forensic - odontology
by Leif Kullman
A useful forum for research in Forensic Odontology
For different reasons I haven't had any opportunity for a long time to read the
Journal of Forensic Odonto-Stomatology, which is the large and
international well-known Journal in Forensic Odontology. However, recently I
got the time.
I became very happy, because I found my reading very stimulating. The
issue contained a great deal of practical interesting tips and research.
Several of the papers were from fields that really are interesting areas within
Forensic Odontology today.
One of the papers came from a research team in Aarhus and was titled
"Discrimination between dental materials by their radiopacity measured in
film radiographs and digital images"(1).
During the last years we have seen a tremendously fast development of
different aesthetic dental filling materials and this fact has caused the
practical working forensic odontologist a lot of trouble. It has become
difficult to perform a reliable and accurate postmortem clinical examination.
In many cases, it has accordingly become important to complete the
postmortem examination with radiographs. In a future, a digital dental
radiography system will also be used, when they have been proved to be as
good as usual film systems.
The aim of the above mentioned study was to investigate the possibility of
differentiating between various dental filling materials by means of their
radiopacity in radiographs. Cavities were cut in extracted teeth and these
were filled with different filling materials, such as amalgam, light-cured
composite, and glass ionomer cement. Radiographs were then taken with
conventional film and with two digital systems. The density in the filling
areas was then studied and the differences between the used systems, the
conventional radiographic versus the digital ones.
Based upon the findings the authors concluded that in the molar region
different materials could well be differentiated from each other with the
conventional film radiographs but not with the digital systems. In the anterior
region the same finding was also true, but to a minor probability or degree
than in the posterior parts of the jaws.
In the conclusion, the authors recommend that a conventional radiographic
technique still be used as a primary adjunct to the clinical examination in
borderline identification cases, where radiographs are necessary.
Another interesting study in the Journal came from two researchers in South
Africa, and was titled- "Person identification by means of a single unique
dental feature"(2).
These authors bring to the fore a classical question in Forensic Odontology,
namely how many concordant points that are necessary to make a positive
identification. Identification is always a comparison between records before
and after the death (the ante- and postmortem records).
In different countries the law requires a different number of concordant
points to establish an identity. In most European countries 12 concordant
points are accepted, if for example fingerprints comparisons are performed.
The same number has been accepted in dental identifications. However,
the opinion about the criteria for what a concordant point is can be
discussed and also the importance of how many points that is necessary.
Some authors have suggested that a single feature or point can be unique
enough for a positive identification.
The authors of the above mentioned study relate two identifications cases
where single features were used.
The unique feature in the first case was a gold inlay restoration. The
deceased was one of the passengers in an airplane crash and no dental
antemortem records were found for this victim. The only antemortem record
was a radiograph from a hospital of the cervical vertebrae, which also
showed this inlay.
Postmortem radiographs, in different angles and orientations could be
taken, which showed the identical "shape of this inlay".
In my opinion, it can be discussed if we really have one or if we have more
unique features in this case. I mean, will not every single surface of the inlay
be one concordant point? Anyway this is perhaps more an academic matter,
in the described case the insurance company, changed their attitude and
accepted this positive identification and compensated the widow financially.
In case two a dental identification was performed of a decomposed male
body by means of a very unusual attrition of an upper left canine. This tooth
was extracted during the autopsy and could later on be shown to the wife of
the reported missing person, who immediately recognized it. This case is
more a visual identification than a dental, a very common identification
method, often used by the police. But the same reasoning as before can be
used, how many unique features did we have in this tooth? Was it just one
or several attrition facets that were recognized by the wife? What was the
importance of the general shape and size of the crown?
Well, dear reader…personally I think that these last two cases
describes a great true that once have been stated by Ibsen, I think:
"A truth lasts utmost 20 years!"
There is always different ways to look upon the truth!
1. A. Wenzel, H. Heintze and P. Hoersted-Bindslev. Discrimination between
dental materials by their radiopacity measured in film radiographs and
digital images J Forensic Odontostomatol 1998; 16: 8-13.
2. C.J. Villiers and V.M. Phillips. Person identification by means of a single
unique dental feature. J Forensic Odontostomatol 1998; 16: 17-19.
