New technologies about Bitemarks- A potent tool in forensic dentistry

2. CONTENTS
 Introduction
 History
 Classification
 Collection
 DNA sampling
 References
 Conclusion

3. INTRODUCTION
Forensic Odontology is the application of
dentistry in legal proceedings deriving from
any evidence that pertains to teeth.
OR
Area of dentistry concerned with the correct
management, examination , evaluation &
presentation of dental evidence in civil/criminal
legal proceedings in the interest of justice
( Neville)

4. A SOURCE OF IDENTIFICATION
 Every human body ages in a similar
manner, the teeth also follow a semi-
standardized pattern. These quantitative
measurements help establish relative age of
person.
 Each human has an individual set of teeth
which can be traced back to established
dental records to find missing individuals.

5.  Teeth is made of enamel (hardest tissue of
the body) - withstand trauma
(decomposition, heat degradation, water
immersion, and desiccation) better than other
tissues in body.
 Teeth are a source of DNA: dental pulp or a
crushed tooth can provide nuclear or
mitochondrial DNA that to help identify a
person.

6. HISTORY OF FORENSIC ODONTOLOGY
 66AD – First body identified using teeth
 Lollia Paulina
 Revolutionary War
 Paul Revere was the first forensic dentist in the
United States because he identified fallen
revolutionary soldiers.
 1849 – Mass deaths at Vienna Opera House
Fire
 Dental evidence is first admitted into court system in
US

7.  Salim witch trials-1692- first reported
incidence of bitemark identification
 Doyle v/s State-first bitemark to be reported
as an american judiciary opinion( 1954)-
Cheese thief

8. FRYE- DAUBERT V/S MERELL DOWS
 Techniques-tested & testable
 Peer review and publication of results-admit
evidence in court
 Standards-evaluation of scientific methods &
error rates
 Acceptance of scientific principles-general
acceptance & scientific validity
 Federal rule of evidence-702-705

9. TEETH BASICS
 Approximately 32 teeth in
adult mouth
 Four types of teeth:
 Molars
 Premolars
 Canine
 Incisors
 Teeth differ in:
 Size
 Shape
 Root type

10. BITEMARKS
 Mac donald- a mark caused by the teeth
either alone or in combination with other
mouth parts
 Recorded, documented and described -
size, location and severity
 Attack injuries (present on the victim)
 defensive wounds ( present on the suspect)

11.  Severity: force – medium severity significant
-original injury was inflicted
-anatomical location bitten
- time elapsed between infliction and
presentation

12. CLASSIFCATION
Cameron & Sims- type of agent producing &
material exhibiting
 Agents-Human & Animal
 Materials
- skin, body tissue
- Foodstuff
- Other materials

13. MAC DONALDS- ETIOLOGIC
Macdonald DG. Bite Mark Recognition And Interpretation. J Forensic Sci Soc 1974;
14(3): 229
 Tooth pressure marks-tissue-direct
application of pressure by teeth. Eg-
incisal/occlusal surfaces
 Tongue pressure marks- sufficient amount of
tissue in mouth-presses against rigid areas-
lingual surface of teeth & palatal rugae
-marks left on skin- Suckling
 Tooth scrape marks- scraping of teeth across
bitten material. caused by ant teeth,
scratches & superficial abrasion

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

15. Webster’s –foodstuff-
theft/robbery
 Type 1- food item fractures readily-limited
tooth penetration eg- hard chocolate
Type 2- considerable food
penetration eg- apple & other firm fruits
 Type 3- complete penetration of food item
with slide marks-eg cheese

16. TYPE OF INJURY
 Abrasion
 Ecchymosis
 Laceration
 Petechial hemorrhage
 Incision
 Artefactorial- proximate stab & bullet wound-
distort pattern by separation of anatomic
cleavage lines-langer’s lines

17. IDENTIFYING INJURY AS A BITE MARK
 Gross features:
-circular/elliptical mark-upper & lower arch
-central area ecchymosis- sucking action-
distinct
 Class features: differentiate b/n tooth type
-incisors-rectangular
-canines-triangular
-premolars + molars – spherical/point shaped
- Depends on attrition

19.  Bicuspid-figure of eight
 Greatest dimension of adult arch-4 cm
 Single arch-crescent shaped
 Class II malocclusion-palatal surface of ant
teeth-shield like pattern
 TMD midline shift, inability to open mouth-
muscle force, bite pattern, tongue thrusting

20.  Individual features:
fractures/rotations/spacing
 Site of bitemark: Pretty & Sweet
-females-sexual assualt-breast & legs
-males- fights- arms & shoulders

21. DIFF B/N HUMAN & CARNIVORE BITE
Features Human Carnivore
Arch size & shape Broad, u-shaped, Narrow ant aspect,
circular V-
shaped/elongated
Teeth Broad central, Narrow central,
narrow lateral, broad lateral, long
blunt & sharp canines
Injury pattern Bruising, Severe laceration,
laceration avulsion, greater
skin damage
Site Breast, abdomen, Extremities,
back, shoulder exposed skin

22. COLLECTION OF BITEMARKS
Photography(bite victim)
 With and without the ABFO No. 2 scale
 In colour and black and white
 On and off camera flash (oblique flashes -the
three-dimensional nature
 An overall body shot showing the location of
the injury

23.  Close-ups that can easily be scaled 1:1
 UV photography if the injury is fading
 If the bite is on a moveable location-several
body shots-effect of movement
 Camera at 90° (perpendicular) to the injury
 Regular 24 hour intervals on both the
deceased and living victim

