The practice of forensic odontology regularly requires the forensic dental expert to establish a degree of
concordance between two objects, one or both of which have undergone minimal degrees of warping,
shrinkage and distortion collectively described as deformations. These comparisons can be between the
suspect’s or victim’s dentition and bite marks on inanimate objects/skin, two radiological images, palatal
rugae patterns, dental arches, lip prints and other unique scenarios which are presented in forensic
This paper will define the mathematical concept of affine transformation as it pertains to forensic
matters and explains how it can be applied to a case study involving pattern deformations. Although the
deformation of the evidence may be minimal in extent, it creates a measure of uncertainty when expert
evidence is given in court cases. Any metric discrepancy caused by deformation of the evidence will
necessitate the application of pattern association and negate the use of metric analysis. It has been
shown that a pattern association analysis of evidence will not be affected by minimal amounts of
deformation. The mathematical limits of these deformations which will significantly affect the
comparisons have not yet been determined. In the case study presented the deformations were
considered minimal and thus explainable by a pattern association analysis.
The mathematical concepts will empower the expert to explain to a court of law how two samples
which were not a perfect match, could in fact be deformed equivalents of common origin.