anat. 2017; 4(2): 1067.

A Study of Palatal Rugae Patterns in the Populations of Mongoloid and Tharu Ethnic Groups of Eastern Nepal

Basnet BB*, Parajuli PK and Shakya R

Department of Prosthodontics, BP Koirala Institute of Health Sciences, Nepal

*Corresponding author: Basnet BB, Department of Prosthodontics, BP Koirala Institute of Health Sciences, Dharan, Nepal

Received: December 01, 2016; Accepted: February 15, 2017; Published: February 20, 2017

Abstract

Background and Cbjectives: Palatal rugae patterns are relatively unique to an individual and are well protected by the lips, buccal pad of fat and teeth. They are considered to be stable throughout life following completion of growth, although there is considerable debate on the matter, they can be used successfully in post mortem identification provided an antemortem record exists. Thus the aim of this study was to examine palatal rugae shape and pattern among two Nepalese populations.

Methods: The study was conducted in 200 maxillary casts obtained by making impressions of 200 people from two ethnic groups of Nepal. Impression of maxillary arch was obtained using alginate impression material and stone cast was made. The rugae was delineated on the cast using a sharp graphite pencil under adequate light and magnification and recorded according to classification given by Thomas and Kotze (1983).

Results: Chi-Square analysis showed significant difference in straight and curved patterns between the two populations. The mean number of primary palatal rugae in Mongoloids is 4.2 in right side and 4.8 in left side. The curved pattern is more prevalent in Mongoloids (42.81%). In Tharus, number of primary rugae is 5.6 in right side and 4.8 in left side. The straight pattern of rugae is more prevalent than other patterns in Tharu ethnic group (56.72%).

Conclusion: The number of palatal rugae on right and left sides was not significantly different in both ethnic groups. The pattern of rugae was seen different in these ethnic groups.

Keywords: Palatal rugae; Palate; Human identification

Introduction

The use of teeth in postmortem identification has gained prominence over the last half-century. Postmortem dental identification is, however, not possible in the edentulous and the palatal rugae can be used as a supplement in such instances. The rugae are ridges present on the anterior palate, just behind the incisive papilla on either side of the median palatine raphae. They have been equated with fingerprints [1] and are unique to an individual [2,3]. The rugae are well protected by the lips, buccal pad of fat and teeth and, hence, survive postmortem insults [4]. They are considered to be stable throughout life following completion of growth, [5] although there is considerable debate on the matter [6-8]. However, Thomas and van Wyk [9] successfully identified a severely burnt edentulous body by comparing the rugae to those on the victim’s old denture indicating, among other things, that rugae are stable in adult life. Thus, palatal rugae appear to possess the features of an ideal forensic identification parameter uniqueness, postmortem resistance and stability. Hence, they can be used in postmortem identification provided an antemortem record exists. In addition, rugae pattern may be specific to racial groups [6,10,11] facilitating population identification (which may be required post-disasters). In fact, differences in rugae pattern have been found in relatively similar population groups [10].

The study was an attempt to find the similarities and differences in the two major ethnic groups that dwell in Eastern Nepal.

Objectives

The objective of the study was to investigate differences in the shape of the palatal rugae in two populations of Eastern Nepal (Tharus & Mongoloids) and find the association of rugae pattern to identify the populations.

Materials and Methods

This study was commenced after obtaining the ethical clearance from the Institute Ethical Review Board (IERB), BPKIHS. The sample comprised of two heterogeneous linguistic groups from different regions of eastern Nepal. After making impression with alginate impression material, 100 dental casts of each Tharu and Mongoloid ethnicity were poured and only the clean and clear casts (Figure 1) showing acceptable delineation of individual rugae were sorted into two study groups.