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Bite marks introduction to medical and dental students of IMU.

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  1. 1. If you cover the bottom part of the picture, everything seems normal, but once the bottom part is revealed, the two workers below should be “hanging” but the picture explains otherwise.
  2. 2. What do you think ? What will happen to this bird. Yummy Yummy Yummy He loves me He loves me not ???
  3. 3. Sometime finding the real culprit is very difficult
  4. 4. Dr. Muneer Gohar Babar [email_address] Ext No: 1210
  5. 5. Bite Marks Investigation It is not everybody job … training is required.
  6. 6. <ul><li>Forensic odontology / dentistry is the application of dental principles to legal issues. </li></ul><ul><li>Applications: </li></ul><ul><li>- Bite mark analysis </li></ul><ul><li>- Individual Identification </li></ul><ul><li>- Mass Disaster Identification </li></ul><ul><li>- Malpractice </li></ul>
  7. 7. <ul><li>We will focus on a one element of forensic Science – specifically, Bite Marks </li></ul><ul><ul><li>Here, a forensic scientist/forensic dentist is required to compare the impressions and bruises left in the skin or some other object by one person biting another to a suspect’s teeth. </li></ul></ul><ul><li>However, another important element of forensic dentistry involves the identification of human remains by comparing dental charts to the teeth of the victim. </li></ul>
  8. 8. A Crash Course in Dentistry
  9. 9. <ul><li>3rd Molar (wisdom tooth) </li></ul><ul><li>2nd Molar (12-yr molar) </li></ul><ul><li>1st Molar (6-yr molar) </li></ul><ul><li>2nd Bicuspid (2nd premolar) </li></ul><ul><li>1st Bicuspid (1st premolar) </li></ul><ul><li>Cuspid (canine/eye tooth) </li></ul><ul><li>Lateral incisor </li></ul><ul><li>Central incisor </li></ul><ul><li>Central incisor </li></ul><ul><li>Lateral incisor </li></ul><ul><li>Cuspid (canine/eye tooth) </li></ul><ul><li>1st Bicuspid (1st premolar) </li></ul><ul><li>2nd Bicuspid (2nd premolar) </li></ul><ul><li>1st Molar (6-yr molar) </li></ul><ul><li>2nd Molar (12-yr molar) </li></ul><ul><li>3rd Molar (wisdom tooth) </li></ul><ul><li>3rd Molar (wisdom tooth) </li></ul><ul><li>2nd Molar (12-yr molar) </li></ul><ul><li>1st Molar (6-yr molar) </li></ul><ul><li>2nd Bicuspid (2nd premolar) </li></ul><ul><li>1st Bicuspid (1st premolar) </li></ul><ul><li>Cuspid (canine/eye tooth) </li></ul><ul><li>Lateral incisor </li></ul><ul><li>Central incisor </li></ul><ul><li>Central incisor </li></ul><ul><li>Lateral incisor </li></ul><ul><li>Cuspid (canine/eye tooth) </li></ul><ul><li>1st Bicuspid (1st premolar) </li></ul><ul><li>2nd Bicuspid (2nd premolar) </li></ul><ul><li>1st Molar (6-yr molar) </li></ul><ul><li>2nd Molar (12-yr molar) </li></ul><ul><li>3rd Molar (wisdom tooth) </li></ul>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.
  10. 10. Dental Restorations <ul><li>Crowns </li></ul><ul><li>Fillings </li></ul><ul><li>Root canal </li></ul><ul><li>Bridge </li></ul><ul><li>Extractions </li></ul>
  11. 12. BRITISH DENTAL JOURNAL, VOLUME 190, NO. 7, APRIL 14 2001 Shovel-shaped incisors Cusp of Carabelli
  12. 13. BRITISH DENTAL JOURNAL, VOLUME 190, NO. 7, APRIL 14 2001
  13. 14. Criminals can lie through their teeth but their teeth rarely lie!
  14. 15. Bite marks and shark attack.
