1. Forensic Dentistry (II) (bite Marks)
Dr. Abdelmonem
Altarhony
Forensic Dentistry (II) (bite Marks)

2. Definition
Bite mark:
A physical alteration in a medium caused by the contact of teeth.
A representative pattern left in an object or tissue by the dental structures of an animal or human.

3. Sites of occurrence of bite injuries
Variations:
1. type of crime
2. sex and
3. age of the victim

4. Bite marks can be found also:
on objects present at the scene of a crime.
on a suspect when a victim attempts to defend him/herself.

5. The possibility of two persons having the exact same bite marks is of billion which indicates that it is practically impossible.
Even twins present differences

6. Questions we should know during the investigation of a bite mark.
Is it a bite mark?
Is it caused by human or animal?
Is it caused by a child or adult or if it is self-inflicted?
Is it identifiable?
Does the teeth marks present have enough unique characteristics to be attributable to one particular perpetrator?

7. Differences between human and animal bite marks
Human bite:
superficial– most bruises or abrasion a broad,
U-shaped somewhat circular or oval,
2 curved rows of abrasions that meet in an elliptical form
Separated at their bases by open spaces.
Following the periphery of the arches are a series of individual abrasions, contusions and/or lacerations .

8. Animal bite – mammals (dogs):
A narrow in the anterior aspect,
V shaped and elongated,
Morphology of the teeth is different.
2 parallel horizontal rows,
Deep tissue penetration, tearing,
Lacerations, incision, avulsion.

9. Mammals
Heterodont dentition, diphyodont (deciduous and permanent).

11. Fish
conical, homodont (one type), heterodont (various types) or polyphydont (continually
discarded through time life).
•ER: Take an X-ray to be sure of lose teeth inside the wound.

12. Reptiles Homodont conical or only tricuspid teeth.
Venomous snakes: single row, palatal to this are two poison fangs containing canal or groove for venom release.
Non-Venomous: two rows of maxillary teeth.

13. Features of a suspect’s dentition useful in bite mark analysis
Incisor: rectangular
Canines: triangular
Premolars: spherical or
point shaped
Molars: seldom present
copy occlusal morphology
Gums, roots and cusps

14. Comparing physical characteristics of bite wound and suspect’s teeth
Inter canine distance
Type of mouth arch
The evidence of a tooth out of alignment
Teeth width and thickness and the spacing between teeth
Missing teeth- gaps
The curves of biting edges
Wear patterns, such as grinding

15. Steps on bite analysis 1.Identify the bite 2. Identify the bite origin
Analysis of a bite injury must be done as early as possible, as the clarity and shape of the mark may change rapidly in both living and dead victims.
2. Identify the bite origin
(human; animal; self inflicted)

16. 3. Swabbing of the unwashed injury site for DNA analysis of the saliva of the biter that may be left- (make a control near from bite).
(double-swab technique)
DNA techniques = analysis of DNA from the nucleus and mitochondria.

17. Sources of DNA for forensics analysis

18. (soon better / the changing nature of the bites)
4. Take photographs.
(soon better / the changing nature of the bites)
The bite photography must be conducted precisely ( 90 degree to the bite – prevent distortions),
using rulers and other scales to accurately depict the orientation, depth and size of the bite photos repeated in intervals

19. This known dimensional reference allows the examiner to compare 1:1 pictures of the evidence materials using software programs like Adobe Photoshop.
Photographic study and image enhancement with comparative study may exclude or positively identify a suspect.

20. Consider ultraviolet photography for older injuries that may no longer be visible.

21. 5. Preservation of the bite marks :
Dorion method: excision and fixation of bitten tissue for microscopic examination and production of a silicone cast of the bite mark.
Scanning electron microscopy.
Computer-enhanced digitization.
Xeroradiology.

22. 6. Take measurements of each individual bite mark and record it.

23. Once a suspect is apprehended:
Take impressions of the suspect's teeth,
Prepare transparent overlays of the biting edges of the teeth from the dental models,
Compare them to the recorded bite marks,
Renders an opinion of the probability of a match.

24. Currently, the best method for overlay production to achieve accuracy and reproducibility is the computer-generated method.

25. CASE
An eight month-old Hispanic male infant was admitted to the Loma Care Unit with multiple injuries.
A pattern of suspected child abuse was established.
After clinical examination, numerous ovoid and circular pattern injuries were observed.
She immediately notified Dr. Golden to request a forensic bite mark examination and photographic documentation of the injuries.

26. The photographs below depict three of the more obvious bites inflicted to the cheek, knee, and calf.
There were other bites noted elsewhere on the child's body.

27. It was determined that the bite on the calf would be the most useful as evidence for comparative purposes.
There were two suspects; the child parents.
Stone dental casts were made of each person's teeth, as are shown in the digital scanned images below:

28. With the use of Adobe Photoshop® imaging software,
overlays of the biting edges of the 12 anterior teeth were made for comparison to life-sized images of the bite mark.
Additional image enhancement was employed with LucisPro® 5.0 Imaging Software to bring out more detail in the bruise pattern.

29. Factors that may affect the accuracy of bite mark identification
The skin is usually a poor impression material.
Time-dependent changes of the bite mark on living and dead bodies,
Effects of where the bite mark was found.
Damage on soft tissue
The extent of the trauma, the area and the characteristics of the skin bitten

30. 6. Poor technique: photography, impressions, or measurement of dentition characteristics.
7. Dental profiles are subject to change ( tooth loss, caries, restorations- time related).

31. Bite marks aren't like fingerprints and DNA -- they can't tell you 100 percent who the biter was

32. Now some critics feel that bite-mark analysis should be used only to eliminate, not to identify, a suspect.
Others say that it's acceptable to state there is a probability that a suspect created the mark, but that it's important to clarify that bite marks can't be the only thing linking the suspect to the crime.

33. Lip marks- cheiloscopy
Like fingerprints, lip grooves are permanent and unchangeable.
This is unique for individuals but can not differentiate twins.
Serve as a useful evidence in forensic dentistry

34. Rugoscopy
Ridges on the anterior part of the palatal mucosa, each side of the median palatal raphae and behind the incisive papilla.
Unchangeble except in length, due to normal growth, remaining in the same position throughout an entire person's life.

35. Thank you