Forensic Odontology (simplified)

Forensic science is most simply defined as the science that is applied to the law. Criminal cases many times call for the examination of evidence that can tie a suspect or victim to a crime scene or to one another. These physical traces frequently include blood and other bodily fluids, hair, fibers, and even bite marks. Here we will focus our attention to the latter, as it applies to the field of forensic science referred to forensic odontology or forensic dentistry.

Forensic odontology is the field of forensic science dealing with the recognition of unique attributes present in each individual's dental composition. This branch of forensics relies heavily on extensive and detailed knowledge of the teeth, jaws, and dental anatomy possessed by a dentist. In addition to this knowledge, the forensic dentist must be well-versed in the interpretations of radiographs, pathology, charting, and types of dental treatment. The forensic dentist is dutifully responsible for the proper handling, assessment, and evaluation of dental evidence in the name of justice. He/She is the key to identification based upon the distinctive features present in the dental structures of each individual.

Identification of deceased individuals who cannot be identified by other means, identification of human remains, identification of victims in mass fatalities, assessment of bite mark patterns, and age estimation using teeth are all part of the role of forensic odontologists as well. Other duties include evidence collection and examination in cases of child abuse, spousal abuse, and malpractice. Identification of an assailant by comparing a record of their dentition (set of teeth) with a record of a bite mark left on a victim and the presentation of bite mark evidence in court as an expert witness are also done as part of the job.

Bite mark comparison is one of the major and newer parts of this forensic discipline that has been evolving since the 1970s. Investigators noticed that criminals often leave bite impressions at crime scenes which can be used as evidence on items such as food products, chewing gum, and the skin of victims (many times in cases of battery, rape, child abuse, and homicide).

There are seven types of bite mark classifications and four degrees of impression used to document each mark. The classifications are the following:

1. Hemorrhage (small, bleeding spot)

2. Abrasion (mark on skin-undamaging)

3. Contusion (bruise, ruptured blood vessel)

4. Laceration (skin is punctured or torn)

5. Incision (neat tear of the skin)

6. Avulsion (skin is removed)

7. Artifact (piece of the body is bitten off)

The four degrees of impression are divided into these following categories as well:

1. Clearly defined (significant pressure)

2. Obviously defined (first-degree pressure)

3. Quite noticeable (violent pressure)

4. Laceration (skin is torn from the body)

Of the types of bite marks, contusions are the most common. Females are most commonly bitten on the breasts, hands, and legs during sexual assaults and males are most often bitten on the arms and shoulders during these assaults. The bite marks from these injuries are examined to be compared with impressions or DNA from a suspect. When there are incisions these give the best 3-dimensional images of the teeth.

When bite mark evidence is collected, a saliva sample is first taken from the wound by the forensic dentist. It is important to take the sample of saliva for DNA carefully so that the mark is not disturbed and other evidence is not lost. The bite mark is photographed in specific lighting in order to properly capture all angles. A ruler is placed next to the mark in the photo as a measurement gauge. Descriptive documentation of the injury including size, location on the body, and the extent of the injury are recorded.

If it is necessary molds, impressions, and casts of bite marks are taken. If there is a suspect, the forensic odontologist takes impressions, x-rays, and bite samples for comparison with the bite mark. Physical forensic comparison is completed and biological comparisons are then done using the saliva samples and DNA from the suspect.

Dental identification of deceased individuals is the most prominent role of the forensic odontologist. It is done to identify victims who cannot be identified

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