AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 85:293-298 (1991)
Tooth Dislocation: The Relationship With Tooth Wear and Dental Abscesses NIGEL G. CLARKE AND ROBERT S. HIRSCH Department of Dentistry, University of Adelaide, Adelaide, South Australia 5000
Attrition, Tooth tilting, Abscesses
KEY WORDS
ABSTRACT Tooth dislocation (tilting) was recorded in 1,200 skulls from 34 museum collections. The findings of dislocation by tooth type, tooth wear, and abscess location are presented. A model for dislocation based upon the progressive loss of tooth support provides a rational explanation for the phenomenon. Physiological continuous tooth eruption was considered to account for a component of the progressive loss of tooth attachment. The process of attrition, pulp perforation, and dental abscess cavity formation resulted in further, more severe loss of tooth support. Heavy functional forces, in association with greatly reduced bone support, tilted the crown lingually and root buccally. When the tooth had tilted to such an extent that the root apices protruded from the bone and, presumably (in life) through the gingival/ mucosal tissues, the infected root canals were effectively isolated from the internal environment. The tooth continued to function. The more typical consequence of severe attrition and dental abscess formation was tooth loss; it also isolated an infected tooth from living tissue, but without the benefit of retaining function. A dislocated tooth has the crown tilted lingually and the root apices tilted buccally. The occlusal surface of a fully dislocated tooth lies at 90” to the occlusal plane. Dislocation is unusual in contemporary societies, but appears to have been more common in earlier populations. In the beginning of this century, some writers inferred that a relationship existed between dislocation, tooth wear, and dental abscesses. “All the teeth subject to dislocation have had the ulp chamber opened through attrition, an the subsequent alveolar abscesses have destroyed a portion of the external alveolar plate, thus considerably weakening it” (Pickerill, 1912). Ruffer (1920) sug ested that suppuration had destroyed the a veoli of dislocated teeth, allowing them to yield to applied forces and be pushed into an aberrant position. Leigh ( 1925)proposed a quasi-physiological rocess in which senile osteoporosis was glamed for the loss of buccal plate and exfoliation of the teeth, with the a ices protruding through the facial plate. aylor (1963) noted that apical abscesses most commonly
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@ 1991 WILEY-LISS, INC.
formed sinuses in the buccal late of the alveolus, which he considered toYle an essential factor in dislocation. Reinhardt (1983) proposed a model to account for dislocation in which severe attrition was an integral component, with pulp necrosis and abscessing said to cause gradual exfoliation of the necrotic tooth. Bruxism, triggered by the modified occlusal relationships, was considered to be the major factor accounting for the continuing attrition and dislocation (Reinhardt, 1983). The purpose of the present study is to re-examine the relationship between severe tooth attrition, dental abscess formation, and dislocation. A new h othesis is offered for the initiation and deve opment of dislocation.
YP
MATERIALS AND METHODS
Skull selection Approximately 3,200 adult skulls from 34 museum collections in locations previously Received September 12,1990; accepted January 17,1991.
294
N.G. CLARKE M D R.S. HIRSCH
reported (Clarke et al., 1986) provided data for the present paper. Where possible, approximately forty skulls with the re uired degree of dental disease were selecte from each population. Criteria for inclusion of a skull in the study required one or more of the following characteristics: severe tooth wear, dislocation, caries, horizontal loss of margnal bone (periodontitis), and dental abscess cavities classified as angular marginal loss of bone, furcation lesions, apical lesions, and lateral eriodontal defects (Clarke, 1990).All sku 1s with dislocated teeth were included in the study. Given that there is a correlation between advanced age and the development of chronic dental diseases, it is probable that the measured skulls were among the older members of each group as they had maximally developed pathology for the group, The actual age at death for most of the subjects was not known; therefore it is not possible to compare the distribution of dislocation between grou s by age. The potential for variation in t e average age at death among the various cultural groups may have been considerable. The data reorted in the present aper were derived from the subset of sku 1s which had tooth dislocation.
Tooth assessment Attrition. The degree of tooth attrition was measured using the Davies and Pedersen (1955) method modified by Lavelle (1973). Each tooth was graded into one of four categories: TW 1-attrition of enamel only; TW 2-attrition of both enamel and dentin; TW 3-attrition involving secondary dentin; TW &exposure of the pulp chamber by attrition. Dislocation. Dislocation was identified when the crown of a tooth was tilted linally, leavin the root pointing buccally Fig. 1).Both t e crown and roots of a dislocated tooth have rotated out of alignment with adjacent teeth in the arch. Many of the teeth were fully dislocated, 1 ing at right angles to their origmal vertica axis.
Fig. 1. Portion of a mandible of a n Australian aboriginal skull with a first molar which has rotated through approximately 90" to the occlusal plane. The crown has tilted toward the tongue and the roots toward the cheek. The polished occlusal surface which extends from the crown margin to the root apices demonstrates that
the entire tooth length was in function. The wear into the canals of the root surface probably indicates that the tooth had been functioning in this position for an extended period. The remaining alveolar support was free of periodontitis or other athologcal change. The tooth appeared to be stable anicapable of further service.
