AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 82247-256 (1990) Concepts of Occlusion: Australian Evidence T. BROWN, G.C. TOWNSEND, L.C. RICHARDS, ANI) V.B. BURGESS Department of Dentistry, The University of Adelaide, Adelaide, South Australia 5000 Dental occlusion, Tooth size, Craniofacial growth, KEY WORDS Australian aborigmals ABSTRACT Longtudinal studies of aboriginal children over a 20-year period have drawn attention to the wide variation in morphologicalfeatures of the dentition and the way in which occlusal relationships develop. This paper summarizes some important determinants of optimal occlusal development, namely, tooth size relationships within and between dentitions, the patterns of alveolar growth, and tooth migrations during the transition from primary t o permanent teeth and the nature of growth changes in the dental arches. Dental occlusion constantly changes throughout life in response to changing functional requirements. Observations limited to cross-sectional material provide an incomplete, and sometimes misleading, concept of dental occlusion and masticatory function. Morphological variations in the craniofacia1 structures of past and present Australasian populations are well-documented in an extensive literature spanning the last century. Reviews, bibliographies, and, in some instances, original data are provided in many reports (for exam le, Morant, 1927; Hrdlicka, 1928; Campbe 1 et al., 1936; Fenner, 1939; Abbie, 1963; Howells, 1973; Brown, 1973;Thorne, 1976; Houghton, 1978; Prokopec, 1979; Thorne and Wolpoff, 1981; Kean and Houghton, 1982; Brown, 1982; Pietrusewsky, 1984; Macho and Freedman, 1987). Most descriptions have been concerned with metric and nonmetric features of the skull, but the dentition has also received considerable attention, particularly with respect to regional differences, phylogenetic chan es, crown morphology, and, more recently, tfle effects of Western foods and food habits that are replacing the more traditional forms of hunting, gathering, and agriculture in many regions (Campbell, 1925; Campbell and Barrett, 1953; Taylor, 1962; Barrett, 1969; Lombardi and Bailit, 1972; Hanihara, 1976; Townsend and Brown, 1979;Brace, 1980; Smith et al., 1981; Molnar et al., 1983; Corruccini and Pacciani, 1983; Sekikawa et al., 1986). The majority of investigations have been cross-sectional in design using museum material of varying antiquity or field observations of contemporary groups. Studies such f @ 1990 WILEY-LISS, INC as these are limited, as they relate t o populations and individuals at the time of examination; they can provide only indirect information on growth changes and the effects of agmg and changing functional requirements on the craniofacial structures. However, knowledge of the various determinants of occlusal relationships throughout the life of an individual provides additional valuable insights into the nature of dental occlusion and masticatory function, which have important implications for population comparisons and the study of evolutionary changes in the face and dentition. In some circumstances, the examination of museum material representing earlier populations that lived under harsher environmental conditions than exist today provides the only means to study occlusal adaptation in dentitions and jaw structures subjected to heavy loading through both masticatory and nonmasticatory use (Richards and Brown, 1981; Richards, 1983,1987). This paper is based on records obtained during a longitudinal growth study of aborig~ ~~~ Received May 13, 1988; accepted July 6, 1988. Address reprint requests to Professor T. Brown, Department of Dentistry. The University ofAdelaide, Adelaide, South Australia 5000. This paper was presented as a n introduction to the Symposium "The Face and Dentition ofAustralasian Populations" a t the 57th Annual Meeting, American Association of Physical Anthropolog s t s , Kansas City, March 1988. 