Radiographic study of the Broadbeach Aboriginal dentition

Radiographic Study of the Broadbeach Aboriginal DentitionMARK W. ELVERY,1 NEIL W. SAVAGE,1* AND WALTER B. WOOD2

1Department of Dentistry, The University of Queensland,St. Lucia, Australia2Department of Anatomical Sciences, The University of Queensland,St. Lucia, Australia

KEY WORDS dental anthropology; dental pathology; AustralianAborigine

ABSTRACT This study forms part of a larger anthropological investiga-tion of the Ngaraangbal Aboriginal Tribe’s ancestral burial ground at Broad-beach, Australia. It examines the dentition, records the associated pathologyin a noninvasive manner, and relates this to the likely subsistence diet of thetribe. The Broadbeach osteological collection was returned for reburial in1985; however, radiographic and photographic records of 36 adult males wereavailable. These form the basis of our study. The pathology noted in the studysample was compared with a representative sample (n 5 38) of pre-EuropeanAboriginal remains from throughout Queensland for verification purposesonly. Rates of dental pathology and injury were calculated from the radio-graphic and photographic records. There was a significant rate of tooth-wearrelated intra-bony pathology (4.0%), moderate to severe alveolar bone loss,and heavy dental attrition, of which the mandibular posterior teeth were themost severely affected. Caries prevalence (0.8%) was low for hunter-gathererpopulations. A large number of molar pulp chambers had a distinctive‘‘cruciate’’ morphology resulting from the formation of secondary dentine andpulp stones. Injuries and abnormalities included upper central incisoravulsion (58.3%) and taurodontism. These results support the proposal thatthe Ngaraangbal tribe was a hunter-gatherer population subsisting on anabrasive diet that included marine foods. Am J Phys Anthropol 107:211–219,1998. r 1998 Wiley-Liss, Inc.

The Broadbeach Aboriginal burial groundwas excavated on the Gold Coast, Queens-land, by Laila Haglund and W.B. Woodduring 1965–1967.An excavation report (Ha-glund, 1976) and several skeletal studies(Wood, 1968; Freedman and Wood, 1977;Smith et al., 1981; Hobson and Collier, 1984)provide detailed features of the Broadbeachskeletal collection.

In summary, a total of approximately 150individual skeletons were recovered over the3-year excavation period, with approximately58% regarded as juvenile (less than 20 yearsold). A total of 64 adult crania were repre-sented in the collection, but sex could bedetermined in only 58 using both cranial and

associated postcranial criteria (Larnach andFreedman, 1964; Davivongs, 1963a,b; VanDongen, 1963). Of these, only six were fe-male and the remaining 52 were male. Thiscemetery population, therefore, was biasedstrongly in favour of adult males and juve-niles, with adult females poorly represented.

Only 41 maxillae and mandibles (36 maleand 5 female) were associated with the adultcrania. These formed the basis of the metri-cal study of the crania and mandibles car-

*Correspondence to: Dr. N.W. Savage, Department of Den-tistry, University of Queensland, Turbot St., QLD. 4000. Austra-lia. E-mail: [email protected]

Received 9 July 1996; accepted 3 May 1998.

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 107:211–219 (1998)

r 1998 WILEY-LISS, INC.

ried out by Freedman and Wood (1977). Atthat time, the maxillae and mandibles werephotographed and radiographed as part ofthe general recording of the Broadbeachcollection. Prior to the present study, thedental pathology of this largely precontactAboriginal population had not been ad-dressed.

In 1985, the Broadbeach skeletal collec-tion was claimed for repatriation and re-burial by the Kombumerri clan of the Ngara-angbal people, who are direct descendants ofthe Broadbeach Aboriginal population. Theremains were reburied in 1987.

Carbon dating indicates that the Broad-beach burial ground was in active use from750 AD to approximately 1900 AD, just afterEuropean settlement in the area (Haglund,1968, 1976). Reports on the proportion ofmarine food in the diet of this populationhave been equivocal. Haglund (1976) statesthat the diet had only a small marine supple-ment, but Hobson and Collier (1984) pro-posed that the population was dependent onmarine resources.

