Dental Anthropology - Research Methods in Human Skeletal Biology - page 264

FIGURE 10.4 Radiograph of a chimpanzee permanent first mandibular molar at stage 4 d crown completion to
the cementoenamel junction. Small spicules of root growth are visible.
(1941) . Reproduced in various forms in countless publications, this was one of the earlier
examples of an illustrated publication depicting the appearance of the developing teeth for
reference by dental clinicians. This reference chronicles the development of the human denti-
tion from the early fetal stage through maturity and includes both the primary and perma-
nent teeth. Although the population studied is not mentioned in the paper, AlQahtani and
colleagues (2010) point out that Smith (1991) mentions the population as potentially being
the same that appears in the earlier work of Logan and Kronfeld (1933) . 5
The second method, the dental age approach, assigns numbers to arbitrary stages of tooth
development, indicating the degree of completion of the crown and root.With thismethod, the
development of each tooth is ranked on a scale with each category representing a certain frac-
tion of the crown or root growth. Teeth that are not visible radiographically are given a score of
zero. Frequently, the stages represent roughly one-third of crown or root growth or refer to the
proportion of the crown and root (e.g., “Root growth is less than crown height”).
As an illustration, Figure 10.4 shows a digital X-ray of a developing mandibular molar in
a chimpanzee at a stage of 4 d crown completion d with small spicules of root formation
present. The total amount of calcification that has taken place for each individual is then rep-
resented by the total of the numbers assigned to all teeth. This method was first proposed by
Demirjian and colleagues (1973), and has been utilized in various forms by several authors
(e.g., Sirianni and Swindler, 1985; Dean, 1987; Conroy and Mahoney, 1991; Simpson et al.,
1991; Kuykendall, 1996; Simpson and Kunos, 1998 ).
5 Interestingly, the population involved in the Schour and Massler atlas is somewhat of a mystery. It is not
revealed in the original publication and so at this time, the primary reference for the population used is
Smith's (1991) historical account.