248 T. BROWN ET AL inals from Yuendumu in Central Australia conducted between 1951 and 1971. Data from this source are being used for a variety of projects concerned with genetic and environmental interactions on dental morphology, facial growth, and dental occlusion. While acknowledging the multiplicity of factors concerned with the development, maintenance, and degeneration of occlusal relationships in human populations, the paper addresses three factors that are relevant during the early phases of occlusal development, namely, tooth size associations within and between primary and permanent dentitions, compensatory alveolar growth, and growth changes in dental arch relationships. their subsequent alignment into optimal esthetic and functional positions (Moorrees, 1959). Suboptimal occlusion, as found in many modern Western dentitions, most commonly results from inadequate space for the emerging permanent teeth, poor alveolar growth, and at times dysharmonious jaw relationships. Our studies of the developing aboriginal dentition have helped to clarify the ways in which some of these factors interact (Brown et al., 1980a, 1980b; Townsend and Brown, 1981). Table 1 shows the correlations between the coronal diameters of maxillary and mandibular teeth of Yuendumu children. Sexspecific correlations were averaged by the z-transformation method of Fisher (1958). SUBJECTS AND METHODS Two main trends are apparent: first, all The longitudinal study of Australian ab- coefficients are significant and reasonably original children and adults, which provided high, indicating strong tooth size relationdata for the present analyses, was carried ships between arches in both deciduous and out at Yuendumu, a small community lo- permanent dentitions; second, coordination cated about 285 km northwest of Alice in size was generally reater for buccolinSprings in the Northern Territory of Austra- gual than mesiodistal fiameters, perhaps a lia. All subjects were of pure aboriginal an- reflection of the tendency for dimensions of cestry, and they belonged predominantly to the skull to be more highly correlated in the the Wailbri tribe, although a few were Pin- coronal plane than in the sagittal (Brown, tubi people, who are the western neighbours 1969).When the mesiodistal tooth diameters of the Wailbri. The objectives of the growth of single teeth were combined, a third trend study with descriptions ofYuendumu and its became evident: the coefficients for compeople were outlined by Barrett et al. (1965a) bined tooth size of all teeth anterior to the and Brown and Barrett (1973). Further de- permanent first molar were greater than tails of the methods used in the various those for sin le teeth. It is interesting to note aspects of the study including subject selec- that the toot size associations in the aborigtion, analytic procedures, and computer inal children were generally stronger than techniques are provided in the relevant ref- those reported for North American whites from Oregon (Arya et al., 1974) and for Japerences cited in this report. anese (Yamada, 19771, suggesting a particuTOOTH SIZE RELATIONSHIPS larly close control over interarch tooth size The size relationships between teeth of relationships in the aboriginals. Size relationships between primary teeth opposing dental arches and between primary teeth and their permanent successors are and their permanent successors are also imimportant during the emergence of teeth and portant factors in occlusal development, as !i TABLE: 1. Corrrlation coefficients for. corrr~sporit~ing ( ' r o w t i diamctc~rs112 thc maxilla arid mundihlr,' 1)cciduous tooth Mesiodistal N r Huccolingud N r dil dii (1 c dm I dmr 18 18 37 132 40 141 148 157 0.77 0.71 0.64 0.77 0.73 155 162 0.89 0.61 0.77 0.74 0.84 Permanent tooth 11 172 166 159 161 I' c I' I 1'2 155 MI M2 d i l to dmz 15 I I to 0.83 ' Data from Hrown et a1. (1980b). 