348 Forensic dentistrydentition and human skin’s ability to record the features of teeth will be dis-
cussed in Sections 14.4.1 and 14.4.2. The challenge for forensic odontologists
is to consider all of the known and possible variables with bitemark evidence
when forming their initial investigative opinions, during their analyses, and
when forming their final opinions.14.3.3 Comparison of Injury and Dental Evidence
The methodology for comparing information from bitemarks to the teeth or
facsimiles of the teeth that may have caused them has developed over time into a
robust, comprehensive, and detailed process. The bitemark analysis guidelines
developed by the ABFO are described and discussed in the ABFO Diplomates
Reference Manual^35 and Bitemark Evidence.^36 In this section discussion will
center not on methodology, but on issues related to that methodology.
14.3.3.1 Methods of Comparison
Comparisons between bitemarks and the teeth that may have made them are
accomplished by comparing features of the teeth of suspected biters to fea-
tures in the bitemark. The methods used may be direct and indirect. Direct
methods do not include directly placing the actual teeth of suspected biters
against skin or images, but signify that exemplars or models of the teeth are
employed for comparisons.
14.3.3.1.1 Direct Comparisons on Skin Direct comparison of dental
models to bitemarks on skin is an acceptable screening technique if properly
conducted. Opaque stone dental models impede the view of the underlying
marks, making meaningful, in-depth feature comparison impossible. Some
useful initial screening information may be gleaned from such comparisons.
However, the placement of stone dental models directly on skin and moving
them to facilitate visualization or mimic possible bite mechanisms can cause
serious problems, including a real possibility of creating iatrogenic artifacts.
Such artifacts could then be confused with actual injury pattern information.
Videotapes of direct comparisons in actual casework have demonstrated this
exact scenario in some of the problem cases.
14.3.3.1.2 Dental Exemplars Dental exemplars are facsimiles of the bit-
ing surfaces of teeth that facilitate comparisons to injury patterns. Exemplars
of the solid- and hollow-volume type have been created by various means,
ranging from freehand tracing onto transparent acetate sheets to radiographs
of opaque materials placed into teeth indentations into wax or other media
to computer-generated methods. In 1996 Dr. Heidi Christensen developed
a method of scanning dental models on a flatbed scanner, then generating
solid- and hollow-volume overlays using Adobe Photoshop.^45 The method