DO ENAMEL MICROSTRUCTURES HAVE REGULAR TIME DEPENDENCY - CONCLUSIONS FROM THE LITERATURE AND A LARGE-SCALE STUDY

This paper is structured in two parts. The first briefly reviews a num ber of lines of published evidence, including direct experimental evid ence, supporting the contention that enamel microstructures are time d ependent and have a regular periodicity. The second presents the resul ts of a large-scale study designed to test a central assumption underl ying most histological ageing approaches in enamel: that the number of cross striations between adjacent striae of Retzius, called the circa septan interval, are uniform within a tooth and between all teeth in t he dentition of an individual. The study uses a sample of 158 anterior teeth from three modem human populations. Teeth were sectioned and ci rcaseptan intervals were determined by dividing measurements of the di stance between adjacent striae of Retzius, by cross-striation length. In order to exercise as much procedural rigour as possible, all measur ements were made from photomicrographs. Two sections were taken from e ach tooth, the sampling location within each teeth was recorded, and a ll populations included multiple teeth from single individuals. Result s statistically validate the uniformity hypothesis within the anterior dentition. These, together with the weight of published evidence, sug gest that data derived from the use of enamel microstructures in age e stimation techniques and growth and development studies, are valid. (C ) 1998 Academic Press.