Dental identification of unknown human remains will often become part of a legal proceeding and therefore must be handled in such a way that the identification can be proven and historically preserved. This is done using methodology that will protect the identification by following what is called the legal chain of custody. It is not uncommon for the legal proceeding associated with the identification to occur long after the actual identification, many times several years or more. Therefore, accurate and well-preserved records are required.
The identification process is divided into three processes which include the production of the AM and PM dental records, followed by a report of the results of the comparison of these records. Each part of the entire process is created independently of the others and should follow a standard protocol so that each and every case is done the same way.
The first part of the protocol is to create the PM dental record. The PM record will include photographs and PM radiographs of the dental remains. This will often necessitate gaining access to the oral cavity so that the dental structures can be cleaned, examined, viewed, imaged and finally charted. A complete and accurate PM dental record will include notations of all of the dental evidence recovered. Occasionally it may be necessary to take intraoral impressions in order to capture palatal rugae or unusual dental anomalies that may become helpful in the identification. Once all of the PM data has been collected, it is transferred to a PM dental chart (Figure 13b).
The second part of the process involves the creation of the AM dental record. Law enforcement or representatives of the medical examiner’s or coroner’s office will work to obtain the AM dental record, if one exists! This is usually done by following leads on persons reported to be missing or associated with the scene where the death occurred (i.e., a fiery automobile accident with human remains inside the car). Once the AM dental record has been secured the task of deciphering the information contained in the record begins. This process can be especially difficult if the dental record is in a foreign language, or a handwritten record versus a digital dental record. A log of the contents of the AM record is created and attached to the final report in order to document all information used in the creation of the AM record (Figure 13a).
The entire dental record is reviewed in chronological order to understand its complete content and to guide the creation of the AM dental chart. It is important to note changes in teeth that may not correspond with the chart’s radiographs. An example of an “explainable discrepancy” would be a bitewing radiograph showing a virgin tooth on the date of the radiograph followed by a chart entry on a later date, indicating that a restoration had been placed in the tooth. If the AM dental record contains film-based dental radiographs, their proper locations and orientation must be known before using the films to chart that portion of the AM dental record.
Once the AM and PM dental charts have been created, they are placed side-by-side for comparison. Most forensic dental identification AM and PM dental charting systems are designed to be mirror images of each other. This facilitates laying them side-by-side for comparison (Figures 13a and 13b). The comparison is completed primarily by identifying restorations charted as completed in teeth and fabrication of prosthetic appliances (Figures 14 and 15). Similarly, the AM radiographs (if any exist) and the PM radiographs are also compared side-by-side for similarities in nasal sinus outline, radicular bone patterns, pulp stones, dilacerated root anatomy, dental implants, etc. (Figures 2a and 2b). All concordant matches are charted on the comparison form and an opinion is formed regarding the identification.
Using the terminology of the American Board of Forensic Odontology, the four conclusions of the comparison are:
The conclusion “possible identification” is typically used in a situation wherein no AM radiographs are immediately available, or their retrieval is delayed. In such instances, reviewing the procedural chart entries produces no unexplainable discrepancies and several concordant points of treatment to PM features, but nothing unique enough to positively make the identification (Figures 16a and 16b).
Any unexplainable discrepancy between the AM dental record and PM remains precludes a positive identification. Explainable discrepancies have been discussed. However, an unexplainable discrepancy such as an antemortem tooth with a restoration and the same postmortem tooth without a restoration is impossible. Like it or not, the technology to remove a filling in a living person and subsequently have re-growth of dentin and enamel in adult erupted teeth has yet to be discovered.
Once all of the AM and PM records have been charted, compared and the opinion established, a final report is prepared. The report can be as simple as including copies of the AM, PM and comparison charts, or an extensive report that details the entire case, containing dental records, radiographs and photographic images and explanations of the entire comparison process. The type of report and extent of details can be directed by the agency needing the report. Copies of all the collected dental evidence (exclusive of the human remains!) should be retained so that they are available if subpoenaed in a future legal proceeding that requires proof of the identification.