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Classification of dental abscess cavitation A classification and illustration of dental abscess cavities was based on the location of the defect within the alveolar bone adjacent to the tooth root (Clarke 1990). Periapical abscess cavity (PA)-perfora-
295
TOOTH DISLOCATION
tion of the cortical plate to form a localized area of bone destruction at the root apex. Complex abscess cavity (CAkangular (vertical) defects alone or in combination with furcation defects and apical abscess cavities. Apical abscess cavities extending through the periodontal structures to the alveolar crest were included in this category. Furcation abscess cavities (FA)-alveolar damage limited to bone in the root fork. The defects were differentiated for dental or non-dental etiology (tumours, cysts, etc.). On1 dental defects were recorded in this stu y. Non-dental defects were rarely encountered in the jaws examined.
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RESULTS
Dislocation by population groups Dislocation was observed in 23 of the 34 population groups of skulls examined (Table 1). The proportion of dislocated teeth varied eatly, ranging from 0.1% in Bolivian gcasica, Romano-British Poundbura and Romano-French Maule to 4.2% in aoris (Auckland). Overall, approximately 1.2% (265121,7691 of teeth examined in the 23 populations were dislocated. Single-tooth dislocations were predominant (96 skulls); two, three, and four dislocations were found
in 50, 9, and 7 skulls, respectively. Three skulls had five or more dislocated teeth. The grou s demonstrating severe attrition had more islocation than groups where attrition was less severe. Multiple dislocations were predominantly found in New Zealand Maoris, Australian Aboriginals, and to a lesser extent, in the Eskimos. The pattern of dislocation in cultural groups with lesser attrition varied widely among groups and among subjects within the group.
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Dislocation by tooth type The maxillary first molar was the most commonly dislocated tooth (6.2%of all maxillary M1 were dislocated); 42.3%of all dislocations were in the maxillary first molar tooth (Table 2). The mandibular first molar was the second most common tooth to dislocate (5.3% of all mandibular first molars were dislocated; 30.9% of all dislocations were mandibular first molars). At least one dislocated example was found for other tooth types, except for the maxillary third molar and the maxillary lateral incisor. First molars, mandibular second molars, and maxillary second premolars comprised 84% of the total dislocations.
TABLE 1. Dislocation by population groups Teeth Normal Populations Australian Aboriginal (S.A.) Grasshopper Indian USA Woodland Indian USA Eskimo Tananuk Alaska Egyptian XI1 Dynasty Peru Chicama Mexico Yucatan Bolivia Sicasica Hungary Kexco Rom-British Poundbury Egyptian Hawara 200 AD Ram-French Maule Eskimo Greenland Rom-Danish 300 BC Egyptian Nubia 350 AD Denmark OM 800 AD Czech Ducova Mid Ages Czech Rajarad 900 AD Israel Jerusalem (unknown) S. African Bantu Modern N. Zealand Maori Auckland N. Zealand Maori Dunedin Australian Aboriginal (Canberra) Total
n
‘81
1,461 1,104 1,086 1,082 715 687 1,036 289 1,053 1,084 532 776 595 986 832 1,253 875 1,146 364 1,390 966 991 1,204 21,507
98.2 99.8 98.9 98.6 97.5 99.5 99.8 99.9 99.7 99.9 97.9 99.6 98.6 98.7 99.5 99.2 99.3 99.4 99.7 99.7 95.6 96 96.7 98.8
Total Dislocated n w
Teeth n
Skulls n
26 2
1.7 0.2
11
1
11 18 3 2 1 3
1,487 1,106 1,097 1,093 733 690 1,038 287 1,056 1,085 543 777 603 999 836 1,263 88 1 1,152 365 1,393 1,008 1,032 1,245 21,769
51 50 40 40 32 47 39 20 40 40 20 54 22 37 32 42 33 40 16 50 46 53 40 884
1
1 2.4 0.5 0.2 0.1 0.3 0.1 2.1 0. I
8
1.3
13 4 10 6 6 1
1.3 0.4 0.1 0.7 0.5 0.3 0.3 4.2 4 3.3 1.2
1 11
3 42 41 41 265
296
N.G. CLARI(E AND R.S. HIRSCH
Dislocation by tooth wear A strong relationship was found between dislocation and tooth wear. The ulp chamber was ex osed (TW4) in more t an half of the 265 disfocated teeth (53.2%);27.5%were associated with category TW3 (severe wear into reparative dentin). Wear into dentine (TW2) was associated with 5.2% of dislocations and the least attrition (TW1)was associated with 14% of the dislocated teeth (Table 3). Dislocation and abscess cavitation Abscess cavities were detected on 192 of the 265 dislocated teeth (Table 4).The status
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TABLE 2. Dislocation for given tooth type Tooth Type Maxilla Premolar PM2 Molar M1 Mandible Molar M1 Molar M2 Other teeth Total
Normal n %
Dislocated n %
Total
2062 1706
99.3 93.8
15 112
0.7 6.2
2077 1818
1467 1631
94.7 96.8 96.8
5.3 1.2 14 3.2
1549 1650
6866
82 19 37 265
of the remaining teeth was difficult to determine because, in a fully dislocated tooth, the root apices had perforated the buccal late of bone. The dislocation then providecfconditions for repair and resolution of any abscess cavitation. However, assuming an unknown abscess status for the 73 unassessable teeth, the data, using a chi-square test of homogeneity, show that there was a very high association between abscess formation and dislocation (P < .001). DISCUSSION
Examination of dislocated teeth suggests that the process of dislocation has a relatively simple natural history based upon the loss of tooth attachment to the alveolus. The physiological process of continuous tooth eruption (CTE) results in steady, progressive loss of attachment, while catastrophic loss of supporting alveolar bone can occur as a result of infection of the pul and the subsequent development of bone estruction at any or all sectors of the alveolus. Attrition may be viewed as a central factor in both the physiological and patholo ical components of periodontal attachment oss.
