dental observations on australian aborigines: mesiodistal crown diameters of permanent teeth

I 50 Australian Dental Journal, April. I963

Dental observations on Australian aborigines: mesiodistal crown diameters of permanent teeth*

M . J. Barrett, M.D.S. Reader in Prosthetic Dentistry. Vniversity of Adelaide

T. Brown, B.D.S. Lecturer in Dental Anatomy, University of Adelaide

and

M . R. Macdonald Student. Farul ty of Dental Science. University of Adelaide

Introduction

It has been shown by Seipel"' that the size of the teeth and the amount of space available for them in the tooth-bearing parts of the jaws are dominant factors in determining the positions taken up by the teeth in the dental arches. Tooth crowding or spacing are most frequently associated with discrepancies in this size-space relation, but irregularities in the positions of teeth sometimes occur which are seemingly independent of this relation. Moorrees and Reed@) have also shown that crowding or spacing of teeth depend in large measure on the relation between the size of the teeth and the size of the bony dental arch.

As part of a longitudinal study on age changes in tooth position and tooth occlusion

*Investigation supported by a grant from the

Received for publication May, 1 9 6 2 . University of Adelaide.

(1) Seipel, C. M.-Variations of tooth position. Svensk Tandlakare-Tidskrift, 3 9 : Suppl., 1946 .

(2) Moorrees, C. F. A , , and Reed, R. B.-Biometrics of crowding and spacing of the teeth in the mandible. Am. J. Phys. Anthrop., n.s. 1 2 : 77-88 (Mar.) 1854 .

i t is planned to evaluate this size-space relation for individuals belonging to a group of Central Australian aborigines. The main purpose of the present investigation was to obtain mesiodistal crown diameter measurements of the permanent teeth of these subjects for future use in the study. A secondary objective was to compare the tooth size measurements with findings previously reported for Australian aborigines and for other population groups.

Campbell('J) and Gabriel'" have studied tooth dimensions of Australian aborigines by measuring teeth in skulls. Campbell's material was collected from widely separated regions of Australia and it represented many different tribal groups, whereas Gabriel's material came from a n area inhabited by a localized group of aborigines.

Comparable data from ten different population groups have been summarized and dis-

c') Campbell, T. D.-Dentition and palate of the Australian aboriginal. Iiniversity of Adelaide Publication. 1 9 2 5 (nu. 17 . 9 1 ) . .-

(4) Gabriel, A.-The correlation of the size of human teeth with one another and with certain jaw measurements. D. J. Australia, 2 7 : 174-186 (Oct.) 1 9 5 5 .

Australian Dental Journal, April. 1963

cussed by MoorreeV. He has tabulated the results of studies on the Aleuts (Moorrees(6)), Chinese (Hosaka(a)), East Greenland Eskimos (Pedersen")) , Japanese ( Yamada(8)), Javanese ( Mijsberg(B)), Norwegian Lapps (Selmer- Olsen('O)), Pecos Indians (Nelson'")), Swedes (Seipel")), Tristanites ( Thomsen(12)), and North American Whites (Moorrees, Thomsen, Jensen and Yen(u)).

Material Subjects of the study were full-blood Aus-

tralian aborigines known as Wailbri who live under settlement conditions at Yuendumu, 185 miles north-west of Alice Springs in Central Australia. They have been under observation by staff members of the Dental School of the University of Adelaide over a period of ten years and previous papers have reported on the environment of the natives, their food sources and eating habits, and their dental

The material measured consisted of 253 dental casts selected from a total of 636 sets collected during the ten-year period of the Yuendumu investigations. O n each visit to the Settlement every endeavour was made to examine and obtain casts for subjects seen previously. Hence for many individuals the collection contained serial casts taken at different ages. In the material selected for the present study each subject was represented

c~nditions.(l~)~~6)l1E)(17)(1E)(18)fW0)(~)(22)(25)(21)

Age Group

Juvenile Adolescent

Adult . .

