Archs oral Bid. Vol.36, No. 8, pp. 553-559, 1991 Printedin Great Britain.All rightsreserved

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PREVALENCE AND DISTRIBUTION OF DENTAL CARIES IN A LATE MEDIEVAL POPULATION IN FINLAND TIINA M. VARRELA Institute of Dentistry, University of Turku, Lemminklisenkatu (Accepted

2, SF-20500 Turku, Finland

27 March 1991)

Summary-The aim was to document the late medieval material and to compare the results with findings in other medieval populations and present-day Finns. The sample consisted of the remains of 410 individuals and included 4581 permanent and 600 deciduous teeth. Age determination was based on the stage of dental development and on the attrition pattern in the molar region. Scoring the presence and location of caries was done visually with the aid of a dental probe. In the younger age groups, caries was most prevalent in the occlusal fissures, but the proportion of cavities at these sites declined with age, possibly because occlusal attrition progressed more rapidly than did caries. In the permanent dentition, carious lesions were most frequently observed at the cementum-enamel junction, particularly on the approximal surfaces. The prevalence of caries was lower than among modern populations of similar ages. In addition, the relative distribution of caries was strikingly different, with root caries being the most common type. Key words: palaeontology, caries, epidemiology, attrition.

INTRODUCTION Dental caries is considered to be an infectious disease of multifactorial aetiology determined by interactions between the host, microflora, substrate and time (Keyes, 1962; Newburn, 1978). Studies of skeletal material show that caries is as old as man and universal (Begg, 1954; Clement, 1956; Robinson, 1952). The prevalence and distribution of caries show considerable variation throughout the ages but, without exception, its prevalence has been lower than it is today (Brinch and M(iller-Christensen, 1949; Clement, 1956; Molnar and Molnar, 1985; Moore and Corbett, 1971, 1973, 1975; Sognnas, 1956; Whittaker et al., 1981). A strong correlation between diet and dental caries has been shown by several studies (Bibby, 1981; Brothwell, 1959; Corbett and Moore, 1976; Davies and Picton, 1963; Gustafsson, 1954; Hardwick, 1960; Theilade and Birkhed, 1986). The present high prevalence of caries is a consequence of change in diet during the nineteenth century (Hardwick, 1960). With industrialization, food became more refined and rich in sucrose and other rapidly fermentable carbohydrates; at the same time the prevalence of caries rose markedly. In earlier human populations the site of caries has differed from that in modern material, with lesions at the cementum+namel junction or in the cementum, usually on the approximal surfaces. Occlusal fissure caries is usually found only in the younger age groups (Brdndum, 1981; Moore and Corbett 1971, 1973, 1975; Klafstad, 1978; Lunt, 1974; Olsson and Sagne, 1976; Whittaker et al., 1981). The reasons for the different sites of caries are poorly understood. Because caries produces characteristic changes that are distinguishable from other causes of tooth destruction, it is possible to investigate the occurrence of caries with a high degree of accuracy in skeletal AOB MICA

populations (Moore and Corbett, 1971). My aim was to examine the prevalence and distribution of caries in a Finnish medieval sample and to compare the results with findings in other medieval populations and present-day Finns.

MATERIALSAND

METHODS

The skeletal remains of over 600 individuals were unearthed during archaeological excavations of a cemetery used from the late medieval period until 1650. The main part of the sample was from the fifteenth and sixteenth centuries. The cemetery was in the centre of the town of Turku (Kykyri, 1987). Mainly poorer and Finnish-speaking citizens of Turku were buried in this cemetery (Gardberg, 1965; Laaksonen, 1965). The archaeological excavations were made in two stages, in 1964 and 1983-5. The jaws and teeth of 410 skulls were examined. The material comprised 4581 permanent teeth and 600 deciduous teeth. The number of teeth missing ante mortem was 622 (Fig. 1) and post mortem, 1300 (Fig. 2). Sex was determined for 68 females and 56 males; the sex of 286 individuals remained unknown. The distribution and prevalence of caries is therefore a pooled value for the whole population. Most of the skeletons were incomplete and many of the long bones and pelvises were so fragmented that it was not possible to use the postcranial material for sexing and ageing. The sex determination was based on the anatomy of the skull, especially on the degree of development of supraorbital ridges, nuchal crests and mastoid process and on the shape of the muscular ridges (Brothwell, 1981). The sex was estimated only if the skull was relatively intact and the individual was over 16yr old.

