Forensic Odontology


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Here's an introduction to the field of Forensic Odontology; role and scope. A summary of the type of cases where the expertise of an odontologist is required. Special emphasis is given on the dental profiling.

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Forensic Odontology

  1. 1. Definition • Forensic Odontology is the application of dental science to the administration of the law and the furtherance of justice. OR • The application of principles & expertise of dentistry for the purpose of law & criminal investigation. OR • Branch of dentistry which deals with the proper handling, examination & evaluation of dental evidences and with the proper presentation of dental findings in the interest of justice. OR • Forensic dentistry is a specialty that relates dental evidence to investigation.  It provides an important community service in both the civil and criminal jurisdictions.  Forensic dental services are of value both in death investigations and in clinical forensic medicine for evaluation of living victims of sexual assault, child abuse & other domestic violence cases. 10/6/2016 1saurabh bhargava
  2. 2. Dentistry Vs Forensic Odontology • Dentistry is the "evaluation, diagnosis, prevention and/or treatment (nonsurgical, surgical or related procedures) of diseases, disorders and/or conditions of the oral cavity, maxillofacial area and/or the adjacent and associated structures and their impact on the human body". Dentistry is necessary for complete oral health. • Forensic odontology is the proper handling, examination and evaluation of dental evidence, which will be then presented in the interest of justice. The evidence that may be derived from teeth, is the age (in children) and identification of the person to whom the teeth belong. This is done using dental records or ante-mortem (prior to death) photographs. 10/6/2016 2saurabh bhargava
  3. 3. •The THEORY behind forensic dentistry is that no two mouths are alike (even identical twins are different), and that teeth, like tools, leave recognizable marks. •Most people have dental records, or these can be created through making a dental impression from a suspect. These can then be compared to either teeth found on a corpse or bite marks found at the scene of a crime. •It relies on sound knowledge of teeth and jaws, possessed by dentist and incorporates dental anatomy, histology radiography, dental materials and developmental anomalies of dentition. •The interpretation of dental evidence is a specialist task, undertaken by a forensic odontologist who may be called as an expert witness in a case. Basic Concept 10/6/2016 3saurabh bhargava
  4. 4. Historical Aspects • 1st dental identification was made between 49-66 AD ( Agrippina ,Emperor Claudius , Lollia Paulina). • King William ; 1066 AD is supposed to be the 1st to use bite marks for identification. • The earliest known identification from teeth is in 1775 by Paul Revere. – Paul Revere made a silver bridge for one man. The man was killed in the Revolutionary War. – Body was in mass grave and identified by his silver dental work. • 1837- Dr Edwin Saunders established the eruption sequence. • 1897- Dr Oscar Amoedo ( father of forensic odontology ) wrote the first book of forensic dentistry→ L’Art Dentaire en Medicine Legale. 10/6/2016 4saurabh bhargava
  5. 5. High profile cases • Ted Bundy was identified from a bite mark. • John Wilkes Booth was identified by a “gold plug” on the right side of his jaw. • Elaborate dental records including radiographs and spare crowns identified the body of Adolf Hitler. • Another famous case involving the use of forensic dentistry for identification was that of Czar Nicholas II. 10/6/2016 5saurabh bhargava
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  8. 8. • American Society of Forensic Dentistry (1970). • International Society for Forensic Odonto- stomatology (1976). • Similar organizations exist in various countries. 10/6/2016 8saurabh bhargava
  9. 9. The Role • Forensic dentistry plays a major role in identification in man made or natural disaster –events that result in multiple fatalities that may not be identifiable through conventional methods such as finger prints. • This field is very important in identifying human remains that are decomposed, mutilated, or visually unrecognizable. • The scope of forensic odontology is wide and includes the identification of victims of transport accidents, gunshot/heavy artillery, and incineration in vehicles and house fires. • It also includes the examination of bite marks inflicted by humans (commonly found in violent crimes & child abuse cases) and animals in a variety of circumstances. • Teeth marks may be left in food, pencils or other items left at crime scenes. 10/6/2016 9saurabh bhargava
