Sexual Dimorphism and Tooth Size Variation in the Permanent Dentition of the Uva Bintenna Veddas of Sri Lanka

doi:10.4236/aa.2014.41001

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Advances in Anthropology

2014. Vol.4, No.1, 1-6

Published Online February 2014 in SciRes (http://www.scirp.org/journal/aa) http://dx.doi.org/10.4236/aa.2014.41001

Sexual Dimorphism and Tooth Size Variation in the Permanent

Dentition of the Uva Bintenna Veddas of Sri Lanka

Thushari H e wapathira na 1, Roshan Peiris1, Deepthi Nanayakkara1,

Malkanthi Chandrasekara2, Eugine Wikramanayake2

1Department of Basic Sciences, Faculty of Dental Sciences, University of Peradeniya, Peradeniya, Sri Lanka

2Department of Anatomy, Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka

Email: [email protected]

Received October 14th, 2013; revised November 16th, 2013; accepted December 13th, 2013

Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium,

provided the original work is properly cited. In accordance of the Creative Commons Attribution License all

Forty-eight dental casts (37 males, 11 females) of Uva Bintenna Veddas were the population. Mesiodistal

(MD) and buccolingual (BL) diameters were measured and analyzed for sexual dimorphism and size

variation. In males, MD of maxillary canines and mandibular first molars were significantly greater at p <

0.01 and maxillary first molars and mandibular second molars at p < 0.05. Crown area was significantly

greater at p < 0.01 for maxillary and mandibular first molars. Crown module was significantly greater at p

< 0.01 for mandibular first molars and at p < 0.05 for maxillary first premolars, first molars and mandibu-

lar second molars. Maxillary canines, maxillary first molars and mandibular canines were the most sex

ually dimorphic. First tooth of each tooth class I1, P1, and M1 showed least variability in both arches and

in both sexes. In males, both MD and BL showed high variability in maxillary lateral incisors and man-

dibular second premolars.

Keywords: Uva Bintenna Veddas; Sexual Dimorphism; Size Variation; Crown Diameters; Permanent

Teeth

Introduction

The earliest account of the existence of, habitations, life style,

language and religious ceremonies of the Veddas of Sri Lanka

was by Knox (1681). However, the scientific study of their

physical anthropology had to await the publications of Virchow

and the Sarasins two centuries later in 1886 (Virchow, 1886;

Sarasin & Sarasin, 1886). After a lapse of another fifty years

Osman Hill, Professor of Anatomy, Ceylon Medical College

initiated his studies on personally identified Veddas (Hill,

1932). The somatometry, craniometry and the variations of the

dentition have been reported (Hill, 1945).

Meanwhile, from 1937-1939, the anthropological and anth-

roposcopic data for the Ethnological Survey of Ceylon was

collected by H. R. de la Haule Marett an assistant in Ethnology,

Colombo Museum. The Veddas were identified by their Wa-

riges (clan names). Marett regarded the Veddas with the Sinha-

lese and Tamils as the primary ethnic groups of Sri Lanka. Ma-

rett had included variation in the dentition. After the untimely

death of Marett, the data was analyzed and published as the

Physical Anthropology of Ceylon (Stoudt, 1961). The Vedda

country had been divided geographically into a northern Tam-

mankaduwa and a southern Binntenne, with Binntenne further

subdivided into Uva Binntenne in the west and Wellassa in the

east. The Uva Binntenne Veddas were clustered in Kandegan-

vila and Dambana (Hill, 1941).