A number of recent studies in severalcountries have attempted to correlate thepatterns of dental pathology with the diet ofprecontact indigenous populations (Hall etal., 1986; Jurmain, 1990; Littleton andFrohlich, 1993; Sealy et al., 1992). The com-position of prehistoric diets can be deter-mined by the utilization of stable carbonisotope ratios in bones, as used by Hobsonand Collier (1984). However, this method ofdetermining the proportion of marine foodin the diet can produce results which conflictwith the outcomes of traditional studies, asdietary supplements cannot be distinguishedfrom the staple composition of the diet (Sealyet al., 1992)

The aim of the present study, therefore,was to examine the dentition of all adultaboriginal males that had been radiographedand photographed and to detail both dentaland bony pathology. Reference to previousliterature should then allow a qualified state-ment on whether the diet was marine-basedor contained a marine supplement.

MATERIALS AND METHODS

The dental condition of the Broadbeachpopulation was determined from the radio-

graphic, photographic, and written recordsof 36 adult male individuals. The maxillaeand mandibles of 38 additional adult maleaboriginal individuals from Queensland col-lections were radiographed and studied forcomparison with and verification of the pa-thology or abnormalities observed in theBroadbeach collection. The comparativegroup originated from scattered locationsthroughout Queensland.

The approximate age of all specimens wasestimated using the morphology of the pubicsymphysis and state of epiphysial fusion(McKern and Stewart, 1957), dental attri-tion (Brothwell, 1963), and the presence ofvertebral arthritis (Stewart, 1958). Basedon these criteria, only two specimens couldbe regarded as elderly. The remainder wereestimated to be young to middle-aged adultmales. All jaws had been radiographed fromthree directions: postero-anterior for the an-terior jaw segment, and postero-lateral forboth posterior segments.

All pathology and other abnormalities ob-served in both the Broadbeach and the com-parative Queensland groups were recorded.Dental attrition was scored as one of eightlevels using the method of Molnar (1971).This could be applied to radiographic imageswith relatively little error (0.23 of a scoredunit overestimated on average by referenceto the comparative Queensland group). Whileinterproximal wear was considered, no sta-tistical analysis was conducted, as measure-ment of interproximal wear could not bemade accurately due to lateral radiographicoverlap. Rates of caries incidence, intra-bony radiolucencies (commonly referred toas periapical pathology), and antemortemtooth loss (AMTL) were calculated. Where itwas possible to measure apparent alveolarbone loss, a measurement was recorded. Theloss of alveolar bone crestal height wasmeasured from the cemento-enamel junc-tion of the teeth to the crest of the alveolarbone. A correction for both continuous erup-tion and natural crest height was made.

The measured features were distributedaccording to both tooth type and positionand were analysed for significance using aChi-square test.

212 M.W. ELVERY ET AL.

RESULTS

Attrition

Tooth attrition in the Broadbeach samplewas moderately heavy, with the majority ofincisors, canines, and premolars showingexposed secondary dentine on the incisaland occlusal surfaces. The molars showedlarge areas of exposed occlusal secondarydentine. In nearly all cases, at least 7 mm ofthe anatomical crown remained above thecrest of the alveolus on at least one point oneach tooth.

The heaviest dental attrition was appar-ent on the molars in both the maxilla andmandible, of which the mandibular molarswere significantly (P , 0.05) more wornthan the maxillary molars. Attritional gradi-ents in the maxillary and mandibular denti-tions are shown in Figure 1.

Acharacteristic pattern of occlusal concav-ity or scooping was present on many man-dibular molars (Fig. 2). This involved mainlythe first and second molars with a markedincrease in wear from the mesial to thedistal surface, often resulting in a wedge-shaped crown profile. As far as could bedetermined, this was associated with a recip-rocal pattern in the maxilla, although the

degree of wear seemed much less, resultingin a less steep gradient. There was no asym-metry associated with this pattern. Statisti-cal analyses were not undertaken for thispattern.

