The Dental Investigation

After mass fatalities, such as 9/11, hurricane Katrina, and the Oklahoma City bombing, identification of individuals through dental records is often necessary. Forensic dentistry can help identify unknown victims of mass casualty and criminal incidents. Dental forensics or forensic odontology are terms used interchangeably and they describe the management, examination, evaluation, and presentation of dental evidence in criminal or civil proceedings.¹ The first forensic dentist in the United States was Paul Revere who was able to identify fallen revolutionary soldiers by their dental records.²

Forensic dentistry has several areas of specialty, including assessment of bitemark injuries; assessment of abuse (child, domestic partner, or family); identification of found human remains; and identification in mass fatalities.

BITEMARKS

Bitemarks are either left on a victim (by the attacker), on a perpetrator (by the victim of an attack), or on an inanimate object found at the crime scene. Human bitemarks are most often found on the skin and soft tissue areas. Area bitemarks on women are most frequently found on the breasts and legs. On men, bitemarks are commonly seen on the arms and shoulders.^3,4 When a person is in a defensive position, such as when the arms are held up to ward off an attacker, the arms and hands are often bitten.⁶ Bitemarks are frequently found on children who are abused.²

Human bitemarks are elliptical or circular injuries that record the specific characteristics of the teeth (Figure 1).^5,6 The bitemark may be in the shape of a doughnut with characteristics recorded around the perimeter of the mark.⁷ Also it may be composed of two U-shaped arches that are separated at their bases by an open space. Typically the diameter of the injury is from 25 mm to 40 mm.⁷ Often the injury has a central area of bruising that is seen within the bitemark. This is caused by pressure from the teeth as they compress the tissue inward from the perimeter of the mark.⁷

Upon collection of dental evidence, the forensic odontologist analyzes and compares the bitemarks. Early forensic investigators analyzed marks left by dental casts in wax, clear overlays, and other media. Others attempted to simulate the consistency of human tissue by using articulated dental models to “bite” baker’s dough and sponge rubber.⁸

Many factors can affect the accuracy of bitemark identification, including time-dependent changes of the bitemark on living bodies, effects of where the bitemark was found, damage on soft tissue, and similarities in dentition among individuals.⁹ Elasticity and the inflammatory process of human tissue hinder the identification process of bitemark registration. Placement of the limb in the exact position as when the attack occurred is necessary to recreate the correct bite relationship; this information is not always known.

ABUSE

Abuse can affect all types of people but is frequently perpetrated against children and older people. The dental team can aid in the early detection of abuse by looking for signs within the oral cavity. See Table 1 for common symptoms.²

Dental professionals are obligated to act when abuse of a child is suspected.² Child abuse is any act that endangers or impairs a child’s physical or emotional health or development. Neglect occurs in 55% of child abuse cases.² Dental neglect is one type of abuse because it is the willful failure of a parent or guardian to seek and obtain treatment for dental problems that cause pain, infection, or interfere with adequate function.

The United States Department of Justice indicates that violent crimes against people ages 65 and older occur approximately in four out of 1,000 people.¹⁰ After neglect and emotional/psychological abuse, the third most common type of abuse in older people is physical abuse.¹⁰ Dental professionals may encounter clues that indicate older people are being physically abused such as bruises, lacerations, puncture wounds, or injuries with improbable explanations.

IDENTIFICATION

Dental identification assumes a primary role in identifying remains when post-mortem changes occur, traumatic tissue injuries are present, or no fingerprint records exist.¹ Identification is crucial when the deceased is decomposed, burned, dismembered, or skeletonized.¹ The advantage of dental evidence is that, like other hard tissues, it is often preserved after death.¹

The evidence that may be derived from teeth is the age estimation and identification of the person. This is done using dental records or antemortem (prior to death) radiographs and photographs, and comparing them to post-mortem records. Dental professionals should always document information in dental records clearly, correctly, and specifically in case the records are ever needed for identification.

