In Search of Clarity: A Comparison of Current and Novel Measurement Techniques Involved in the Description of Age-Related Transparent Root Dentine In the Human Permanent Dentition

Abstract

<p>The primary goal of this thesis is the determination of the most appropriate means of measuring physiological root dentine transparency in the permanent human dentition to estimate age-at-death of skeletal remains. Although a number of internal and external factors may conceivably contribute to the observed discrepancies between predicted values and true ages, the magnitude of the influence exerted by such extraneous factors cannot be quantified until a standardized means of measurement has been agreed upon. To this end, two samples of teeth, one derived from an archaeological context (N=32) and the other a sample of recently-extracted teeth (N=32), have been examined as intact and sectioned specimens. Traditional area and linear measurements of transparency have been made under stereomicroscope. In addition, a novel volumetric measurement of transparent regions has been approximated via micro-CT analysis of densitometric differences within affected root areas. The relative value of each measurement in the prediction of age has been assessed via a description of the association with chronological age for each variable, with unscaled measurements of area displaying the highest correlation with age (r=0.711 ). Alternative curve fitting techniques have also been explored. The poor correlation with chronological age reported for densitometric measurements of transparent dentine (r=0.142) is likely indicative of local differences in root dentine histology prior to the advancement of transparency. This research has also served to illustrate the amount of variance in measurements of transparency irrespective of the means of measurement applied. Future research should be directed towards the development of age-predictive formulae based on area measurements of transparency made on sectioned specimens. However, until the ultimate causal mechanism underlying the progression of root dentine transparency is uncovered, the strength of the association of this phenomenon with chronological age will continue to fluctuate between teeth in an unpredictable manner. Such error will limit the accuracy of age predictions within both the archaeological and forensic contexts.</p>