Following on the footsteps of Hill, a team of researchers

from the University of Peradeniya commenced a comprehen-

sive longitudinal biometric study of the genetics, somatometry,

nutrition, oral health and dentition of the Uva Binntenne Ved-

das of Kandeganvila from 1971-1973. As these Veddas had

been colonized in 1958, the field studies could be organized at

the level of identified households. For the first time in Vedda

studies, three-generation pedigrees were compiled for the dif-

ferent Wariges. Veddas of Vedda matings of at least three gen-

erations identified from these pedigrees were the research pop-

ulation. The results of the first phase have been published, the

genetics (Ellepola & Wikramanayake, 1986; Hanihara et al.,

1988), secular trends in physical anthropology (Wikrama-

nayake & Wikramanayake, 1992), oral disease patterns and

tooth wear (Pathmanathan & Wikramanayake, 1993), and body

mass index (Wikramanayake et al., 1994). This research was

reviewed later (Wikramanayake, 2002).

With the declaration of the traditional hunting grounds of the

Uva Binntenne Veddas as a National Park in 1982, the Kande-

ganvila Veddas were relocated in Hennanigala South of the

Mahaweli Irrigation System C. In the second phase of the study

from 1993-1996, it was decided to study the Uva Binntenne

Veddas in the two different locations, those of Kandeganvila in

their relocated households in Hennanigala and those of Dam-

bana in their traditional habitat. Figure 1 gives a map of the

Vedda country with the three locations studied Kandeganvila

(1971-1973) and Hennanigala and Dambana (1993-1996) un-

derlined. At Hennanigala, somatometry, nutrition, oral health

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T. HEWAPATHIRANA ET AL.

Figure 1.

The location of Vedda settlements (three locations studied are underlined).

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T. HEWAPATHIRANA ET AL.

and dentition were repeated. Additionally craniometry and

blood pressure measurements were included. At Dambana,

three-generation pedigrees of the different Wariges were com-

piled. As in the first phase, Veddas identified from these pedi-

grees as those from Vedda matings were the research popula-

tion for the biometry both at Hennanigala and Dambana.

Additionally, at Dambana alginate impressions of the denti-

tion of Veddas were made in the field with informed consent.

The present study based on these dental casts investigates the

sexual dimorphism and tooth size variation of the permanent

dentition of the Uva Bintenne Veddas of Dambana living in

their traditional hunter-gatherer habitat. This is the first report

of the dentition from in Sri Lanka.

Materials and Methods

The forty-eight dental casts, 37 from males (age range 17 -

70 years) and 11 from females were measured and analyzed.

Measurements were done only if teeth were morphologically

normal, fully erupted, and not noticeably affected by attrition or

cavities. The selected teeth of both upper and lower arches of

the left side were measured to the nearest 0.01 mm using a di-

gital caliper. When a tooth on the left side could not be meas-

ured because of absence, abnormality or heavy wear the cor-

responding tooth on the right side was measured. The measure-

ments of the mesiodistal (MD) and buccolingual (BL) crown

diameters were made according to Fujita (1949). For the deter-

mination of measurement errors, thirty casts were selected at

random three months later. Measurements were redone on these

casts and an analysis of error was done according to the method

of Dahlberg (1940). Using the equation, Error = d2/2N (d =

difference between two determinations, N = number of double

determinations). The measurement errors ranged from 0.04 mm

to 0.11 mm. As these were small values compared with the

means, no effect on the statistical analysis was expected. Using

the MD and BL diameters the following indices, crown index,

crown area and crown module were also calculated for the

posterior teeth. Crown index = MD/BL × 100, Crown area =

MD × BL, Crown module = MD + BL/2.

Results

Table 1 gives the results of the MD diameters of the mandi-

bular and maxillary permanent dentition and Table 2 gives the

results of their BL diameter. Both maxillary and mandibular

teeth of males were greater in MD and BL diameters than those

of females except for the MD of the mandibular central incisor

and BL of the mandibular lateral incisor. The differences were

significant at p < 0.01 for MD of maxillary canines and mandi-

bular first molar and at p < 0.05 for MD of maxillary first molar,

maxillary canine, mandibular second molar, BL of maxillary

canine, maxillary first and second molar, and the mandibular

first molar. The coefficients of variation were taken as indica-

tors of trends in the relative variability of tooth size. In each

arch the first molar was the least variable tooth in both MD and

BL diameters. There was no clearly defined pattern of relative

variability in the MD and BL diameters in either sex. In the

males, both MD and BL of the maxillary lateral incisor and

mandibular second premolar showed high variability. In the

females, variability was randomly distributed.