Periapical pathology

Intra-bony radiolucencies were recordedunder the general term of ‘‘periapical pathol-

Fig. 1. Average attritional scores in the maxillary and mandibular dentitions of the Broadbeach adultmale Aborigines (n 5 sample number).

Fig. 2. Molar scooping was seen most commonly inthe mandible, generally on the first and second molars.

213BROADBEACH ABORIGINAL DENTITION

ogy,’’ as the exact pathological process can-not be determined from radiographs alone.Notwithstanding this, the often large size ofthe areas and the smooth outline suggests aslowly enlarging lesion, most likely cysticrather than an active osteomyelitic process.

Four percent of the teeth examined radio-graphically had associated periapical pathol-ogy. Of these, there was a 2:1 ratio of man-dibular to maxillary lesions. Overall, 26.0%of the adult male population had at least onelesion (the most severely affected mandiblecontained five separate lesions). Approxi-mately 56% of teeth with periapical pathol-ogy had an attritional score of five or more(Fig. 3).

Antemortem tooth loss

Fifty-eight percent of adult males had oneor both maxillary central incisors missing.This was a statistically significant finding(P , 0.01), indicating that the traditionalavulsion of one or both permanent centralincisors in males upon their initiation intomanhood was responsible for tooth lossrather than disease.

There were only two other cases of ante-mortem tooth loss involving a maxillary leftlateral incisor and a mandibular left third

molar. In the case of the incisor, there wascomplete healing of the alveolus and mesialdrift of the adjacent teeth with partial clo-sure of the gap. The third molar site showedincomplete healing and appeared relativelyrecent, but with no evidence of local traumaor other indication of the method of loss,such as bone resorption due to periodontaldisease.

Alveolar bone loss

Eighty-seven percent of individuals hadeither moderate (2–5 mm) or severe (.5mm) loss of bone from the alveolar crest. Thearea of greatest loss of alveolar crest heightwas in the anterior segment (incisors andcanines), with more than one half in thesevere category. The average loss in theanterior segment was 3.5 mm and 1.7 mm inthe posterior segment.

Dental caries

Six cases of dental caries (0.8%) were seenin five individuals (Fig. 4). Three lesionswere found in maxillary teeth, with twobeing located on the mesial surfaces of bothcanines in one maxilla. The third lesion waslocated in the distal occlusal developmentalpit of a right maxillary premolar. All man-

Fig. 3. Periapical radiolucencies of varying size were observed in the Broadbeach group. These rangedfrom poorly defined unilocular radiolucencies (A) to more discrete areas with a sclerotic margin (B,C).


dibular tooth lesions were present on theocclusal surfaces of the right third molarsand measured up to 6 mm in diameter atthe enamel surface. It is noteworthy thatthis tooth was least affected by occlusalattrition with clear preservation of the devel-opmental pits and fissures. All cases of car-ies were confirmed by the characteristicappearance on both radiographs and photo-graphs.

Other pathology and anomalies

Moderate malocclusion was relatively com-mon among the lower anterior teeth. Thismanifested as a malalignment with arch-line irregularity and tooth rotation indica-tive of an arch length deficiency. Only a fewindividuals showed severe malocclusionswith multiple impactions, transposition ofteeth, and anterior crowding. Impaction ofteeth other than third molars (seen in threecases) was rare, but when this occurred theimpactions were multiple. In one youngadult, both mandibular third molars and theleft mandibular second premolar were im-pacted and the mandibular anterior teethwere crowded. In addition, the left maxillarycanine was transposed to a position disto-buccal to the left first premolar.

Mesotaurodontism (Mena, 1971) was ob-served in the majority of posterior teeth.This occurs when the tooth root furcation is

found in the apical one half of the root trunkcomplex, but with an apparent normal over-all root length (Fig. 5). The pulp chamberswere elongated without the dentinal andenamel thickness of the crown and furcationareas being compromised.

Pulp stones were observed in 34.2% ofmandibular molars but in only 2.9% of max-illary molars. In the mandible, 53% werefound in first molars, 41% in second molars,and 6% in third molars. The distribution ofpulp stones between the maxilla and man-dible and between the molar teeth positionswere statistically significant (P , 0.01). Thispattern also correlated directly with thedegree of attrition.