  15. 16. WHAT IS A BITE MARK? <ul><li>Bite Mark: </li></ul><ul><ul><li>A physical alteration in a medium caused by the contact of teeth. </li></ul></ul><ul><ul><li>A representative pattern left in an object or tissue by the dental structures of an animal or human. </li></ul></ul><ul><li>Cutaneous Human Bite Mark: </li></ul><ul><ul><li>An injury in skin caused by contacting teeth (with or without the lips or tongue) which shows the representational pattern of the oral structures. </li></ul></ul>
  16. 17. What are limitations to both? <ul><li>What are evidential limitations to Bite Marks in the following substances: </li></ul><ul><ul><li>Wax </li></ul></ul><ul><ul><li>Fruit </li></ul></ul><ul><ul><li>Skin </li></ul></ul><ul><ul><li>Paper </li></ul></ul><ul><ul><li>Chewing gum </li></ul></ul>
  17. 18. WHY ARE BITE MARKS USEFUL? <ul><li>We can use bite marks to carry out bite mark analysis. i.e. a comparison of a known person’s dentition to a patterned injury which appears consistent with a bite mark </li></ul><ul><li>This type of comparison is used to confirm or eliminate the identity of a suspect in relation to the bite mark . </li></ul>
  18. 19. Bite mark Analysis <ul><li>In a bite mark comparison, you are looking for and matching unique features between the bite mark and exemplar castings. These features may include: </li></ul><ul><ul><li>Gaps </li></ul></ul><ul><ul><li>Rotation (angle) </li></ul></ul><ul><ul><li>Size of teeth (e.g. width at tip) </li></ul></ul><ul><ul><li>Width from tooth to tooth (e.g. cuspid to cuspid) </li></ul></ul>
  19. 20. Cases – Asian Tsunami <ul><li>“ Around mid-March, (of some 800+ identified bodies) 90% were identified by dental records … </li></ul><ul><li>If you post pictures of your loved ones on the bulleting boards/web boards, choose picture with a broad smile so that front teeth can be seen. A better approach is to post dental X-ray films and leave email/phone number of the dentist.” </li></ul><ul><li>----- Tsunami Relief website </li></ul>A forensic expert examines a film of the teeth of a tsunami victim in Phuket of Thailand, on Jan. 11, 2005.
  20. 21. Evidential Value of Bite Marks <ul><li>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. </li></ul><ul><li>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). </li></ul><ul><li>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. </li></ul>
  21. 22. How are bite marks analyzed? <ul><li>There are over 20 different methods of bite mark analysis. </li></ul><ul><li>The most common used are: </li></ul><ul><li>1.Comparing an acetate overlay manually fabricated from study models to a life size photograph of the wound. </li></ul><ul><li>2.Comparing study models to a life size photograph of the wound </li></ul><ul><li>3.Comparing an acetate overlay manually fabricated from bites in wax to a photograph of the wound </li></ul><ul><li>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. </li></ul><ul><li>5. Comparing an acetate overlay manually fabricated from a photocopy of study models to a life size photograph of the wound. </li></ul>
  22. 23. Impression Variation <ul><li>Each dentition can produce variable impressions </li></ul><ul><li>Change based on pressure and surface of contact </li></ul>Impressions from the same dentition
  23. 24. Ted Bundy: Murdered at least 100 women. Ted Bundy: Attractive, smart, and had a future in politics. Bundy worked on the re-election campaign of Washington's Republican Governor Dan Evans. Evans was elected and he appointed Bundy to the Seattle Crime Prevention Advisory Committee. Bundy's political future seemed secure, when in 1973 he became assistant to Ross Davis, chairman of the Washington State Republican Party.
  24. 25. Cases – Ted Bundy <ul><li>The most famous bite mark case </li></ul>The bite mark was on the body of a victim Wax bite exemplar Transparent overlays superimposed
  25. 26. Sample Analysis
  26. 27. Sample Analysis Bite mark : Upper Jaw Distance Suspect ; Upper Jaw Distance Cuspid to cuspid Cuspid to cuspid 38mm 42mm   Bite mark: 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
  27. 28. Computer Aided Forensic Odontology <ul><li>3D Bite mark analysis </li></ul><ul><li>Automatic dental code matching </li></ul><ul><li>OdontoSearch </li></ul><ul><li>Automatic dental identification system </li></ul>
  28. 29. Bite mark Analysis Using 3D Scans-- DentalPrint™ 3D scans of dental casts are used to generate overlays using various pressure and deviation .