  10. 10. Scope of Forensic Odontology 1. Identifying unknown human remains through dental records & cranio- facial bones. 2. Age estimation of both the living and deceased. 3. Recognition and analysis of bite marks found on victims. 4. Analysis of oro-facial trauma associated with person abuse. 5. Determining the gender of an unidentified individual. 6. Eliciting the ethnicity. 7. Assisting in building up a picture of lifestyle and diet of skeletal remains. 8. Analysis of dental malpractice claims. 9. Presenting evidence in court as an expert witness. 10/6/2016 10saurabh bhargava
  11. 11. Parameters to be compared.. 1. Teeth. 2. Prosthetic appliance– bridges, partials, crown, false teeth. 3. Shape, form (morphological) peculiarities. 4. Genetic anomalies. 10/6/2016 11saurabh bhargava
  12. 12. Case study 10/6/2016 12saurabh bhargava
  13. 13. Basic Dentistry • Each tooth has a crown (visible portion that protrudes above gum) and a root (embedded into the socket in the jaw bone). • Crown is capped by enamel , under the enamel is a layer of dentin which surrounds the pulp cavity. • The root is surrounded by cementum. • Periodontal ligament present between cementum and bone of the jaw holds the tooth in jaw. 10/6/2016 13saurabh bhargava
  14. 14. Two arches present in the oral cavity- -Maxillary arch -Mandibular arch Since both arches are symmetrical ; the whole dentition is divided into 4 quadrant ; each containing the same number & same types of teeth , as- •2 Incisors •1 Canine •2 Pre molars •3 Molars MANDIBLE AND MAXILLA 10/6/2016 14saurabh bhargava
  16. 16. 2 INCISOR 1 CANINE 2 PREMOLAR 3 MOLAR ONE QUADRENT DENTITION 10/6/2016 16saurabh bhargava
  17. 17.  Each tooth has 5 surfaces- • Incisal/ Occlusal surface • Buccal/ Labial/ Facial surface • Lingual/ Palatal surface • Mesial surface • Distal surface 10/6/2016 17saurabh bhargava
  18. 18. INCISORS • Eight in number (four in each arch) • Anterior teeth with wide crown and thin, sharp, chisel like incisal/ cutting edge • Has a single root • Used for cutting purposes 10/6/2016 18saurabh bhargava
  19. 19. CANINES • Four in number ( two in each arch ) • Also called cuspid, as they have a sharp/pointed cusp • Present at the corner of the arch • Has a single root • Used for tearing of the eatables; that’s why more prominent in carnivorous animals. 10/6/2016 19saurabh bhargava
  20. 20. PRE MOLARS • Eight in number ( four in each arch ) • Present only in permanent dentition • Each premolar typically has two cusps • Premolars (other than 1st maxillary premolars which has two roots) possess a single root 10/6/2016 20saurabh bhargava
  21. 21. MOLARS • Twelve in number (six in each arch). • Posterior most teeth in dentition. • Usually have 3-5 cusps • Multi-rooted teeth. • Wide occlusal surface adapted for chewing & crushing of food. • 3rd molar is the last tooth to erupt. 10/6/2016 21saurabh bhargava
  22. 22. Incisors (I) Adapted for biting, cutting and stripping Canines (C) Adapted for seizing, piercing and tearing Premolars (P) Adapted for grinding, crushing, shearing and slicing Molars (M) Adapted for grinding and crushing Each type of tooth is adapted to perform the specific functions listed below. 10/6/2016 22saurabh bhargava
  23. 23. Dental Formula • A mammal's dental formula designates the number of each type of tooth found in its dentition • It provides one kind of quantitative measure of the differences between – different sexes and ages of the same species, – different species, and – animal groups having different feeding strategies or diets • Dental formulas are used to quantify difference between samples. • Our specific goal in this studying the dental formulae is to be able to quantitatively compare and identification of carnivores, herbivores, omnivores, and an insectivore. 10/6/2016 23saurabh bhargava
  24. 24. Can you tell the differences of these bite marks? 10/6/2016 24saurabh bhargava
  25. 25. What to look for..? • The shape or curvature • No. of tooth marks • Horizontal diameter • Vertical diameter • Depth of depression • Distances between two teeth • Orientation of each tooth • Other reasonable answers 10/6/2016 25saurabh bhargava
  26. 26. Human Dentition Incisors: 2 Canine: 1 Premolar: 2 Molar: 3 Dental formula of a human adult is: i 2/2, c 1/1, pm 2/2, m 3/3 simply 2123 2123 10/6/2016 26saurabh bhargava
  27. 27. Identify the most probable animal just by looking at the dentition 10/6/2016 27saurabh bhargava