~-

1 5 1

-

Approsi- Number of subjects

years Males inales Total

Dental 1nat,C _ _ _ _ ~ Criteria agr in ~ Fe-

_ _ ~ _ _ _ _ ~ Mixed dentition 6-12 50 37 87 P e r m a n e n t 13-18 45 45 90 second molars erupted

erupted Third molars 19-28 ~ 41 35 76

~~

(fiJ Moorrees, C . F. A,-The Aleut dentition. Cam- bridge, M a s s , Harvard University Press, 1 9 5 7 (D. 7 7 - 1 0 1 ) .

Total . . . . ~~ ~~ ~- ~ ~ ~~~

(6) Hosaka, T.-Statistische Untersuchungen uber die Zlihne hei Chinesen mit besonderer Berucksichtigung der Itassenunterschiede. J. Oriental Med., 24 : 1065-1090 , 1 2 3 0 - 1 2 5 1 ; 2 5 : 348-368 , 1936 . (Cited by Moorrees'".)

(7) Pedersen, P. 0.-The East Greenland Eskimo den:ition. Meddelelser, on GrGnland, 1 4 2 : 1-256 , 1 9 4 9 .

(6) Yamanda, E.--The anthropological s tudy of the Japanfse teeth. J. Niiipon Dent. Assoc., 25 : 1 5 e t seq., 1932 . (Cited by Moorreed").)

( 0 ) Mijsberg, W. A.-On sexual differences in the teeth of the Javanese. Konikl. Akad. Weten- schap., Amsterdam, Proc. Sec. Sci., 3 4 : 1 1 1 1 - 1116 , 1931 . (Cited by Moorrees'").)

(10) Selmer-Olsen, R.-An odontometrical s tudy on the Norwegian Lapps. Oslo, I Kommisjon Hos J a r o b Dybwad, 1 9 4 9 (p. 2 9 - 5 1 ) .

(11) Nelson, C. T.-The teeth of the Indians of T'ecos Pueblo. Am. J. Phys. Anthrop., 2 3 : 261-293 ( Jan . ) 1 9 3 8 .

(12) Thomsen S.---Dent a l morphology a n d occlusion in the beoplt: of Tris tan D a Cunha, Resulls of the Norwegian Scientific Expedition to Tris tan D a Cunha, 1937-1938 , No. 25 . Oslo, Det Norske Videnskaps-Akademi, 1955 .

(D) M-orrees. C. F. A,, Thomsen, Selma 8.. Jensen. Elli and Yen, P. Kxi-Jm-Mesiodistal crown diameters of the deciduous a n d permanent teeth in individuals. J. D. Res., 3 6 : 3947 (Feb.) 1957 .

. . l F l < F ~ T G ~

~~ ~~~~

once only by the most recently obtained set of casts.

Accurate information on the ages of the subjects was not available except for some of the children born at the Settlement within the last few years. For this reason age grouping based on dental and other criteria was adopted. The sex and age group distribution of subjects is shown in Table 1.

Cran, J. caries.

. A.-Relationship Austral. D. J., 4 : 1

of diet to dental 82-190 ( J u n e ) 1959 .

(24) Cran, J. A.-The histological s t ructure of the teeth of Central Australian aborigines and the relationship to dental car ies incidence. Austral. D. J., 5 : 1 0 0 - 1 0 4 (Apr.) 1960 .

I 5 2 Australian Dental Journal, April, 1963

quantities of good quality dental stone mixed with rain water to the recommended water/ powder ratio.

Measurement niethods Following Seipel"' and Moorrees and others,(xj)

the mesiodistal crown diameter of a tooth was obtained by measuring the greatest distance between the approximate surfaces of the crown with a sliding caliper held parallel to the occlusal and vestibular surfaces of the crown. Where a tooth was rotated or malposed in relation to the dental arch, the measurement was taken between the points on the approximate surfaces of the crown where it was judged that contact with neighbouring teeth "normally" should have occurred. Mesiodistal crown diameter measured in this manner represents the space required by the tooth in the dental arch-sometimes called "orthodontic tooth size".