Excessive secondary dentine formationwas found in 11.1% of molar teeth. Thissecondary dentine almost completely obliter-ated the pulp chambers, leaving a smallspace which appeared as an ’X’ configurationradiographically (Fig. 6). Accordingly, thesepulp chambers were referred to as ‘‘cruciatepulp chambers.’’ There was an even distribu-tion of this pattern between the maxillaryand mandibular molars; however, the firstmolars were involved more commonly thanthe second molars in both the maxilla (2.5:1,P , 0.05) and mandible (4.3:1, P , 0.01).There were no instances of third molarinvolvement.

Fig. 4. Caries werefound most commonlyon the occlusal surfaceof mandibular thirdmolars. The three casesnoted in the Broadbeachgroup each involved theright mandibular thirdmolar.


DISCUSSION

The pattern and severity of dental attri-tion in the Broadbeach Aboriginal adultmale population indicates that this groupwas not fully marine-dependent. The attri-tional scores were within the accepted limitsfor hunter-gatherer populations who have asignificant marine content in their diet, butthe values were located toward the lowerend of this range (Table 1). In an entirelymarine-dependent group the values shouldbe toward the upper end of the range. It

seems likely from the specific wear patternsthat a significant amount of the attritionobserved in the dental record was due totask activities. The pattern of wear gradi-ents and molar concavities suggest an actionof habitual abrasion that could be producedby gripping cord, vine, or sinew between theupper and lower teeth and pulling it throughto strip and prepare it for binding material.

Periapical pathology was not related di-rectly to dental caries and subsequent pulpalinfection in the generally accepted progres-sion pattern. There were no instances of acarious lesion being associated with periapi-cal pathology. The other reasonable causefor the presence of periapical pathology inthe Broadbeach population is the extensiveamount of dental wear (Hall et al., 1986;Littleton and Frohlich, 1993). This is sup-ported by the higher attritional scores andincidence of periapical pathology in the man-dible, as well as the greater degree of attri-tion seen in those teeth with periapicalpathology. This also supports the premise ofa diet based on hunting and gathering.

In the overall dental record, only 33.2%and 38.6% of teeth in the maxilla and man-dible, respectively, scored an attritional levelof five or greater, yet for those teeth withassociated periapical pathology this propor-tion rose to 55.6%. Furthermore, teeth withperiapical pathology showed high rates ofpulp stones and cruciate pulp chambers,both of which have been associated withheavy dental wear (Ramfjord andAsh, 1971).

The tradition of avulsing one or bothupper central incisors of boys at the age ofinitiation into adult life is reported in histori-cal accounts and personal journals (Petrie,1983) and in itself does not represent spe-cific pathology. The degree of alveolar boneloss is consistent with the heavy attritionobserved in the dental record. This latterfinding further strengthens the proposal of adiet that is composed of marine, hunting,and gathering sources.

The apparent absence of dental caries isattributable to a combination of factors. Theinhibitory action of attrition and prehistoric‘‘cleaning’’ or dental hygiene on caries haveboth been documented (Hall et al., 1986;

Fig. 5. Mesotaurodontism was noted in over 10% ofmolars. This radiograph of the left maxillary and man-dibular first and second molars shows the elongatedpulp chamber and root trunk, particularly obvious in themaxilla.


Brown and Molnar, 1990) and are clearlypresent in the dental record of the Broad-beach population. Fluoride has a direct in-hibitory affect on the development of dentalcaries, and while there is no evidence tosuggest natural fluoride in the local water,fluoride would be gained directly from amarine supplement to the diet (Pu andLilienthal, 1961). The absence of caries alsoindicates a high proportion of dietary pro-tein and fat, both of which have a protectiveeffect, and a relative absence of carbohy-drates and grain foods, as seen in agricul-tural populations (Littleton and Frohlich,1993).