  28. 28. Identify the most probable animal just by looking at the dentition 10/6/2016 28saurabh bhargava
  29. 29. Identify the most probable animal just by looking at the dentition 10/6/2016 29saurabh bhargava
  30. 30. Identify the most probable animal just by looking at the dentition 10/6/2016 30saurabh bhargava
  31. 31. Tooth type & Diet type • Tooth size, shape, and arrangement in the mouth are important determinants of the type of food an animal can obtain and consume. • Teeth can be used to tell what type of diet an animal has. • Four major groups of animals with respect to diet – Carnivore (meat eater) – Herbivore (plant eater) – Insectivore (insect & worm eater) – Omnivore (an animal that eats a variety of foods including meat and plants). 10/6/2016 31saurabh bhargava
  32. 32. Carnivores Carnivores share special adaptations for life as predators. 32 Canine Incisor Molar 10/6/2016 saurabh bhargava • Large slicing canines for piercing the skin of prey, and for cutting and chewing meat • Pointed incisors for tearing flesh • Even the cusps on a carnivore’s molars are high and pointed, because these teeth too are used in tearing and chewing flesh. • Long roots on all teeth so that they are well anchored for working on the tough food material • Carnivores also have front facing eyes, heavy skulls that support the large muscles needed to work the jaws, and jaws that are very strong but that move only up and down, not from side to side.
  33. 33. Herbivores • Feed on plant material. They need to clip green leafy material off from grass roots (grazers) and tree branches (browsers). The cellulose in leaves is ground down into a mash that can be more easily digested. • Incisors have a flat cutting edge, for use in clipping off plant stems. Since these teeth wear down from this work, there is continuous tooth growth in many species. • Canines are often lacking entirely, as the food does not need to be captured, though squirrels may have pointed incisors that look like canines, which they use to break nuts open. • Molar teeth are tall and very broad. They have flat upper jaw surfaces sometimes with ridges on them to help grind plant material. Incisor Deer Molar Molar 10/6/2016 33saurabh bhargava
  34. 34. Insectivores • They have a mouthful of sharp little peg-like teeth that are similar in size and shape. • These are used in seizing and crushing hard-shelled insects, and for gripping on to worms as they are pulled from their burrows. 10/6/2016 34saurabh bhargava
  35. 35. Omnivores • Omnivores have the most variable teeth, used for eating both plant and animal material that make up their broad diet. • Incisors are more shovel-shaped than pointed • Long, sharp canines are used for puncturing and grabbing onto animal prey. • Wide molar and premolar teeth handle both the chewing of meat and the grinding of plant material. They have low bumpy crowns. incisors molar premolar canine 10/6/2016 35saurabh bhargava
  36. 36. Dental Identification is Required when-- – Decomposing remains – Skeletonized remains – Charred remains – Doe Identification; Intact remains without any putative victim – Scientific verification of identity is anticipated – Multiple bodies recovered from a common location – Mass disaster 10/6/2016 36saurabh bhargava
  37. 37. ESTABLISHMENT OF A PERSONAL IDENTIFICATION IS REQUIRED FOR LEGAL AND HUMANITARIAN REASONS- • Legal aspects- - Charging the suspect with a crime - Will probation - Insurance benefits - Bussiness matters - Lawsuits settlement - Remarriage sanction - Settlement of property related issues • Humanitarian aspects- - Proper interment/cremation according to religion & family wishes. 10/6/2016 37saurabh bhargava
  38. 38. Methods of Identification • Visual recognition by acquaintances • Personal effects/belongings (Rigor mortis, decomposition, animal predation, deliberate misidentification, borrowed & stolen objects etc can obscure the visual identification). • Fingerprinting technique • Dental identification • DNA techniques (Scientific, reliable, valid and objective techniques) 10/6/2016 38saurabh bhargava
  39. 39. Dentition; a perfect identifier..? • Written below are the qualities that are present in dentition and associated structures ; making them the perfect scientific identifier – 1. Stable & durable (tooth material & restorative materials) – Teeth are the most durable organs in the body and can be heated to temperature of 1600°C without appreciable loss of micro structure. 2. Uniqueness (size/shape/pattern/wear/repair) – The 16 missing teeth can produce is approximately 600 million different number of combinations . – Four missing and four filled teeth in a mouth combined can produce more than 700 millions combinations. – Although teeth are relatively resistant to environmental insults after death, during life they are susceptible to physiological and pathological changes. 3. Previous records 10/6/2016 39saurabh bhargava
