Teeth
By: Bridget Stackpole
Bite-mark analysis is commonly used in rape and sexual assault cases. This analysis is very difficult and many steps are involved for a forensic dentist to identity the suspect. The dentists must be called in immediately because bite marks change over time, especially if the victim is dead. There are multiple types of impressions such as, a clean impression, which means significant pressure was made, an obvious impression where medium pressure was applied and a noticeable impression that signifies violent pressure was used by the attacker. Crooked teeth, braces, missing teeth, gaps and chipped teeth all leave distinct impressions that a forensic dentist must examine.
When the dentist arrives at the crime scene they have many steps in analyzing the bite mark. First, they must identify the bite mark as a human. Animal teeth are different from human so they leave a distinctive pattern. Next, the bite mark is swabbed for DNA from the saliva of the attacker; the dentist also has to determine if the bite was self-inflicted. Pictures of the bite mark are taken, along with measurements of each mark and recorded. The photos are used to measure the depth and size of the bite and then are magnified, enhanced and examined. Lastly, if the bite mark is on a deceased victim then the mark is cut out from the skin of the corpse and preserved in formalin, so the forensic dentists can make a silicone impression of the bite mark.
The forensic dentist does not take part in identifying the victim but when investigators have a suspect, a warrant goes out to take a mold of their teeth, as well as pictures of the mouth. The pictures of the suspect’s mouth and pictures of the bite marks are compared, along with the molds of each bite mark. Movement of the person’s jaw and tongue during the bite indicates the type of mark that is left on the victim. Also, depending on the bite, it is not likely to find a mark where both upper and lower teeth leave vivid impressions. Another factor is that if the victim is moving or still during the attack. All of these factors are taken in account for when the investigators build a case around bite mark analysis.