'All coefficients differ from zero at P < 0.01. Mrsiodistnl N r 1'2 171 1:12 151 0.67 0.58 0.72 0.76 0.66 0.66 0.73 0.85 ' Huccolingual N r 170 152 I50 0.72 0.58 0.75 0.70 0.78 0.71) 160 154 172 124 0.78 249 DENTAL OCCLUSION IN ABORIGINALS there is a space deficiency of almost 30% in the incisor region, this is compensated by a size excess of more than 30% in the case of the second primary molar relative to the second premolar in the maxilla and more than 40% in the mandible (Brown et al., 1980b). The leeway space, expressed as the size excess of the primary canine and molars compared with their ermanent successors on one side of the ental arch, must be adequate for unimpeded emergence and alignment of the canine and premolars during the second phase of dental development, which takes place between the ages of 9 and 12 years. Table 3 shows that the leeway space in aboriginal children tends to exceed that reported for a North American Caucasian population for which longitudinal data were used, especially in the mandible. Brown et al. (1980a) calculated leeway spacing from cross-sectional data for a number of other o ulations for a comparison that confirme t e relatively large size of this dimension in Australian aboriginals. The effects of adequate and inadequate leeway space on occlusal ali ment are shown in the two aborigmal c ildren illustrated in Figures 1 and 2. Observations of contemporary aboriginal children support the view that coordination of tooth size, both within and between denti- the determine to a large extent the availabi ity of space for emerging teeth. Table 2 summarizes these associations, which were stronger for buccolingual diameters than for mesiodistal diameters. The coordination of total tooth size, expressed as the combined mesiodistal diameters of all teeth anterior to the permanent first molar, was greater than for any other single tooth comparison. The coordination of total tooth size between dentitions was also stronger in the aboriginals than in the North American white children reported by Moorrees and Reed (1964).Thus, from the available comparative data, t e coordination of crown size within and between dentitions in the aboriginal children appears to be higher than in North American whites and Japanese. It is likely that the biological control and growth coordination exerted during odontogenesis determine relative crown diameters, thereby affecting the establishment of occlusal relationships many years later. When the primary teeth are exfoliated at between 6 and 12 years of age, the resulting spaces within the dental arch may be excessive, adequate, or deficient for the emerging permanent successors. It is interesting that the differences in mesiodistal diameters between ermanent and primary teeth decrease rom the earlier to the later erupting permanent teeth. For example, although P B Judgina BK f? P TABLE 2. Correlation coefficients for crown diameters of deciduous teeth and permanent successors1 Teeth comnared Deciduous dil di:! dc dmi dmL dil to dm, Permanent 11 12 C PI PL II to P, Maxilla Mesiodistal N r 38 73 154 153 152 33 0.57 0.54 0.25 0.36 0.44 0.65 Mandible Buccolingual N r 38 72 150 156 153 0.56 0.31 0.41 0.41 0.58 Mesiodistal N r 21 44 144 147 146 19 0.52* 0.38* 0.35 0.45 0.42 0.68 Buccolingual N r 21 40 125 151 150 0.53" 0.62 0.42 0.47 0.60 ' 1)ata from Brown et al. (1YllOb). *Coefficient differs from zero a t P < 0.05: all other coefficients differ from zero at P < 0.01 TABLE 3. Leeway space calculated in individual children from longitudinal data showing mcans a n d standard deviations (in parentheses)' Maxilla GrouD Australian aboriginak? North American Caucasoids," ' Mandible Males Females Malps Fpmalpn 1.5 (1.1) 1.2 (0.9) 1.4 (1.1) 1.5 (0.9) 2.9 (1.2) 2.2 (0.9) 3.3 (0.8) 2.6 (0.9) Calculated in mm as the difference between combined mesiodistal diameters of t h e deciduous canine a n d molars and the permanent pccessors on one side of the dental arch. sData from Brown et al. (1983). Data from Muorrees and Chadha (1962). 250 T. BROWN ET AL. Fi 1 Dental development in a n aboriginal girl with adequate leeway space and alveolar devefopment. The mandibular incisor crowding a t age 8 has almost disappeared at age 15 years. Leeway space is 3.2 mm in the maxilla and 4.8 mm in the mandible. tions, is an essential component of the developmental processes that determine the mode of dental occlusion and its functional efficiency. Australian aboriginal children display a high level of coordination in tooth relationships, and they also benefit from liberal leeway spacing, an important advantage during emergence of the postincisor dentition. It could be postulated that during evolutionary reduction of tooth size, the size relationships between primary and permanent dentitions