Forensic odontology applies dental science to legal investigations, primarily involving identifying the offender by comparing dental records to a bite mark left on the victim or at the scene or identification of human remains based on dental records.
Forensic odontology works on the principle that no two people have exactly the same dental imprints. Extractions, fillings, chipped, gapped, or closely spaced teeth can all be used to identify who the teeth marks are from. Some teeth may even be twisted or tilted. Even with individuals who have had their teeth straightened through the use of braces, there will be some distinctive features that can be used to identify them based on their dental work.
Bite marks can be left on the victim (by the attacker), the criminal (by the victim of an attack), and an inanimate object found at the crime scene, such as food or chewing gum. Most often found on the skin and soft tissue areas of all parts of the victim’s body or sometimes on the criminal’s body (in defensive circumstances, by the victim), primarily observed in sexual and physical abuse cases.
When discovered, numerous steps must be taken when collecting dental evidence, including a description of the bite mark regarding the demographics, location, shape, size, color, type of injury, and any other required information for records. According to the guidelines established by the American Board of Forensic Odontology (ABFO), the following steps must be followed:
- Photography: Orientation and close-up photographs should be obtained with and without the presence of a scale placed adjacent to the bite mark. The scale must be positioned within the same plane as the bite mark and should include a linear and circular reference to eliminate possible distortion. The film resolution should be high quality with proper color balance. Serial photographs are recommended in living victims.
- Salivary Swabbing: Saliva swabs should be collected in circumstances in which the bite site area has not been altered from the time when the bite was inflicted. – for potential DNA evidence.
- Impressions: Impressions of the bite site area should be taken when there is sufficient surface detail which may yield beneficial information. The material used must meet the American Dental Association specifications, and suitable support should be included for proper support and reproducibility of the body site contour.
- Tissue Samples: Tissue samples should be retained if it appears they may yield helpful information.
Upon collection of dental evidence, the forensic odontologist analyzes and compares the bite marks with the dental impressions of the suspects.A bite mark is known as registering the cutting edges of teeth on a substance caused by a jaw-closing. The bite marks have been divided into seven classifications:
- Hemorrhage: A small bleeding spot.
- Abrasion: Undamaging mark on the skin.
- Contusion: Ruptured blood vessels, bruising.
- Laceration: Punctured or torn skin.
- Incision: Neat puncture of the skin.
- Avulsion: Removal of the skin.
- Artefact: Bitten off a piece of the body.
The duration of a bite mark is determined by the magnitude and how long the victim had been bitten. A bite mark’s accuracy and quality are dependent on a variety of factors, such as time-dependent changes, dental similarity, and damage to the soft tissue, quality of photographs, impression, and measurements.
Ideally, records related to the teeth should be obtained in order to compare and identify human remains. Other clues may also be found in the teeth. A tooth eruption is linked to a certain age, which can give an estimate of the victim’s age.
In identifying human remains based on their teeth, dental records should ideally be obtained and compared to those of the unidentified body. If this is not possible, other clues in the teeth may be useful. Tooth eruption is linked to a certain extent with age, giving a possible rough estimation of the victim. When working with a young victim, the stage of development of a child’s teeth may be used to determine their age, though this can only be an estimate. The patterns and state of an individual’s teeth can reveal a lot about their health and lifestyle. They can also help determine their age and diet.
The standard method of comparison involves recording the edges of a suspect’s teeth using transparent overlays. Usually, these are drawn on acetate sheets, which can then be used over one another for comparison. If possible, a dental cast may be made for the identification of a bite mark for comparison in a later stage.
However, the reliability of forensic odontology has been questioned on numerous occasions. Due to the nature of the skin’s irregularities that might cause distortion, skin is not a suitable medium for creating dental impressions. Bite marks can also be altered through stretching, movement, or environmental change. There is also no standard by which to evaluate and compare bite marks.
Aside from criminal cases, forensic dentists and odontologists are also involved in identifying victims of mass disasters.