Malocclusion has been associated withsoft diets, which fail to promote adequateinterdental wear/attrition during the devel-opmental period of the permanent dentition,resulting in insufficient arch length for theeruption of some secondary teeth (Begg,1965). Notwithstanding the heavy wear bothocclusally and interproximally, there was amoderate degree of malocclusion and ante-rior crowding in the Broadbeach population.Certain teeth of this population, when ana-lysed metrically, were found to be largerthan normal (Smith et al., 1981). This maybe explained by the presence of taurodontismof the molar teeth, where the pulp chambersare of normal proportions but within an

enlarged root trunk. The presence of maloc-clusion and crowding in the dental recordsuggests that the attrition, although heavy,was inadequate to provide sufficient spacefor the eruption of teeth later in the dentalsequence.

CONCLUSION

The pattern and severity of dental attri-tion within the Broadbeach adult male popu-lation indicates a diet that was not marine-dependent. Periapical pathology caused bywear has been associated with hunter-gatherer populations (Jurmain, 1990). Therate and amount of antemortem tooth lossand alveolar bone loss together with a rela-tively low incidence of caries (Table 1) pro-vide evidence to support a hunting andgathering diet with a significant marinecontribution.

This study has differentiated the impor-tance of marine and terrestrial food in thediet of the Broadbeach Aboriginal popula-tion based on the specific patterns of dentalpathology. These findings are supported byboth historical accounts and the archaeologi-cal analysis of the original excavation site.

ACKNOWLEDGMENTS

The authors thank the Australian DentalResearch Foundation, Inc., for their sup-

Fig. 6. Thephenomenon of‘‘cruciate pulpchambers’’ wasobserved in 11.1%of molar teeth.


port. We also thank Drs. M. Cullinan, A.Forrest, and K. Romaniuk for their assis-tance and valuable discussion and Mrs. A.Ryan for practical radiographic instruction.

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TABLE 1. Adapted table of dietary related pathology among comparative populations

Samplesize

Attrition1 Caries Cyst formationAntemortem

tooth loss

Incisor/canines Premolars Molars % n % n % n

Marine-dependent dietRas El Hamra2 49 12.3% Severe 0.00 600 Multiple 600 Low-nil 600

60.7% ModerateCoastal SW Cape3

(213 # d13C # 210) 18 6 4 3 0.00 309 — — — —Hunting and gathering diet

Oakhurst3 48 6 5 3 17.7 192 — — — —Coastal SW Cape3

(218 # d13C # 215) 13 4 3 3 4.4 249 — — — —CA-Ala-3294 195 5.71 5.71 5.59 0.57 — 39 Individuals 107 — —

Mixed economy diet (pasto-ralism, fishing, andagriculture)

Umm An-Nar2 108 5 3 2 2.4 327 5.9 779 9.6 779Bronze Age Shimal2 26 4 2 2 4.6 43 — — 35. 110Iron Age Galilah2 53 3 2 1 1.2 261 — — 35.3 167Failaka2 9 — — — 5.3 207 3.9 207 1.9 207

Mixed farming dietIslamic Bahrain2 38 2 2 2 14 471 5.3 626 20.8 626Iron Age Maysar2 50 Slight/moderate — — — — — —Faraoskop3 16 6/7 4 9 8.7 138 — — — —

Intensive gardening dietBronze Age Bahrain2 75 11.4% Moderate5 13.3 308 2.1 928 31 928Iron Age Bahrain2 129 25% Moderate5 17.2 495 5.2 834 36.1 834Ras-al-Khaimah 32 6 Light/moderate 1.2 31 3 34 36.4 34Ras-al-Khaimah 52 81 Light 25 28 2.3 112 27.6 112

Broadbeach Aboriginal 36 3.8 3.4 4.4 0.8 660 5.0 1120 0.1 1,120Burial ground sample 21.2% Severe 26 Individuals 36

34.9% Moderate1 Molnar, 1971.2 Littleton and Frohlich, 1993.3 Sealy et al., 1992.4 Jurmain, 1990.5 Pronounced to extreme attrition on the anterior teeth and slight on the posterior teeth.


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Radiographic study of the Broadbeach Aboriginal dentition