Palatal rugae in population differentiation between South and North Indians: A discriminant function analysis

The present study is aimed at delineation of different types of rugae in two different populations and developing a discriminant function for the same.

A total of 940 subjects were included in the present study. The sample consisted of 466 subjects from South Indian population and 474 from North Indian population in the age group of 18-23 years. Neo colloid Easy flow((™)) alginate impressions of maxillary arch were made and casts were immediately poured with Type IV dental stone. A sharp graphite pencil was used to delineate the rugae and patterns were recorded according to the classification given by Kapali et al. The association between different population and different sexes was analyzed with chi-square test and a stepwise discriminant function analysis was also performed to develop a discriminant formula.

Wavy, curved and straight rugae were the most common forms in both groups. Chi-square analysis for association between rugae shape and population groups showed significant differences among all the rugae patterns at the P < 5%. Chi-square analysis for assessing sex differences in the rugae shapes showed significant difference in straight, unification and circular type. Five rugae shapes - curved, wavy, nonspecific, unification and circular - were selected for discriminant function.

The discriminant function equation obtained from the different rugae shapes in the present study was highly accurate enough to distinguish the Southern and Northern Indian population with the classification accuracy of 87.8%. Thus to identify a specific population, separate discriminant function formulae have to be developed. Hence, the study of palatal rugae is one of the simple and reliable tools for population identification in forensic science.