1. Analysis of Bitemarks

2. Forensic Dentistry
We will focus on a specific element of forensic dentistry – specifically, bitemark analysis
Here, a dentist is required to compare the impressions and bruises left in the skin by one person biting another to a suspect’s teeth.
Another important element = identification of human remains by comparing dental charts to the teeth of the victim
This has only been around for about 50 or so years. Why?

3. Male or Female?

4. WHAT IS A BITEMARK? Bitemark:
A physical alteration in a medium (usually skin)
caused by the contact of teeth
leaves a representative pattern that can be analyzed

5. What are limitations? All of these items can record patterns. Wax
Fruit
Skin
Paper
Chewing gum

6. WHY ARE BITEMARKS USEFUL?
We can use bitemarks to carry out bitemark analysis.
This type of comparison is used to confirm or eliminate the identity of a suspect in relation to the bitemark.

7. A Crash Course in Dentistry
3rd Molar (wisdom tooth)
2nd Molar (12-yr molar)
1st Molar (6-yr molar)
2nd Bicuspid (2nd premolar)
1st Bicuspid (1st premolar)
Cuspid (canine/eye tooth)
Lateral incisor
Central incisor
Please note: When you look at the tooth chart, you are looking into a person's mouth with the jaws open. You're facing the person, so their upper right jaw will be on the left of this image.

8. Bitemark Analysis
In a bitemark comparison, you are looking for and matching unique features between the bitemark and exemplar castings. These features may include:
Gaps
Rotation (angle)
Size of teeth (e.g. width at tip)
Width from tooth to tooth (e.g. cuspid to cuspid)

9. Evidential Value of Bitemarks
By establishing the uniqueness of the biter's teeth and then applying those unique properties to the bite pattern, a degree of confidence relating the biter's teeth to the injury pattern is described.
This opinion can range for excluded ( the suspect did not do the biting) to likely and without a doubt (the bite was witnessed and there is not question the suspected biter inflicted the bite).
Despite the unique nature of the position and arrangement of the human teeth, it is usually easier to rule out a suspect as a potential biter than it is to include a suspect as a potential biter.

10. How are bite marks analyzed?
There are over 20 different methods of bitemark analysis.
The most common used are:
1.Comparing an acetate overlay manually fabricated from study models to a life size photograph of the wound.
2.Comparing study models to a life size photograph of the wound
3.Comparing an acetate overlay manually fabricated from bites in wax to a photograph of the wound
4.Comparing an acetate overlay manually fabricated from x-rays of radiopaque material placed in a wax bite to a life size photograph of the wound.
5. Comparing an acetate overlay manually fabricated from a photocopy of study models to a life size photograph of the wound.

11. Sample Analysis

12. Sample Analysis Bitemark : Upper Jaw Distance
Suspect; Upper Jaw Distance
Cuspid to cuspid
38mm
42mm
Bitemark: Distance
Suspect: : Distance
Tooth 6 to Tooth 10
 44.25mm
39.65mm
Angle: Degrees
Angle: Degrees

13. ACETATE OVERLAYS
Most of these techniques involve the fabrication of an acetate overlay
An acetate overlay is an outline of the biting edge of someone’s teeth as traced onto and seen on a clear transparency
They can be fabricated in a number of ways
A review of the literature has found over 15 methods
These include tracing from dental models, photographs, wax bites, photocopies.

14. Conviction of a Serial Killer
Case Profile-Ted Bundy
Forensic Odontology

15. Ted Bundy Bite Mark Analysis

16. COMPUTER PROGRAMS
Have been developed to overcome some of these problems
Theoretically they can;
Correct for distortion
Generate the overlay objectively
Carry out the comparison objectively
Reproduce the overlay

17. Considerations & Limitations
Daubert Standards and Bitemarks

18. Consider the Following
Outlines of the same set of teeth. The different perimeter shapes depend on how far the teeth are pressed into the test substrate.

19. Some sample casts
You will be making impressions in the next activity
Then we will use transparencies to make an acetate overlay