Key Words

antemortem, DNA, forensic dentist, odontology, postmortem,

Introduction

Identification is an establishment of individuality of a person either dead or living. Identification may be required in living persons in the case of absconding criminals, soldiers, missing persons, impostors, escaped prisoners, lunatics, etc. Identification may be essential where unclaimed dead bodies are found, bodies which are decomposed beyond recognition and in cases where highly mutilated bodies or skeletal remains are found. Forensic odontology is a branch of forensic medicine which, deals with the proper examination, handling and presentation of dental evidence in court of law. The forensic odontologist deal with: identification of bite marks on the victims of attack, comparison of bite marks with the teeth of a suspect and presentation of the evidence in court as an expert witness, identification of bite marks in other substances such as wood, leather and foodstuffs, identification of unknown bodies through dental records, age estimation of skeletal remnant.

The most common role of the forensic dentist is the identification of deceased individuals.1 Dental identification takes two main forms. Firstly the most frequently performed examination is a comparative identification is used to establish the remnants of a decedent and a person represented by antemortem dental records are of the same individual. Information from the body or circumstances usually contains clues of the victim. Secondly, in those cases where antemortem records are not available, and no clues to the possible identity exist, a postmortem dental profile is completed by the forensic dentist suggesting characteristics of the individual likely to confine the search for the antemortem materials.2

Dental identification of human being plays an important role in criminal, monetary disputes marital, social, burial, and identification of individual missing for prolonged periods. 3 Identification plays an important role in civil cases like insurance claims, matrimonial disputes, property disputes, impersonation, and issue of passport, and various licences. Identification of the dead body or remnants of a human body are essential in the establishment of a criminal case. Disfigurement or mutilation in mass casualties may be near total. It is very difficult to established the identity of an individual who has been a victim of mass disaster, like i.e. violent crimes, fire accident, road traffic accidents or work place accident.4 Reliable identification of such mutilated bodies are not possible by the family members.5 Persons who have been deceased for some time prior to discovery and those found in water also present unpleasant and difficult visual identifications. Dental identifications plays an important role in the identification of casualties associated with aviation disasters.6 Due to lack of a comprehensive fingerprint database, dental identification continues to be crucial for vast population. 7

Comparative Dental Identification

Concept of dental identification is a complex process which requires comparative study of antemortem and postmortem dental details, to establish the identity. The postmortem dental remains can be compared with antemortem dental records, including written notes, radiographs, study casts. Individuals with numerous and complex dental treatments alongwith the well preserved records of the dental treatment are often easier to identify than those individuals with little or no restorative treatment. The teeth represent a suitable permanent record of such unique and identifiable features, it also survives most postmortem events that can disfigure or distort other body tissues.2

Police initiates a request for dental identification after taking possession of the human remains. Usually a presumptive or tentative identification is available i.e. identity card or driving licence and this will enable antemortem records to be located. Besides, the geographical location in which the body is recovered or other physical characteristics and circumstantial evidence, may enables a putative identification is to be made, frequently using data from the missing person’s database. Antemortem records are then obtained from the record of dentist. 7

The forensic odontologist produces the postmortem record by careful charting and written descriptions of the dental structures and radiographs If the antemortem records are available at this time, postmortem radiographs should be taken to replicate the type and angle of these.8 Radiographs should be marked with holes to prevent confusion — one hole for antemortem films and two holes for postmortem films. (Figure-1A & 1B)

Figure- 1A Antemortem OPG with single hole

During the comparison process similarities and discrepancies should be noted.9 Two types of discrepancy may be present. Explainable

Figure- 1B Postmortem OPG with two holes

discrepancies normally relate to the time elapsed between the antemortem and postmortem records. Examples include teeth extracted or restorations placed or enlarged (ie Periapical pathology in both maxillary central incisors has been treated with RCT, and Periapical pathology in right mandibular first molar has been treated with RCT).

Figure- 2 Intra Oral Periapical (IOP) X-Ray showing explainable discrepancies.

