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Bitemarks

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New technologies about Bitemarks- A potent tool in forensic dentistry

New technologies about Bitemarks- A potent tool in forensic dentistry

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  • 1. CONTENTS Introduction History Classification Collection DNA sampling References Conclusion
  • 2. INTRODUCTIONForensic Odontology is the application ofdentistry in legal proceedings deriving fromany evidence that pertains to teeth. ORArea of dentistry concerned with the correctmanagement, examination , evaluation &presentation of dental evidence in civil/criminallegal proceedings in the interest of justice( Neville)
  • 3. 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.
  • 4.  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.
  • 5. 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
  • 6.  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
  • 7. 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
  • 8. TEETH BASICS Approximately 32 teeth in adult mouth Four types of teeth:  Molars  Premolars  Canine  Incisors Teeth differ in:  Size  Shape  Root type
  • 9. 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)
  • 10.  Severity: force – medium severity significant-original injury was inflicted-anatomical location bitten- time elapsed between infliction and presentation
  • 11. CLASSIFCATIONCameron & Sims- type of agent producing & material exhibiting Agents-Human & Animal Materials- skin, body tissue- Foodstuff- Other materials
  • 12. MAC DONALDS- ETIOLOGICMacdonald 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
  • 13. Outlines of the same set of teeth. Thedifferent perimeter shapes depend onhow far the teeth are pressed into the test substrate.
  • 14. Webster’s –foodstuff- theft/robbery Type 1- food item fractures readily-limited tooth penetration eg- hard chocolateType 2- considerable foodpenetration eg- apple & other firm fruits Type 3- complete penetration of food item with slide marks-eg cheese
  • 15. 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
  • 16. 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
  • 17.  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
  • 18.  Individual features: fractures/rotations/spacing Site of bitemark: Pretty & Sweet-females-sexual assualt-breast & legs-males- fights- arms & shoulders
  • 19. DIFF B/N HUMAN & CARNIVORE BITE Features Human CarnivoreArch size & shape Broad, u-shaped, Narrow ant aspect, circular V- shaped/elongatedTeeth Broad central, Narrow central, narrow lateral, broad lateral, long blunt & sharp caninesInjury pattern Bruising, Severe laceration, laceration avulsion, greater skin damageSite Breast, abdomen, Extremities, back, shoulder exposed skin
  • 20. COLLECTION OF BITEMARKSPhotography(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
  • 21.  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
  • 22. 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
  • 23. 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
  • 24.  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
  • 25. WAX BITEImpression materials & trays Cast with & without prosthesis
  • 26. Visual index of the bitemark severity and significance scale
  • 27. 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.
  • 28.  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.
  • 29. 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
  • 30. 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
  • 31. SAMPLE ANALYSISBitemark : Upper Jaw Distance Suspect; Upper Jaw DistanceCuspid to cuspid Cuspid to cuspid38mm 42mmBitemark: Distance Suspect: : DistanceTooth 6 to Tooth 10 Tooth 6 to Tooth 1044.25mm 39.65mmAngle: + 14.5 Degrees Angle: + 12.52 Degrees
  • 32. METHODS OF OVERLAY PRODUCTION Computer-based radiographic Xerographic Hand-traced(acetate sheets and marker pen)
  • 33. 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
  • 34. bite mark image generatedA typical digitized dental model by the dental casts. importedinto Rapidform editing software Digitized 3D dental model with intersecting plane and captured tooth contour.
  • 35. A. Van Der Velden. Bite Mark Analysis And Comparison Using ImagePerception 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.
  • 36. Original photograph Image artificially coloured with image perception technology software Corresponding incisal detail in bite Pseudo 3-D image- markvisible bite mark detail
  • 37. 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
  • 38.  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’ DNAPretty 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
  • 39.  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
  • 40. TECHNIQUES DNA typing DNA probe RFLP analysis (restriction fragment length polymorphism) FISH- Fluorescence in situ hybribization
  • 41. BITES ON PERISHABLE ITEMS, NONHUMAN SUBSTRATES Apples, cannabis resin, sandwiches, bank books, pencils,pacifiers, Styrofoam cups, envelopesNegative impressions of the bite mark Positive impressions of the bite mark taken from the apple taken with plaster from the negative
  • 42. LIMITATIONSReliable scientific tool or not1. Numerous methods of fabrication2. Relies on manual fabrication3. Subjective element in fabrication4. Subjective element in comparison5. Distortion6. Loss of data, contamination
  • 43. 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
  • 44. 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.

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