Table 3 gives the crown index, Table 4 the crown area and

Table 5 the crown module of the maxillary and mandibular

premolars and molars (first and second). All the indices were

greater in males. The differences were significant at p < 0.01

Table 1.

Mesiodistal diameters for permanent teeth of mandibular and maxillary teeth of the study.

Male Female Sex difference

N Mean SD Coefficient of variation N Mean SD Coefficient of variation

Maxillary I1 25 8.06 0.65 8.06 12 8.06 0.62 7.69

I2 27 6.61 0.54 8.16 11 6.37 0.39 6.12

C 29 7.50 0.52 6.93 13 6.95 0.46 6.61 **

P1 31 6.81 0.47 6.90 13 6.54 0.65 9.93

P2 31 6.42 0.56 8.72 13 6.11 0.55 9.00

M1 31 10.14 0.52 5.12 13 9.72 0.67 6.89 *

M2 31 9.27 0.70 7.55 13 8.96 0.91 10.47

Mandibular I1 23 5.06 0.46 9.09 11 5.27 1.12 21.25

I2 24 5.73 0.43 7.50 10 5.38 0.69 12.82

C 30 6.58 0.30 4.55 12 6.28 0.61 9.71 *

P1 31 6.71 0.48 7.15 13 6.59 0.32 4.85

P2 31 6.75 0.65 9.62 12 6.61 0.76 11.49

M1 29 10.93 0.58 5.30 12 10.09 0.75 7.43 **

M2 30 10.11 0.71 7.02 12 9.41 0.96 10.20 *

Note: *p < 0.05; **p < 0.01.

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T. HEWAPATHIRANA ET AL.

Table 2.

Buccolingual diameters for permanent teeth of mandibular and maxillary teeth of the study.

Male Female Sex difference

N Mean SD Coefficient of variation N Mean SD Coefficient of variation

Maxillary I1 25 7.10 0.66 9.29 12 6.91 0.78 11.28

I2 27 6.45 0.74 11.47 11 6.02 0.52 8.63

C 28 7.86 0.51 6.48 13 7.41 0.57 7.69 *

P1 31 8.76 0.60 6.84 13 8.39 0.57 6.79

P2 31 8.53 0.75 8.79 13 8.45 0.89 10.53

M1 31 10.73 0.67 6.24 13 10.18 0.77 7.56 *

M2 31 10.39 0.78 7.50 13 9.73 1.20 12.33 *

Mandibular I1 25 5.98 0.53 8.86 12 6.02 0.89 14.78

I2 25 6.28 0.62 9.87 10 6.41 0.99 15.44

C 30 7.26 0.52 7.16 12 7.07 1.12 15.84

P1 31 7.49 0.53 7.07 13 7.16 1.00 13.96

P2 31 7.68 0.66 8.59 12 7.39 1.08 14.61

M1 29 10.14 0.49 4.83 12 9.63 0.87 9.03 *

M2 30 9.68 0.63 6.50 12 9.31 1.04 11.17

Note: *p < 0.05; **p < 0.01.

Table 3.

Crown index of the permanent prem olars and molars of the study populat ion.

Male Female

N Mean Standard devi ation Coefficient of variation N Mean Standard deviation Coefficient of variation

Maxillary P1 31 79.01 7.76 9.82 13 78.14 6.52 8.34

P2 31 75.82 5.65 7.45 13 72.65 7.15 9.84

M1 31 94.76 5.82 6.14 13 95.68 6.73 7.03

M2 31 89.81 8.93 9.94 13 93.20 14.19 15.22

Mandibular P1 31 89.40 7.86 8.79 13 92.30 11.31 12.25

P2 31 88.29 9.13 10.34 12 90.88 15.58 17.14

M1 29 107.53 6.02 5.59 12 105.36 8.43 8.00

M2 30 104.49 4.07 3.89 12 101.92 12.1 11.87

for crown area and crown module of mandibular first molar and

at p < 0.05 for crown area and crown module of maxillary first

premolar, maxillary first molar and mandibular second molar.

