Insights from the inside: Histological analysis of abnormal enamel microstructure associated with hypoplastic enamel defects in human teeth

Abstract

We studied the abnormalities in enamel microstructure associated with enamel hypoplasia in human teeth from the early medieval (5th-7th century AD) cemetery of Barbing, Germany, using light and scanning electron microscopy. The main aim of the study was to test the hypothesis that by analyzing the microstructure of fully formed enamel it is possible to reconstruct the reaction pattern of secretory ameloblasts to stress events leading to enamel hypoplasia. From the histological findings, a sequence of increasing impairment of secretory ameloblast function involving three thresholds was deduced. Surpassing of each of these thresholds is assumed to result in characteristic changes in enamel microstructure attributable to specific functional/morphological alterations of secretory ameloblasts. Based on our results we propose a model identifying the principal factors influencing the reaction of secretory ameloblasts to stress. The present study demonstrates that by including microscopic analysis in the study of enamel hypoplasia, it is possible to obtain a more complete picture of the formation of these developmental defects than is possible by inspection of crown surface features alone, and to draw more substantiated conclusions about the possible nature of developmental defects of enamel.

New regression formula to estimate the prenatal crown formation time of human deciduous central incisors derived from a Roman Imperial sample (Velia, Salerno, Italy, I-II cent. CE)

“…in [41]). Physiological stresses exceeding a certain threshold leave their permanent marks in the corresponding position of the secretory ameloblast front, producing Accentuated Lines (AL or Wilson bands [9, 41, 42]) that are superimposed onto the regular physiological growth markings. The birth event is recorded in the forming enamel of individuals surviving the perinatal stage, and leaves an Accentuated Line, known as Neonatal Line (NL, rev.…”

“Missing perikymata”—fact or fiction? A study on chimpanzee (Pan troglodytes verus) canines

“…In this enamel zone, individual Retzius increments comprise a zone of aprismatic enamel external to a stria of Retzius and a zone of prismatic enamel further peripherally. This is regarded to reflect the fact that in late secretory ameloblasts, the recovery to full secretory activity and the concomitant re-establishment of a fully developed Tomes' process, required for the formation of prismatic enamel (Boyde, 1989;Kierdorf and Kierdorf, 1997;Witzel et al, 2006Witzel et al, , 2008, is delayed following the occurrence of a stria of Retzius. In our interpretation, the "minor striae" of Skinner and Pruetz (2012) constitute fracture faces formed at the transition between aprismatic enamel and prismatic enamel within a Retzius increment.…”

“…Thus far, only in the case of severe, plane-type hypoplastic enamel defects of human teeth has the presence of striae of Retzius whose outcrop at the OES was not recordable on external inspection been reported (Gustafson, 1959;Witzel et al, 2008). This condition occurred in the ledge region positioned cervical to the exposed incremental plane and was caused by an extreme bending and convergence of striae of Retzius that formed a very acute angle with the OES.…”

Paleohistology and the study of human remains: past, present and future approaches

“…Microscopic examination of linear enamel defects, such as Wilson bands, is also an important tool for understanding the physiological mechanisms responsible for growth disruptions during dental development (e.g. Rose, 1977;Rose et al, 1978;Marks and Rose, 1985;Goodman and Rose, 1990;King et al, 2005;Witzel et al, 2008).…”