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Since dental pulp, the soft tissue within the tooth, contains different types of cell (such as
fibroblasts, the mother cells of dental pulp, macrophage, odontoblasts, blood cells and
peripheral nerve cells), enough can be obtained to carry out a DNA analysis. The number of cells
in the pulp organs decreases with age. Not all teeth contain the same amount of dental pulp, so
that a single tooth can provide between 15 and 20 micrograms of DNA. (xi)
Two methods of extracting DNA from dental pulp are used: total pulverisation of the tooth, and
transversal or horizontal sectioning of the tooth. (xi)
Analysis of bites
Bite marks are the impressions made by the teeth on different substrata capable of becoming
deformed. That deformation allows the characteristics of the teeth to be transferred to the
surface.
Each tooth leaves a characteristic trace, such as:
• Incisor: elongated rectangle
• Upper canine: wide triangle
• Lower canine: narrow triangle
• Upper premolar: double triangle
• Lower premolar: single triangle
• Molar: rare, but when found it looks like a wide rectangle.
Fig. 7: Bite mark
This is a very useful crime lab method, since the teeth may have been used as weapons of either
defence or attack. Bite marks are often found in crimes of a sexual nature, cases of child abuse,
and fights. They can also be a source of DNA since they may also contain the attacker’s saliva
and/or blood.
Bite marks can indicated the type of bite – whether done in defence or attack – and depending
on the location of the bite the type of crime can be determined. It is also possibly to identify
whether the marks were made by third parties or by the parties themselves, guiding the
investigation; they can be used to link a suspect with a crime, and, along with psychological
evaluation, they can be used to build a psychological profile of an attacker. (xii)
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