Forensic dentistry starts with dental professionals. Quality radiographs and accurate charting are the first steps toward a positive identification. A person’s teeth change throughout a lifetime and the combination of decayed, missing, and filled teeth is measurable and comparable at any fixed point in time. Dental records are used to aid in the identification of those who are victims of criminal acts, murder investigations, missing persons, or mass fatalities.¹ Pulp chamber and root morphology may also provide valuable information in identification. The pulp chamber can be used to distinguish the approximate age of the individual since the chamber size varies from primary to permanent dentition. Sometimes teeth are found outside of the deceased’s maxilla or mandible. The root morphology along with the pulp chambers can assist in determining whether the tooth is from the maxillary or mandibular arch and whether it is an anterior or posterior tooth.¹¹ Incidents, such as plane crashes and explosions, can damage the coronal surface of the tooth. A positive identification is still possible by comparing the pulp chamber and root morphology. The root surfaces of teeth have unique shapes and bends. Studies are currently underway to determine the accuracy of comparing root surfaces.

Computer identification databases, such as WinID^© and National Crime Information Center (NCIC), are used today to compare ante-mortem and post-mortem data in the identification of deceased or missing individuals. WinID is a dental computer system that matches missing persons to unidentified human remains. WinID makes use of dental and anthropometric characteristics to rank possible matches. WinID is used by forensic dentists, forensic odontologists, pathologists, coroners, medical examiners, forensic anthropologists, and those in law enforcement and criminal justice to identify missing persons. This program was used in 2005 for the first time to assist in the identification of hurricane Katrina victims.

NCIC is the Federal Bureau of Investigation’s computer database. It houses information about missing or unidentified persons, crimes, and criminals and is accessible by criminal justice agencies. This information assists in the apprehension of fugitives, the location of missing persons, the location and return of stolen pro perty, and in the protection of law enforcement officers.

MASS FATALITY

A mass fatality incident is defined as: “An incident where more deaths occur than can be handled by local resources.”¹² Mass disasters/ fatalities, such as transportation accidents, explosions, fires, volcanic eruptions, mass murders, and mass suicides, often leave many bodies in poor condition for identification. The National Disaster Medical System (NDMS) is a federally coordinated system that augments the nation’s medical response capability. NDMS has five response teams, one of which is the Disaster Mortuary Operational Response Team (DMORT). DMORT is a federal level response organization designed to provide mortuary assistance in the case of a mass fatality incident or cemetery-related incident. In the event of flooding, it is sometimes necessary to recover caskets, re-identify displaced individuals, and disinter remains. DMORT works under the local jurisdictional authorities such as coroner/ medical examiners, law enforcement, and emergency managers. There are 10 regions within DMORT and each region consists of a team from specific states (see Figure 2).

Dental forensics played a key role in identifying individuals killed during the Oklahoma City bombing. Unfortunately, positive identification of all remains is not always possible. In Oklahoma City, 70% to 80% of victims were identified.¹³ Approximately 20% of victims of 9/11 were identified, 90% of victims of the 2004 tsunami in Southeast Asia were identified, and 15% to 20% of hurricane Katrina victims were identified.^14,15

EDUCATION AND TRAINING

Proper education and specialty training are required to enter the field of forensic odontology. A traditional dental education does not provide the curriculum and experience needed to function in this field. Dental hygienists can become involved in dental forensics by collecting post-mortem information (radiographs, photos, dental charting, etc) needed for the proper identification of a deceased individual. They can also serve as dental assistants with DMORT. Currently, 35 dental hygienists work with DMORT.¹⁵

The American Academy of Forensic Science (AAFS) is the forum for forensic dental lectures, demonstrations, and practical courses. The AAFS is affiliated with the American Board of Forensic Odontology (ABFO), which serves as the credentialing body for dentists who have satisfied the experience and training requirements needed to sit for the ABFO examination.¹⁵

Basic courses in forensic science and medicolegal death investigation are strongly recommended because specialized knowledge is necessary to participate in forensic investigations.¹⁶ The American Society of Forensic Odontology has annual meetings, and the Armed Forces Institute of Pathology offers week-long dental courses in odontology and pathology. The University of Texas Health Sciences Center, San Antonio, provides an annual program and a forensic dentistry fellowship program. The New York Society of Forensic Dentistry and the New York County Dental Society offer introductory courses in forensic odontology.

