Blue Bridge Lane
&
Fishergate House
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Dental enamel hypoplasia (DEH) can be defined as depressed lines, grooves or pits on the crown surface of the teeth which relate to periods of physiological stress during tooth formation, causing cessation in the tooth's development, comparable to Harris lines in bones. However, unlike Harris lines, DEH is clearly visible without the need for radiography. Causes of DEH can include nutritional deficiencies, childhood fevers, measles and other illnesses (Lukacs 1989, 267), which are sufficiently severe to require the body to divert energy from development to survival (Aufderheide and Rodríguez-Martín 1998, 405). Dental enamel hypoplasia can thus provide information on the period of life when the stress was experienced. Thus, the presence of DEH in the deciduous dentition indicates that stress was experienced during the last two trimesters of pregnancy or the first year of life, while DEH in the permanent dentition is indicative of stress experienced during the first to sixth year of life (Goodman and Armelagos 1989, 230).
Nineteen percent of teeth showed evidence for dental enamel hypoplasia, most of which (88%) were noted in the form of lines. A total of 8% of lesions were expressed as grooves and only 4% as pits. Both pits and grooves were restricted primarily to the canines, whereas lines could affect any tooth.
The lesions affected the incisors and canines almost exclusively, with very
occasional lines on the premolars and only one individual with lesions on
the molars. In most cases, DEH was noted in permanent teeth, although it
also affected twelve deciduous teeth (Plate 30, right). It was by far the
most prevalent form of dental disease in the children (32% of children affected,
with 30.2% of permanent children's teeth and 2% of deciduous teeth affected).
However, many individuals with DEH survived into adulthood, resulting in
88% of females and 60% of males exhibiting the stress manifestations (22.5%
of male teeth and 29.4% of female teeth).
It is interesting to note that unlike at Fishergate House, at the other medieval sites, males had a greater prevalence of DEH than females (St Andrew's, 59% of males and 48.4% of females; at St Helen's-on-the-Walls, 35.5% of males and 46% of females; at Hull Magistrate's Court, 44% of males and 41% of females). This suggests that at Fishergate House, females suffered more stress during the early years of life, or alternatively, a greater number females survived who had developed the lines during childhood.
Similar to other populations, individuals with DEH lesions were not more likely to die early (Palubeckaité et al2002). While adolescents, young adults and young middle adults had similar rates of DEH (46%), old middle adults and mature adults had a higher rate (68% and 54%). This implies that those who had suffered physiological stress expressed in the form of DEH during childhood, and survived, suffered no adverse effects to their health later in life. Those suffering from severe stress during childhood appear either to have succumbed before the stress lines could develop, or survived into late adulthood. This is also suggested by the higher prevalence of DEH in children from the early medieval cemetery of Raunds (Northamptonshire) and the late medieval cemetery of Chichester, where prevalence rates were 49% and 38% respectively (Ribot and Roberts 1996, 72).
More than half of the Fishergate House population (52.2% of individuals; 19% of teeth) showed evidence for DEH. This prevalence is considerably higher than that observed at contemporary cemeteries, such as at Pennell Street Lincoln (37.5% of individuals affected), and at Blackfriars (11% of teeth affected). The high incidence of DEH at Fishergate House points to considerable physiological stress during early childhood, which affected the whole population. It is difficult to assess when the episodes of stress took place, as most deciduous teeth would have been lost ante-mortem, therefore causing a probable underestimation of DEH. However, the fact that only 2% of the 889 deciduous teeth show the lines suggests that DEH was more likely to be the result of physiological stress during the first five years of life, rather than during gestation.
The four juveniles (C1033, C1135, C1545 and C1585) with DEH of the deciduous teeth were aged between three and five and a half years. C1135 had lines on the canines, similar to the DEH in most adults. However, the other two children had more severe lesions, which distorted the surfaces of the molars through pitting and irregularities. Additionally, the crown of a first permanent molar was affected. In C1545, the enamel was so severely weakened that this individual already had one carious lesion and the enamel of some of the teeth had splintered off. DEH was less severe in C1033 and C1585, although it had also partly distorted the crown surfaces. Skeleton C1585 also suffered from caries, as well as one ante-mortem fracture of a left mandibular canine. DEH of comparative severity has been observed by the author in only one other skeleton, a five to seven year old Roman juvenile from 41 Piccadilly, York (Holst et al 1998).
DEH lesions in older juveniles and adults were less severe than those observed in the young children. This trend was probably the result of stress experienced between the ages of one and five, an age when weaning and childhood illnesses such as gastro-intestinal and respiratory infections cause a peak in childhood mortality. It is therefore probable that the individuals with dental manifestations of stress were the survivors of childhood diseases. This evidence, together with the high prevalence of childhood mortality between the ages of one to six, suggests that the young children in this population suffered a significant amount of stress during the first few years of childhood, which many succumbed to. The survivors suffered cessation of growth, manifested as lines on the teeth. Most individuals only had one or two of these lines, but some individuals appeared to have suffered four or five episodes of stress.
Associations between DEH and different types of pathological conditions were tested (Table 52). More than half the population from Fishergate House had suffered from DEH, and a large proportion of these individuals also showed evidence for disease; it is probable that DEH was caused by some of the conditions observed, and it is also probable that some conditions suffered later in life may not have developed without the episode of stress suffered during childhood. It is possible that episodes of stress causing DEH during childhood contributed to conditions which developed in older age, such as osteoporosis. Other conditions, such as Harris lines, cribra orbitalia and sinusitis may be related to the same episode of stress as that causing DEH. The association between DEH and os acromiale was unexpected, and it is probable that the associations between fungal disease, leprosy and DEH are coincidental.
| Pathological Condition | No. of individuals with DEH and pathological conditions | Percentage |
|---|---|---|
| Fungal disease | 1/1 | 100 |
| Leprosy | 1/1 | 100 |
| General periostitis | 36/101 | 36 |
| Cranial periostitis | 14/38 | 37 |
| Osteitis | 4/9 | 44 |
| Osteomyelitis | 1/2 | 50 |
| Sinusitis | 37/58 | 64 |
| Cribra orbitalia | 27/49 | 55 |
| Rickets | 3/6 | 50 |
| Porotic hyperostosis | 1/1 | 100 |
| Harris Lines | 4/10 | 40 |
| Osteoporosis | 5/6 | 83 |
| Fractures | 17/27 | 63 |
| Os acromiale | 3/3 | 100 |
Few DEH lesions were associated with caries. However, this may be due to a tendency for caries to affect the posterior teeth, whereas DEH affects primarily anterior teeth. Nevertheless, 57% of infractions occurred in teeth which showed evidence for DEH, suggesting that this condition had weakened the dental enamel, causing greater susceptibility to fracturing.
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