Tooth
Description
Teeth are used to chew up food and — together with bones — they form the skeleton. All mammals have a similar structure of dentition, although the number of teeth and their morphological characteristics vary depending on the species.
The permanent dentition of humans consists of 32 teeth, including four upper and four lower incisors, two upper and two lower canines, four upper and four lower premolars and six upper and six lower molars. The human deciduous dentition lacks the premolars and the third molars (wisdom teeth), and consists of 20 teeth.
Teeth to be submitted for analysis should be identified according to the FDI (Féderation Dentaire Internationale) scheme, which classifies the dentition into four quadrants (permanent dentition: quadrant 1: upper right, quadrant 2: upper left, quadrant 3: lower left, quadrant 4: lower right; deciduous dentition: quadrant 5: upper right, quadrant 6: upper left, quadrant 7: lower left, quadrant 8: lower right). The teeth are numbered per quadrant from 1 to 8 (permanent dentition) or 1 to 5 (deciduous dentition) starting with the front teeth and ending with the back teeth, i.e. from the incisors to the molars. The scheme identifies each tooth unambiguously and we ask you to use this scheme for the designation of teeth intended for sampling.
Teeth have a root, with which the tooth is fixed in the socket (alveolus) and a crown, which protrudes into the oral cavity. Both parts consist mainly of dentine, which is covered by enamel in the area of the crown and by dental cement in the area of the root. The pulp cavitiy is situated inside the root and parts of the crown. It contains blood vessels, nerves as well as connective tissue and serves to supply the tooth.
Enamel and dentine are formed between earliest childhood and early adulthood. Depending on tooth type, they have different periods of mineralization beginning with the deciduous teeth before birth and ending with the wisdom teeth in adolescence or early adulthood. During this process, they store main and trace elements taken in with food and drinking water. The concentrations of some of theses elements as well as their isotope compositions provide the foundation for the reconstruction of eating habits and mobility in the past.
Sample properties
Teeth are a fundamental study material of physical anthropology. Here, they are considered as far as possible in the totality of the dentition.
Isotope analyses
For isotope analyses, the main sample materials include enamel (strontium, oxygen, carbon isotope analyses) and dentin (nitrogen and carbon, occationally strontium isotope analyses).
The teeth to be sampled should be determined regarding their anatomical position or specifically selected, based on the research question. The anatomical position of teeth can always be determined with greater certainty in the context of the remaining dentition or other loose teeth of the same individual than for single specimens.
Using teeth with caries lesions, conspicuous grinding facets or epigenetic traits for destructive analyses should be avoided if possible. For element and isotope analyses of enamel of human teeth, crown hights should still be at least 2-3 mm, and the enamel should not already be lost due to severe abrasion or chipping.
Teeth intended for analysis should be packed individually and provided with the appropriate contextual information.
14C dating
14C dating of collagen is performed exclusively on the dentine, which is usually taken from the roots. The required sample size is 0.5 – 1g. Occationally, sampling several roots of the same tooth may be necessary.