Biology Reference
In-Depth Information
transition to agriculture worldwide (e.g., see papers in
Cohen and Armelagos, 1984
).
For a thorough review of the study of dental caries in archaeological material, see
Larsen and colleagues (1991).
Hillson (2000)
notes the differences in caries rates evident between populations that
follow a low-carbohydrate diet (i.e., hunter-gatherer populations such as the !Kung
Bushmen) and those that ingest greater amounts of carbohydrates. In the first group, caries
are limited mainly to older adults with chipped or greatly worn teeth and are sparse in
younger individuals. By extension, these distribution patterns can be applied to archaeo-
logical populations. Population differences in age distribution, missing teeth (which
may be evidence of previous caries that necessitated extraction), and diagnostic error along
with a host of other methodological issues accompany the recording of caries in a popu-
lation. As such, Hillson (2001) recommends comparisons that are specific to tooth type,
sex, age, and caries expression in order to accurately characterize caries rate in a given
population.
Periodontitis
Dental plaque is a substance that consists of bacteria enmeshed in a biofilm that covers the
surface of the teeth. Accumulation of dental plaque can lead to gingivitis (inflammation of
the gums and soft tissues in the oral cavity) and also periodontitis. Early stages of infection
of this sort are limited to inflammation of the oral soft tissues (gingivitis) and do not leave
traces in the bone. With advanced cases that progress to periodontitis, the periodontal liga-
ments and alveolus become involved and it is at this point that the disease can be observed in
skeletal remains.
Generally, the infection progresses into the gomphosis of the tooth and affects the peri-
odontal ligaments holding the tooth in place. The resulting inflammation, accumulation of
plaque, and loss of periodontal attachment result in alveolar bone resorption and loss (
Hill-
son, 2000
). This loss is most often found in the molars and ultimately presents as a recession
of the alveolus and exposure of the root. The surface of the alveolus may present as porotic
and may extend beyond a single tooth. Affected teeth may be loose in their sockets due to the
bone resorption and loss of periodontal ligaments. Standards for the recording of periodontal
disease can be found in
Hildebolt and Molnar (1991)
.
Unlike caries, there appears to be a significant genetic component to the susceptibility to
periodontal disease (
Corey et al., 1993; Michalowicz et al., 2000
). Michalowicz and colleagues
(2000) estimate a heritability rate of 50% based on their study of twins. This indicates that
earlier studies that had reported variation in prevalence between populations attributed to
hygiene differences (
Loe et al., 1992
) may have overlooked the underlying genetic predispo-
sition to periodontal disease.
Enamel Hypoplasia
Although the development of teeth is under tight genetic constraints and they are gener-
ally less susceptible to environmental insults than other elements of the skeleton, episodes
of illness or malnutrition during the development of teeth can leave their mark. These
episodes manifest in the enamel of the tooth as enamel defects or hypoplasias and result