A Helios sliding caliper with vernier scale (provided by courtesy of Professor C. M. Seipel) was used for all measurements. This instrument has superposed measuring beaks S mm long with points specially hardened and sharpened to a dimension of 0.1 mm. Measurements were made under a n illuminated magnifier by one observer (M.R.M.) and recorded to 0.1 mm.

Teeth not fully erupted and thcse in which interproximal attrition had markedly reduced the crown diameter were not measured. In a few instances it was not possible to take measurements because of cast defects.

h'rrors o f measurement Errors involved in tooth size measurements

have been investigated and discussed by Seipel,") Lundstrom,(*") Selmer-Olsen,(lo) War- rer,'m' Moorrees and others,(m) and Hunter and Priest.(n) It may be concluded from these reports that satisfactorily accurate measurements are a t ta inabk when a carefully con- trolled measuring technique is used.

Investigation of errors of measurement in the present study indicated that intra-oral measurements were less reliable than those obtained from dental casts. Mean values for the differences between double determinations

1s) Lundstrom, A,-Tooth size and occlusion in twins. Basle, S. Karger, 2nd ed., 1948.

( 2 ' : ) Warrer, E.-Metrisk analyse of gibsmodeller. Tandlaege-bladet, 6 6 : 95-1 0 5 , 1952. (Cited by Moorrees'G).)

l l i l Hunter, W. S., and Priest, W. R.-Errors and discrepancies in measurement of tooth size. J. D. Res., 39: 405-414 (March-April) 1960.

of niesiodistal crown diameters obtained from dental casts ranged from 0.02 to 0.09 mm for the ten separate tooth classes investigated. The error of measurement expressed as the standard deviation of a single determination ranged from 0.09 to 0.13 mm.*

Statistical methods When calculating standard errors the

number of subjects studied was used, not the number of teeth.

Results and discuss ion Occasionally a marked size difference

between corresponding teeth on right and left was noted, especially in third molars and maxillary lateral incisors. However, differences between mean values obtained for corresponding right and left teeth were small in every instance and none of the differences was statistically significant.

It follows that either right side or left side measurements could be taken to represent tooth size of the Yuendumu material. However, to simplify further analysis and to conform with the method used by most previous investigators, measurements for right and left teeth were combined. Results are summarized in Table 2.

Sex differences in tooth size have been observed in other population groups(6) and the mandibular canine usually shows the most marked difference. The present results show that mean values of mesiodistal crown diameters were greater in males than in females and that the sex differences were statistically significant for all teeth except third molars and mandibular first premolars. The most pronounced differences were shown by mandibular canines and by first molars and the smallest differences by maxillary third molars and by first premolars.

The standard deviations and coefficients of variation in Table 2 show that variability in rnesiodistal crown diameters differed between the tooth classes measured. Third molars and maxillary lateral incisors varied in size most and first molars least. I t is interesting to note that. maxillary canines showed a greater

* .I.lagiiititde of nieasii~enrent errors : Three series o f double determinations were obtained for 31 subjects and analysed statistically after the method o f Dahlberg-.'"] c') Dahlherg, G.-Statistical methods for medical

and biological students. London. George Allen & Unwin Ltd., 1940 (PP. 122-132).

Australian Dental Journal, April, 1963

TABLE 2

iMesiodista1 crown diameters of the permnent teeth of 136 male and 117 ,ferrude Centrtcl Auutrcdian aboraginesmeasurements in miUirnelre.8 obtained from dental casts. Average uulues of right and. left side measurements are shown for males and females-number of subjects stdied (n ) , mean (M), error of the mean (EM), standard deviation (s), range of

variation (Range) and coeficient of variation ( V )

6 ('

2 9 3 p 6 9

t' 6 5' 6 $1

6 0

I 5 3

136 117 130 112 98 95 95 85 89 82

1 l!) 101 82 80 33 33

Tooth EM 1 s (mm.) (mm.)

