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Notes for the Instructor

In this lesson students will be introduced to the field of forensic dentistry or forensic odontology. The field includes the examination of bite marks inflicted by humans and animals. These dentists are board-certified specialists and deal primarily with bite-mark evidence. Forensic dentists specialize in evidence at a crime scene related to teeth and the mouth. In addition to studying bite marks, they also use teeth to determine age in living and deceased people, use teeth to identify human remains, assess oral trauma to the skin, and provide testimony for dental malpractice.

Forensic dentists are called to the scene of a crime when a bite mark is discovered. They must act quickly because bite marks can change over time. First a forensic dentist will determine if the bite is human or otherwise. Next, it is important to get a saliva sample from the bite, if possible. Saliva is the liquid secreted by glands in the mouth. Saliva helps you chew, swallow and digest your food. Saliva samples may contain cheek cells, which will have DNA – biological material specific to one individual. This is very valuable in an investigation.

Next, forensic dentists carefully measure and record each bite. Photographs are taken next to a small linear scale for size reference. It is important to accurately record the size, orientation, and depth of bite marks. Finally, the forensic dentist may make a number of casts or molds of the bite mark.

A bite can provide a lot of clues to investigators in a case. Marks found at a scene can reveal whether or not a child or adult inflicted the bite, whether or not a person has any missing or broken teeth, and if he wears braces or not. Marks may also reveal the level of struggle or movement during the bite.

If a case has suspects, the forensic dentist will take photos and make molds of the suspect’s teeth in order to compare them to bite marks found at the crime scene. Investigators will pay attention to both top and bottom teeth, as well as how the mouth looks open and while biting. Computerized bite analysis software is available to help in the analysis.

Bite marks are considered unique evidence as opposed to class evidence. This means that a bite can be examined and ultimately traced back to one individual.

In this lesson, students will first create their own bite marks and study the positions of their teeth. Students will then analyze the pattern of teeth found in children and adults, noting the differences. Finally, armed with this knowledge, students will examine bite marks found at the crime scene. One of our suspects left a partially eaten cookie on Mrs. Randall’s desk. Students will attempt to match the bite patterns on the cookie with bite marks taken from our four suspects.

The activities in this lesson address Next Generation Science Standards practices of Planning and Carrying Out Investigations and Analyzing and Interpreting Data. In addition, they address Common Core Learning Standards. See the appendix on page 105 for more details.