The role of dentist in person identification


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The role of dentist in person identification

  2. 2. INTRODUCTION • Odontological examinations are critical determinant in search for identity of individual human remains. • The most reliable means of identification include:Fingerprints, Dental comparisons and biological methods such as DNA profiling HISTORY  The first treatise on Forensic Odontology as a subject in its own right was written in 1898 by Dr. Oscar Amedo, who is the father of Forensic Odontology.  Though this particular science has been given importance recently, on the contrary, teeth have been used for identification for more than 2000 years.  One of the earliest known “Authentic cases of the application of dental information leading to the identification of an individual was that of Lollia paullina in the year 49AD, she was the second wife of Claudicus, the emperor of Rome and was identified by her teeth which has certain distinct characteristics.  The first formally reported case of dental identification was that of the 80 year old English warrior John Talbot, who fell in the battle of Castillon in 1453.
  3. 3.  The scientific employment of dental evidence in identification of individuals began only in 17th century.  Some Examples are… 1692: Bite marks evidence were used to prove the guilt of Reverend George Burroughs who solicited young women into witchcraft. 1850: Dr. George Parkmen was identified through dental evidence, by a partial denture and portion of the jaw which was incinerated and then disposed in privacy. 1870: Bite marks were used to prove the guilt of Mr. Robinson by bite marks on the body of the victims and model of his teeth. 1897: After a mass disaster by fire, dental identification was used.COMMON REASONS FOR IDENTIFICATION OF FOUND HUMAN REMAINS  CRIMINAL  MARRIAGE  MONETARY  BURIAL  MASS DISASTERS  CLOSURE
  4. 4.  Teeth are the most durable organs in the body and can be heated to temperatures of 1600°C without appreciable loss of micro structure. BASIS FOR DENTAL IDENTIFICATION The basis for dental identification is based on the fact that human dentition is never the same in any two individuals.  Although teeth are relatively resistant to environmental insults after death, during life they are susceptible to physiological and pathological changes.  The number of combinations 16 missing teeth can produce is approximately 600 million.  Four missing and four filled teeth in a mouth combined can produce more than 700 million combinations.DENTAL IDENTIFICATION PROCEDURES• There are essentially two forms of dental identification-The first known as comparative identification and the second, reconstructing identification or dental profiling. • Dental profiling is undertaken when virtually no clue exists about the identity of the deceased.
  5. 5. • It is a conventional method of post-mortem dental identification and includes four steps namely: • ORAL AUTOPSY • OBTAINING DENTAL RECORDS • COMPARING POST- AND ANTE-MORTEM DENTAL DATA • WRITING A REPORT AND DRAWING CONCLUSIONS 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.
  6. 6. 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.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. 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
  7. 7. 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 IDENTIFICATION FROM DENTAL DNAo 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.o Since teeth can resist extreme conditions, they are the excellent source of DNA.o Routinely applied technique in forensic investigations, known as polymerized chain reactions allows amplification of even highly degraded DNA.
  8. 8. o 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. o If the persons ante-mortem sample is unavailable, the DNA pattern may be compared to a parent or a sibling, thus allowing identification. DENTAL PROFILING • Dental profiling includes extracting a triad of information-the decedents ethnic origin, gender and age. • The information from this process will enable a more focused search for ante-mortem records. IDENTIFYING ETHNIC ORIGIN FROM TEETH Anthropologists have divided race into following broad groups(i) Caucasoid (ii) Negroid (iii) Mongoloid (iv) Eskimos (v)American Indians (vi) Orientals Size of teeth: Both deciduous and permanent dentitions are considered. The size of the teeth varies in different races
  9. 9.  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. GENETIC AND ENVIRONMENTAL INFLUENCES ON TEETH 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.  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 ,eg: whether carabellis cusp is present or absent.
  10. 10.  NONMETRIC DENTAL FEATURES More than 30 nonmetric features of the tooth crown and root have been describe and analyzed by Scott and Turner. CROWN FEATURES 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 accesory ridge 15Premolar accessory ridge
  11. 11. 16.Premolar lingual cusp 17.Mesial marginal complex of upper molars 18.Parastyle 19.Protostylid ROOT FEATURES 1. Two-rooted upper premolar 2. Two rooted upper molar 3. Two rooted lower canine 4. Tomes root 5. Three rooted lower molar 6. Single rooted lower molar SEX DETERMINATIONDetermining the sex of unknown human remains is the second step in building a dental profile. Gender can be determined based on data from---1. CRANIOFACIAL MORPHOLOGY AND DIMENSIONS
  12. 12. 2. SEX DIFFERENCES IN TOOTH SIZE 3. TOOTH MORPHOLOGY 4. 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 nonidentical genes.  Preparing DNA from teeth by ultrasonification, and subsequent PCR amplification, these authors obtained 100% success in determining the sex of the individual. DENTAL AGE ESTIMATION • The final step in triad of dental profiling, age estimation is an important subspecialty of forensic sciences. • DENTAL AGE ESTIMATION METHODS  Dental age estimation makes use of morphologic, radiographic, histologic and biochemical methods to examine the age dependent changes in teeth.
