Strive-Who Are You? Forensic Dentistry and Your Identity

September - October, 2011 edition  

Who Are You? Forensic Dentistry and Your Identity
By Bridget Andrieu, Jamie Johnson, Amber Kreko and Amanda Giacona

Forensics has become a more widely known science because of popular television shows like CSI, Bones and Forensic Files. However, the discipline can be underestimated because shows like these solve a case within an hour. Forensic dentistry, also known as forensic odontology, is an integral part of the forensic sciences that helps with the identification of people.[1] Teeth are the hardest substance in the body, and this fact, combined with their location—protected behind soft tissues of the cheeks and jawbones—is the reason they are useful in identification.[2] Forensic dentists use teeth to identify victims in both mass disasters and individual cases. Forensic dentists are also involved in cases to assess bite marks that may have been left on a victim from their attacker, whether from child abuse, murder or sexual assault.[3]

Forensic dentistry dates back as far as 66 A.D., during the time of the Roman emperor Nero. Nero’s mother, Agrippina, had her soldiers kill a woman named Lollia Paulina, with instructions to bring back her head as proof. Agrippina, unable to positively identify the head, examined the teeth and, seeing a discolored front tooth, confirmed identity.[4] The first forensic odontologist in the United States was Dr. Paul Revere, who identified the body of Dr. Joseph Warren. Dr. Revere constructed and installed a bridge made from silver and ivory two years before he used it to identify Warren.[4] One of the earliest cases of bite mark evidence occurred in Quebec, Canada in 1930. It involved the murder of an infant who had bite marks in multiple areas; photographs were taken to use as evidence in the case.[5] Perhaps the best-known use of bite marks is the case of Ted Bundy, whose unique dentition was tied to the murder of Lisa Levy by a bite mark left on her body. Forensic dentistry also had an important role identifying victims in wars as well as mass disasters including Hurricane Katrina, the World Trade Center bombing, and the recent tsunami.[4]

In accidents or natural disasters involving severe trauma and fire, the use of fingerprints, facial recognition methods and DNA comparisons can be difficult or even impossible. Enamel and dentin are dense, hard materials that resist burning, decay and even being buried underground and will outlast bone.[6] Identification can be made by the comparison of antemortem (before death) records and postmortem (after death) records. A postmortem record is created by a forensic dentist to identify the victim by determining age, ancestry, sex and socio-economic class.[7] Ancestry can be determined by the shape and form of the skull and by characteristics such as cusps of Carabelli, shovel-shaped incisors and multi-cusped premolars.[7] Sex can be determined by skull shape and form; however, there are no apparent differences in tooth morphology between sexes.[7] Microscopic examination of the pulp of teeth for the presence and/or absence of y-chromatin in DNA analysis can reveal the sex with absolute certainty.[8] Age of children can be determined by tooth development and can be accurate within 1.5 years.[7] Other visible characteristics such as erosion suggest someone with an eating disorder or alcohol and substance abuse problems, while staining can suggest smoking, tetracycline use or betel nut chewing.[7] Socio-economic class can be indicated by the quality, quantity, and presence or absence of dental treatment.[7]

Additionally, dental treatment can indicate the person’s country of residence; for example, someone with permanent acrylic and stainless steel crowns would come from Russia, where these materials are most likely to be used for crowns.[7] A forensic dentist will use all these methods to narrow down the identity of the deceased, which will enable the search for the antemortem records.[8]

Antemortem records are what we create every day in practice and can include radiographs, written notes, study casts, etc. When there are few restorations, a forensic dentist can use other oral features including supernumerary teeth, malpositioned teeth, crown morphology and root morphology.[7] There are two types of discrepancies that can be found when comparing antemortem records to postmortem. An explainable discrepancy is when dental work was done after the antemortem record was taken.[9] An example would be an amalgam that was later replaced by a crown. An unexplainable discrepancy is when there are inconsistencies with the records. For example, you cannot unfill a tooth, so if remains include no fillings, they cannot be identified as those of someone who is recorded as having had a restoration.[9] If there is even just one unexplainable discrepancy, then the result is an exclusion. This is why it is extremely important for dentists to record and maintain accurate dental records to ensure an individual’s remains will be correctly identified.[10]