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TABLE 3. Dislocation by category of tooth wear Populations Australian Aboriginal (S.A.) Grasshopper Indian USA Woodland Indian USA Eskimo Tananuk Alaska Egyptian XI1 Dynasty Peru Chicama Mexico Yucatan Bolivia Sicasica Hungary Kexco Rom-British Poundhury Egyptian Hawara 200 AD Rom-French M a d e Eskimo Greenland Rom-Danish 300 BC Egyptian Nuhia 350 AD Denmark OM 800 AD Czech Ducova Mid Ages Czech Rajarad 900 AD Israel J’salem (unknown) S. African Bantu Modern N. Zealand Maori Auckland N. Zealand Maori Dunedin Australian Aboriginal (Canberra) Total %
TW1 n
TW2 n
TW3 n
TW4 n
Total n
4
22
26 2
4 5 8 2
4 5 5
11
2 2 1 4
1
1
1 1
1
2
1 1
2
3
3
1
1 1
5 1 4
1
5 1 3 4 1
2 1 2
1
12 4.5
7 7 11 73 27.5
11
5 3 39 14.7
2
11 18 3 1 3 1 11 1
1 8 3 7 2 1 24 29 27 141 53.2
8 13 4 10 6 6 1 3 42 41 41 265 100
297
TOOTH DISLOCATION TABLE 4. Dislocation by abscess type and tooth wear Normal
Abscess
21 8 32 12 73
18 4 41 129 192
TW1 TW2 TW3 TW4 Total
Total 39 12 73 141
265
Dislocation and the physiological effects of attrition Two types of physiological change are intimately related to a physiological loss of periodontal attachment (for a review, see Clarke and Hirsch, 1991). Compensatory vertical tooth movement maintains the face height where there is loss of tooth structure from attrition (Murphy, 1959; Barker, 1975). Compensatory tooth movement is also required to maintain articulation as a result of growth of the cranial structures, a process that continues into the sixth decade of life (Behrents, 1985). Slow, continuous tooth eruption throughout life tends to maintain the clinical crown height, but at the ex ense of bone-su ported root length (Whitta er et al., 1985; anenberg et al., in press). CTE results in a proximately 0.07 mm of reduced tooth attac ment er year, even where attrition is minimal (&ittaker et al., 1990). In this study, approximate1 80% of dislocated teeth demonstrated eit er severe occlusal attrition or an occlusal exposure of the pulp. This finding agrees with Ruffer (19201, who observed that attrition was associated with dislocation in which tooth roots, comletel denuded of bone, tilted toward the ucca side and displaced the crown lingually. Taylor (1963) observed that attrition was compensated for by continuous tooth eruption. He also recognized that alveolar abscesses were most frequently found in the buccal plate, and that they were an essential feature in the development of a dislocation. However, he did not associate continuous tooth eruption (and the concomitant loss of periodontal attachment) with the development of abscesses as co-factors in the reduction of tooth support leading to the dislocation process. The diminished socket length, shortened as a result of active eru tion for tooth wear pounds the effect of of bone.
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Dislocation and the pathological effects of attrition Reinhardt (1983)proposed that a force and disease feedback loop were in operation for the severe attrition which was an integral component in dislocation. Pulp necrosis and abscessing were suggested to cause gradual exfoliation of the necrotic tooth. However, Reinhardt considered bruxism, triggered by the modified occlusal relationships, to be the major factor accounting for the continuing attrition and dislocation. Despite the many assertions in the dental literature that there is a relationship between occlusal interferences and the masticator parafunction of bruxism, no such relations ip has been demonstrated. Moreover, although the physiology of sleep is understood to involve a reduction in peripheral nervous system awareness during sleep, the assertion that occlusal relationships trigger bruxism depends on the contradictory concept of a heightened eripheral awareness. There is considera le evidence to show that bruxism is of central, rather than peripheral nervous origm (Clarke and Townsend, 1984). Perhaps the force-diseaseloop of Reinhardt (1983)should be replaced by a ph siological loop, and the disease loop shoul be modified after the sta e of pul exposure. &en p u k exposure occurs, it inevitably results in infection of the endodontic space and in the formation of a dental abscess cavity (Linn et al., 1987). Su porting bone ma be destro ed at the toot neck in the earyy phase o coronal pulpitis (Kelly and Ellin er, 1988). After the development of an alveo ar abscess at the root apex, it may extend toward the tooth crown along the eriodontal structures within the spongy gone adjacent to the periodontal li ament (Walton and Garnick, 1986). Comp ex abscess cavities involving the loss of considerable tooth-supportin bone may result when apical abscesses com ine with abscess cavities that had formed earlier in the history of the pulpal pathosis at more coronal locations (e. furcalions). t h e buccal plate of bone is lost as a result of inflammation within the dental D U ~ D in. ducing inflammatory changes in the xdjacent periodontal ligament, and cortical buccal bone. The loss of buccal bone probably reduces the resistance ofthe periodontium to functional forces applied to teeth. Therefore, dislocation would seem to be dependent upon the loss of tooth attachment as a result of
