One of the main reasons why teeth provide key clues in identifying a person's remains is that they're often among the only evidence intact, explains Dr. Michael Messina, a consumer advisor for the American Medical Association.
"Teeth have a tremendous degree of permanence," Messina says. "It's very difficult to destroy teeth, as opposed to fingerprints, which actually decompose pretty quickly, particularly if a body is out in the elements where flesh decomposes pretty rapidly."In addition, each person's arrangement of teeth is virtually unique, making it possible to study a set of teeth and compare it with a set of dental records. This comparison "allows dentists to establish a person's identity, just like fingerprints or DNA evidence," the American Dental Association (ADA) says.
In disasters like last week's terrorist attacks in New York City, Washington, D.C., and Pennsylvania, dental records can be the primary source of identification, Messina says.
"You can burn a body and the teeth will make it through, unless it's extremely hot," he says.
The durability of teeth can also help them preserve valuable DNA.
"One of the things we've learned is that the nerve chamber within a tooth represents sometimes a very safe chest for the storing of DNA material over time," Messina says. "So it's possible to extract DNA material from inside a tooth to help provide a further match."
Dental records are still typically the first avenue for identifying bodies because DNA matching can be complicated, says Dr. Gary Bell, a forensic dental advisor with the Washington State Patrol in Seattle. That's particularly true in missing-person cases.
"DNA work is expensive, and there aren't that many labs that are geared up to handle the amount of DNA samples that would be necessary to make comparisons," Bell says. "Most DNA labs in the U.S. are already backlogged with criminal issues, not missing persons, so we have the dental to work with. It's easy to obtain if we can find the dentist that treated the missing person."
Given the large number of missing Americans at any one time also makes DNA testing a daunting task, Messina adds.
"DNA matching is a long and fairly involved process," he says. "At any given time, there are about 100,000 people missing in the United States, so if we come across an unidentified body, you'd rather not attempt to do a DNA match against all 100,000. But if dental records can rule out all but about 20 people, then that would be much more preferable."
And he adds, "It's very important to identify a person as truly being deceased because it provides closure for the family."
Also, he notes, "Most insurance policies won't pay unless they can definitely show a person is dead."
To facilitate efforts in dental matching, the ADA is working with the FBI to bring dental records into the digital age.
"One of the enhancements to the existing dental database we're asking the FBI to do is to digitize photographs and X-rays," Bell says. "A few states already do that, but we want the FBI to establish a national sort of repository for dental digital images. They're in the process of developing that."
What to Do: Read more about dental identification developments at this American Dental Association Web site. To learn more about how dental identification will be used to help identify the victims of last week's terrorist attacks, see this ADA site.