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cementochronology.com

Principle

of cementochronology

Estimating individual age at death from human skeletal remains is a crucial step in bioarchaeological and forensic contexts. Methods for adult age estimation are mainly based on bone remodeling, maturation indicators, or degenerative processes. Cementochronology relies on the seductive principle of the annual record in dental cementum providing a direct access to a continuous indicator highly correlated to chronological age. 


Cementum refers to the mineralized connective tissues covering the root surfaces and its main function is to anchor collagen fibers of the periodontal ligament to the root surface. Like bone, cementum is composed of an organic and a mineral matrix, but unlike bone, this avascular and not innervated tissue exhibits little or no remodeling processes throughout life 


When viewed under a light microscope, a cross section of these incremental lines surrounding a tooth root appears as layers of alternating dark and light bands. One pair composed of a single light and a single dark line is considered to represent one calendar year and age estimation is calculated by adding the average age of tooth eruption to the line count determined.

Age at death= Σ pairs of lines + age of root completion

Protocol

Each tooth is cleaned and dried, and the root is embedded in a two-component epoxy resin. 

The crown and upper third of the root are removed and five sequential 100-μm non decalcified cross-sections from the middle third of the root are prepared using Low Speed Saw fitted with a diamond-coated blade and mounted on slides.

Observations are conducted at ×100; ×200; ×400 magnifications. Segments that showed AEFC layering structure are captured as JPEG images exclusively at ×400 magnification. 

Annuli counts are performed using the count tool functionality in Adobe Photoshop on the micrographs obtained from the cross-sections.

In 2013, a protocol has been certified ISO 9001. This international standard obviously do not guarantee the reliability of the estimation but is a recognition of the preparation process conformity and continuous improvement. This procedure has been published in the International Journal of Legal Medicine:

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Colard T, Bertrand B et al. (2017) Toward the adoption of cementochronology in forensic context. Int J Legal Med.


Because acellular dental cementum is considered to be formed continually throughout life and to not undergo remodeling processes, cementochronology is considered to be a method with the potential for directly assessing chronological age. Considering that most previous studies on humans have assumed the superior performance of this method, it is surprising that this technique is not more widely adopted in anthropology. To understand this controversy, we highlight that there is no standardized procedure for sample preparation. The numerous technical approaches that exist impact the reliability of the method, and the recent creation of an international work group (Cementochronology Research Program) demonstrates the need for researchers to share their experience to overcome these obstacles. This paper aims to address this paradox by debating the aspects that contribute to the limited use of this method and by illustrating its potential through an application on forensic cases. A protocol, which was recently certified according to the ISO-9001, was applied to nine anthropological cases from the Forensic Medicine Institute of Lille (northern France) and compared with routine osteological and dental methods. The results show that traditional methods matched the known age due to the wide extent of their range, while the accuracy and precision of cementochronological estimates was also notable. This paper establishes that cementochronology may serve as a particularly important tool for age estimation for forensic anthropologists and should, at least, be used in addition to other methods.

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Bertrand B, Cunha E, Bécart A, Gosset D, Hédouin V (2019) Age at death estimation by cementochronology: Too precise to be true or too precise to be accurate? Am J Phys Anthropol 169(3):464–481.


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.

Service

Lazare
Age at death

Dental cementum

Established in 2016 in Northern France, as an organization under the French law of 1901, Lazare is dedicated to promoting discoveries, experiences, ideas, and new data on the potential of dental cementum investigations in anthropology.


Lazare provides dental expertise and histological lab services for age at death estimation, in the fields of zooarchaeology, bioarcheology and forensic anthropology. 


Prior to Lazare’s inception, cementum age at death estimations were restricted to the Academia (e.g. Archaeology or Anthropology Departments). Lazare’s commitment to meet the archaeology and anthropology communities’ need for rigorous yet fast preparations and accurate, but realistic, age at death estimation led to its rapid success.


Lazare was founded by Benoit Bertrand, Ph.D. (Lille University). He has been instrumental in the development of cementochronology since 2006, and has published numerous papers related to dental histology, in specialized journals within the fields of forensic sciences, anthropology, and archaeology. Before becoming the president of Lazare, Benoit Bertrand was the director of the Microanalytical Lab at the Archaeology Department in Douai, France, for 6 years. Currently he is researcher at the Forensic Taphonomy Unit at Lille University.


By applying standardized protocols to stay ahead of demand, Lazare has maintained its commitment to quality over the years.

Prices

1 Three sequential 100μm non decalcified cross-sections per tooth, mounted on a single slide, labelled and organized in a box (Bertrand 2013)

2 Three micrographs per tooth showing typical cross-sections prepared from the dental sample + three annuli counts performed on sections showing typical cementum structure and age at death estimation (Bertrand, 2019)

* Depending upon the extent of the taphonomic or thermal damages, preparation and age estimation are not guaranteed

Bertrand B. (2013). Procédure ISO-9001 - Communauté d'Agglomération du Douaisis - Cémentochronologie, référence: MOP-Dap-04, Indice A.

Bertrand B, Cunha E, Bécart A, Gosset D, Hédouin V. (2019). Age at death estimation by cementochronology: Too precise to be true or too precise to be accurate? Am J Phys Anthropol. 1–18. https://doi.org/ 10.1002/ajpa.23849

Turnover time

Normal turnover time (sample size < 5 teeth): 10 days after receiving the sample

Express turnover time (sample size < 5 teeth): less than 1 week after receiving the sample
(+50% extra fee)

For larger sample sizes or collaborative research contact us.

Why choose Lazare for cementum investigations?


Unique dental cementum age-at-death estimation service worldwide

Lazare is the only organization to provide dental preparation for zooarchaeologists, bioarcheologists and forensic anthropologists’ studies. All analyses are performed by a professional recognized for his research on dental cementum annulation.


Published standardized procedures for dental preparation and cementum investigation

We established procedures to ensure reproducibility of the age estimates, by adopting an ISO-9001 certified protocol to reduce the instinctive approach (Bertrand, 2013; Colard, Bertrand, Naji, Delannoy, & Bécart, 2018). This procedure enables an extremely low failure rate, that contrasts with previously established values reaching 80% on archaeological material.


Fastest dental cementum investigation service: results within 10 days (Express Service less than a week)

Lazare is able to provide fast service because all analyses are done in our organization. The lab dedicates a scientist to working overtime, if necessary, to meet its promised delivery times. 


Professional with more than 10 years of experience in cementum investigations

Lazare’s researcher is leader in cementum age at death estimation in archaeological teeth, having reported more than 1370 dental preparations (human & faunal remains, fresh & ancient).


Unlimited methodological consultation

Lazare’s researcher welcomes discussions before, during, and after the analyses. Collaborators are not charged for consultation.


Prompt response to inquiries within 48 hours

Lazare provides shipping assistance to global clientele and offers consultation throughout the submittal and analytical procedure by email or phone.

Contact

contact@cementochronology.com