may have changed also leading t o a reduction in the leeway dimension and less space for good tooth alignment, particularly in the mandible. Unfortunately, it is unlikely that data representing both primary and permanent dentitions will become available in an adequate number of precontemporary populations to test this concept. ALVEOLAR GROWTH AND TOOTH MIGRATION Occlusal relationships are established as part of the ongoing maturation of the facial skeleton extending from early childhood through adolescence to adulthood. This pe- riod is characterized by extensive alveolar growth, remodelling of the jaws, rotation of the face relative to the cranial base, and tooth migrations along directions that are correlated with the pattern of jaw rotation (Bjork and Skieller, 1972). The growth processes have a profound effect on final tooth positions and relationships. It has been shown in longitudinal cephalometric studies with implants, for example, that the mesial migration of mandibular incisors and molars during growth is significantly associated with growth variables such as resorption of the ramus and the direction of condylar growth (Bjork and Skieller, 1983). The same authors analyzed growth records of Danish children re orting a forward migration of incisors an molars of 3.2 mm and 5.2 mm, respectively, which led to a shortening of mandibular arch length by 2.0 mm on average. The degree of forward migration of the dentition and the accompanying alveolar development are major determinants of the differences in the facial profiles of modern populations. As assessed by comparative radiographic cephalometry, these differences 8 DENTAL OCCLUSION IN ABORIGINALS 251 Fig. 2. Dental development in an aboriginal girl with inadequate leeway space and alveolar develo ment Crowding has persisted in the mandibular incisors and developed in the maxillary premofars. Leeway space is 2.0 mm in the maxilla and 3.1 mm in the mandible. reside almost entirely in the midfacial or alveolar region (Brown, 1988). Information on the patterns ofjaw growth, tooth mi ation, and alveolar development in indivi uals can be obtained by the examination of standardized longitudinal cephalograms. Ideally, serial cephalograms should be su erimposed on metallic implants inserte in mandible and maxilla at the beginning of the observation period. However, a reasonable interpretation of growth directions and magnitudes can be gained by superimposing the successive records according to the structural method of Bjork and Skieller (1983).Thus, further understanding of these growth mechanisms in living populations is dependent on the availability of serial growth records. The anal sis of facial growth in Australian Aborigina s is proceeding, but as the method is exceedingly timeconsuming and cannot be automated, our findings to date must be considered to be preliminary (Bjork et al., 1984). Figure 3 illustrates growth changes in the craniofa- f cp P ’\ ... Fig. 3. Facial growth in a n aboriginal boy as traced from lateral cephalograms at ages 7,12, and 16 years. 252 T.BROWN ET AL cia1 profile of an aboriginal boy between 7 and 16 ears. Growth of the jaws and their remode ling and rotation relative to the cranial base are highlighted by this form of growth analysis, which also emphasizes the straightening of the facial profile with age, the increase in facial height, and the rotation of the occlusal plane. Figures 4 and 5 show alveolar growth, tooth migrations, and jaw remodelling in the mandible and maxilla of the same boy. During the 9-year eriod, there was substantial alveolar growt and migration of the entire dental arches occlusally and forward. In the mandible, the forward migration of the first permanent molars was 7.4 mm, compared with 4.4 mm for the incisors, leading to a reduction in dental arch length of 3.0 mm. The reduction was due partly to closure of the leeway space and partly to an increase of 5 mm in intermolar arch breadth over the P K growth period. The overall advantage of the tooth migrations and alveolar development was provision of additional space anterior to the coronoid process for unimpeded emergence and alignment of the later erupting teeth, including third