Abstract:
Enamel hypoplasia is a useful indicator of systemic stress experienced during childhood. Due to the time dependent nature of enamel formation hypoplastic defects can be related to the age of the individual when the defect was formed. Therefore it is possible to know the individual’s age when they experienced the stress event. Unfortunately, accurate age determinations have only been accomplished through histological analysis of cross sectioned teeth, which is difficult, time consuming and necessitates the destruction of the tooth sample. Recent research, however, has identified a strong negative correlation between the total number of striae of Retzius in lower canines and the number of days associated with their regular occurrence, or periodicity. This relationship may allow for a tooth’s periodicity to be accurately estimated from a surface examination, allowing a more precise age estimation to be established without the need to destroy the tooth. The research presented in this thesis was undertaken, first, to investigate whether the correlation was present in a different sample and, second, to determine whether counts of perikymata in particular deciles of crown height, as opposed to a count of the total number of striae of Retzius, may be used to accurately estimate periodicity. This involved the histological analysis of 16 cross sectioned mandibular and maxillary canines from a modern New Zealand population. Results suggest that the reported correlation does exist in the New Zealand sample and further more that certain combinations of decile counts may produce a stronger correlation to striae of Retzius periodicity than total counts. Based on these preliminary findings, a simple non-destructive method is proposed that may allow for the striae of Retzius periodicity to be known from a crown surface examination. The application, as well as the implications, of this proposed method regarding age assessments of hypoplastic defects is also discussed.
