Forensic dental identification 177
procedures that have been established for mitochondrial DNA comparisons .”^19
Two databases have been created: one reflects a U.S. military population for
which the data were collected from 1994 to 2000 and the other a U.S. civilian
population, data collected from 1998 to 2004. When searching this database
for a particular combination of dental characteristics, the user can select one
or both of the databases for comparison. The OdontoSearch online program
uses the universal numbering system and does not consider the third molars.
These databases and search protocols consider twenty-eight adult teeth only
and do not consider any teeth distal to the second molars. Searches can be
performed by selection of one or both of the databases and entering a combi-
nation of desired dental information for the twenty-eight teeth. In a detailed
search this information can include any combination of restored surfaces of
M, D, F, and L for anterior restorations; M, O, D, F, and L for posterior restored
teeth; MDFL and MODFL, respectively, for anterior and posterior crowns;
and X for missing and V for unrestored or virgin teeth. If a generic search is
desired, R is selected for a tooth that has any type of restoration instead of
using the specific surfaces. The trial entry of data in these fields produces for
the user a probability of the specific combination of coding existing in the
given database. To apply the technique, the strength of a match is considered
a function of the frequency in which the given dental pattern is observed in
the reference database(s):
X
N+
+⋅1
1100 , where X is the total number of patternmatches and N is the sample size of the data set(s). If no matches are found,
X = 0, and the observed pattern is unique within the database. Since the
pattern in question is known to exist in at least one person (the case indi-
vidual), the number of matches (X) and the sample size (N) are increased by
one. Inverting this frequency gives the likelihood ratio of identification. By
utilizing this empirically derived probability value, matches can be quanti-
fied in a manner that is easily defensible in a court of law.^17
9.6 ABFO Guidelines and Standards
In 1994, the American Board of Forensic Odontology established guidelines
and standards for dental identification. These guidelines have been published
in the Journal of the American Dental Association and are available online at
the ABFO website.20,21 The guidelines offer the specific and detailed informa-
tion outlined below:
I. Collection and preservation of postmortem dental evidence
A. The remains—examination procedures
B. Photography