molars. Alveolar growth and tooth movements were also marked in the maxilla, leading to a reduction of 2.5 mm in arch depth during the period. Midfacial pro athism increased also. Although only a ew complete analyses of facial growth have been completed for the aboriginals, it is our feeling that the pattern described above, which contrasts with that referred to above for the Danes, is characteristic of this contemporary Australian population. In many industrialized populations, masticatory function is not vigorous; hence there is less stimulation for midfacial growth and development of the alveolar processes. As a P E E 9 -3 P r; h I I 1 I I I I I Fig. 4. Mandibular alveolar growth and tooth migrations in an Aboriginal boy between 7 and 16 years. Fig. 5. Maxillary alveolar growth and tooth migrations in an Aboriginal boy between 7 and 16 years. 253 DENTAL OCCLUSION IN ABORIGINALS consequence, the provision of space for optimal occlusal development is often inadequate, resulting in varying degrees of tooth crowding, malocclusion, and third molar impaction (Brash, 1956; Davies, 1972; Corruccini, 1984). The absence of appreciable interproximal attrition in modern populations also increases the possibility of tooth crowding (Begg, 1954). GROWTH CHANGES IN THE DENTAL ARCHES Studies presently under way are extending our knowledge of dental arch development in the aboriginal children from Yuendumu by using a number of breadth and depth variables to describe growth changes in the arches and to identify various patterns of differential growth between maxillary and mandibular arches. In common with the pattern of arch development in Caucasian children, the dental arches of aboriginals undergo considerable changes in size and shape during growth. Our previous studies have DENTAL ARCH PLDT SUBJECT: 330 SEX: H AGE 8.22 Y R I 10 SCALE 1.5 1 ii 12 13 14 15 16 17 YRB Yas YRS YRI YRE YRI YRS YRB Maxilla shown that, on the average, there is a reduction in dental arch depth and an increase in breadth, as shown in Figure 6 (Barrett et al., 196513; Brown et al., 1983, 1987). However, the age changes in the upper and lower arches are not necessarily similar in magnitude and direction, resulting in constantly changing occlusal relationships in the sagittal and coronal planes. An interesting type of growth change, shown in Figure 7, is marked by a greater increase in maxillary arch breadth than in mandibular breadth. It occurs in about 70% of the aboriginal males and 40% of the females. This growth pattern leads to a variant of dental occlusion termed alternate intercuspation, which resembles the transverse dental arch relationships found in many species of herbivorous animals. It may be present from an early age or may develop to various degrees of expression at later ages. We believe that alternate intercuspation, which would be regarded as a malocclusion SUBJECT. 254 DENTAL ARCH PLOT SCALE 1.5 ' SEX: M AGE: 7 YRL 8.39 YRL 9 97 Yas 1 1 1 . 7 6 YRB 12 76 YRC 1 4 . 7 6 YRB 15 76 YRE 16.76 YRE 17.76 YRE 1 8 . 7 6 YRE Maxllla 25 0 1 : : : : : : 0 50 : : : A Handlble Fig. 6. Changes in the dental arches of an Aboriginal boy between 8 and 17 years showing similar breadth increases in maxilla and mandible and progressive reduction in arch depth. 1 25 : : : : : : 50 : : : 1 Mandible Fig. 7. Changes in the dental arches of an Aboriginal boy between 7 and 19 years showing divergent breadth increases in maxilla and mandible and progressive reduction in arch depth. 254 T. BROWN ET AL. and termed scissors bite if assessed accord- dynamic quality of dental occlusion in the ing to modern clinical concepts, is in reality full functional dentition of preindustrialan efficient adaptation to masticatory func- ize groups. These clinical concepts are often tion involving wide, powerful crushing and used by anthropologists to describe dentigrinding strokes accompanied by progres- tions of skeletal populations. The value of longitudinal studies of dental sive tooth attrition. The growth pattern leading to alternate intercuspation was illus- development, craniofacial growth, and tooth trated and described in detail previously occlusion lies in the clearer insight that such (Brown et al., 