24. COLLECTION OF ITEMS
 Dental impression of the victim − self-biting
/bite injuries of suspect
 DNA swabbing of the injury site –double
swab – the first moistened with distilled water
and the second dry
 Impression of the bite injury –significant
degree of three-dimensional detail is present
 Skin removal –permits trans-illumination of
bitemark, Flawed- skin contraction

25. COLLECTION OF EVIDENCE FROM THE BITE
SUSPECT
 Overall facial shot
 Close-up photograph of the teeth in normal
occlusion and biting edge to edge
 Photograph of the individual opening as
wide as possible
 Lateral view
-dental charting
- condition of each teeth

26.  High quality impressions - upper + lower
arches
 Prosthesis-with & without
 poly-vinyl siloxane (PVS) impression
material+ plastic stock trays-multiple times
 Alginate-pour-1−2 hours- contraction
 sheet of softened wax-occlusal record

27. WAX BITE
Impression materials & trays
Cast with & without prosthesis

29. Visual index of
the bitemark
severity and
significance
scale

30. ANALYSIS OF BITEMARK INJURIES
 Accidental or non-accidental
 American board of forensic
odontology(ABFO)
 Exclusion – the injury is not a bitemark.
 Possible bitemark – injury showing a pattern
that may or may not be caused by teeth,
could be caused by other factors but biting
cannot be ruled out.

31.  Probable bitemark – the pattern strongly
suggests or supports origin from teeth but
could conceivably be caused by something
else.
 Definite bitemark – there is no reasonable
doubt that teeth created the pattern.

33. CONCLUSIONS –BITE MARK ANALYSIS
 Definite biter: medical certainity + bitemark
dimension/pattern similar to suspect teeth
 Probable biter: degree of specificity with suspect
teeth-> matching points
 Possible biter: consistency- non specific match
 Not the biter: not at all consistent
 Exclusion: not a bitemark

34. PATTERN ANALYSIS IN BITEMARK EVIDENCE
 Biometric analysis
 Transparent overlay-dental casts of
suspects-biting edges- reproduced on
transparent sheets
 Overlays placed over the scaled 1:1
photographs of the bite injuries & compared

35. SAMPLE ANALYSIS
Bitemark : Upper Jaw Distance Suspect; Upper Jaw Distance
Cuspid to cuspid Cuspid to cuspid
38mm 42mm
Bitemark: Distance Suspect: : Distance
Tooth 6 to Tooth 10 Tooth 6 to Tooth 10
44.25mm 39.65mm
Angle: + 14.5 Degrees Angle: + 12.52 Degrees

36. METHODS OF OVERLAY PRODUCTION
 Computer-based
 radiographic
 Xerographic
 Hand-traced(acetate sheets and marker pen)

37. 3-D ANALYSIS
 Have been developed to overcome some of
these problems
 Theoretically :
 Correct for distortion
 Generate the overlay objectively
 Carry out the comparison objectively
 Reproduce the overlay

38. bite mark image generated
A typical digitized dental model
by the dental casts.
imported
into Rapidform editing software
Digitized 3D dental model with
intersecting
plane and captured tooth contour.

39. A. Van Der Velden. Bite Mark Analysis And Comparison Using Image
Perception Technology J Forensic Odontostomatol 2006;24:14-7
 New method of analysing bite marks- Image
Perception Technology
 Artificially colour areas with equal intensity
values
 2-D image as a pseudo-3-d surface object.

40. Original photograph
Image artificially coloured with image
perception technology software
Corresponding incisal detail in bite
Pseudo 3-D image- mark
visible bite mark detail

41. BITEMARKS AND DNA
 Wet swab rehydrates the salivary
constituents, releasing more epithelial cells
from the dried deposit
 DNA typing of bacteria & its recovery / SEM
analysis of bite wounds

42.  Presence of nucleic acid-degrading enzymes
(nucleases) saliva can rapidly degrade
DNA, (living victim) skin temperature
accelerate
 Sweet’s double swab technique-rather than
just relying upon pure ‘salivary’ DNA
Pretty IA, Sweet D. Anatomical location of bitemarks and associated findings in
101 cases from the United States. J Forensic Sci 2000; 45(4): 812−814

43.  Genotypic identification of oral streptococci
 one year later and found that their
genotypes-same
a. Kit- including two swabs (for skin
only, buccal suspect swabs require
only one), gloves, card drying
rack, evidence stickers, sealable
plastic bag, documentation and
evidence
envelope
b. dried prior to placement in sealed
evidence bag. Drying is a crucial
stage and can take up to 30

44. TECHNIQUES
 DNA typing
 DNA probe
 RFLP analysis (restriction fragment length
polymorphism)
 FISH- Fluorescence in situ hybribization

45. BITES ON PERISHABLE ITEMS, NONHUMAN
SUBSTRATES
 Apples, cannabis resin, sandwiches, bank
books, pencils,pacifiers, Styrofoam
cups, envelopes
Negative impressions of the bite mark
Positive impressions of the bite mark
taken from the apple taken with plaster from the negative

46. LIMITATIONS
Reliable scientific tool or not
1. Numerous methods of fabrication
2. Relies on manual fabrication
3. Subjective element in fabrication
4. Subjective element in comparison
5. Distortion
6. Loss of data, contamination

47. CONCLUSION
 Case no., date of examination, name of
examiner
 Orientation & location of mark
 Type of injury
 Colour, size, shape
 Contour, texture, elasticity of bite
 Diff b/n upper & lower arch/ individual teeth

48. REFERENCES
 Shafer’s –textbook of oral pathology
 Lessig R*, Wenzel V, Weber M. Bite mark
analysis in forensic routine case work .
EXCLI Journal 2006;5:93
 Iain A Pretty. Forensic dentistry &
bitemarks. Dental update 2008.