  40. 40. A perfect identifier..?? • Since teeth can resist extreme conditions, they are the excellent source of DNA. • This facilitates comparison with the known biological ante-mortem sample of the person such as hair, epithelial cells from a tooth brush or a biopsy specimen. • If the persons ante-mortem sample is unavailable, the DNA pattern may be compared to a parent or a sibling, thus allowing identification. 10/6/2016 40saurabh bhargava
  42. 42. Oral Autopsy • It involves examination of deceased, usually with dissection to expose the organs, to determine the cause of death. • It has a systemic protocol starting with critical examination of external features of the body such as gender, ethnicity, build, wounds, scars, tattoos. • Oral examination is an essential part of post-mortem procedure. • A thorough examination of soft tissue injuries, fractures and presence of foreign bodies is undertaken and samples of hard and soft tissues may be obtained for further investigations. • All this information is entered on to the standard “Interpol postmortem form” which is color coded in pink. 10/6/2016 42saurabh bhargava
  43. 43. Obtaining Dental Records • Dental records contain information of treatment and dental status of a person during his/her lifetime. • Such records may be in the form of dental charts, radio graphs, casts and/or photographs. • The contents of all available dental records should be transcribed onto the standard “Interpol ante-mortem form” which is color coded in yellow. 10/6/2016 43saurabh bhargava
  44. 44. Comparing Post- and Ante-Mortem Dental Data • Once the post-mortem evidence and dental records are available, the data can be compared. • Features compared include tooth morphology and associated bony structures, pathology and dental restorations . 10/6/2016 44saurabh bhargava
  45. 45. Writing A Report and Drawing Conclusions • One needs to remember that any attempt at establishing identity is addressed to the legal authorities. • Therefore, a detailed report and factual conclusion, based on comparison, must be clearly stated. • Acharya and Taylor have suggested a range of conclusions, which include: 1. Confirms Identification 2. Probable Identification 3. Possible Identification 4. Insufficient Information 5. Excludes Identification 10/6/2016 45saurabh bhargava
  46. 46. Division of work among different dental teams in mass disaster identification programme Post-mortem unit Ante-mortem unit Comparison unit • Photography, collection of personal belongings, finger printing, full body radiography, autopsy precede the dental examination •Photography •Radiography •Charts, x-rays, specimens are labelled, initialled and delivered to comparison unit •Most difficult part •Gathers as much information as possible •Tries to collect the ante- mortem dental records in the form of X-rays, dental charts, dental photographs, plaster modals etc •Communicates with family/relatives, friends, dental office etc •Constitutes the ante- mortem charts and deliver them to comparison unit •Comparison & confirmation of identification •Ante-mortem and post- mortem dental records are analyzed & compared either manually or with the help of a computer. •Final decision on identification/ verification is done by the chief 10/6/2016 46saurabh bhargava
  47. 47. Identification From Dental DNA • The conventional method of dental identification described thus far requires one basic element that may not always be readily available- adequate or complete dental records. • Since teeth can resist extreme conditions, they are the excellent source of DNA. • Routinely applied technique in forensic investigations, known as polymerized chain reactions allows amplification of even highly degraded DNA. • This facilitates comparison with the known biological ante-mortem sample of the person such as hair, epithelial cells from a tooth brush or a biopsy specimen. • If the person’s ante-mortem sample is unavailable, the DNA pattern may be compared to a parent or a sibling, thus allowing identification 10/6/2016 47saurabh bhargava
  48. 48. The Role of Palatal Rugae in Identification • Useful in edentulous persons • Rugae patterns like teeth are considered unique to an individual • Rugae patterns on the decedent’s maxilla or maxillary dentures may be compared to old dentures that may be recovered from the decedent’s residence or plaster model from dental office. RUGAE- -PRIMARY RUGAE (>5mm) -SECONDARY RUGAE(3- 5mm) -FRAGMANTARY RUGAE (2-3mm) OR -BRANCHED -UNIFIED -CROSS-LINKED -ANNULAR -PAPILLARY 10/6/2016 48saurabh bhargava