11

12

c 1' I

1'2

nl I

*M 2

M3

11

12

c P1

P2

hi I

B.12

h14

_. .

__ 130 1 1 1 11.5 104 80 84 ! )8

!I6 83

115 1 OR 82 79 36 35

xti

~-

! I . 35t

7.651'

8.311'

7 . ti!)*

7 .19t

11.351'

!J. 00

7.34

7 . !J5

7 . 5 3

7 . 0 1

10.92

10.31

9 . 7 6

10.701'

9 . 8 7

Maxilla

k0.051 t 0 . 0 5 5

1 0 . 0 6 0 *0.064 *0*046 f0.046 1 0 . 0 4 5 1 0 . 0 4 4 C0.048 z0.048 10 .048 10.078 k0.069 *0.137 +0'126

1 0 . 0 5 9

5.871'

6 .60t

7.4!,t

7 .49

7.561'

12.041'

I I .45t

11.61

5 .68

6 .36

7.01

7 . 3 6

7 . 3 1

I I .ti2

1 1 . 0 7

t0 .034 k0 .039 A0.036 +0.039 &0.047 &0.039 *0.056 k0.044 k0.054 k0.048 t 0 . 0 5 6 *0.055 1 0 . 0 7 5 i 0 . 0 7 3 k 0 . 1 6 3 &0.119

0 . 5 8 0 . 5 8 0 .63 0 .63 0 .57 0.41 0 .46 0.41 0.43 0.44 0 .52 0.50 0 .71 0.61 0 .82 0.7d

0 .40 0 .43 0.42 0.41 0 .46 0 . 3 8 0 .54 0.41 0.51 0 .44 0 . H I 0 . 5 5 0 . 6 8 0 .65 0 .93 0.68

7 . !)-lo. ti 7.2-10.6 6.4-- 9 . 6 5.6- 8 . 8 7 . 0 - ! ) . 6 6 . 8 - 8 . 9 6.6- 8 . 8 6.4.. 8 . 5 6.3- 8 . 3 5.9- 8 . 3

10.1-12.6 9.8-12.1 9.3-1 2 . 3 8.9-1 1 . 9 8.5-1 2.1 7.611.0

4.7- 6 . 7 4 . 6 6 . 5 5.6- 7 . 8 5 . 2 - 7 . 2 6.5- 8 . 7 6 .0 - 8 . 0 5 . 6 - 8 . 7 6.1- 8 . 2 6.5- 8.') 6.2- 8 . 2

10.7-1 3 . 5 10.5-1 3 . 3 10.0-1 2 . !) 9.5-1 2 . 8 9.8-1 3 . 4

10.1-13.1

6.'' 6 . 5 8 . 3 8 . 6 6.') 5 . 2 8 . 0 5 . 5 6 . 0 6 . 3 4 . 6 4 . 6 6 . 6 5 . 9

7 . 6 8 . 3

6 . 8 7 . 5 6 . 3 6 . 4 6 . 2 5.5 7 . 3 5 . 6 6 . 7 6 . 0 5 . 0 4 . 8 6 . 0 5 . 9 8.0 6 . 0

_ _ _ _ * Hex difference between means is statistically significant a t the p=0.05 level. t Hex difference between means is statistically significant a t the p=0.01 level.

size variability in inales than in females, the difference being probably significant.

Butler,(m) Dahlberg,':'") Thomuen'") and Moor- reed6) have drawn attention to observations which show that certain characteristics are

(,") Butler, P. M.-Studies of the mammalian dentition. Differentiation of the post-canine dentition. T'roc. Zool. S O C . London, ser. B, 1 0 9 : 1 - 3 6 , 1935 .

(:I") Dahlberg, A . A,-The changing dentition of man. J.A.U.A., 3 2 : 676-690 ( June) 1945 .