  29. 30. Bite mark Analysis Using 3D Scans-- DentalPrint ™ <ul><li>The overlays are compared with the photograph of the bite marks. </li></ul> /
  30. 31. Matching Using Dental Codes – CAPMI* / WinID * Computer Assisted Post Mortem Identification
  31. 32. Automatic Dental Identification System Genuine image has a smaller matching distance than the imposter image. Images with smaller distance are included in the candidate list . Query Image Genuine Matching Distance = 4.22 Imposter Matching Distance = 27.57
  32. 33. ACETATE OVERLAYS <ul><li>Most of these techniques involve the fabrication of an acetate overlay </li></ul><ul><li>An acetate overlay is an outline of the biting edge of someone’s teeth as traced onto and seen on a clear transparency </li></ul><ul><li>They can be fabricated in a number of ways </li></ul><ul><li>A review of the literature has found over 15 methods </li></ul><ul><li>These include tracing from dental models, photographs, wax bites, photocopies. </li></ul>
  33. 34. COMPUTER PROGRAMS <ul><li>Have been developed to overcome some of these problems </li></ul><ul><li>Theoretically they can; </li></ul><ul><ul><li>Correct for distortion </li></ul></ul><ul><ul><li>Generate the overlay objectively </li></ul></ul><ul><ul><li>Carry out the comparison objectively </li></ul></ul><ul><ul><li>Reproduce the overlay </li></ul></ul>
  34. 35. * Daubert Standards and Bite marks *The Daubert standard is a legal precedent set in 1993 by the Supreme Court of the United States regarding the admissibility of expert witnesses' testimony during federal legal proceedings. A Daubert is a motion, raised before or during trial, to exclude the presentation of unqualified evidence to the jury. This is a special case of motion in limine, usually used to exclude the testimony of an expert witness who has no such expertise or used questionable methods to obtain the information.
  35. 36. CRITISISMS OF BITEMARK ANALYSIS <ul><li>In recent years it has been questioned as a reliable scientific tool. This is based on: </li></ul><ul><li>1. Numerous methods of fabrication </li></ul><ul><li>2. Relies on manual fabrication </li></ul><ul><li>3. Subjective element in fabrication </li></ul><ul><li>4. Subjective element in comparison </li></ul><ul><li>5. Distortion which occurs </li></ul><ul><li>As a result of this it has been suggested that bite mark analysis using acetate overlays are inaccurate, subjective and non-reproducible </li></ul>
  36. 37. The Accuracy of Skin as a Substrate for a Bite mark <ul><li>The threshold variable in bite mark analysis is the fact that, in cases of physical assault having skin injuries, the anatomy and physiology of the skin, and the position the victim was in affects the detail and shape of the bite mark. </li></ul><ul><li>There is one article from the early 1970's that showed how the positioning of the test bite on a bicep varied whether the arm was flexed or pronated. </li></ul><ul><li>What is significant is that there is no way to experimentally control or establish the amount of positional variation in an actual bite mark case. </li></ul><ul><li>The bottom line is that skin is usually a poor impression material. No significant  tests have been published on this subject since 1971 in the odontology literature. </li></ul>
  37. 38. What Standards Does Dentistry Meet? <ul><li>There is a considerable body of literature on the subject ( ) </li></ul><ul><li>There are rigid and strict standards ( ) </li></ul><ul><li>Related to this, there is a known error rate </li></ul><ul><li>Legal precedents on the admissibility of bitemark analyses exist ( ) </li></ul><ul><ul><li>The include the famous Ted Bundy case </li></ul></ul>
  38. 39. 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.