1987). Contrasting with alter- studies provide into the range of variation in nate intercuspation, the unworn and inter- growth patterns between individuals and locking cusps of modern dentitions can be the extent of variations within the same regarded as another example of the regres- individual over time. Although many longision in morphology and function that follows tudinal studies of modern Caucasian populathe adoption of softer preprepared diets. tions have been undertaken, opportunities for recording craniofacial and dental development in other groups have been very few THE VALUE OF LONGITUDINAL STUDIES in the past, and they are likely to diminish in The majority of studies dealing with den- the future. titions and craniofacial structures of human Our investigation of aboriginal children populations have, of necessity, been cross- from Central Australia has provided a sectional. This approach has provided an unique op ortunity to study the changing immense pool of data for investigators to nature of ental occlusion in a trace evolutionary trends in dental morphol- ple who had abandoned their unter-gathOf peaogy and describe population similarities and erer life-style in favour of a settlement existdifferences. Unfortunately, the cross-sec- ence with access to a plentiful supply of tional design can throw no light on the extent water, European foods, and other amenities. of variation within individuals for morpho- The aboriginals, however, are still tribally logical characters that are affected by age or oriented, hold traditional beliefs, and pracchanging function. Some dental features, tise many of the customs of former days. such as the size of tooth crowns and their When supplemented by the examination of nonmetric characters, are not affected by age skeletal material representing earlier abalone unless masticatory or nonmasticatory original populations, the studies increase tooth wear or pathological processes alter our understanding of the nature of dental crown morphology. Others are subject to age relationships and functional occlusion, parchanges that are quite substantial. ticularly as they are affected by normal deFor example, the mode of dental occlusion velopmental rocesses, age changes, heavy is not a static entity, but one that changes occlusal loa(Qing, and pathological condithroughout life according to natural growth tions. processes, superimposed environmental conThis paper, based on longitudinal observaditions, and changing functional demands. tions, has drawn attention to some aspects of In a disease-free dentition, changes in tooth dental occlusion that are important during positions and occlusal relationships are min- the years of active facial growth and tooth imal after adulthood is reached. However, in emergence. In particular: dentitions subject to heavy or unusual forms of occlusal loading, tooth morphology, tooth Strong coordination of tooth size bepositions, and dental occlusion are subject to tween the primary teeth and their percontinuing change throughout life. manent successors and between maxilConcepts about dental occlusion have delary and mandibular teeth within the veloped primarily from a need to establish same dentition tends to reduce the clinical objectives and criteria for the restochances of discrepant occlusion due to ration of maloccluded or otherwise impaired irregularities in the size relationships dentitions. With few exceptions, these conbetween succedaneous or opposing cepts have been based on observations of teeth. modern dentitions not subjected to the heavy Liberal leeway spacing in the aboripfunctional demands faced by earlier opulanal children, especially in the manditions. As a result, concepts of “norma occluble, combined with rominent alveolar sion”convey a sense of static morphology and bone growth, providpes adequate space unchanging relationships; they ignore the B a P aoup DENTAL OCCLUSI(IN IN ABORIGINALS for the permanent teeth to emerge into good occlusal alignment. Interproximal tooth attrition assists in this process to some extent. 