The biology of cementum increments (with an archaeological application)

Abstract

Cementum, a bone‐like tissue that surrounds the roots of teeth, anchoring them to the periodontal ligament, is useful for determining the age at and season of death of mammals, an issue of concern for both archaeologists and biologists. When a tooth is sectioned and examined microscopically, cementum appears in bands that differ in their optical properties and are well correlated with seasonal growth. Because it is a continually deposited tissue that is rarely modified or resorbed, cementum records the history of a variety of seasonal factors that affect its growth. An understanding of the biological nature of cementum is crucial to the identification of these factors and interpretation of the resulting incremental structure. This paper outlines current knowledge of the development, histology and function of cementum in the context of the mammalian masticatory apparatus. Of the various types of cementum, acellular cementum is often more appropriate for seasonal correlations. Differences between acellular cementum increments are probably related to specific dietary factors that often vary between seasons. Cellular cementum increments probably result from phasic cementogenesis triggered by tooth eruption. This paper outlines a study of cementum bands in Gazella gazella for which there is an excellent correlation between the season of death and incremental structures in their cementum. This correlation can be used to estimate the season of death of gazelles from archaeological sites in the Levant. Problems for future research are outlined.

Digital cementum luminance analysis (DCLA): a tool for the analysis of climatic and seasonal signals in dental cementum

“…Its properties are similar to that of bone in that it contains branching cells lying in lacunae and it is penetrated by collagenous fibre bundles (which attach a tooth to the alveolus) (Manley et al, 1955;Shroff, 1966: 137). Unlike bone, however, cementum is more stable and is only reabsorbed under extreme and rare circumstances (Manley et al, 1955;Lieberman & Meadow, 1992;Lieberman, 1993). Much of this is due to the fact that cementum does not receive nutrients from the tooth pulp (Jenkins, 1978: 193); even if a tooth dies, the cementum will continue to function, remain stable, and ensure that the tooth remains attached to the periodontal fibres -cementum has a tendency to form regardless of circumstances (Shroff, 1966: 146).…”

“…Acellular cementum is the preferred cementum type for seasonality studies of Artiodactyla ungulates, because of evidence suggesting that acellular cementum is an accurate measure of season-of-death and age-at-death (Gordon, 1988;Pike-Tay, 1991, 2000Lieberman & Meadow, 1992;O'Brien, 1994). Cellular cementum conversely forms directly in response to tooth growth and displacement and may be less accurate as a measure of season of death amongst ungulates (Lieberman & Meadow, 1992;O'Brien, 1994), although some evidence suggests it is still a valid source of information on the age at death (Lieberman & Shea, 1994).…”

Estimating the Age- and Season-of-Death for Wild Equids: a Comparison of Techniques Utilising a Sample from the Late Neolithic Site of Bad Buchau-Dullenried, Germany

“…Also, staining and demineralisation of thin-sections, which may damage the specimens, is not required. As a result, the thin-sectioning protocol becomes simpler, more consistent, and less timeconsuming (Lieberman & Meadow 1992;Hillson 2005). This procedure was followed here.…”

“…The same technique was followed as with age-of-death since both estimates rely upon the recognition and counting of bands (Burke 1995;Pike-Tay 1991;Lieberman & Meadow 1992;Lieberman 1994). The line profile histogram was plotted at several locations on the cementum strip in order to find a suitable area free of taphonomic damage and/or cellular components.…”

From coral reefs to whale teeth: estimating mortality from natural accumulations of skeletal materials

“…8; Brodie et al 2013). In mammals with no obvious seasonality of life events, such as humans, there is still a correlation between the age of the individual and the thickness of the cementum, which has been used for many years to estimate the age of individuals in forensic studies (Lieberman & Meadow 1992, Lieberman 1993, Fisher et al 2003, Fišáková 2014, El Adli et al 2015. In marine mammals, the annual growth rings can additionally be counted on earplugs, which also carry indispensable information on other life history events such as attaining sexual maturity, exposure to contaminants, reconstruction of life-time profiles of hormonal activities (e.g.…”