In 1999, Donald Blom was the main suspect for the murder of 19-year-old Katie Poirier. Investigators found bone fragments and one lone tooth within a fire-pit located on Blom's property.
In situations where DNA is scarce or non-existent, dental evidence may hold the key to identifying remains.
In the Donald Blom case, forensic dental expert Dr. Ann Norrlander was able to locate remnants of a filling. This filling would later help lead to Blom's life sentence for the murder of Poirier.
Today, Ray Miller, a Forensic Odontologist in the Department of Oral Diagnostic Sciences, Peter Bush, director of the South Campus Instrument Center and Mary Bush, assistant professor of restorative dentistry, are working to improve this technique through extensive research
In a recent controlled experiment, six cadavers were used to insert over ten different resins into the teeth of each body, totaling 70 fillings conducted by Mary Bush, Peter Bush and Miller.
The cadavers were cremated at 1,850 degrees for about two-and-a-half hours. The remains were then collected and analyzed. In this experiment, the researchers were 100 percent successful in distinguishing the identity between the six cadavers.
Due to their research, UB has created the Laboratory for Odontology Research. In addition, the results of their study will be published in the Journal of Forensic Science in January 2007.
The scientists received a grant from the American Society of Forensic Odontology to assemble their data. Much of this data may be utilized by the FBI, who has offered to include it in their own database.
The process of matching a body to a tooth filling, though, is tedious and time consuming.
When the remains of an individual are burnt to an extreme such as cremation, "DNA and other organic material will be destroyed," Mary said.
While teeth can usually sustain these circumstances, they are still liable to disintegrate, according to Peter.
"In such instances, the only substances that will survive will be inorganic, non-biological materials," Peter Bush said. "Tooth-colored resin fillings are now one of those materials scientists can use to aid identification, mostly due to the inorganic filler particles."
The inorganic elements of tooth-color filling can withstand temperatures in excess of 1,800 degrees Fahrenheit. Tooth-colored fillings consist of an organic matrix and inorganic filler particles. The organic matrix will burn off, but the inorganic filler particles will be left behind, and virtually unchanged, thus allowing distinction between brand and brand groups.
Manufacturers of filling material utilize various inorganic filler elements mainly for radiopacity purposes. This makes the filling material appear very bright on a dental x-ray.
"By studying the elemental composition and microstructure of a filling, we can identify its unique chemical configuration," Peter said. This allows for the classification of the different filling brands or brand groups.
In the Katie Poirier instance, the filling elements found in the tooth matched the brand of material stated in her dental records. The combination of tooth number, class of restoration and brand of filling all matched. The chance that this was someone other than Katie was extremely low.
"Matching fillings is not like matching DNA," Mary said. "But it can give investigators another level of certainty in making an identification, especially in situations when very few clues remain."
This technique of identification does have flaws. If the dental records are lacking, or not properly reported, then identifying the chemical composition of the filling would be rendered useless because researchers would have no basis for comparison. The known dental filling used must be documented in the patient's dental chart.
"We have found in our research that within the 50 brands of modern restorative materials on the market today, some have overlapping elemental signatures," Mary said. "If element compositions are similar, then researchers can not distinguish individual brands but brand groups. We are attempting to further differentiate between these similar groups now."
Photo: Courtesy of Laron Fomby
