Cementum Aging Analysis
The basis for cementum aging is the cyclic nature of cementum growth, which results in an annular pattern of “rings” in the tooth like that formed in the wood of trees. A darkly staining ring, or “annulus,” is formed during winter. Abundant, lightly staining cementum is formed during the growth seasons of spring and summer. The underlying physiologic and metabolic mechanisms for cyclic cementum growth are not known.
Very darkly staining rings are formed in southern regions of North America, but it is generally true that most mammals in these regions have less distinct annuli than their counterparts in more northern regions. Incidentally, human teeth have similar annuli, but the deposition pattern is irregular compared to that of most wild mammals (we have no expertise in the aging of human teeth).
Matson’s uses a standardized cementum aging model for each species, with original models being continually expanded upon. Cementum analysis training is ongoing at our lab, and all aging is completed by certified agers. Technicians become certified when their results yield a precision of 85-95%, a level that varies with population and species. After a technician is certified to age a given population of a species, at least 10% of each sample aged by that technician is checked for quality control before the age report is sent.
Standard Tooth Types
Matson’s cementum age analyses are not only species-specific, but are also based on a standardized tooth type.
Mixing of tooth types in a sample can cause error because of differences in age at eruption and cementum patterns.
Martens & Fishers
Standard Tooth Types for Live Mammals
For live pull animals, it is often not possible to take the standard tooth.
In this case, these less invasive tooth types are recommended by the lab.
Lynx & Bobcats
Archaeological & Anthropological Specimens
Matson’s is unable to process fossilized specimens. The decalcification protocol we use dissolves the mineral of the tooth, leaving behind the collagenous ground substance. Decalcified teeth are composed almost entirely of this collagen, which contains the annular structures that are counted to determine age.
In most specimens that have been in the soil for long periods, the collagen has been replaced by minerals. After decalcification, there is no intact collagen and no annular structure. Techniques that don’t involve decalcification are more suitable for archaeological materials.
Remarkable exceptions are preserved specimens that have been frozen in arctic regions.