  49. 49. Rugae Pattern 10/6/2016 49saurabh bhargava
  50. 50. DENTAL PROFILING • Dental profiling includes extracting a triad of information-the decedent’s ethnic origin, gender and age. • The information from this process will enable a more focused search for ante-mortem records . • There are a total of three steps in a dental profiling- 10/6/2016 50saurabh bhargava
  51. 51. Identifying Ethnic Origin From Teeth • Anthropologists have divided race into following broad groups- (i) Caucasoid (ii) Negroid (iii) Mongoloid (iv) Eskimos (v) American Indians • Dental features used to describe population differences are broadly categorized as metric (tooth size) and non metric (tooth shape). • Metric features are based on measurements and non metric in terms of presence or absence of a particular feature , e.g: whether carabelli’s cusp is present or absent. 10/6/2016 51saurabh bhargava
  52. 52. Metric Features • Size of teeth: Both deciduous and permanent dentitions are considered. The size of the teeth varies in different races • Larger teeth are seen in Australian, South American Indian tribes. • Lateral incisor is relatively large compared to central incisor in mongoloids. • Intermediate sized teeth are seen in Taiwanese Aborigines and Australian whites respectively. 10/6/2016 52saurabh bhargava
  53. 53. Scott and Turner suggested that characteristic dental features have evolved over time as a result of genetic and environmental factors that have influenced different population groups. More than 30 non-metric features of the tooth crown and root have been describe and analyzed by Scott and Turner. • NON METRIC FEATURES OF CROWN 1. Shoveling 2. Double shoveling 3. Carabelli’s feature 4. Three cusped upper 2nd molar 5. Cusp 5 6. Cusp 6 7. Winging 8. Five cusped lower second molar 9. Lower molar groove pattern 10. Interruption groove 11. Enamel extension 12. Odontome 13. Lateral incisor variants 14. Distal accessory ridge 15. Premolar accessory ridge 16. Premolar lingual cusp 17. Mesial marginal complex of upper molars 18. Parastyle 19. Protostylid • NON METRIC FEATURES OF ROOT 1. Two-rooted upper premolar 2. Two rooted upper molar 3. Two rooted lower canine 4. Three rooted lower molar & Single rooted lower molar etc. 10/6/2016 53saurabh bhargava
  54. 54. Sex Determination From Teeth • Determining the sex of unknown human remains is the second step in building a dental profile. • Gender can be determined based on data from--- – Cranio-facial morphology and dimensions – Sex differences in tooth dimensions – Tooth morphology – Sex determination by DNA analysis • Amelogenin (AMEL) is one of the major matrix proteins secreted by the ameloblasts of the enamel. • The AMEL gene, coding for a highly conserved protein, is located on X- and Y chromosomes in humans. • Thus the females (XX) have two identical AMEL genes but the males (XY) have two non identical genes. • Preparing DNA from teeth by ultra sonification, and subsequent PCR amplification, 100% success in determining the sex of the individual has been obtained by some scientists. 10/6/2016 54saurabh bhargava
  55. 55. 10/6/2016 saurabh bhargava 55 Sex determination • Mandibular cuspid shows the maximum sexual dimorphism- – Mesio-distal diameter < 6.7 mm (in females) – Mesio-distal diameter > 7 mm (in male) – Root length of maxillary cuspid is >3 mm more in males than females. – Distance b/w tips of coronoid processes(cm) x distance b/w angles of jaw…  if > 90 ; then male  if < 78 ; then female
  56. 56. Age estimation from dentition • The final step in triad of dental profiling, age estimation is an important subspecialty of forensic sciences. • Dental age estimation makes use of morphologic, radiographic, histologic, and biochemical methods to examine the age dependent changes in teeth. • It is grouped into three phases: 1. Ageing in prenatal, neonatal and early postnatal. 2. Age estimation in children and adolescents. 3. Age estimation in adults. 10/6/2016 saurabh bhargava 56
  57. 57. 10/6/2016 saurabh bhargava 57 Phases in tooth development and eruption 1. Utero ( from 16 weeks) to eruption of 1st tooth at 6 months. 2. Primary dentition (milk teeth): from 6 months to 6 years. 3. Mixed dentition: 6 to 12 years. 4. Permanent dentition: From 12 years on