The identification process for mass disasters is basically the same as a comparative dental identification, except on a much grander scale, meaning that the need for accuracy is much greater. After a mass disaster occurs, a temporary morgue will be established if the local facilities become overwhelmed; frequently this is either in an airport hangar or large warehouse.[6] In the dental area, photographs and radiographs are taken.[6] Postmortem dental profiling is done by one person while another confirms the findings and a third person records the findings on the proper charts.[6] The antemortem team contacts families to identify the treating dentists, who are then requested to send antemortem records.[6] The team then spends time deciphering codes, translating, deciphering illegible handwriting, interpreting notations, and contacting the treating dentists for clarification.6 These findings are then transferred to a document identical to the postmortem form, and comparisons begin.[6] Inconsistencies will be due to time, additional treatment and human error.[6] This type of mass comparison was used in Croatia in July 1998, where 1,000 human remains were exhumed from a mass grave; forensic dentistry was able to positively identify 824 of the remains.[11]

Bite mark evidence recovery and analysis is the most complex and demanding role that the forensic dentist plays in the criminal justice system.1 When collecting bite mark evidence to identify a perpetrator, there are many different processes a medical examiner and forensic dentist use. These processes include photography, digital imagery, saliva swabbing for DNA, scanning electron microscopy (SEM) and bite mark impressions.[5] Evidence from the injury and the teeth are recorded and used for comparison of the shapes, sizes and pattern present in the bite mark.[13] Since human skin is curved, elastic, distortable and undergoes oedema, this comparative analysis is often very difficult.[13]

The use of bite mark impressions is one of the most important processes in the application of forensic odontology.[5] This process is done by making an impression of the suspect’s dentition and applying the impression to the actual bite mark itself.[12] Additionally, traces of saliva left in the bite mark can contain DNA, which can be analyzed to identify who left the bite mark.[13] Currently, there is no agreement among forensic dentists about the individuality of the dentition or the behavior of human skin during biting. Although these issues have never been proven scientifically, research is currently under way in an attempt to prove the suspicion that each human dentition is unique.[13]

So how can a dental hygienist get involved? One way is through dental records. Personal identification by means of dental records is probably one of the most important forensic responsibilities. There is a strong, compelling societal need that each person’s identity be dignified by its continuation following death, and in situations such as mass disasters, forensic evidence is necessary to confirm the identity before it can be preserved.[2] Dental hygienists are often the ones to chart and document specific details about individuals’ mouths. The dental hygienist is ideally qualified to handle the equally important task of controlling the flow and security of the records in a mass fatality incident.[14] The comparison of antemortem to postmortem dental records is a widely accepted and dependable method of forensic identification.[2] The dental hygienist can assist in this activity in two ways. First, by ensuring that both the dental hygienist’s and the dental team’s records are detailed and accurate. Second, by assisting a practicing forensic odontologist in examining and recovering data from the dead body.[2]

Another way the dental hygienist can help in mass disaster cases is by participating on a forensic dental response team. Such teams provide invaluable assistance in cases of mass disasters in which large numbers of deceased victims must be identified.[1] Dental hygienists can select areas of the response team that interest them and dedicate themselves to training in that specific area. For example, dental hygienists who are not interested in working with the recovered bodies at autopsy can volunteer in the section dealing with antemortem records.[1]

The dental hygienist also plays a role in recognition and analysis of the injuries associated with family violence.[1] As practicing clinicians, dental hygienists and dentists can play a pivotal role, since they can be the first to see and recognize the signs of abuse.[1] As much as 50 percent of the signs of physical abuse injuries occur on the head, neck and face.[1] The dental hygienist is in a good position to better help the forensic team. With additional education and experience, dental hygienists who are interested can likely become more involved with a forensic team and offer greater contributions in areas such as evidence gathering and documentation, personal identification by means of the teeth, and mass disaster responses.[1]

