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Dentition of Bedouin in Israel. II. Morphology

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Dentition of Bedouin in Israel
11.
MORPHOLOGY
’
KURT A. ROSENZWEIG A N D YERUCHAM ZILBERMAN
The Hebrew University-Hadassak School of Dentul Medicine,
Jerusalem, Israel
Plaster casts of the dentition of 137 Bedouin, mostly members of the
Abu Rabiya tribe in the Negev desert, were subjected to odontometric and morphologic
analysis. They show a marked sexual dimorphism, very strongly developed maxillary
and mandibular first molars and much reduced second molars. They exhibit the
characteristics of middle-eastern populations with a rather weak expression of the
shovel trait, upper premolars with relatively short BL diameters, a high prevalence
of Carabelli’s complex on the first maxillary molar and virtually complete absence
of the protostylid. In general, the Bedouin have larger teeth than three other ethnic
groups living in Israel whose dentitions have been recently investigated. Further
similarities and differences are discussed.
ABSTRACT
In 1963 a n epidemiological survey of
different ethnic-Jews
and non-Jewsgroups residing in Israel, was conducted.
Included were about 600 Bedouin of all
ages. In the course of the field work a
maximum of impressions from dentulous
subjects were secured, mostly from young
adolescents 13 to 15 years of age. While
the epidemiological findings have been
recently published (Rosenzweig, ’ 6 8 ) , the
following report is concerned with odontometry and morphologic aspects of the
permanent teeth.
the last century they were joined by a
number of families who had been fellaheen (peasants), but felt compelled to
leave their villages because of drought or
for other reasons. Those who were accepted into the tribe, together with the
descendants of freed negro slaves, assumed the name of their former masters.
None of these “new Bedouin” are considered as equals by the members of the
original tribe and there is no intermarriage. They number about 500 persons
and recently they have been seeking
recognition as a n independent tribe. The
The population
Bedouin pattern of life has been changing
Almost all of the subjects investigated fast during the last two decades. Instead
belonged to the Abu Rabiya tribe. They of roaming the desert in search of pasture
live in the Negev desert South-East of the for their herds of goats, sheep and camels,
city of Beer-Sheba. The Abu Rabiya are which supplied them with meat, milk and
the largest tribe among the 17,000 wool predominantly destined for their own
Bedouin registered in Israel and comprise use, they now devote more and more effort
approximately 3,200 persons. The name to growing wheat and other cereals, using
of the tribe is derived from the family modern agricultural equipment and fertiname of the Sheikh (fig. l ) , whose office lizers. Simultaneously they leave their
is inherited. Originally the Sheikh was tents and build permanent settlements.
the highest authority of the tribe in all Today all Bedouin children attend grade
matters, even those concerning life and schools. Many Bedouin are employed in
death. The tribe is subdivided into ex- industrial plants and in other trades and
tended families and as a rule spouses are a few are entering the free professions.
selected from within these groups. Mar- These developments are causing a change
riages between first cousins are favored. in the social structure of the community
The Abu Rabiya proper hailed, according and as of now the Sheikh is little more
to their tradition, from the Arabian penin1This investigation was supported by USPHS Resula, whence they migrated hundreds of
search grant DE 01724, National Institute of Dental
years ago to their present area. During Research,
National Institutes of Health, Bethesda, Md.
AM. J. PHYS.ANTHROP.,31: 199-204.
199
200
K. A. R O S E N Z W E I G A N D Y. Z I L B E R M A N
Fig. 1 Sheikh Hammad Abu Rabiya (left) and his uncle Hassan, the “Elder Statesman”
of the Negev Bedouin.
Fig. 2
Two little girls of the Abu Rabiya tribe.
DENTITION O F BEDOUIN I N ISRAEL: 11. MORPHOLOGY
20 1
than the mediator between the population
and the governmental authorities.