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  59. 59. 10/6/2016 saurabh bhargava 59 Age Estimation • Presence of neonatal line indicates a live births • By dry weight of mineralized tooth (at six month IU- 60mg, newborn-0.5g, six month post natal-1.8g) • Histological examination is more precise in neonatal age estimation than radiography. • Examining teeth eruption patterns • Gustafson method (looking for six signs of wear) • Lamendin method (looking at transparency of roots/dentin translucency) • Age estimation based on ratio of D-Aspartic acid to L-Aspartic acid
  60. 60. Deciduous Dentition Eruption Sequence •Incisors: 7-12 months •Canines: 2 years •1st Premolar: none •2nd Premolar: none •1st Molar: 3 years •2nd Molar: 3 years •3rd Molar: none 10/6/2016 saurabh bhargava 60
  61. 61. Permanent Dentition Eruption Sequence •Incisors: 6.5 •Canines: 10.8 •1st Premolar: 10.4 •2nd Premolar: 11 •1st Molar: 6.2 •2nd Molar: 12.2 •3rd Molar: 18 10/6/2016 saurabh bhargava 61
  62. 62. 10/6/2016 saurabh bhargava 62 Age Determination in children and adolescents
  63. 63. 10/6/2016 saurabh bhargava 63 Showing the presence of unerupted permanent dentition
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  65. 65. 10/6/2016 saurabh bhargava 65 GUSTAFSON’S METHOD • This method is based on morphological and histological changes of the teeth. • This assessed regressive changes such as: a) Amount of occlusal attrition(A) b) Coronal secondary dentine deposition(S) c) Loss of periodontal attachment(P) d) Cementum apposition at the root apex(C) e) Root resorption at the apex(R) f) Dentine translucency(T) An+ Sn+ Pn+ Cn+ Rn+ Tn = X; a total score •Age was estimated using the formula Age = ( 11.43 + 3.63X ) years •It was found that an increase in the total score corresponds to an increase in age
  66. 66. Regressive changes • For each of these regressive changes or variables, different scores ranging from 0-3 were assigned. STAGE 0 – indicates no change STAGE 1 – beginning of change STAGE 2 – obvious change STAGE 3 – maximum change Attrition (A)  A0—no attrition  A1—attrition limited to enamel level  A2—attrition limited to dentine level  A3—attrition up to pulp cavity Secondary Dentin (S)  S0—no secondary dentin formation  S1—secondary dentin up to upper part of pulp cavity  S2—secondary dentin up to 2/3rd of the pulp cavity  S3—diffuse calcification of entire pulp cavity Periodontal Disease (P)  P0—no obvious periodontal disease  P1—beginning of periodontal disease but no bone loss  P2—periodontal disease more than 1/3rd of the root  P3—periodontal disease more than 2/3rd of the root 10/6/2016 saurabh bhargava 66
  67. 67. Root Translucency (T)  T0—no translucency  T1—beginning of translucency  T2—translucency more than 1/3rd of the apical root  T3—translucency more than 2/3rd of the apical root Cementum Apposition (C)  C0—normal cementum  C1—thickness of cementum more normal  C2—abnormal thickness of cementum near the apex of the root  C3—generalized abnormal thickness of cementum throughout the apex of the root Root Resorption (R)  R0- no resorption  R1- apical 1/3rd root resoption  R2- apical 2/3rd root resorption  R3- comlete root resorption • Kashyap and Koteswara Rao omitted periodontosis and root resorption from Gustafson’s method and calculated the index values of various parameters undergoing regressive changes. • Their modified method gave an error of + 1.59 years 10/6/2016 saurabh bhargava 67
  68. 68. Dentin Translucency • Bang and Ramm were the first to use dentine translucency alone for estimating age. • Root dentine starts to become translucent during the third decade (30s) of life beginning at the apex and advancing coronally. • Root dentin starts to become translucent due to the increased intratubular calcification. • Therefore dental root translucency increases with advancing age. • AGE = B0+B1X where B0 –regression constant B1-regression coefficient X-length of translucency 10/6/2016 saurabh bhargava 68
  69. 69. Amino acid racemization • All amino acids (except glycine) are optically active, having a stereocenter at their α-C atom. • This means that the amino acid can have two different configurations, "D" or "L" which are mirror images of each other. • Living organisms keep all their amino acids in the "L" configuration. • When an organism dies, control over the configuration of the amino acids ceases, and the ratio of D to L moves from a value near 0 towards an equilibrium value near 1, a process called racemization. • Thus, measuring the ratio of D to L in a sample enables one to estimate how long ago the specimen died. • Helfman and Bada first suggested a relationship between dentinal age and the extent of aspartic acid racemisation in dentine. • The extent of racemization of aspartic acid in coronal dentin of normal permanent teeth can be used to estimate the age of an individual at the time of death. • This method is accurate with age estimates within plus/minus three years of actual age. 10/6/2016 saurabh bhargava 69