A few dental schools offer an elective or practicum in dental forensics that allows dental and dental hygiene students to attend local meetings and guest lectures about various topics regarding forensic dentistry and response to mass fatalities. Some students may have the opportunity to tour their local medical examiner office or crime scene investigation laboratory, meet a cadaver dog and trainer, view autopsies, and assist the forensic dentist in an identification case.

Other educational opportunities for dental professionals interested in dental forensics or mass fatality response include attending continuing education seminars or workshops. There are week-long seminars that focus on medical examiner investigation or 2-week to 3-week classes in crime scene investigation. Those involved with DMORT receive annual training opportunities, including online courses or weekend training. State and regional disaster teams are additional sources of education and involvement.

Forensic dentistry roles in the past have traditionally been limited to dentists but dental hygienists and dental assistants are increasingly being used in the area of forensic dentistry. Dental hygienists can play an important role in dental forensics by maintaining accurate dental records, assisting at a coroner’s or medical examiner’s office, helping police departments enter dental information into a computer system, and joining a DMORT to help with mass fatalities. All of these avenues will assist in the identification of human remains.

Most important, the first step in a positive identification is quality ante-mortem records. Researching local dental professionals who assist the coroner/medical examiner’s office and volunteering to assist can be a good way to enter forensics. Attending forensic seminars and meetings can also open doors. Being an active member in the local medical reserve corps or state disaster teams can provide a great avenue to get involved in forensics. Forensics is not for everyone; participating in an organized disaster deployment is a good way to determine if the rigors of forensic dentistry are for you.

REFERENCES

1. Avon SL. Forensic odontology: the roles and responsibilities of the dentist. J Can Dent Assoc. 2004;70: 453-458.
2. Dudley MH. Forensic Medical Investigation—A Comprehensive Review. Kansas City, Mo: Dudley Publishing; 2008.
3. Vale GL, Noguchi TT. Anatomical distribution of human bitemarks in a series of 67 cases. J Forensic Sci. 1983;28:61-69.
4. Pretty IA, Sweet D. Anatomical locations of bitemarks and associated findings in 101 cases from the United States. J Forensic Sci. 2000:45:812-814.
5. Bowers CM, Bell GL. In: Bowers CM, Bell GL, eds. Manual of Forensic Odontology. 3rd ed. Colorado Springs, Colo: American Society of Forensic Odontology; 1995:299, 334-353.
6. American Board of Forensic Odontology. ID & Bitemark Guidelines. Available at: www.abfo.org/id_mark_guidelines.htm. Accessed September 18, 2009.
7. Sweet D, Pretty IA. A look at forensic dentistry—Part 2: Teeth as weapons of violence—identification of bitemark perpetrators. Br Dent J. 2001;190:415-418.
8. Rothwell BR. Bite marks in forensic dentistry: a review of legal, scientific issues. J Am Dent Assoc. 1995; 126:223-232.
9. Kubic T, Petraco N. Forensic Science Laboratory Manual and Workbook. 3rd ed. Boca Raton, Fla: CRC Press; 2009:187-211.
10. Rennison C. Criminal Victimization 1999, Changes 1998-99 with Trends, 1993-1999, NCJ 182734. Washington, DC: US Department of Justice, Bureau of Justice Statistics; August 2000.
11. Isselhard B. Antatomy of Orofacial Structures. 7th ed. St. Louis: Mosby; 2003:104-117, 194-217.
12. California Health and Safety Code §103451. Available at www.ca.gov/Health/LawsAndRegs.html. Accessed September 21, 2009.
13. Flam F. Forensic experts’ task is daunting identifying the dead could take months. The Seattle Times. September 13. 2001.
14. Chen H, Jackson C. Case Study CSE 891: Forensic Odontology. Available at: www.cse.msu.edu/~cse891/Sect601/CaseStudy/Jackson&Chen.ppt#1. Accessed September 18, 2009.
15. Louisiana Department of Health and Hospitals. Hurricane Katrina. Available at: www.dhh.louisiana.gov/offices/page.asp?ID=192&Detail=5279. Accessed September 18, 2009.
16. American Academy of Forensic Sciences. Choosing a Career. Available at: www.aafs.org/default.asp?section_id=resources&page_id=choosing_a_career. Accessed September 17, 2009.

From Dimensions of Dental Hygiene. October 2009; 7(10): 58-61.