identification of human bodies is a very difficult task in situ ations such as natural disaster , traffic accidents , acts of terrorism , and burns . in such situations ,
examination of teeth is more reliable ; however , detection by dental archives may not be conclusive because of dental treatment . in some situations , where teeth may be lost because of trauma ,
palatal rugae are unique in their own way by forming a pattern in the anterior part of the palate .
, they are protected from trauma and high temperature by the lips , cheeks , tongue and buccal pad of fat , teeth , and bone .
shetty et al . in their study compared palatal rugae shapes in mysore and tibetians .
el - fotoh and el - sharkawy in their study concluded that rugae patterns were unique to an individual and could be used for identification .
houser et al . compared swazi and greek populations and concluded that definite differences exist between the two .
therefore , rugae patterns and shapes have been used in medical and forensic identification processes .
hence , in this study , we attempted to assess the prevalence of palatal rugae shapes in karnataka and kerala population .
the sample was selected based on discriminant function analysis , which included 100 participants aged 1723 years in each group , equally distributed between the genders over a period of two months .
healthy subjects with a full set of dentition without inflammation , orthodontic treatment , or trauma were selected . after obtaining ethical clearance and informed consent ,
impressions were made by alginate of the maxillary arch and cast was prepared by dental stone and base using plaster of paris .
the rugae pattern was listed according to the thomas and kotze classification proposed in 1983 .
rugae were categorized as straight , curved , wavy , and circular [ figure 1a and b ] .
in addition , if rugae were having two arms , they were categorized as  unification . 
the margins of the rugae were traced on the casts using a sharp graphite pencil .
the correlation between rugae shape and population and rugae shape and gender were tested by chi - square / fischer exact analysis and discriminant function analysis using the statistical package for the social sciences version 22 ( ibm corp . ) .
various rugae shapes are s = straight , w = wavy , c = curved , u = unification
the data collected after study were statistically analyzed by chi - square / fischer exact test .
the frequency of different rugae shapes in the population of kerala were curved 29.4% , wavy 29.4% , straight 28.5% , circular 1.5% , unification 2.4% , unification divergent 6.5% , and unification convergent 2.4% using chi
the incidence of different rugae shapes in the population of karnataka were curved 20.5% , wavy 22.6% , straight 44.1% , circular 0.5% , unification 6.3% , unification divergent 3.7% , and unification convergent [ table 1 ] .
incidence between different rugae shapes in karnataka and kerala population the chi square / fischer exact analysis was conducted in order to asses the differences in the distribution of rugae shapes between the two study populations .
the test result revealed the kerala population had an increased percentage of curved rugae forms at 53.2% ( n = 100 ) as compared to the karnataka population at 46.8% ( n = 88 ) .
however , the difference in distribution of other rugae forms between two study populations did not yield statistically significant difference / association [ table 2 ] .
chi square / fischer exact analysis for analyzing the differences in rugae shapes in kerala and karnataka population the chi - square / fischer exact analysis conducted for assessing gender distribution in kerala and karnataka population gave a statistical significant result for curved rugae in females belonging to the karnataka population ( p = 0.03 ) .
whereas unification rugae form was statistically significant in females belonging to both kerala and karnataka populations ( p < 0.001 and p < 0.02 , respectively ) [ table 3 ] .
chi square / fischer exact analysis for analyzing gender - wise differences in rugae shapes in kerala and karnataka population the degree of freedom was analyzed using stepwise discriminant analysis for different rugae shapes for population detection .
curved and straight shapes are statistically significant . with a significant value of p < 0.001 [ table 4 ] .
step - wise discriminant function analysis of different rugae shapes for population identification the standardized and unstandardized coefficients , group centroids , and structured matrix in the section point of the dicriminant function is explained in table 5 .
discriminant score higher than the sectioning point is considered as belonging to kerala and lower than sectioning point is categorized as belonging to karnataka .
lysell classified palatal rugae for the first time in 1955 , and thomas and kotze modified the classification in 1983 .
palatoscopy or palatal rugoscopy is the study of palatal rugae and was first put forth by a spaniard trobo hermosa in 1932 .
included the shape of the palatal rugae in the classification , which was unique to different individuals .
rugae maintains a constant shape throughout life and may facilitate in the identification of population as it is specific for different racial groups .
there is a need for a simple and reliable method for the classification of palatal rugae .
hence , we have considered classifying palatal rugae based on its shape in the current study , which is easier to record and is more reliable .
fischer exact test shows significant population difference for curved and straight rugae [ table 4 ] .
further , unification rugae pattern showed significant results in karnataka male and female population . in a comparison of tibetans and indians , shetty et al . reported that the indian population had a significant high number of curved rugae . on the other hand , wavy pattern was predominant in tibetans .
reported higher wavy rugae pattern among australian aborigines , whereas straight pattern were more common in australian caucasians .
using jackknife test noted that 36.7% of south indians consisted of migrated population from western india ; this is attributed to migration to southern parts of india .
both western indians and south indians preserve distinct rugae patterns , which allows moderate level of identification .
measurement of rugae length and primary rugae were considered to be longer in kerala population than that in manipuri population , whereas secondary rugae were longer in manipuri population . in regards to shape ,
similar findings were reported by kapali et al . the study conducted by shetty et al . compared palatal rugae pattern among kodava and malayalee population in south india .
the wavy pattern was highest in the kodava population , which was statistically significant compared to the malayalee population .
this is in contrast to our study where unification pattern was statistically significant among kerala and karnataka population .
therefore , the difference between rugae shapes among two populations may be attributed to genetic factors .
palatal rugae remains constant and consistent from its development until degeneration of oral mucosa after death .
because of the extremely unique nature of palatal rugae , it can be used as a supplementary method for human identification and gender determination .
further studies with larger sample size may throw light on the use of palatal rugae for forensic identification .
identification of human remains is a challenging task after natural disasters , traffic accidents , and fires .
in such situations , examination of teeth is known to serve as acceptable evidence ; however , when teeth are lost , the remaining soft tissues such as palatal rugae may still provide useful population - specific information .
the present study found that the curved and straight rugae patterns were significantly more frequent in the kerala population compared to the karnataka population .
 aims and objectives : this study was conducted to assess the incidence and prevalence of palatal rugae shapes in the male and female populations of karnataka and kerala.materials and methods : this study consisted of 100 plaster models of each group , which were equally distributed between both the genders , with an age range of 1723 years . 
 the rugae patterns were recorded by using thomas and kotze classification . 
 correlation between the rugae shape and population as well as the rugae shape and gender were analyzed using chi - square analysis and discriminant function analysis using the statistical package for the social sciences version 22 ( ibm corp).results : curved , straight , and wavy rugae patterns were the most common in both kerala and karnataka sample populations . 
 chi - square analysis showed significant differences between the populations for the curved pattern ; discriminant function analysis showed significant differences between the populations for the curved and straight patterns . 
 significant gender differences were found in the curved pattern for karnataka population and in unification patterns for both populations by chi - square / fischer exact test.conclusions:the curved and straight rugae patterns were significantly more frequent in the kerala population compared to the karnataka population . because of the limited sample size of this study , further cross - sectional studies are suggested . 
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
CONCLUSION
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