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298
N.G. CLARKE AND R.S. HIRSCH
buccal alveolar bone from the alveolar crest to the root apex. Cultural practices in which the teeth are used as tools for various pur oses may result in heavy tooth wear; and t e forces generated cause lingual pressure on the crown and tilt the roots toward the buccal mucosa (Osborn, 1982). Continued functional loads result in continued tilting until the tooth reaches a horizontal position with the entire root and buccal crown length in occlusal function (Fig. 1).The root a ex tilts buccally and moves outside of the a veolar structure and the mucosa. The root apex is then external to the host tissues, and at that stage irritation to the host can no longer occur as a result of endodontic infection. Although the attachment of dislocated teeth is greatly reduced compared with normal teeth, the polished functional surfaces often seen from crown tip to root a ex show that the dislocated tooth continue Ep to function (Fig. l), even under the heavy load conditions which initiated the original tilting. Dislocation probably represents the best possible dental adaptation t o a sequence of events that usually lead to severe loss of tooth attachment, progressive mobility, and exfoliation. Thus, dislocation may actual1 represent an advantage, because tilting e fectively shields the remainin supporting structure of the tooth from t e source of irritation in the endodontic canal. The dislocated teeth observed in this study appeared to be stable with good integrity of the suporting bone on the remaining attached surrace of the tooth. Dislocation appears to provide a satisfactory outcome for the natural progression of attrition, perforation, abscess develo ment, and loss of tooth support. Most teeth, owever, are lost as a consequence of the combined loss of attachment from physi010 'cal and pathological causes. They do not dis aocate and are lost when the remaining attachment is insufficient to maintain function.
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LITERATURE CITED Barker BCW (1975) Relation of the alveolus to the cemento-enameljunction following attritional wear in aboriginal skulls. J. Periodontol. 46:357-363.
Behrents RG (1985) Growth in the Ageing Craniofacial Skeleton. Monograph 17: Craniofacial Growth Series, Center for Human Growth and Development. Ann Arbor: The University of Michigan, pp. 110-111. Clarke NG (1990) Periodontal defects of pul al origin: Evidence in early man. Am. J. Phys. k t h r o p o l . 82~371-376. Clarke NG, and Hirsch RS (1991) Physiolo 'cal pulpal and eriodontal factors influencin alveoyar done. In CS t a r s e n and M Kelly (eds.): Aivances in Dental Anthropology. New York: Alan R. Liss, pp 241-266. Clarke NG, and Townsend G (1984) Distribution of nocturnal bruxism in man. J. Oral Rehabilitation 11.529-534. Clarke NG, Carey SE, Srikandi W, Hirsch RS, and Leppard PI (1986) Periodontal disease in ancient populations. Am. J. Phys. Anthropol. 71:173-183. Danenberg PJ, Hirsch RS, Clarke NG, Leppard PI, and Richards LC (in press) Continuous tooth eruption in Australian aborigmal skulls. Am. J. Phys. Anthropol. Davies TGH, and Pedersen PD (19551 The degree of attrition ofthe first permanent molars of the primitive and urbanised Greenland natives. Brit. Dent. J. 99:35-43. Kelly WH, and Ellinger RF (1988) Pulpal-periradicular pathosis causing sinus tract formation through the periodontal ligament of adjacent teeth. J. Endodontics 14:251-257. Lavelle CLB (1973)Alveolarbone loss and tooth attrition in skulls from different populations. J. Periodontal Research 8:395-399. Leigh RW (1925)Dental pathology of the Eskimo. Dent. Cosmos 67:884-898. Linn J, Srikandi W, Clarke NG, and Smith T (1987) Radiographic and visual assessment of alveolar pathology in first molars in dry skulls. J. Phys. Anthropol. 72:5 15-52 1. Murphy J 11959) Compensatory mechanisms in facial height adjustment to functional tooth attrition. Aust. Dent. J. 4:312-323. Osborne JW (19821Helicoidal plane of dental occlusion. Am. J. Phys. Anthropol. 57:273-281. Pickerill HP (1912) Some atholo ical conditions found in the teeth and jaws of haori sfulls in New Zealand. Med. 5:155-165. Proc. Roy. SOC. Reinhardt GA (19831 Relationships between attrition and lingual tilting in human teeth. Am. J. Phys. Anthropol. 61:227-237. Ruffer A (1920) Study of abnormalities and pathology of ancient Egyptian teeth. Am. J. Phys. Anthropol. 3:335-382. Ta lor RMS (1963) Cause and effect of wear of teeth. Kcta Anat. 53:97-157. Walton RE, and Garnick JJ (1986) The histology of periapical inflammatory lesions in permanent molars in monkeys. J. Endodontics 12:49-53. Whittaker DK, Molleson T, Daniel AT, Williams JT, Rose P, and Resteghini R (1985)Quantitative assessment of tooth wear, alveolar crest height and continuing eruption in a Romano-British population. Arch. oral Biol. 30t493-501. Whittaker DK, Griffiths S, Robson A, Roger-Davies P, Thomas G, and Molleson T (1990) Continuing tooth eruption and alveolar crest height in an eighteenthcentury population from Spitalfields, East London. Arch. oral Biol. 35:81-85.