TIINAM. VARRELA

554

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50

Fig. 1. The prevalence of teeth missing ante mortem. In children and juveniles under 21 yr, the age determination was based on the stage of development of dentition. The tables of Haavikko (1970) for the formation of the permanent teeth in the Finnish population were used as a reference. In the other age groups the age was determined from the attrition patterns of the molars, as suggested by Miles (1963). This method has been used by other investigators, who have shown that it is reliable and valid in ageing ancient populations (Nowell, 1978; Sagne, 1976). The stage of development was judged directly by visual inspection of the tooth, if possible. Radiographs were taken if necessary. The rates of tooth wear were first established for the molars in 6-21-yr-old individuals, then the population-specific, age-attrition chart was drawn to assess the age of population over 21 yr old. For individuals under 21 yr, age could be determined to an accuracy of 1 yr. The age determination for older age groups was more complicated. It is not possible to assess the age of adults at death with as much accuracy as in the younger age groups. Especially in the older age groups, age can be determined only approximately, to an accuracy of 5-10 yr.

The dentition was examined under standardized lighting conditions by careful visual inspection with the aid of a dental probe. According to Rudney, Katz and Brand (1983), who studied the inter-observer reliability of scoring dental caries, visual inspection is the most reliable method for caries in skeletal populations. If possible, teeth were removed from the alveolus for the study. Lesions were judged to be carious if there was a detectable defect in the integrity of the enamel or cementum surface. Lesions were classified by their initiation surface and by their overall location. Examinations were made twice, by me, with a 6-month interval between. The reproducibility was good, with no difference between the two examinations. If a tooth was missing, the decision whether it had been lost ante or post mortem was based on the extent of marginal destruction of the alveolus and of periodontal bone loss. It was assumed that a tooth had been lost post mortem if there was an empty alveolus with no sign of healing. A third molar was only recorded as lost ante mortem when it had left distinct traces on its neigh-

Fig. 2. The prevalence of teeth missing post mortem.

Caries occurrence in a medieval population

555

Table 1. Criteria used for grading severity of occlusal attrition

Table 2. The distribution of caries and ante mortem tooth loss by tooth tvpe -* in the nermanent dentition

0 = Unworn. No visible wear facet 1= Wear facet only in the enamel 2 = Wear facet in enamel and in dentine. Slight secondary

Tooth tvne -_

dentine formation. 3 = Occlusal surface of teeth worn flat. Moderate or heavy secondary dentine formation 4 = Crown worn down to the cementum-enamel junction.

Extensive secondary dentine formation or pulp exposure bours. All root remains were recorded as remaining teeth. Occlusal attrition was recorded by visual inspection using a modified scale by Carlsson, Johansson and Lundqvist (1985). Criteria used for grading severity of occlusal attrition are listed in Table 1. Grades 3 and 4 were considered as severe attrition. RESULTS

The skulls were classified into the following age groups: (1) O-16 yr (29.8%), (2) 17-21 yr (1 l.O%), (3) 21-25 yr (1 l.O%), (4) 26-35 yr (24.2%), (5) 3645 yr (14.6%). (6) over 45 yr (5.1%) and (7) edentulous (1.2%). Permanent dentition In the whole material, 13.1% of the remaining permanent teeth and 54.1% of individuals with permanent teeth had at least one carious lesion. Most of the individuals with caries had only one (34.3%) or two (20.6%) decayed teeth. In Table 2, caries prevalence rates are calculated for each tooth type as a percentage of the total number of teeth of each type present. There was an increase in caries prevalence from incisors to molars (Fig. 3). The prevalence was highest in the second and third molars: 32.0 and 36.4%. A similar increase from incisors to molars was also seen for teeth missing ante mortem (Fig. 1). Caries occurred slightly more frequently in the upper than in the lower jaw.

Incisors Canines Premolars MI M2

M3

N

NC

%NC

AMTL

1036 602 1231 725 619

69 41 128 119 198

6.7 6.8 10.4 16.4 32.0

97 22 106 166 124

368

134

36.4

109

N = number of teeth present. NC = number of carious teeth, %NC = percentage of caries of the total teeth present, AMTL = ante mortem tooth loss.

In most cases the lesions were small and involved only one surface (81.3%). If they had progressed further, usually both approximal and buccal surfaces were affected. The number of gross cavities was relatively small (4.1%). In the permanent dentition, lesions were most frequently observed at the cementum-enamel junction (42.2%), particularly on the approximal surfaces (30.0%). The prevalence of cavities in the cementum was 4.3%. The total proportion of lesions that had begun in fissures, including the buccal fissures, was 38.8%. Carious lesions at contact areas were rare (1.7%). Root remains accounted for 8.2% of all carious lesions recorded. In 4.1% of cases, lesions extended to pulpal tissue. In Table 3 the carious lesions are classified according to their initiation surface and their overall location in different age groups. In the younger age groups, caries was most prevalent in the occlusal fissures but the proportion of cavities at this site declined with age. Lesions at the cementum+namel junction began to appear from the age of 16 onwards. The proportion of cavities at the cementum-enamel junction increased with age and it was the most common site of caries in age groups 4, 5 and 6. Severe attrition was a common phenomenon, leading in some cases to pulpal exposure (0.6%) and abscess formation. In the case of extreme wear the pulp cavity had disappeared altogether and was filled by secondary dentine. The most attrition was in the molars, but with increasing age there was also

70 60

-

50

-

40

-

30

-

20 10 -

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o-

3

10 20 30 40

-

50

-

60

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70 -

Fig. 3. The prevalence and distribution of carious teeth.