E

more stable in their occurrence in a particular tooth within the incisor, premolar, and molar tooth groups. The pattern of stability usually follows the rule that the more anterior or mesial tooth of each morphological group is less variable. An exception is the mandibular incisor group where the lateral incisor is usually less variable. The present results show that the relative variability in size of the separate teeth within the morphological

I 5 4 Australian Dental Journal, April, I963

TABLE :I Meun vulues in millimetres, and standurd errors of the meuns f o r mesiodLsttcl crown rlaometcr.\ of tltr per?m,wwlt teeth of u group of Central Australian aborigines compared wtth vulues for poptrlatiota groups w h o s ~ tooth size

approximates that of the Australtans

Australian Aborigines 9.35 & O . 05

7.65 f 0 . 06

8.3110.05

7.69 1 0 . 0 5

7.19 f 0.04

I I-34&0.05

10.70&0.08

9.87 f 0 . 14

5.87 f 0 . 03

6.60 1 0 . 0 4

7 * 49 & O . 05

7.49 LO. 06

7 * 66 & O . 05

12.04f0.06

11.46f0.08

1 1 ~ 6 l f O ~ l S ~- ~

Males

Swedes

Aleuts 8.84*0.03t

7.29 f0.05t

Swedes

E w t Gr.

Javanese

East Gr.

8.10*0.02t

Eskimos 7.65 * O . 18

7.0 *0.05t

Eskimos 10.84*O.lOt

Swedes

East Gr. 10.47+0.05*

Eskimos 9.65 f 0.18

5.56f0.03t

6.2 f0 .05t

Chinese

Javanese

Chinese

Javanese

Swedes

East Gr. Eskimos

12.02*0.11 East ar.

Eskimos 11.52-J=0*12 East Ch.

Eskimos 11.42+0*16

7.31f0.03t

7 .3 f0.05*

7-41f0.04

Tristanites

Japanese

East Gr.

8.7810.05t

7 .1 5 0 . 0 3 t

Eskimos 8.09 & O . 067

Juvanese

Swedes 7.5 *o.o5t

6 .9710.04t

Am. Whites l0 .8 l f0 .06t

Am. Whites 10.36 f0 .08t

Swedes

Tristccnites

Chinese

East Gr.

7.28&

7.27 f 0 . 03.1

9.48 & O . 17

5.54&0.047

6.15 f0 .03t

Eskimos

Swedes

Javanese 7.3 *o.o5t

Aleuts l l .56f0 .08t

Aleuts 11.1910.14

swedes 11.32*0.12

Maxillary I1

I2

c

PI

P2

,M 1

M2

M3

I1

I 2

ilandibula

c PI

P 2

M1

1112

M3

Australian Aborigines 9.00 & O . 06

7.34 & O . 06

7 . 95 &0. 05

7.53 hO.05

7.01 1 0 . 0 5

0.92 & O . 05

0.3110.07

9.76 & O . 13

5.68 1 0 . 0 4

6.36 & O . 04

7.01 k0.04

7.36_tO. 04

7.31 hO.05

1.62 * O . 06

1.07 & O . 07

1.32 & O * 12

Females

Swedes

A Ze zt ts 8 .62&0.02t

7.08fO.05t

Tristccnites 7.74 :kO. 04t

Javcmese

Javanese

East Gr.

10.53fO.lOt East Gr.

Eskimos 10.08&0~15

Eskimos

Tristanites

Javanese

h'ast Cr.

6 . 9 3 1

7 . 1 6 j 0 . 0 3 7

7.2110.04

7.3 l 0 . 0 7 t

6 .9 &0.09

Eskimos

East Gr.

9.46h0.25

5.49kO.04t

6 .1 *O.O9t

Eskimos

Swedes

Swedes

East Gr. Eskimos

11.47 + O . 18 East Gr.

Eskimos 11.2910.17

Aleuts 11.30+0.13

Tristanites

Nomu. Lapps 8.60 *O.O.St

6.70k0.051-

Javanese

ICast Gr.