Bedouin of both sexes. The first molars
in both jaws and the lower incisors and
canines are relatively large. Sex-dimorMETHODS
phism manifests itself by the larger
When this investigation was carried out measurements of male teeth (table 1).
the Abu Rabiya still adhered very much The difference is greatest in the manto their traditions. Thus all the impres- dibular canines and least in the maxillary
sions-with the exception of the students lateral incisors. A comparison of the preof the grade school at A Ksephah-were
molars and the second molar with the
taken in tents, using algenate material. first molar is presented in table 2. The
They were stored in humidors and poured shape of these teeth is further indicated
in stone plaster within a period of eight by the Crown Index, while the overall
hours at most. Measurements were taken size is expressed by the Crown Module.
to 0.05 m m by means of a sliding caliper The very low maxillary BL P2,'Ml ratio,
with a Vernier scale. Morphologic traits 81.21 per cent in males and 77.76 per
were determined as described in a previous cent in females, are typical for this
publication (Rosenzweig and Zilberman, Eastern-Mediterranean population.
'67). Calculations were based on the teeth
Tooth variability, expressed by the coof the right side. Only when these teeth efficient of variation, is of the same order
were missing or mutilated by caries, in both sexes, with the exception of the
abrasion of technical faults were they re- MD diameters of maxillary T2 and P2
placed by their antimeres.
which are more variable in females. In
males the second molar is more variable
RESULTS
in both jaws. The least variable tooth is
Table 1 contains the absolute mean the first molar.
values of the tooth diameters, standard
The maxillary molars are very strongly
deviations and coefficients of variation. developed. The metacone of the first molar
The dimensions of the teeth of Bedouin is uniformly of the highest possible degree
are within the range of those reported for of expression. The hypocone is somewhat
other Caucasoid populations, although more variable but still generally well
somewhat below the mean in the MD di- formed. I n n o instance was any of the
mension, with the sole exception of the two cusps absent. The second molar exupper central incisor, which is larger in hibits the usual criteria of reduction. The
TABLE I
Tooth nzeasurements of Bedouin-Mesiodistal
__-
Male
ith
MD
n
I
x
u
v
(MD) a n d Buccoliriguul ( B L ) , by sex
Female
_ _ ~
X
~ ~ _ _ _ _
-~
~~~
EL
a
-
n
v
-
_X
__
MD
d
V
~ _ _ _
-x
BL
.~
u
V
~~
xilla
1
2
'1
'2
41
62
83
80
58
62
60
78
35
8.76
6.89
7.80
7.02
6.75
10.63
10.03
0.55
0.48
0.49
0.46
0.47
0.58
0.70
6.29
6.98
6.13
6.52
6.91
5.47
7.00
75
77
59
63
51
75
39
5.45
6.09
7.03
7.03
7.21
11.27
10.49
0.37
0.39
0.49
0.46
0.47
0.55
0.69
6.82
6.37
6.97
6.57
6.49
4.91
6.64
53
38
8.49
6.79
7.46
6.72
6.53
10.22
9.52
0.59
0.63
0.49
0.39
0.59
0.62
0.57
6.95
9.32
6.66
5.90
8.99
6.03
5.96
8.87
9.03
11.12
11.03
0.54
0.58
0.61
0.60
6.15
6.47
5.53
5.45
51
53
47
47
46
54
40
5.23 0.33
5.88 0.44
6.52 0.44
6.78 0.40
6.92 0.44
10.76 0.64
10.05 0.50
6.22
7.53
6.76
5.94
6.38
5.94
4.97
7.40 0.49
8.04 0.54
10.34 0.49
10.06 0.52
6.58
6.66
4.79
5.20
54
53
46
9.20
9.42
11.54
11.55
0.66
0.63
0.65
0.76
7.20
6.65
5.64
6.54
45
46
ndible
1
2
'1
'2
41
42
7.96
8.49
10.77
10.44
0.48
0.71
0.53
0.61
5.99
8.39
4.94
5.87
K. A. ROSENZWEIG AND Y. ZILBERMAN
process is more evident in the hypocone
than in the metacone. The mandibular
first molar has as a rule 5 and the second molar 4 cusps; these traits are associated with the occlusal pattern, which
is predominantly the dryopithecoid Y in
the former and in the latter. This association is weak for the first molar (Xz
with Yates' correction = 2.74; p > 0.05).