  39. 40. Some sample casts
  40. 41. Bite Force <ul><li>Remarkably, marsupials appear to have some of the highest Bite Force Quotients in the world, along with Clouded Leopards and Tasmanian Devils, thrusting animals like the crocodile right out of the competition. However, a high Bite Force Quotient doesn't necessarily mean that an animal will do the most damage; marsupials like koalas can deal a lot of damage for their body size, for example, but most people would prefer a koala bite to a lion bite, because lions are so much larger and more powerful. </li></ul>When a Bite Force Quotient is calculated, researchers take the bite force data and consider it alongside the animal's size, the maximum size of its prey, and the types of prey it consumes. All of this information is plugged into a formula which generates a single number reflecting the bite force with adjustments for external factors. A Bite Force Quotient (BFQ) is a numerical value which is used to represent the bite force of an animal while also taking factors like the animal's size into account. sharks bite was tested and it was only 660Ib. Shark doesn't have strong bite. A crocodile bite is 2700Ib.Crocodile bite is 4 times greater than sharks. Bite force of the Bengal tiger has been measured at 1000psi. The lion at 950 psi.1
  41. 42. Structure of the dog and human jaw. Mandible (M) the main body of the lower jaw; the Rami (R), a broad structure out of the place of the teeth; the Coronoid Process (CP) sits within the zygomatic arch and is the point of attachment for the temporalis muscle (TM ); the Condylar Process (CY) that is the temporomandibular joint. The masseter muscle is across the rami, a much larger structure in humans. The Medial and Lateral Pterygoids are more prominent in humans than in dogs.
  42. 43. Human Bite by children.
  43. 44. Anger / Rage
  44. 55. Thank You for Listening
  45. 56. References <ul><li>1.    Adams, B. The diversity of adult dental patterns in the United States and the implications for personal identification. J Forensic Sci 2003; 48(3). </li></ul><ul><li>2.  Adams, B. Establishing personal identification based on specific patterns of missing, filled and unrestored teeth. J Forensic Sci 2003; 48(3). </li></ul><ul><li>3.  Anguita, C. DentalPrint 2.0. Department of Forensic Medicine and Forensic Odontology: software engineering department. (2003). 27 Feb 2005 <>. </li></ul><ul><li>4.  Bowers, C. Arguments on the individuality of human teeth. 22 Feb 2005 <>. </li></ul><ul><li>5.  Bowers, C., Johansen, R. Digital imaging methods as an aid in dental identification of human remains. J Forensic Sci 2002; 47(2):354-359. </li></ul><ul><li>6.  Brannon, R., Connick, C. The role of the dental hygienist in mass disasters. J Forensic Sci 2000; 45(2):381-383. </li></ul><ul><li>7.  Brannon, R., Kessler, H. Problems in mass-disaster determination: a retrospective review. J Forensic Sci 1999; 44(1):123-127. </li></ul><ul><li>8.   “Central Identification Laboratory at JPAC: the world’s largest forensic laboratory.” Joint POW/MIA Accounting Command. 26 Feb 2005 <>. </li></ul><ul><li>9.   Fahmy, G. et. al, “Automated Dental Identification System (ADIS).” 30 Jan 2005 <>. </li></ul>
  46. 57. References <ul><li>10.  “Forensic Odontology.” Dental Students: The dental students network. (2000). 30 Jan 2005 <> </li></ul><ul><li>11.  “Forensic Odontology.” (2004). 27 Feb 2005> </li></ul><ul><li>12.  “Forensic Odontology.” The thin blue line: information section. 27 Feb 2005 <>. </li></ul><ul><li>13.  James, S., Nordby, J., Eds. Forensic science: an introduction to scientific and investigative techniques. CRC Press, New York, 2003. </li></ul><ul><li>14.  Kouble, R., Craig, G. A comparison between direct and indirect methods available for human bite mark analysis. J Forensic Sci 2004; 49(1). </li></ul><ul><li>15.  Lee, S., Choi, J., Yoon, C., Kim, C., Shin, K., The diversity of dental patterns in orthopantomography and its significance in human identification. J Forensic Science 2004; 49(4). </li></ul><ul><li>16.  Lewis, C. Leventhal, L. Locator system versus WinID3 versus CAPM14: identifying vicims from dental remains in a large disaster. J of Forensic Identification 2004; 52(4):185-202. </li></ul><ul><li>17.  Martin-de las Heras, S., Valenzuela, A., Ogayar, C., Valverde, A., Torres, J., Computer-based production of comparison overlays from 3D-scanned dental casts for bite mark analysis. J Forensic Sci 2005; 50(1). </li></ul>