3. The size and the shape of the dental arches continually change during growth, the arch depths reducing considerably, and the arch breadths increasing to a lesser extent. Dental arch development, together with the characteristic occlusal and forward movement of the dentition during growth, maintains tooth relationships in the aboriginals, who are enerally free of major crowding or ot er forms of malocclusion, and capable of vigorous and efficient masticatory function. a Concepts of so called “normal occlusion,^' as used in clinical procedures as well as in anthropological contexts, should be modified to take into account the dynamic character of dental occlusion as it existed in the fully functional dentitions of human populations until relatively recent times. ACKNOWLEDGMENTS The authors acknowledge with gratitude the assistance provided by Mrs. S.K. Pinkerton and Miss F. Rowett in data analysis and preparation of the illustrations. The material used for the research was gathered with the financial support of NIDR Grant DE 02034 to M.J. Barrett and T. Brown. Currently the research is supported by the National Health and Medical Research Council, Canberra, Australia. LITERATURE CITED Abbie AA (1963) Physical characters of Australian Aborigines. In H. Sheils (ed.): Australian Aboriginal Studies. Melbourne: Oxford University Press, pp. 89-107. Arya BS, Thomas DR, Savara BS, and Clarkson QD (1974) Correlations among tooth size in a sample of Oregon Caucasoid children. Hum. Biol. 46:693498. Barrett MJ (1969) Functioning occlusion. Ann. Aust. Coll. Dent. Surg. 2:68-80. Barrett MJ, Brown T, and Fanning EA (1965a) A longterm study of the dental and craniofacial characteristics of a tribe of Central Australian Aborigines. Aust. Dent. J. 10:63-68. Barrett MJ, Brown T, and Macdonald MR (196513)Size of dental arches in a tribe of Central Australian Aborigines. J. Dent. Res. 44:912-920. Begg PR (1954) Stone age man’s dentition. Am. J . Orthod. 40:29%312,373-383,462-475. Bjork A, and Skieller V (1972) Facial development and tooth eruption. An implant study ofthe age of puberty. Am. J . Orthod. 62:339-383. Bjork A and Skieller V (1983) Normal and abnormal 255 growth studies of the mandible. A synthesis of longitudinal implant studies over a period of 25 years. Eur. J. Orthod. 5:1-46. Bjork A, Brown T, and Skieller V (1984) Comparison of craniofacial growth in an Australian Aboriginal and Danes, illustrated by longitudinal cephalometric analysis. Eur. Orthod. J . 6:l-14. Brace CL (1980) Australian tooth-size clines and the death of a stereotype. Curr. Anthropol. 21:141-164. Brash J C (1956) The Aetiology of Irregularity and Malocclusion of the Teeth. Part l . London: The Dental Board of the United Kingdom. Brown P J (1982) Coobool Creek: A Prehistoric Hominid Population. Ph.D. Thesis. Canberra: Australian National University. Brown T (1969) Facial growth patterns and co-ordination. Aust. Orthod. J. 2:5-11. Brown T (1973) Morphology of the Australian Skull Studied by Multivariate Analysis. Canberra: Australian Institute of Aboriginal Studies. Brown T (1988) Physical growth and adaptation in the tropics with special reference to the craniofacial structure. In SR Prabhu, DF Wilson, DK Daftary, and NW Johnson (eds.):Oral Diseases in the Tropics. London: Blackwell Scientific Publications. (in Press). Brown T and Barrett MJ (1973) Dental and craniofacial growth studies of Australian Aborigines. In RL Kirk (ed.):The Human Biology of Aborigines in Cape York. Canberra: Australian Institute of Aborigmal Studies, pp. 69-80. Brown T, Abbott A, and Burgess VB (1983)Age changes in dental arch dimensions of Australian Aboriginals. Am. J . Phys. Anthropol. 62:291-303. Brown T, Abbott A, and Burgess VB (1987) Longitudinal study of dental arch relationships in Australian Aboriginals with reference to alternate intercuspation. Am. J. Phys. Anthropol. 72.49-57. Brown T, Margetts B, and Townsend GC (1980a) Comparison of mesiodistal crown diameters of the deciduous and permanent teeth in Australian Aboriginals. Aust. Dent. J.2528-33. Brown T, Margetts B, and Townsend GC (1980b)Correlations between crown diameters of the deciduous and permanent teeth in Australian Aboriginals. Aust. Dent. J . 