The University Record, July 22, 2002

Forensic dentistry gains prominence since Sept. 11

By Jerry Mastey
School of Dentistry

Immediately after airplanes slammed into the World Trade Center in New York City, the Pentagon, and a field in Pennsylvania, dental schools around the country received e-mails seeking help from forensic dentists to assist in identifying human remains.

One of those asked to help was Jack Gobetti, dentistry professor and a forensic dentist at the School of Dentistry.

“I said I was willing to help if I could,” he said. “But as it turned out, my help wasn’t needed.” Of the nearly 3,000 persons who died in New York City, the remains of about 850 had been positively identified by the spring.

Since 1968, Gobetti has been called to the scenes of individual tragedies and mass disasters to assist in identifying human remains. His first call to help identify a burn victim that year sparked his interest in forensics and dental identification.

After completing Armed Forces Institute of Pathology courses in the early 1970s, which further expanded his knowledge of the subject, he volunteered to help the Washtenaw County medical examiner and several other police agencies. All dental identification of victims in individual tragedies or mass disasters is a comparison of antemortem and postmortem records.

Because teeth are the hardest substance in a body, lasting longer than bones or tissues, they’re ideal for making a positive identification, Gobetti said.

Unlike other hard tissues in the body, teeth are usually not vulnerable to destruction by external forces. “Teeth can be susceptible to forces such as tooth decay or periodontal disease,” he said, “but once an individual dies, the forces that destroy teeth don’t exist, so the teeth provide an excellent, stable and reliable means for identifying human remains.”

Consequently, in some cases it’s possible for examinations to be conducted on sections of the jaw, perhaps only containing one or two teeth.

Even in the case of a disaster that includes a fire, many clues can be garnered from dental findings. Gobetti said teeth generally become brittle at 400 degrees Fahrenheit and begin turning to ash between 1,000 and 1,200 degrees. However, many restorations, such as partial dentures, crowns, and bridges, survive these temperatures and can help make identification possible.

In most mass disasters, several teams are working simultaneously, Gobetti said. Police agencies gather records and the names of possible victims. A group of dentists conduct antemortem examinations of record information that is later coded and entered into computers. Another team conducts a complete examination of bodies using dental and clinical information as well as radiographs (x-rays).

After this process has been completed and the information has been entered into a computer, a list of probable victims is generated. Final, positive identification is then made comparing the records from both teams of examiners.

Conclusive identification of a person is only possible by looking at teeth, jaws, dental charts, periodontal charts, x-rays and individual restorations.

It’s a painstaking process because forensic dentists compare dental remains with dental records. To try to positively identify a person, each state has laws mandating a specific number of “points of comparison.”

“There have been times when I have identified an individual using only five points of comparison,” Gobetti said. “On the other hand, there was one instance where I was involved in 78 different points of comparison to positively identify a person.”

After the points of comparison are noted, the forensic dentist then assigns one of four labels to the remains based on the evidence—positively identified, possibly identified, insufficient evidence to identify or not the individual.

In addition to testifying in court as an expert witness on forensic dental matters, Gobetti teaches a continuing dental education course on forensic dentistry. His next class is July 26 at St. John’s Golf and Conference Center in Plymouth. The three-hour course is open to dentists, hygienists, assistants and other oral health care professionals, as well as legal and law enforcement officials. The course starts at 9 a.m., with registration beginning at 8:30 a.m. For more information, call the School of Dentistry Office of Continuing Dental Education, (734) 763-5070.