  70. 70. Some other techniques of age determination.. 1. Pulp diameter to crown diameter ratio and pulp / root length, pulp /root width was measured. 2. An interesting method using intensity of fluorescence in dentin and cementum, which shows strong correlation between age, deepening of colour of the tooth and increase in intensity of fluorescence. The colour changes in the cementum and dentin are caused by infusion of decomposition products from erythrocytes. 3. The incremental lines of cementum will help to determine the age of adults. A major disadvantage of this method is the necessity to extract or section the tooth. It is not practical among living individuals. 10/6/2016 saurabh bhargava 70
  71. 71. Bitemarks • Cutaneous bitemarks represent patterned injuries in skin produced by teeth. Or • A mark caused by teeth either alone or in combination with other mouth parts (Mac Donald). • May be inflicted by humans or animals (most commonly by dogs and cats); may be on tissue, food items or other objects. • Those of forensic significance most often accompany violent crimes such as homicide, sexual assault, child abuse, domestic violence, and battery. 10/6/2016 saurabh bhargava 71
  72. 72. 10/6/2016 saurabh bhargava 72 • Human bite broad, U-shaped somewhat circular or oval. • Animal bite narrow in the anterior aspect , V shaped and elongated also morphology of the teeth is different. Usual Sites of Bite Marks • Females on breast, legs( inner part of thigh)-sexual assault • Children genitals, oral & paraoral regions-child abuse • Adult Males finger, arms and shoulders-fight
  73. 73. 10/6/2016 saurabh bhargava 73 The Concept • Each human dentition is unique, differing even in identical twins. • Its imprint in skin can show this individualization, making the identification of perpetrator possible • For this reason, bite marks have been referred to as “dental fingerprints”.
  74. 74. 10/6/2016 saurabh bhargava 74 Objectives of bite mark investigation • To recognize the bite mark  if a patterned injury is not detected or recognized as a bite mark, the entire investigation is pre-empted because the forensic dentist will not be notified. • To ensure that they are accurately documented  proper photography, collection etc is must to make the further comparisons with ante-mortal records • To compare them to the teeth of alleged perpetrator  comparison of impression, photographs with gypsum replicas of suspect’s teeth.
  75. 75. 10/6/2016 saurabh bhargava 75 BITE MARKS
  76. 76. 10/6/2016 saurabh bhargava 76 Diagrammatic depiction of human bite mark showing typical pattern of contacting surfaces of teeth • Is composed of two separate, curved arches facing one another. • Each arch is composed of a row of contusions, abrasions, lacerations or depressions approximating the size & shape of biting surfaces of human front teeth.
  77. 77. 10/6/2016 saurabh bhargava 77 Typical presentation of bite mark injuries • A representative human bite is described as an elliptical or circular injury that records the specific characteristics of the teeth • Alternatively, it may be composed of two U-shaped arches that are separated at their bases by an open space. • The diameter of the injury typically ranges from 25-40 mm. • This extra-vascular bleeding is caused by pressure from the teeth as they compress the tissue inward from the perimeter of the mark. Class features: Incisorrectangular Caninestriangular or rectangular Premolars and molars spherical or point shaped Individual features: Rotation, Dental work, diastema, fracture etc.
  78. 78. CLASSIFICATION OF BITE MARKS A. Cameron and Sims Classification 1. Causing Agents -Humans -Animals 2. Substrate Materials -Skin , body tissue -Food stuff -Other materials B. Mac Donald’s classifications -Tooth pressure mark -Tongue pressure mark -Tooth scrape mark 10/6/2016 saurabh bhargava 78
  79. 79. 10/6/2016 saurabh bhargava 79 C. Based on severity of injury a. hemorrhage -- small bleeding spot b. abrasion -- undamaging mark on skin c. contusion -- ruptured blood vessel, bruise d. laceration -- punctured or torn skin e. incision -- neat puncture of skin f. avulsion -- removal of skin
  80. 80. 10/6/2016 saurabh bhargava 80 Bite marks analysis 1. Recognition (human or animal bite mark) 2. Documentation (Photography/sketching) 3. Evidence collection and preservation (DNA and physical evidence). 4. Physical dental profiling of the questioned evidence (bite mark). 5. Physical dental profiling of the known evidence (suspect). 6. Physical comparison of (4) and (5) 7. Communication of results to authorities and legal counsel.