7.26&

6.85&0.04t

7.7 *o.ost E S ~ ~ W L O . S

Swedes

Am. Whites 10.52+0.06t

Swedes 10.05&0.04t

Javunese

Swedes

Tristanites

9.1 h0.14t

5.42+0.02t

6.08&0.04t

Tristanites

Il'r istanites

Tristtr nites

6.87f0.041-

7.10&0.05t

7 .1310.04t

Aleuts l l ~ 2 0 * 0 ~ 1 I j

Aleuts 11-16+0.10 East Gr.

11.12? Eskimos

Differs from mean value for Australian aborigines * at the p=O*O5 level. t at the p = O . O l level.

tooth groups followed a similar pattern, although few of the differences were found to be statistically significant.

A comparison of the mesiodistal crown diameters obtained in the present study with those previously reported for Australian aborigines by CampbelP and by Gabriel(') is of limited value because in neither of these previous studies was it possible to record

measurements separately for males and females. However, mean values .reported by Campbell exceed those for males of the present study in all teeth except maxillary lateral incisors. Sufficient statistical information was not available to determine whether or not the differences were significant. As it is most unlikely that Campbell's material consisted of male specimens only, it may be

I 5 5 Australian Dental Journal, April, 1963

assumed that the differences would have been more marked if i t had been possible to separate male from female specimens. Mean values reported by Gabriel exceeded those for males of the present tooth study in nine tooth classes, were equal in one tooth class, and less in six tooth classes. Only two of the differences were statistically significant. Further studies are necessary to find out whether aborigines from different regions of Australia show differences in tooth size.

Measurements obtained in the present study were compared with findings for the ten other population groups summarized by Moorrees.(6) Values for groups whose mesiodistal crown diameters approximate those of the Aus- tralians are shown in Table 3. Mean values for measurements of incisors and canines of Australian aborigines exceeded those reported for all other groups and the differences were statistically significant. With the exception of mandibular second molars, mean values for premolars and molars were also larger than in the other groups. However, not all of the differences for these teeth were statistically significant. Only the second premolars and maxillary first and second molars in males, and the first premolars and the maxillary first molars in females, showed statistically significant differences from the teeth of the other groups next in rank order of tooth size.

Apart from large mesiodistal crown dimensions, the present study revealed no distinc- tive differences between the teeth of the Australian aborigines and of the population groups with which they were compared.

Summary Mesiodistal crown diameter measurements

of permanent teeth were obtained from dental casts of 136 male and 117 female Central Australian aborigines. The measurements were analysed statistically and compared with measurements previously reported for Australian aborigines and for ten other population groups.

Results of the investigation: 1. Differences between mean values of mesio-

distal crown diameter measurements for corresponding teeth of the right and left sides of the dental arches were not significant.

2. Mean values of mesiodistal crown diameter measurements for all teeth were larger in males than females. The greatest sex difference was shown by mandibular canines and the smallest difference by maxillary third molars.

3. Third molars and maxillary lateral incisors showed the greatest variability and first molars the least variability in their mesiodistal dimensions.

4. The size variability of maxillary canines was much greater in males than females.

5 . Findings on the relative variability of mesiodistal crown diameters of individual teeth within the incisor, premolar, and molar tooth groups were similar to findings reported for other populations.

6. Differences were noted between the present material and measurements previously obtained from Australian aboriginal skull material but definite conclusions could not be drawn from the comparisons.

7. Mean values for mesiodistal crown diameter measurements of all teeth except mandibular second molars were greater in the Australian aborigines than in the ten other population groups with which they were compared. Although the differences observed for incisors and canines were statistically significant, not all of the premolars and molars showed significant differences from teeth of other population groups next in rank order of size.

Acknowledgements The authors appreciate the cooperation and

assistance of the Commonwealth Minister for Shipping and Transport, the Chief Secretary of the South Australian Government, the Director of Welfare of the Northern Territory Administration and his ofllcers, and Mr. and Mrs. T. J. Fleming of Yuendumu Settlement.

University of Adelaide. Dental School,

dental observations on australian aborigines: mesiodistal crown diameters of permanent teeth

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