Cementum annulation and age determination in Homo sapiens. I. Tooth variability and observer error

Authors

  • Douglas K. Charles,

    Corresponding author
    1. Department of Anthropology, Northwestern University, Chicago, Illinois 60611
    2. Department of Cell Biology and Anatomy, Northwestern University, Chicago, Illinois 60611
    Current affiliation:
    1. Department of Anthropology, Wesleyan University, Middletown CT 06457
    • Department of Anthropology, Wesleyan University, Middletown CT 06457
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  • Keith Condon,

    1. Department of Anthropology, Northwestern University, Chicago, Illinois 60611
    2. Department of Anatomy, University of Illinois at Chicago, Chicago, Illinois 60612
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  • James M. Cheverud,

    1. Department of Anthropology, Northwestern University, Chicago, Illinois 60611
    2. Department of Cell Biology and Anatomy, Northwestern University, Chicago, Illinois 60611
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  • Jane E. Buikstra

    1. Department of Anthropology, Northwestern University, Chicago, Illinois 60611
    Current affiliation:
    1. Department of Anthropology, University of Chicago, Chicago IL 60637
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Abstract

In order to test the feasibility of cementum annulations to estimate age in humans, observer error and tooth variability in cementum ring counts were evaluated in a sample of 42 mandibular canine and first premolar pairs. Additionally, two sectioning techniques were evaluated. Demineralized thin sections (7 μm) stained with hematoxylin are the preferred technique since their age related variance is greater than 75% for all tooth types examined. In contrast, less than 50% of the total variance was accounted for among individuals when mineralized sections (80 μm) stained with alizarin red were used. Intertooth variability in ring counts of demineralized sections was large between canines and premolars (43%). Premolars provide counts with lower interobserver error and are the preferred tooth. In an expanded sample (N = 51) of demineralized premolars, intraobserver and interobserver error accounted for 2% and 5% of the total variance, respectively. Evaluation of several experimental designs showed that increasing the number of slides per tooth has the greatest effect on reducing variance followed by increasing the number of observers. Increasing the number of observations has little effect. Cementum ring counts are measurable to a highly repeatable extent and provide a level of repeatability greater than that reported for the pubic symphysis and auricular surface aging techniques.

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