  13. 13.  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. AGE ESTIMATION IN ADULTS Following completion of growth , changes in the dentition used toestimate age “are influenced not only by age of the individual, but also by numerous endogenous and exogenous factors, such as disease, nutrition and physical strain.” The different methods used are: 1) Gustafson’s method 2) Dentine translucency 3) Radiographic method of Kvaal and associates 4) Amino acid racemisation 5) Other methods 1. GUSTAFSON’S METHOD  This method is based on morphological and histological changes of the teeth.  This assesed regressive changes such as:
  14. 14. 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) For each of these regressive changes or variables, different scores ranging from 0-3 were assigned.  Adding the alloted score for each variable(Eg : A3+S2+P2+C1+R2+T1 = X ) ,a total score was obtained.  Age was estimated using the formula Age = 11.43 + 4.56X. It was found that an increase in the total score corresponds to an increase in age. 2.DENTINE 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 of life beginning at the apex and advancing coronally. Therefore dental root translucency increases with advancing age. 3.AMINO ACID RACEMISATION
  15. 15.  Helfman and Bada first suggested a relationship between dentinal age and the extent of aspartic acid racemisation in dentine.  Aspartic acid has rapid rate of racemisation.  Therefore, there is a constant change in the ratio of L- and D- aspartic acid at different ages and this D-L ratio may be used for age estimation.  This method is accurate with age estimates within plus/minus three years of actual age. CRIME INVESTIGATION  Forensic dentist plays a vital role in criminal investigation.  Crime investigation includes investigation of bite marks, child abuse, and lip prints. BITE MARKS Bite marks have been defined by MacDonald as “a mark caused by the teeth either alone or in combination with other mouth parts. Bite marks may be caused by humans or animals; they may be on tissue, food items, or other objects.  Human bite mark is broad U shaped and somewhat circular or oval whereas bite mark of animal is narrow in anterior aspect and is V shaped
  16. 16.  Bite marks are usually associated with physical abuse, violent fights, child abuse and theft.IDENTIFING THE INJURY AS BITE MARK  Sweet suggested that a human bite mark can be identified by following features:1. GROSS FEATURES- A circular or elliptical mark found on the skin with a central area of ecchymosis. 2. CLASS FEATURES- This enables one to differentiate between different types of teeth. Incisors produce rectangular marks ; canines are triangular or rectangular depending on amount of attrition; premolars and molars are spherical or pin-point. 3. INDIVIDUAL FEATURES- These include characteristics such as fractures, rotations etc. BITES AND CHILD ABUSE Child abuse has been defined by Vale as “any act of commission or omission that endangers or impairs a child’s physical or emotional health and development. Child abuse may be broadly classified as physical abuse, sexual abuse, emotional abuse and neglect of child. Kenney and Clark have sited numerous researches that suggest approximately 50% of injury in child abuse cases occur in oral and perioral region.
  17. 17. BITE MARK INVESTIGATION A. Preliminary questions B. Bite mark evidence collection from the victim The bite mark evidence should be collected when it is first presented and observed. If the suspected bite mark is criminal in nature , it must be reported to law of enforcement agencies. The protocol for bite mark evidence collection includes the following steps,as suggested by American Board of Forensic Odontology i. VISUAL EXAMINATION ii. PHOTOGRAPHY iii. SALIVA SWAB iv. IMPRESSIONS BITE MARK ANALYSIS AND COMPARISION It is important to consider uncommon characteristics of bite marks such as presence or absence of a particular
  18. 18. tooth,rotation,fracture,diastema,and other unusual features ,as these may help in implicating a suspect. CONCLUSIONS OF BITE MARK ANALYSIS Any bite mark analysis has three likely outcomes. 1) Positive identification 2) Possible identification 3) Excludes identification LIP PRINTS  The imprint produced by grooves is termed as ‘lip print’, the examination of which is termed as ‘cheiloscopy’. Lip prints, therefore, can constitute material evidence left at a crime scene similar to fingerprints.  Lip prints were classified by Santos thus: SIMPLE WRINKLES  Straight line  Curved line
  19. 19.  Angled line  Sine-shaped curve COMPOUND WRINKLES  Bifurcated  Trifurcated  Anomolous Tsuchihashi later proposed a separate classification , dividing the pattern of grooves into six types. I. TYPE-Clear-cut vertical grooves that run across the entire lip. II. TYPE-Similar to type1 , but do not cover the entire lip. III. TYPE-Branched grooves IV. TYPE-Intersected grooves V. TYPE-Reticular groovesVI. TYPE-Grooves that cannot be morphologically differentiated DISADVANTAGES OF LIP PRINTS  The permanence of lip patterns is uncertain.  The anatomic position of lip grooves on the zone of transition is close to vermillion border—a zone which is extremely mobile.
  20. 20. CONCLUSION  Although we have attained civilization and culture, still we see deaths due to suicides, homicides, accidents, natural disasters and also sudden, unexpected deaths.  Every citizen should help the noble cause of the defense of the ‘innocent and punishment of the guilty’.  Major dental clues , once upon a time neglected, are now increasingly used to solve crime.  Hence it is the public duty of dentist to assist in problems involving medico legal identification of the unknown body. Dental evidence plays a vital role in establishing the identity of the dead.  The realm of forensic odontology can represent the most challenging and rewarding aspect in the field of dentistry.