In both males and females, crown index and crown module of

the first premolar and the first molar were greater than that of

the second premolar and second molar respectively.

In males, in both dentitions the crown index and crown mod-

ule of the first molar was significantly greater than that of the

second in the maxilla at p < 0.01 and mandible at p < 0.05.

Additionally the crown module of the maxillary first premolar

was significantly greater than the second at p < 0.05. The crown

area was greater in the first molar than that of the second molar

in both dentitions with the maxilla at p < 0.01 and the mandible

at p < 0.05. Variability in the indices was not analyzed statisti-

cally in the females.

Discussion

The present study deals with 48 dental casts (37 male and 11

female) of adult contemporary Uva Bintenne Veddas of Sri

Lanka. The subjects were identified from Vedda matings of at

least three generations and had normal occlusion.

The MD and BL crown diameters of both maxillary and

mandibular teeth except the third molars were measured on the

left side. Using the crown diameters the crown index, crown

area and crown module of the premolars and first and second

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T. HEWAPATHIRANA ET AL.

Table 4.

Crown area of the permanent prem olars and molars of the s tudy population.

Male Female

N Mean Standard deviation Coefficient of variation N Mean Standard deviation Coefficient of variation

Maxillary P1 31 60.72* 8.99 14.80 13 55.08 8.09 14.68

P2 31 55.33 8.54 15.43 13 51.98 9.02 17.35

M1 31 108.96* 10.72 9.83 13 99.48 12.80 12.86

M2 31 96.92 12.51 12.90 13 87.73 17.35 19.77

Mandibular P1 31 50.20 6.31 12.56 13 48.05 7.73 16.08

P2 31 52.05 7.91 15.19 12 49.14 10.32 21.00

M1 29 110.78** 9.34 8.43 12 97.66 13.72 14.04

M2 30 98.33* 13.08 13.30 12 88.08 14.92 16.93

Note: Statistica lly significant difference between ma le and fem ale is denot ed by *. *p < 0.05; **p < 0.01.

Table 5.

Crown module of the permanent premolars and molars of the study populat ion.

Male Female

N Mean Standard deviation Coefficient of variation N Mean Standard deviation Coefficient of variation

Maxillary P1 31 7.83* 0.56 7.15 13 7.46 0.54 7.23

P2 31 7.49 0.59 7.87 13 7.28 0.64 8.79

M1 31 10.43* 0.50 4.79 13 9.96 0.65 6.52

M2 31 9.58 0.62 6.47 13 9.34 0.91 9.74

Mandibular

P1 31 7.09 0.44 6.20 13 6.93 0.58 8.36

P2 31 7.21 0.55 7.62 12 7.00 0.76 10.85

M1 29 10.52**

0.44 4.18 12 9.86 0.71 7.20

M2 30 9.90* 0.65 6.56 12 9.36 0.83 8.86

Note: Statistica lly significant difference between ma le and fem ale is denot ed by *. *p < 0.05; **p < 0.01.

molars were calculated. The results were analyzed for sexual

dimorphism and size variation of the dentition.

The MD and BL diameters of all teeth except the MD of the

mandibular central incisor and BL of the mandibular lateral

incisor were greater in the males. The differences were signifi-

cant at p < 0.01 for the MD of maxillary canine and mandibular

first molar and at p < 0.05 for the maxillary first molar and

mandibular second molar. The BL of the maxillary canine, first

and second molars and mandibular first molar were signifi-

cantly great er at p < 0.05.

The crown dimension indices were also greater in the males.

However, the crown index was not significantly greater in ei-

ther arch. The crown area was significantly greater at p < 0.01

for the maxillary and mandibular first molars and at p < 0.05

for the maxillary first premolar and mandibular second molar.

