Forensics expert Marcel Verhoff of the University of Giessen examines teeth in a jawbone in a mass grave discovered at a construction site on Jan. 25, 2008, in Kassel, Germany.

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Tooth Identification

There is no database of teeth that corresponds with databases of fingerprints or DNA, so dental records are how forensic dentists identify the dead. Tooth enamel (the outer layer of teeth) is harder than any other substance in the human body, which is why teeth remain long after all other parts have decayed. Victims of fires are often identified by their teeth, which can withstand temperatures of more than 2,000 degrees Fahrenheit (1,093 degrees Celsius). Teeth that have been through especially intense heat are very fragile and may shrink, but they can be preserved with lacquer and used for identification as long as they are handled very carefully. Dental work, such as a partial or gold crown, will be distorted by fire but can still aid in identification.

To identify a person from his or her teeth, a forensic dentist must have a dental record or records from the deceased person's dentist. In the case of an incident involving multiple deaths, forensic dentists receive a list of possible individuals and compare available records with the teeth and find a match. Examining the teeth of an intact corpse often requires working in a morgue to expose the jaws surgically. Even if only a few teeth are available, a forensic dentist can still make a positive identification. The best comparisons come from X-rays, but even if those aren't available, notations on the tooth chart can tell the dentist if the teeth are the same.

X-rays are the best way to make a match as far as forensic dentistry is concerned.

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Identifying an individual by his or her teeth without dental records is much more difficult. However, things like broken teeth, missing teeth and gold crowns might be recognized by the friends and family members of the deceased. Things about the biter's lifestyle can be determined by the teeth; a constant pipe smoker or a bagpipe player has a distinctive wear pattern. Dressmakers and tailors, who often put pins and needles in their mouths, may have chipped teeth.

In addition to the dental records, forensic investigators can retrieve DNA samples by extracting the pulp from the center of the tooth. Unlike the enamel, pulp can be damaged by fire and other conditions, but it can also last for hundreds of years. Dental identification is often the last resort, and it isn't always possible -- some people simply can't be identified.

We'll look at the other aspect of forensic dentistry, bite-mark analysis, next.