Age at death estimation by cementochronology: Too precise to be true or too precise to be accurate?

Abstract

Objectives: Cementochronology based on annual deposition of acellular cementum is acknowledged for its superior performance for estimating age-at-death but is also disregarded because of its suspicious effectiveness. This article aims to provide a standardized framework for the validation of the technique and to define and test cementochronology's performance and limitations. Materials and methods:To determine the boundaries of the cementum aging technique, we applied a certified protocol on a sample of 200 healthy canines from individuals of known age, sex, postmortem, and inhumation intervals from anthropological and anatomical collections. We scored readability and preservation of cementum and measured the agreement between estimates, i.e., the precision, and assessed the quality of the accordance between estimates and chronological age, i.e., the accuracy. To investigate the applicability on ancient material, 200 additional canines extracted from archeological assemblages were included. Accuracy and precision were analyzed for each age group in considering postmortem intervals and taphonomical conditions.Results: A strong correlation was found between chronological age and estimates (r = .927; p = .000) but results reveal an association between readability of incremental lines and chronological age (p < .05) and a notable difference in both precision and accuracy between individuals under and over 50 years. Results also demonstrate that taphonomy can be a serious obstacle increasing imprecision by a factor of three.Discussion: Improperly adopted, cementochronology can lead to precise but inaccurate estimations. If methodological, physiological, and taphonomical factors are taken into account, then, and only then, cementochronology will serve as a versatile and powerful tool for age-at-death estimation. K E Y W O R D Sage-at-death estimation, cementochronology, dental cementum, taphonomy

Comparative hard x-ray tomography for virtual histology of zebrafish larva, human tooth cementum, and porcine nerve

“…To date, incremental layers may only be imaged to a satisfying extent at synchrotron radiation facilities 37 or by means of conventional optical microscopy of thin sections. 32,34,36 A laboratorybased μCT was suggested by Mani-Caplazi et al 3 based on physically sliced samples and a close source-sample position. In the current study, we showed that advanced laboratory instrumentation generates great potential for facilitating high-resolution incremental layer imaging in a nondestructive manner.…”

Laboratory-based phase and absorption tomography for micro-imaging of annual layers in human tooth cementum, paraffin-embedded nerve and zebrafish embryo

“…Nonetheless, cervical acellular extrinsic fiber cementum provides the steadiest growth rate conserving layer thickness [20,21,24]. Unfortunately, counting of layers is error-prone and observer-dependent, leading most commonly to an underestimation of age, despite of high-resolution imaging methods [28,29]. Further investigation is therefore desired and suggested in archeological samples with corresponding life history [24,29].…”

“…Until now, incremental layers may only be imaged to satisfying extent at synchrotron radiation facilities [29] or by means of conventional optical microscopy of thin sections [24,26,28]. A laboratory-based µCT was suggested by G. Mani-Caplazi [2] based on physically sliced samples and a close source-sample position.…”

“…However, there is as of yet neither a coherent explanation nor a standard protocol for tooth selection, preparation and layer counting, yet many advances have been made [24,26]. Laboratory-based µCT may benefit region selection applied a priori to SRµCT [2] or conventional microscopy where samples are cut irreversibly in about 100 µm-thin slices [28]. Further, the promising results of the Xradia 620 Versa indicate that laboratory-based µCT alone could be used to quantify these layers, for example in large-scale studies of archeological samples with recorded history to standardize age estimation or examine of influencing factors for the layer growth.…”

Using Histological Staining Techniques to Improve Visualization and Interpretability of Tooth Cementum Annulation Analysis

“…Calculation of the final age is done by adding the age of the root formation to the mean number of counted cementum layers, since forming of cementum begins after the root development. Different studies report different protocols and errors for the described method for age determination (Gauthier & Schutkowski, 2013;Bertrand et al, 2019;Penezic´ et al, 2019) so there is a need for the standardization of the procedure, that can be used within the anthropological, archeological, forensic and histological context.…”