The forensic dentist can bring closure to a family by delivering their loved one’s remains. Law enforcement personnel rely on the forensic dentist to examine teeth, facial features, radiographs and charts to help identify an individual’s remains. Each practitioner has a responsibility to understand the forensic implications associated with the practice of his or her profession. Appreciation of the forensic field should give the dental clinician another reason to maintain legible and legally acceptable records, as well as to assist legal authorities in the identification of victims and suspects.[10]

A diploma in dental hygiene prepares dental hygienists to be involved with forensics in some ways. However, with additional education and experience, dental hygienists who are interested can likely become more involved with a forensic team.[1] Dental hygienists can get additional education through continuing education courses, provincial Digital Visual Interface (DVI) team training sessions, forensic casework, and through the American Society of Forensic Odonotology.[1] Being involved and having a willingness to contribute to forensic dentistry helps our communities, humankind, and gives recognition to the profession of dental hygiene.[1]

References

1. Ferguson DA, Sweet DJ, Craig BJ. Forensic dentistry and dental hygiene: How can the dental hygienist contribute? Can J Dent Hyg. 2008 Jul-Aug; 42(4): 203-11.

2. Weigler S. Bite mark evidence: forensic odontology and the law. J Law Med. 1992 Summer; 2(2).

3. Giordano JJ. Forensic dentistry explained. Worchester, Mass.: c2006 Available at: www.forensicdentistryresourcecenter.com/forensic_dentistry.htm. Accesed Apr 3, 2011.

4. Biology-Online.org. History behind forensic odontology. Biology-Online.org [updated 2009 Jan 31.]. Available at: www.biology-online.org/articles/forensic-odontology/history-behind-forensic-odontology.html. Accessed Apr. 3, 2011.

5. Dorian BJ. Bite mark evidence. forensic science. Marcel Dekker. 2005.

6. Bowers CM. Forensic dental evidence: an investigator’s handbook. San Diego: Elsevier Publishing; 2004.

7. Pretty IA, Sweet D. A look at forensic dentistry – Part 1: The role of teeth in the determination of human identity. Br Dent J. 2001; Apr 14; 190 (7): 359-366.

8. Chandra Shekar BR, Reddy C. Role of dentist in person identification. Ind J Dent Res 2009; 20: 356-60.

9. Senn DR, Stimson PG, editors. Forensic dentistry. Boca Raton: CRC Press; 2010.

10. Avon SL. Forensic odonotology: the roles and responsibilities of the dentist. J Can Dent Assoc. 2004 Jul-Aug; 70 (7): 453-8.

11. Brkic H, Kubat M, Petrovecki V, Strinovic D. Odonological identification of human remains from mass graves in Croatia. Int J Int Med. 2000. 114 (1-2): 22.

12. Dailey JC, Gelles JHW, Shernoff AF. An improved technique in bite mark impressions. J Pros Dent. 1989 Feb; 61 (2): 153-5.

13. Pretty IA, Sweet D. A paradigm shift in the analysis of bitemarks. For Sci Int. 2010 Sep 10; 201(1-3): 38-44.

14. Determining identity through dental forensics. Dimensions of Dental Hygiene. 2005; Oct; 3 (10): 12,14,16-17.

Bridget Andrieu, Jamie Johnson, Amber Kreko and Amanda Giacona are second-year dental hygiene students at the Louisiana State University Health Sciences Center (LSUHSC), New Orleans, who will graduate in May 2012.

Faculty mentor for this project was Tricia S. Barker, RDH, MEd, clinical assistant professor, Comprehensive Dentistry and Biomaterials—Dental Hygiene at the LSUHSC.