25:219-223. Campbell TD (1925)Dentition and Palate of the Australian Aboriginal. Adelaide: University of Adelaide. Campbell TD and Barrett MJ (1953)Dental observations on Australian Aborigines-a changing environment and food patterns. Aust. Dent. J. 57:14. Campbell TD, Gray JH, and Hackett CJ (1936)Physical anthropology of the Aborigines of Central Australia. Part I, Anthropometry. Oceania 7:106-139. Corruccini RS (1984) An epidemiologic transition in dental occlusion in world populations. Am. J . Orthod. 86:419-426. Corruccini RS and Pacciani E (1983) Occlusal variation in Melanesians from Bougainville, Malaita and New Britain. Homo 34:15-22. Davies DM (1972) The Influence of Teeth, Diet, and Habits on the Human Face. London: William Heinemann Medical Books Ltd. Fenner FJ (1939) The Australian Aboriginal skull: Its nonmetrical morphological characters. Trans. R. SOC. South Aust. 63:24&306. Fisher RA (1958)StatisticalMethods for Research Workers (13th Ed.). Edinburgh: Oliver and Boyd, p. 204. Hanihara K (1976) Statistical and Comparative Studies of the Australian Aboriginal Dentition. Bulletin 11, 256 T. BROWN ET AL. The University Museum. Tokyo: The University of Tokyo. Houghton P (1978) Polynesian mandibles. J. Anat. 127:251-260. Howells WW (1973) Cranial Variation in Man. A Study by Multivariate Analysis of Patterns of Differences Among Recent Human Populations. Papers of the Peabody Museum 67:l-259. Hrdlicka A (1928) Catalogue of human crania in the United States National Museum collections. Proc. U.S. Natl. Mus. 71:l-140. Kean MR and Houghton P (1982) The Polynesian head: Growth and form. J. Anat. 135:423435. Lombardi AV, and Bailit HL (1972) Malocclusion in the Kwaio, a Melanesian group on Malaita, Solomon Islands. Am. J. Phys. Anthropol. 36:283-294. Macho G and Freedman L (1987) A re-analysis of Andrew A. Abbie morphometric data on Australian Aborigines. Occasional Papers Hum. Biol. 4:l-80. Molnar S,McKee JK, and Molnar I (1983)Measurements of tooth wear among Australian Aborigmes: 1. Serial loss of the enamel crown. Am. J. Phys. Anthropol. 61:51-65. Moorrees CFA (1959) The Dentition of the Growing Child. A Longtudinal Study of Dental Development Between 3 and 18 Years of Age. Cambridge: Harvard University Press. Moorrees CFA and Reed RB (1964) Correlations among crown diameters of human teeth. Arch. Oral Biol. 9:685497. Morant M (1927) A study of the Australian and Tasmanian skulls, based on previously published measurements. Biometrika 19:417440. Pietrusewsky M (1984) Metric and non-metric cranial variation in Australian Aborigmal populations compared with populations from the Pacific and Asia. Occasional Papers Hum. Biol. 3:l-113. Prokopec M (1979) Demographical and morphological aspects of the Roonka population. Arch. Phys. Anthropol. Oceania 14t11-26. Richards LC (1983) Adaptation in the Masticatory System: Descriptive and Correlative Studies of a PreContemporary Australian Population. Ph.D. Thesis. Adelaide: The University of Adelaide. Richards LC (1987) Temporomandibular joint morphology in two Australian Aboriginal populations. J. Dent. Res. 66:1602-1607. Richards LC and Brown T (1981) Dental attrition and degeneration of the temporomandibular joint. J. Oral Rehabil. 8:293-307. Sekikawa M, Akai J, Kanazawa E, and Ozaki T (1986) Three-dimensional measurement of the occlusal surfaces of lower first molars of Australian Aboriginals. Am. J. Phys. Anthropol. 71:25-32. Smith P, Brown T, and Wood WB (1981) Tooth size and morphology in a recent Australian Aborigmal population from Broadbeach, South East Queensland. Am. J. Phys. Anthropol. 55423-432, Ta lor RMS (1962) The human palate. Acta Anat. 49: .!%ppl. 43:l-189. Thorne A (1976) Moruholoeical contrasts in Dleistocene Australians. In R i Kirkuand AG Thorne ieds.): T h e Origin of the Australians. Canberra: Australian Institute of Aboriginal Studies, pp. 95-112. Thorne AG and Wolpoff MH (1981) Regional continuity in Australasian Pleistocene hominid evolution. Am. J. Phys. Anthropol. 55:337-349. Townsend GC and Brown T (1979)Tooth size characteristics of Australian Aborigines. Occasional Papers in Hum. Biol. 1:17-38. Townsend GC and Brown T (1981) Morphogenetic fields within the dentition. Aust. Orthod. J. 7:3-12. Yamada H (1977)Factor analysis ofhuman teeth, dental arch and palate. Aichi-Gakuin J. Dent. Sc. 15:267287.