The crown module was significantly greater at p < 0.01 for the

mandibular first molar and at p < 0.05 for the maxillary premo-

lar, and first molar and the mandibular second molar.

When the coefficients of variation were taken to indicate rel-

ative variability of tooth size no clearly defined pattern in MD

and BL were observed in either sex. In the males both MD and

BL of the maxillary lateral incisor and mandibular second pre-

molar showed high variability. In the females, variability was

randomly distributed.

Crown index and crown module of the first molar in both

dentitions was significantly greater than that of the second in

the maxilla at p > 0.01 ad mandible at p < 0.05. The crown

module of the maxillary first premolar was significantly greater

than that of the second at p < 0.05 .

With reference to sexual dimorphism the MD identifies the

maxillary canine and mandibular first molar at the higher

probability and the maxillary first molar and mandibular at the

lower. The BL identifies the maxillary canine, first and second

molars and the mandibular first molar at the lower probability.

The crown indices are limited to the posterior teeth. Crwon

index has not been useful in assessing sexual dimorphism.

Crown area identifies the maxillary and mandibular first molars

at the higher probability and the maxillary first premolar and

mandibular second molar at the lower. Crown module identifies

the mandibular first molar at the higher probability and the

OPEN ACCESS 5

T. HEWAPATHIRANA ET AL.

maxillary premolar and first molar and mandibular second mo-

lar at the lower probability.

With reference to relative variability of tooth size, a definite

pattern was not observed in either sex in the MD & BL. The

variability was randomly distributed in the females. In both

sexes in both arches the first tooth of each tooth class (I1, P1,

and M1) showed less variability with the first molar being the

least variable.

Crown area has not been useful in assessing tooth size varia-

bility. Crown index identifies the first molar significantly

greater in the maxilla at the higher probability and the maxillary

first premolar and mandibular second molar at the lower proba-

bility. Crown module identifies the mandibular first molar at

the higher probability and the maxillary premolar and first mo-

lar and mandibular second molar at the lower probability.

The study reveals that MD, crown area and crown module

are more useful in identifying sexual dimorphism. The maxil-

lary teeth are more dimorphic and the maxillary canine and first

molar and mandibular first molar most dimorphic.

With reference to variability of tooth size in the MD and BL

diameters the first tooth of each class (I1, P1, and M1) in both

arches with the first molar being the least variable in both sexes.

In the males both MD and BL of the maxillary lateral incisor

and mandibular second premolar showed high variability. The

variability in MD and BL were randomly distributed in the

females.

With reference to the crown indices in both arches in the

males, the crown index and crown module of the first molar

was significantly greater than that of the second in the maxilla

at the higher probability in the maxilla and in the mandible at

the lower. The crown module of the maxillary first premolar

was significantly greater than that of the second at the lower

probability.

In this study, the MD and BL diameters have not been in-

formative of relative variability of tooth size in the dentition.

The crown area too was not informative. However in the males

both crown index and crown module have identified tooth size

variation between the first and second molars at the higher

probability in the maxillary teeth. Crown module has also iden-

tified variation between the maxillary first premolar and second

at the lower probability. The first tooth of each tooth class I1, P1,

and M1 in both arches in both sexes showed less variability

with the first molar being the least variable. In the males both

MD and BL showed high variability in the maxillary lateral

incisor and mandibular second molar. Differences in the crown

dimension indices crown index, crown area and crown module

are expected to show variability in the shape, robustness and

bulkiness of the teeth respectively (Townsend & Brown, 1979).

In this study crown index was not informative on sexual di-

morphism and crown area on relative variability while crown

module was informative of both. Further studies are necessary

to confirm the relevance of these indices in the dentition.

Conclusion

In conclusion, this study is the first on dental casts of any

population group in Sri Lanka establishing the sexual dimor-

phism and tooth size variation in the permanent dentition of the

contemporary Uva Bintenne Veddas.

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