Tooth Dislocation: The Relationship With Tooth Wear and Dental Abscesses NIGEL G. CLARKE AND ROBERT S. HIRSCH Department of Dentistry, University of Adelaide, Adelaide, South Australia 5000
Attrition, Tooth tilting, Abscesses
KEY WORDS
ABSTRACT Tooth dislocation (tilting) was recorded in 1,200 skulls from 34 museum collections. The findings of dislocation by tooth type, tooth wear, and abscess location are presented. A model for dislocation based upon the progressive loss of tooth support provides a rational explanation for the phenomenon. Physiological continuous tooth eruption was considered to account for a component of the progressive loss of tooth attachment. The process of attrition, pulp perforation, and dental abscess cavity formation resulted in further, more severe loss of tooth support. Heavy functional forces, in association with greatly reduced bone support, tilted the crown lingually and root buccally. When the tooth had tilted to such an extent that the root apices protruded from the bone and, presumably (in life) through the gingival/ mucosal tissues, the infected root canals were effectively isolated from the internal environment. The tooth continued to function. The more typical consequence of severe attrition and dental abscess formation was tooth loss; it also isolated an infected tooth from living tissue, but without the benefit of retaining function. A dislocated tooth has the crown tilted lingually and the root apices tilted buccally. The occlusal surface of a fully dislocated tooth lies at 90” to the occlusal plane. Dislocation is unusual in contemporary societies, but appears to have been more common in earlier populations. In the beginning of this century, some writers inferred that a relationship existed between dislocation, tooth wear, and dental abscesses. “All the teeth subject to dislocation have had the ulp chamber opened through attrition, an the subsequent alveolar abscesses have destroyed a portion of the external alveolar plate, thus considerably weakening it” (Pickerill, 1912). Ruffer (1920) sug ested that suppuration had destroyed the a veoli of dislocated teeth, allowing them to yield to applied forces and be pushed into an aberrant position. Leigh ( 1925)proposed a quasi-physiological rocess in which senile osteoporosis was glamed for the loss of buccal plate and exfoliation of the teeth, with the a ices protruding through the facial plate. aylor (1963) noted that apical abscesses most commonly
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5
@ 1991 WILEY-LISS, INC.
formed sinuses in the buccal late of the alveolus, which he considered toYle an essential factor in dislocation. Reinhardt (1983) proposed a model to account for dislocation in which severe attrition was an integral component, with pulp necrosis and abscessing said to cause gradual exfoliation of the necrotic tooth. Bruxism, triggered by the modified occlusal relationships, was considered to be the major factor accounting for the continuing attrition and dislocation (Reinhardt, 1983). The purpose of the present study is to re-examine the relationship between severe tooth attrition, dental abscess formation, and dislocation. A new h othesis is offered for the initiation and deve opment of dislocation.
YP
MATERIALS AND METHODS
Skull selection Approximately 3,200 adult skulls from 34 museum collections in locations previously Received September 12,1990; accepted January 17,1991.
294
N.G. CLARKE M D R.S. HIRSCH
reported (Clarke et al., 1986) provided data for the present paper. Where possible, approximately forty skulls with the re uired degree of dental disease were selecte from each population. Criteria for inclusion of a skull in the study required one or more of the following characteristics: severe tooth wear, dislocation, caries, horizontal loss of margnal bone (periodontitis), and dental abscess cavities classified as angular marginal loss of bone, furcation lesions, apical lesions, and lateral eriodontal defects (Clarke, 1990).All sku 1s with dislocated teeth were included in the study. Given that there is a correlation between advanced age and the development of chronic dental diseases, it is probable that the measured skulls were among the older members of each group as they had maximally developed pathology for the group, The actual age at death for most of the subjects was not known; therefore it is not possible to compare the distribution of dislocation between grou s by age. The potential for variation in t e average age at death among the various cultural groups may have been considerable. The data reorted in the present aper were derived from the subset of sku 1s which had tooth dislocation.
Tooth assessment Attrition. The degree of tooth attrition was measured using the Davies and Pedersen (1955) method modified by Lavelle (1973). Each tooth was graded into one of four categories: TW 1-attrition of enamel only; TW 2-attrition of both enamel and dentin; TW 3-attrition involving secondary dentin; TW &exposure of the pulp chamber by attrition. Dislocation. Dislocation was identified when the crown of a tooth was tilted linally, leavin the root pointing buccally Fig. 1).Both t e crown and roots of a dislocated tooth have rotated out of alignment with adjacent teeth in the arch. Many of the teeth were fully dislocated, 1 ing at right angles to their origmal vertica axis.
Fig. 1. Portion of a mandible of a n Australian aboriginal skull with a first molar which has rotated through approximately 90" to the occlusal plane. The crown has tilted toward the tongue and the roots toward the cheek. The polished occlusal surface which extends from the crown margin to the root apices demonstrates that
the entire tooth length was in function. The wear into the canals of the root surface probably indicates that the tooth had been functioning in this position for an extended period. The remaining alveolar support was free of periodontitis or other athologcal change. The tooth appeared to be stable anicapable of further service.