It is very strong for the second molar
(Xz = 17.33; p < .OOl). The coefficient
of association Q = 0.95. Cusp number is
also correlated to tooth length (MD diameter). The association is statistically
significant at the 0.05 level only for males,
(median MD = 11.40 mm. X2 = 4.04; Q
= 0 . 8 0 ) , while X2 for females (median
MD = 10.35) was only 2.82. Because of
the small number of teeth these calculations could not be carried out with regard
to the second molar.
The distribution of the shovel trait is
about equal in both the central and lateral
maxillary incisors. Carabelli's tuberculum
is found on almost three out of four teeth.
One fifth have pits of different forms,
while about 50% show cusps of various
degrees.
+
:I
DISCUSSION
c7
w
al
:
3
B
With the small upper premolars (in
comparison to the first molar), the low
prevalence and expression of the shovel
trait, an almost complete absence of the
protostylid and a highly developed tuberculum Carabelli, the Bedouin's dentition
is evidently typical middle eastern (Dahlberg, '63). Therefore it appears appropriate to compare the data with those of
several other ethnic groups of the area,
which were recently explored using identical methods (Rosenzweig and Zilberman,
'67; Rosenzweig, Mass and Smith, '69).
Of these four groups (Jews from Yemen
and Cochin, Samaritans and Bedouin) the
sum of all MD measurements in males is
smallest in the Yemenites (53.11 mm),
larger (54.05 mm) in the Samaritans; the
Cochini are in third place with 54.85 mm
an the Bedouin are fourth (56.22). Cochini
females have the smallest teeth (52.33
mm), followed by Samaritans (53.45 mm),
Yemenites (53.46 mm) and Bedouin
(53.93 mm). However, while the range is
3.11 mm in males it is only 0.48 in females.
Accordingly Cochini show the highest de-
DENTITION O F BEDOUIN I N ISRAEL : 11. MORPHOLOGY
203
molar of the Samaritans is remarkable in
that the metacone is more and the hypocone less reduced that in either Jewish
group. The Bedouin occupy an intermediate
position with regard to both traits. The
distribution of Carabelli's complex in its
various forms is similar in Bedouin and
Samaritans. It has its strongest expression
in Yemenites and its weakest in Cochini.
The rank correlation coefficient between
male first molar size and the occurence
of Carabelli's anomaly is negative (R =
- 0.60). The shovel trait is in Bedouin
slightly less prevalent on the central rnaxillary incisor and more common on the
Y pattern .40 .80
lateral than in both Jewish groups though
the differences are not statistically significant. The incisors of the Samaritans are
Fig. 3 Rank correlation coefficients for tooth
practically free from the trait. The pattern
size, five cusps form and Y pattern in Yemenite
observed is the reverse of that encountered
and Cachini Jews, Samaritans and Bedouin.
by Carbonell ('63) who found the lateral
incisor more universally exhibiting the
gree of sex-dimorphism among the four shovel trait.
groups, followed by Bedouin, Samaritans
The Bedouin have the same proportion
and Yemenites-the latter with a Male/Fe- of 4 and 5 cusped mandibular molars
male ratio of 99.5. It would thus appear as Yemenites and Cochini ( p > 0.05),
that the females of these four groups are while the share of the four cusped teeth
more similar than the males, and it is is significantly lower in Samaritans. The
preferable to base a classification into latter and the Bedouin have preserved the
large-and small-toothed populations on five cusps pattern slightly better than either
the males alone. Interestingly the popula- Jewish group (Dahlberg, '61). The close
tions rank in the same order by the sex association between number of cusps and
ratios of both upper and lower canines as
by the overall sex ratio (table 3; coefficient
TABLE 4
of concordance W = 0.80, p < 0.01). a
Development of molar cusp in Bedouin
fact which would support the postulate,
PerTooth
Cusp Degree
that sex-dimorphism in tooth size is
centage
~due to Y-chromosome involvement (Garn,
Upper
Lewis and Kerewski, '65).