TUNA M. VARRELA

556

Table 3. Initiation of caries attack and its overall location in age groups 26 Age group (2) 17-21 11-M2 (3) :125 II-M2 (4) g35 Il-M2 (5) !?45 Il-M2 M3 (6) over 45 Ii-M2 M3 Total number

GC

R

AC

RR

A

0 0

3 1

2 0

2 0

2 1

0 0

3 0

75 34

17 0

I 2

0

4 1

0 0

2 0

0 0

11 1

94 45

0

93

57

9

1

8

7

6

9 3

0 0

16 0

4 0

157 30

224 52

4 0

5 0

58 8

11 7

5 1

6 0

0 0

8 17

18 0

162 42

104 45

0 0

1 1

1 0

24 1

2 0

4 1

;

0 0

13 1

7 0

48 13

53 5

58

15

9

217

93

31

30

2

60

29

467

735

N

OF

B/LF

ACP

OA

ACEJ B/LCEJ

621 66

48 17

11 14

3 0

0 1

8 0

637 68

49 30

13 10

1 1

1 0

1117 117

30 23

6 4

4 0

766 70

7 12

0 0

201 34

3 1

3697

220

1

AMTL

C

H-M2 = incisors, canines, premolars, first and second molars, M3 = third molars, N = number of teeth, OF = occlusal fissure, B/LF = buccal or lingual fissure, ACP = approximal contact point, OA = occlusal and approximal, ACEJ = approximal cementum-enamel junction, B/LCEJ = buccal or lingual cementum-enamel junction, GC = gross cavity extending to pulpal tissue, R = root surface, AC = approximal and cervical, RR = number of root remains, A = cavities extending to pulpal tissue due to occlusal attrition. AMTL = ante mortem tooth loss and C = number of carious teeth. marked attrition of the incisors. With increasing attrition the contact points were destroyed. Attrition and the number of exposed root surfaces had a

positive correlation. Deciduous and mixed dentition In Table 4, lesions in permanent teeth are classified according to their initiation surface and their overall location in different age groups. In the whole material, 3.3% of remaining deciduous teeth and 16.0% of individuals with deciduous teeth had one or more lesions (Table 5). The most frequent site of initiation was in the occlusal fissures of molars, both in the deciduous (73. IX) and mixed dentition. In the deciduous dentition the prevalence of cavities at the cementum~name1 junction or the contact areas was 11S%. Caries was infrequent cervically (3.8%). The number of lesions increased with age. The youngest infant with caries was 2 yr old. DISCUSSION

The age estimation for children and juveniles was based on the stage of tooth development using present-day Finns as a reference. The adults were aged by the extent of dental wear using a populationspecific, age-attrition chart based on the wear rate in children under 21 yr. Tooth eruption, and probably

also tooth development, are delayed by malnut~tion (Alvarez et al., 1990). As it is likely that the medieval Finns were less well nourished than the modern Finns, the age estimation may be biased, the true ages being somewhat greater. It should be emphasized, however, that the attrition method of Miles (1963) is a tool for grouping the individuals in a skeletal population into their relative position in the life cycle rather than for establishing the exact age at death (Molnar and Molnar, 1985). The large number of teeth missing post mortem may be reflected in the data obtained. A major effect on the distribution of caries, however, is unlikely, because most of the teeth lost were incisors and canines, which seemed to be the most resistant to caries attack (Table 2). On the contrary, the teeth lost ante mortem were mainly molars. The prevalence of caries could be overestimated because the teeth most resistant to caries were not available for study. However, the teeth lost ante mortem were not considered to be carious because in addition to caries, teeth are lost through several other factors: gross attrition, periodontitis, trauma, etc. (von der Fehr, 1986; Kerr, Bruce and Cross, 1988; Whittaker et al., 1981). Because of severe attrition, the relationship between wear and tooth loss may be more important in these people than the relationship between caries and tooth loss. The numbers of teeth lost ante mortem are given their own category in Tables 2 and 3.

Table 4. Site of initiation of caries attack and its overall location in the permanent dentition in children

Age group 6

Prevalence and distribution of dental caries in a late medieval population in Finland.

The aim was to document the late medieval material and to compare the results with findings in other medieval populations and present-day Finns. The s...
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