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Classification of dental abscess cavitation A classification and illustration of dental abscess cavities was based on the location of the defect within the alveolar bone adjacent to the tooth root (Clarke 1990). Periapical abscess cavity (PA)-perfora-
295
TOOTH DISLOCATION
tion of the cortical plate to form a localized area of bone destruction at the root apex. Complex abscess cavity (CAkangular (vertical) defects alone or in combination with furcation defects and apical abscess cavities. Apical abscess cavities extending through the periodontal structures to the alveolar crest were included in this category. Furcation abscess cavities (FA)-alveolar damage limited to bone in the root fork. The defects were differentiated for dental or non-dental etiology (tumours, cysts, etc.). On1 dental defects were recorded in this stu y. Non-dental defects were rarely encountered in the jaws examined.
d
RESULTS
Dislocation by population groups Dislocation was observed in 23 of the 34 population groups of skulls examined (Table 1). The proportion of dislocated teeth varied eatly, ranging from 0.1% in Bolivian gcasica, Romano-British Poundbura and Romano-French Maule to 4.2% in aoris (Auckland). Overall, approximately 1.2% (265121,7691 of teeth examined in the 23 populations were dislocated. Single-tooth dislocations were predominant (96 skulls); two, three, and four dislocations were found
in 50, 9, and 7 skulls, respectively. Three skulls had five or more dislocated teeth. The grou s demonstrating severe attrition had more islocation than groups where attrition was less severe. Multiple dislocations were predominantly found in New Zealand Maoris, Australian Aboriginals, and to a lesser extent, in the Eskimos. The pattern of dislocation in cultural groups with lesser attrition varied widely among groups and among subjects within the group.
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Dislocation by tooth type The maxillary first molar was the most commonly dislocated tooth (6.2%of all maxillary M1 were dislocated); 42.3%of all dislocations were in the maxillary first molar tooth (Table 2). The mandibular first molar was the second most common tooth to dislocate (5.3% of all mandibular first molars were dislocated; 30.9% of all dislocations were mandibular first molars). At least one dislocated example was found for other tooth types, except for the maxillary third molar and the maxillary lateral incisor. First molars, mandibular second molars, and maxillary second premolars comprised 84% of the total dislocations.
TABLE 1. Dislocation by population groups Teeth Normal Populations Australian Aboriginal (S.A.) Grasshopper Indian USA Woodland Indian USA Eskimo Tananuk Alaska Egyptian XI1 Dynasty Peru Chicama Mexico Yucatan Bolivia Sicasica Hungary Kexco Rom-British Poundbury Egyptian Hawara 200 AD Ram-French Maule Eskimo Greenland Rom-Danish 300 BC Egyptian Nubia 350 AD Denmark OM 800 AD Czech Ducova Mid Ages Czech Rajarad 900 AD Israel Jerusalem (unknown) S. African Bantu Modern N. Zealand Maori Auckland N. Zealand Maori Dunedin Australian Aboriginal (Canberra) Total
n
‘81
1,461 1,104 1,086 1,082 715 687 1,036 289 1,053 1,084 532 776 595 986 832 1,253 875 1,146 364 1,390 966 991 1,204 21,507
98.2 99.8 98.9 98.6 97.5 99.5 99.8 99.9 99.7 99.9 97.9 99.6 98.6 98.7 99.5 99.2 99.3 99.4 99.7 99.7 95.6 96 96.7 98.8
Total Dislocated n w
Teeth n
Skulls n
26 2
1.7 0.2
11
1
11 18 3 2 1 3
1,487 1,106 1,097 1,093 733 690 1,038 287 1,056 1,085 543 777 603 999 836 1,263 88 1 1,152 365 1,393 1,008 1,032 1,245 21,769
51 50 40 40 32 47 39 20 40 40 20 54 22 37 32 42 33 40 16 50 46 53 40 884
1
1 2.4 0.5 0.2 0.1 0.3 0.1 2.1 0. I
8
1.3
13 4 10 6 6 1
1.3 0.4 0.1 0.7 0.5 0.3 0.3 4.2 4 3.3 1.2
1 11
3 42 41 41 265
296
N.G. CLARI(E AND R.S. HIRSCH
Dislocation by tooth wear A strong relationship was found between dislocation and tooth wear. The ulp chamber was ex osed (TW4) in more t an half of the 265 disfocated teeth (53.2%);27.5%were associated with category TW3 (severe wear into reparative dentin). Wear into dentine (TW2) was associated with 5.2% of dislocations and the least attrition (TW1)was associated with 14% of the dislocated teeth (Table 3). Dislocation and abscess cavitation Abscess cavities were detected on 192 of the 265 dislocated teeth (Table 4).The status
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TABLE 2. Dislocation for given tooth type Tooth Type Maxilla Premolar PM2 Molar M1 Mandible Molar M1 Molar M2 Other teeth Total
Normal n %
Dislocated n %
Total
2062 1706
99.3 93.8
15 112
0.7 6.2
2077 1818
1467 1631
94.7 96.8 96.8
5.3 1.2 14 3.2
1549 1650
6866
82 19 37 265
of the remaining teeth was difficult to determine because, in a fully dislocated tooth, the root apices had perforated the buccal late of bone. The dislocation then providecfconditions for repair and resolution of any abscess cavitation. However, assuming an unknown abscess status for the 73 unassessable teeth, the data, using a chi-square test of homogeneity, show that there was a very high association between abscess formation and dislocation (P < .001). DISCUSSION
Examination of dislocated teeth suggests that the process of dislocation has a relatively simple natural history based upon the loss of tooth attachment to the alveolus. The physiological process of continuous tooth eruption (CTE) results in steady, progressive loss of attachment, while catastrophic loss of supporting alveolar bone can occur as a result of infection of the pul and the subsequent development of bone estruction at any or all sectors of the alveolus. Attrition may be viewed as a central factor in both the physiological and patholo ical components of periodontal attachment oss.