  81. 81. 10/6/2016 saurabh bhargava 81 Bite Mark Investigation • Preliminary questions • Bite mark evidence collection from the victims Steps: 1.Visual examination 2.Photography -Orientation photographs -close-up photographs 3.Saliva swab: -WBC and sloughed epithelial cells, potential source of DNA 4.Impression: Vinyl polysiloxane, dental acrylic & plaster • Evidence collection from suspect:  using a signed and informed consents or a court order (warrant) also include photograph, two casts, bite registration in centric occlusion and saliva swab from buccal vestibule
  82. 82. Bite marks investigation • Physical characteristics to be studied are- – Distance from cuspid to cuspid – Tooth alignment – Teeth width, thickness, spacing – Missing teeth – Wear patterns including chips and grinding – Dental history including fillings, crowns, etc. 10/6/2016 saurabh bhargava 82
  83. 83. 10/6/2016 saurabh bhargava 83 Structural variations in teeth (human vs non-human) • Dentition differs greatly among various organisms • Most animal teeth reflect specialized dietary adaptations eg.- grazing animals have more grinding teeth unlike carnivores which have more prominent canines • Each animal has a different dental formula (no. of each tooth type in a quadrant of mouth)
  84. 84. 10/6/2016 saurabh bhargava 84 Animal Features of dentition Fish conical, homodont, heterodont or polyphydont Reptiles homodont conical or only tricuspid teeth Venomous snake single row, palatal to this are two poison fangs containing canal or groove for venom release Non- venomous snake two rows of maxillary teeth Carnivorous Larger, sharper, conical canines Other mammals heterodont dentition, diphyodont also have accesssional teeth( permanent molar emerge posterior to deciduous teeth)
  85. 85. 10/6/2016 saurabh bhargava 85 Positive bite-mark Possible bite-mark Definite bite-mark •An 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. •• criteria: general shape and size are present but distinctive features such as tooth marks are missing, incomplete or distorted or a few marks resembling tooth marks are present but the arch configuration is missing. •The pattern strongly suggests or supports origin from teeth but could conceivably be caused by something else. •• criteria: pattern shows some basic general characteristics of teeth arranged around arches. •There is no reasonable doubt that teeth created the pattern; other possibilities were considered and excluded. •• criteria: pattern conclusively illustrates (classic features) (all the characteristics) (typical class characteristics) of dental arches and human teeth in proper arrangement so that it is recognizable as an impression of the human dentition. Inference
  86. 86. 10/6/2016 saurabh bhargava 86 Human or Animal bite
  87. 87. 10/6/2016 saurabh bhargava 87 Dental Malpractice Claims Malpractice suit claims -Alterations of face , jaw , or chin -Unnecessary dental work -Careless/improper dental work Role of Forensic Odontologist • Examines dentition & oral tissues to establish degree of trauma , its possible cause and its potential impact on ability to chew food properly •Present testimony regarding their findings
  88. 88. 10/6/2016 saurabh bhargava 88 Oral findings of child abuse/maltreatment Findings Cause Multiple broken, discolored, missing or avulsed teeth Repeated episodes of mouth trauma Peculiar malocclusions & non occluding jaw segments Healed jaw fractures which were displaced Laceration of labial or lingual frena Forceful lip pulling or slapping Isolated laceration of soft palate Insertion of utensils during forced feeding Horizontal abrasions or contusions extending from lip commissures Application of gag Bite marks on skin Child bite (unsupervised children), adult bite (anger biting) Rampant caries/Nursing Bottle Syndrome Possible child neglect Venereal disease Gonococcal stomatitis, syphlitic lesions indicates sexual abuse
  90. 90. 10/6/2016 saurabh bhargava 90 Shortcomings of dental identification • Difficult to locate than fingerprints • Records may be inadequate • No standardization of dental records (no recognized minimum no. of concordant features required for positive identification) • Written entries are subject to error • Alterations (decayed , filled or extracted) after the last ante-mortem entry