Friday, March 15, 2013

Tooth Enamel and Well-Being

Health in a medieval village.
Accentuated striae (AS) are developmental defects in tooth enamel that form during periods of physiological stress, and have been used in skeletal studies to measure stress and health levels in past populations. However, the assumption that the presence of AS necessarily indicates poor health has not been sufficiently tested. This project builds on past research by investigating the relationship between AS and age at death, since the presence of more AS in younger individuals (those with a higher risk of dying) would support the relationship between AS and poor health. Analytical improvements for testing this relationship include a focus on individuals as the unit of analysis and the use of survival analysis, which corrects for some skeletal sample biases and allows for both juveniles and adults to be included. “Weak” and “strong” AS in permanent teeth from 85 medieval Danish skeletons (ages at death: 0-30 years) are identified in digital images of tooth thin sections and developed into individual defect chronologies using daily and long-period increments in enamel. Chronologies span the period from birth until death or canine crown completion, whichever occurs first. Survival analysis is used to test the relationship of AS in different periods of childhood to the risk of dying at subsequent ages. Weak AS occurring before age seven predict a lower risk of dying after age seven while strong AS show the opposite pattern. (Read entire article.)

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