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TABLE 3. Dislocation by category of tooth wear Populations Australian Aboriginal (S.A.) Grasshopper Indian USA Woodland Indian USA Eskimo Tananuk Alaska Egyptian XI1 Dynasty Peru Chicama Mexico Yucatan Bolivia Sicasica Hungary Kexco Rom-British Poundhury Egyptian Hawara 200 AD Rom-French M a d e Eskimo Greenland Rom-Danish 300 BC Egyptian Nuhia 350 AD Denmark OM 800 AD Czech Ducova Mid Ages Czech Rajarad 900 AD Israel J’salem (unknown) S. African Bantu Modern N. Zealand Maori Auckland N. Zealand Maori Dunedin Australian Aboriginal (Canberra) Total %
TW1 n
TW2 n
TW3 n
TW4 n
Total n
4
22
26 2
4 5 8 2
4 5 5
11
2 2 1 4
1
1
1 1
1
2
1 1
2
3
3
1
1 1
5 1 4
1
5 1 3 4 1
2 1 2
1
12 4.5
7 7 11 73 27.5
11
5 3 39 14.7
2
11 18 3 1 3 1 11 1
1 8 3 7 2 1 24 29 27 141 53.2
8 13 4 10 6 6 1 3 42 41 41 265 100
297
TOOTH DISLOCATION TABLE 4. Dislocation by abscess type and tooth wear Normal
Abscess
21 8 32 12 73
18 4 41 129 192
TW1 TW2 TW3 TW4 Total
Total 39 12 73 141
265
Dislocation and the physiological effects of attrition Two types of physiological change are intimately related to a physiological loss of periodontal attachment (for a review, see Clarke and Hirsch, 1991). Compensatory vertical tooth movement maintains the face height where there is loss of tooth structure from attrition (Murphy, 1959; Barker, 1975). Compensatory tooth movement is also required to maintain articulation as a result of growth of the cranial structures, a process that continues into the sixth decade of life (Behrents, 1985). Slow, continuous tooth eruption throughout life tends to maintain the clinical crown height, but at the ex ense of bone-su ported root length (Whitta er et al., 1985; anenberg et al., in press). CTE results in a proximately 0.07 mm of reduced tooth attac ment er year, even where attrition is minimal (&ittaker et al., 1990). In this study, approximate1 80% of dislocated teeth demonstrated eit er severe occlusal attrition or an occlusal exposure of the pulp. This finding agrees with Ruffer (19201, who observed that attrition was associated with dislocation in which tooth roots, comletel denuded of bone, tilted toward the ucca side and displaced the crown lingually. Taylor (1963) observed that attrition was compensated for by continuous tooth eruption. He also recognized that alveolar abscesses were most frequently found in the buccal plate, and that they were an essential feature in the development of a dislocation. However, he did not associate continuous tooth eruption (and the concomitant loss of periodontal attachment) with the development of abscesses as co-factors in the reduction of tooth support leading to the dislocation process. The diminished socket length, shortened as a result of active eru tion for tooth wear pounds the effect of of bone.
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Dislocation and the pathological effects of attrition Reinhardt (1983)proposed that a force and disease feedback loop were in operation for the severe attrition which was an integral component in dislocation. Pulp necrosis and abscessing were suggested to cause gradual exfoliation of the necrotic tooth. However, Reinhardt considered bruxism, triggered by the modified occlusal relationships, to be the major factor accounting for the continuing attrition and dislocation. Despite the many assertions in the dental literature that there is a relationship between occlusal interferences and the masticator parafunction of bruxism, no such relations ip has been demonstrated. Moreover, although the physiology of sleep is understood to involve a reduction in peripheral nervous system awareness during sleep, the assertion that occlusal relationships trigger bruxism depends on the contradictory concept of a heightened eripheral awareness. There is considera le evidence to show that bruxism is of central, rather than peripheral nervous origm (Clarke and Townsend, 1984). Perhaps the force-diseaseloop of Reinhardt (1983)should be replaced by a ph siological loop, and the disease loop shoul be modified after the sta e of pul exposure. &en p u k exposure occurs, it inevitably results in infection of the endodontic space and in the formation of a dental abscess cavity (Linn et al., 1987). Su porting bone ma be destro ed at the toot neck in the earyy phase o coronal pulpitis (Kelly and Ellin er, 1988). After the development of an alveo ar abscess at the root apex, it may extend toward the tooth crown along the eriodontal structures within the spongy gone adjacent to the periodontal li ament (Walton and Garnick, 1986). Comp ex abscess cavities involving the loss of considerable tooth-supportin bone may result when apical abscesses com ine with abscess cavities that had formed earlier in the history of the pulpal pathosis at more coronal locations (e. furcalions). t h e buccal plate of bone is lost as a result of inflammation within the dental D U ~ D in. ducing inflammatory changes in the xdjacent periodontal ligament, and cortical buccal bone. The loss of buccal bone probably reduces the resistance ofthe periodontium to functional forces applied to teeth. Therefore, dislocation would seem to be dependent upon the loss of tooth attachment as a result of
