Enamel Hypoplasia

From bonepath

Enamel hypoplasia is a defect in tooth enamel deposition that is usually manifest on the tooth crown as lines, pits or grooves along the enamel surface (Roberts and Manchester, 2005). These defects are associated with systemic stress that occurred while a tooth crown was being formed, specifically when ameloblasts (enamel-making cells) are in the phase of depositing matrix. Knowing both the ages and sequence of crown formation, researchers can use the location of enamel hypoplasia to infer when the stressful event occurred in an individual’s life. However, there will be some error in this estimation due to normal variation in tooth development.

Enamel hypoplasia can be a “non-specific” indicator of stress, because a number of conditions could cause enamel defects. Such potential causes include nutritional deficiency, disease, fever, trauma, and congenital abnormalities (Roberts and Manchester, 2005; Armelagos et al. 2009). Seaw (1992) found that unilaterally expressed enamel hypoplasia is likely due to physical trauma, whereas bilaterally expressed hypoplasia indicate systemic stress. These unilateral cases were premature infants of low birth-weight receiving intubation. Thus, while the position of enamel hypoplasias can be used to infer when in a person’s life the stressful event or conditions occurred, the specific cause of the stress is not as simply elucidated. Regardless of the possible causes, numerous analyses of archaeological populations indicate that individuals with some form of hypoplasias have a significantly lower age at death than individuals without hypoplasias (Armelagos et al. 2009).

Poor enamel mineralization may also be congenital, due to amelogenesis imperfecta (AI). AI may arise from a number of mutations, and so can follow autosomal dominant or recessive inheritance, and can also be X-linked (Bartlett 2010).

Enamel defects can occur any time during crown formation, thus layers of enamel beneath the crown surface can be affected but evade visual detection. As a result, it is likely that incidences of enamel hypoplasia (especially minor ones) are higher than current estimations based on crown surface hypoplasias (Ogden, 2008).

More severe enamel defects can result in gross malformation of the tooth crown (See Congenital Syphilis; Hutchinson’s Incisors; Mulberry Molars).

[edit] Examples from Ford Collection

• 96-11-001
• 96-11-005
• 96-11-013
• 96-11-020
• 96-11-052
• 96-11-067
• 96-11-084
• 96-11-098
• 96-11-099
• 96-11-101
• 96-11-127
• 96-11-132
• 96-11-142
• 96-11-150
• 96-11-153
• 96-11-159
• 96-11-163
• 96-11-169

[edit] References

Armelagos GJ, Goodman AH, Harper KN, and Blakey M. 2009. Enamel Hypoplasia and Early Mortality: Bioarcheological Support for the Barker Hypothesis. Evolutionary Anthropology 18: 261-271.

Bartlett JD. 2010. The human genetics of amelogenesis imperfecta. Interface Oral Health Science 2009: 375-81.

Ogden A. 2008. Advances in the Palaeopathology of Teeth and Jaws. In Advances in Paleopathology, Pinhasi and Mays, eds. Hoboken: John Wiley and Sons, Ltd.

Roberts C and Mancester K. 2005. The Archaeology of Disease, 3rd ed. Ithaca: Cornell University Press

Seow WK. 1992. Dental enamel defects in low birthweight children. In Recent Contributions to the Study of Enamel Developmental Defects, Goodman AH and Capasso LL, eds, 321-330. Teramo: Edigrafital.