Figure-2 illustrates explainable discrepancies. If a discrepancy is unexplainable, for example a tooth is not present on the antemortem record but is present on the postmortem record then exclusion must be made.7 (Figure-3A & 3B)

According to American Board of Forensic Odontology four types of suggestions are under mentioned. 10

  • Possible identification: the antemortem and postmortem data have consistent features but, because of the quality of either the postmortem remains or the antemortem evidence, it is not possible to establish identity positively
  • Insufficient evidence: The available information is insufficient to form the basis for a conclusion.
  • Exclusion: the antemortem and postmortem data are clearly inconsistent

Figure- 3A OPG Showing Unexplainable discrepancies

Figure- 3B OPG Showing Unexplainable discrepancies

Unlike fingerprints there is no minimum number of concordant features that are required for a positive identification. A single tooth can be used for identification if it contains sufficient unique features. 10Certain deformities in teeth either due to trauma or congenital could be of immense value when teeth or jaws being sent as physical evidence for identification.. The discretion of identification lies with the odontologist who must be prepared to justify the conclusions in court, surely the ultimate in peer-review. The determination of sex and age from the skull could be done. When a skull is supplied to the forensic expert along with a photograph of the suspected deceased person, identification can be carried out by photographic superimposition techniques. Several new techniques of identification of persons form suture closures, sinus prints have also been propounded by various forensic experts

A. Postmortem dental profiling

When dental records are unavailable and other methods of identification are not possible, the forensic dentist can often produce a “picture” of the general features of the individual2 . This process is known as post-mortem dental profiling. A dental profile will typically provide information on the deceased’s age, ancestry background, sex and socio-economic status. In some instances it is possible to provide additional information regarding occupation, dietary habits, habitual behaviours and dental or systemic diseases. The quality, quantity and presence or absence of dental treatment may give an indication of socio-economic status or likely country of residence. 11

If the postmortem profile does not match with the tentative identity of the deceased then it may become necessary to reconstruct the individual’s appearance during life. On the basis of skull of deceased and with the help of forensic odontologist, artists use the dental profile to make the facial sketch of the deceased. (Figure-5)

B. Other innovative methods of dental identification

Comparative identification and postmortem profiling are the most common methods of dental identification. Apart from above methods, some dentist label their dental prostheses with the patient’s.

Figure- 4 AP View of Skull exhibiting deceased,

Figure- 5 Facial sketch of deceased, produced by forensic artist

name or a unique number.12Labelled dentures may be of great assistance in the Identification of individuals.13 Unlabelled dentures recovered from patients and then fitted to casts retained by the treating dental surgeon or laboratory, and this has been an reliable method of identification.14 Orthodontic appliances have been used for identification too. 15 Rugae patterns of the Palate rendered on dental casts have been compared with recovered remains, and Positive identifications have resulted from this technique.16

C. Role of DNA in dental identifications

Teeth represent an excellent source of DNA material, because they are resistant to environmental assaults.17 DNA can provide the necessary link to prove identity, When conventional methods of dental identification fails.18 polymerase chain reaction (PCR), a technique that allows amplification of DNA at pre-selected, specific sites, this source of evidence is becoming increasingly popular with investigators.7DNA preserved in an extracted from the teeth of an unidentified individual is Compared with DNA of antemortem sample i.e. stored blood, biopsy, cervical smears, hairbrush and clothing, to parents or sibling.2

Genomic DNA is present in the nucleus of each cell (except RBC) and represents the DNA source for most forensic applications.7After decomposition of body tissues the, structures of the dental tissue (enamel, dentine and pulp) complex persist. DNA can be extracted from these calcified tissues. Thus teeth represent an excellent source of genomic DNA. PCR-based analysis produces a DNA profile that can be compared with known antemortem samples or paternal DNA. Conclusions

Forensic dentistry has very crucial role in the identification of those individuals who cannot be identified visually or by any other means. The unique nature and structure of dental tissues play an important role in body identification when body is decomposed and cannot be identified.

Unfortunately in developing countries like India forensic dentistry is not developed up to the mark, and services of forensic dentist are not being utilised. Government should instruct the Indian Dental association and other responsible agencies to direct the dental surgeons of the country to maintain the dental records casts, x-rays etc. and sample of tissue (tooth in case of extraction and debris of tooth material in case of restorations) of the patients treated by dental surgeons. So the preserved materials (Antemortem specimen) may be used in identification of deceased individuals.