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298
N.G. CLARKE AND R.S. HIRSCH
buccal alveolar bone from the alveolar crest to the root apex. Cultural practices in which the teeth are used as tools for various pur oses may result in heavy tooth wear; and t e forces generated cause lingual pressure on the crown and tilt the roots toward the buccal mucosa (Osborn, 1982). Continued functional loads result in continued tilting until the tooth reaches a horizontal position with the entire root and buccal crown length in occlusal function (Fig. 1).The root a ex tilts buccally and moves outside of the a veolar structure and the mucosa. The root apex is then external to the host tissues, and at that stage irritation to the host can no longer occur as a result of endodontic infection. Although the attachment of dislocated teeth is greatly reduced compared with normal teeth, the polished functional surfaces often seen from crown tip to root a ex show that the dislocated tooth continue Ep to function (Fig. l), even under the heavy load conditions which initiated the original tilting. Dislocation probably represents the best possible dental adaptation t o a sequence of events that usually lead to severe loss of tooth attachment, progressive mobility, and exfoliation. Thus, dislocation may actual1 represent an advantage, because tilting e fectively shields the remainin supporting structure of the tooth from t e source of irritation in the endodontic canal. The dislocated teeth observed in this study appeared to be stable with good integrity of the suporting bone on the remaining attached surrace of the tooth. Dislocation appears to provide a satisfactory outcome for the natural progression of attrition, perforation, abscess develo ment, and loss of tooth support. Most teeth, owever, are lost as a consequence of the combined loss of attachment from physi010 'cal and pathological causes. They do not dis aocate and are lost when the remaining attachment is insufficient to maintain function.
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LITERATURE CITED Barker BCW (1975) Relation of the alveolus to the cemento-enameljunction following attritional wear in aboriginal skulls. J. Periodontol. 46:357-363.
Behrents RG (1985) Growth in the Ageing Craniofacial Skeleton. Monograph 17: Craniofacial Growth Series, Center for Human Growth and Development. Ann Arbor: The University of Michigan, pp. 110-111. Clarke NG (1990) Periodontal defects of pul al origin: Evidence in early man. Am. J. Phys. k t h r o p o l . 82~371-376. Clarke NG, and Hirsch RS (1991) Physiolo 'cal pulpal and eriodontal factors influencin alveoyar done. In CS t a r s e n and M Kelly (eds.): Aivances in Dental Anthropology. New York: Alan R. Liss, pp 241-266. Clarke NG, and Townsend G (1984) Distribution of nocturnal bruxism in man. J. Oral Rehabilitation 11.529-534. Clarke NG, Carey SE, Srikandi W, Hirsch RS, and Leppard PI (1986) Periodontal disease in ancient populations. Am. J. Phys. Anthropol. 71:173-183. Danenberg PJ, Hirsch RS, Clarke NG, Leppard PI, and Richards LC (in press) Continuous tooth eruption in Australian aborigmal skulls. Am. J. Phys. Anthropol. Davies TGH, and Pedersen PD (19551 The degree of attrition ofthe first permanent molars of the primitive and urbanised Greenland natives. Brit. Dent. J. 99:35-43. Kelly WH, and Ellinger RF (1988) Pulpal-periradicular pathosis causing sinus tract formation through the periodontal ligament of adjacent teeth. J. Endodontics 14:251-257. Lavelle CLB (1973)Alveolarbone loss and tooth attrition in skulls from different populations. J. Periodontal Research 8:395-399. Leigh RW (1925)Dental pathology of the Eskimo. Dent. Cosmos 67:884-898. Linn J, Srikandi W, Clarke NG, and Smith T (1987) Radiographic and visual assessment of alveolar pathology in first molars in dry skulls. J. Phys. Anthropol. 72:5 15-52 1. Murphy J 11959) Compensatory mechanisms in facial height adjustment to functional tooth attrition. Aust. Dent. J. 4:312-323. Osborne JW (19821Helicoidal plane of dental occlusion. Am. J. Phys. Anthropol. 57:273-281. Pickerill HP (1912) Some atholo ical conditions found in the teeth and jaws of haori sfulls in New Zealand. Med. 5:155-165. Proc. Roy. SOC. Reinhardt GA (19831 Relationships between attrition and lingual tilting in human teeth. Am. J. Phys. Anthropol. 61:227-237. Ruffer A (1920) Study of abnormalities and pathology of ancient Egyptian teeth. Am. J. Phys. Anthropol. 3:335-382. Ta lor RMS (1963) Cause and effect of wear of teeth. Kcta Anat. 53:97-157. Walton RE, and Garnick JJ (1986) The histology of periapical inflammatory lesions in permanent molars in monkeys. J. Endodontics 12:49-53. Whittaker DK, Molleson T, Daniel AT, Williams JT, Rose P, and Resteghini R (1985)Quantitative assessment of tooth wear, alveolar crest height and continuing eruption in a Romano-British population. Arch. oral Biol. 30t493-501. Whittaker DK, Griffiths S, Robson A, Roger-Davies P, Thomas G, and Molleson T (1990) Continuing tooth eruption and alveolar crest height in an eighteenthcentury population from Spitalfields, East London. Arch. oral Biol. 35:81-85.