NI 1
Metacone 4
99.3
The Bedouin have not only the largest
3
0.0
upper first molar among the four groups,
0.7
2
but also the strongest development of
80.9
Hypocone 4
16.8
4metacone and hypocone, however, the dif2.3
3+
ferences are not very marked. The second
79.9
I
I
M2
Metacone
TABLE 3
Hypocone
Sex ratio of maxillary and mandibiilar canines
and of entire dentition i n four ethnic groups
Yemen
szFt:-
43
Cochin Bedouin
U. Canine
103.2
103.3
106.5 104.6
L. Canine
100.9
104.6
106.8 107.8
Entire dentition 99.5
101.4
104.7
104.7
4
3
2
4
M1
M2
Lower
6 cusps
5 cusps
4 cusps
5 cusps
4 cusps
17.6
2.5
6.9
23.6
69.5
2.0
81.6
16.4
7.0
93.0
204
K. A. ROSENZWEIG AND Y. ZILBERMAN
TABLE 5
Morphologic traits of teeth of Bedouin
Tooth
I1
I2
M1
Trait
Percentage
no shovel
trace shovel
semi shovel
no shovel
trace shovel
semi shovel
Carabelli
a
b
C
M2
M1
M2
Y
+Y
+
d
e
f
g
h
a
b
58.5
34.7
6.8
60.7
33.3
6.0
27.7
21.5
-
0.8
0.8
16.2
23.0
10.0
98.7
1.3
70.4
29.6
7.0
93.0
occlusal pattern is again apparent in the
fact that Samaritans exhibit the Y pattern
significantly more frequent than Bedouin,
who in turn show it more frequently than
both Jewish groups. The difference is more
marked between the first (X2 = 10.74; p <
0.01) than between the second molars (X’
= 4.02; p < 0.05). The relationship be-
tween tooth size, Y pattern and five cusp
form in the first molars of all four groups
is well expressed by the rank correlation
coefficients which are presented i n figure
3. Evidently Y pattern and five cusps are
strongly associated; the relation between
size and Y pattern is weak, while there
is no association between five cusps and
tooth size.
LITERATURE CITED
Carbonell, V. M. 1963 Variations in the frequency of shovel-shaped incisors i n different
populations. In: D. R. Brothwell, ed. Dental
Anthropology. Oxford, Pergamon Press, pp.
211-234.
Dahlberg, A. A. 1961 Relationship of tooth size
to cusp number and groove conformation of
occlusal surface patterns of lower molar teeth.
J. Dent. Res., 40: 34-38.
1963 Analysis of the American Indian
dentition. In: D. R. Brothwell, ed. Dental Anthropology. Oxford, Pergamon Press. pp. 149177.
Garn, S. M., A. B. Lewis and R. S. Kerewski 1965
X-linked inheritance of tooth size. J. Dent. Res.,
44: 439-441.
Rosenzweig, K. A., and Y. Zilberman 1967 Dental morphology of Jews from Yemen and
Cochin. Am. J. Phys. Anthrop., 26: 15-22.
Rosenzweig, K. A. 1968 Dentition of Bedouins.
I. Epidemiology. J. Dent. Res., 47: 407-410.
Rosenzweig, K. A., E. Mass, and P. Smith 1969
The Samaritan dentition. Bull. Group. Internat.
Rech. Sc. Stomat., 12: 95-106.
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