Dental Identification: Antemortem to Postmortem Comparison

A dental identification case always runs along two parallel tracks. On one track is the antemortem record: everything that was documented about the person's teeth while they were alive. On the other is the postmortem examination: what the forensic odontologist finds when they examine the remains. The comparison is the moment these two tracks are laid side by side.

Both tracks need to be complete before the comparison is meaningful. An AM record with a single periapical radiograph of one quadrant and a PM examination that documents twelve teeth will produce conclusions only about that narrow overlap. A full-mouth series from a thorough family dentist, compared against a complete PM chart and full-mouth radiographs, gives the analyst much more to work with.

The odontologist examining the AM record is reading another practitioner's work, often recorded with different charting conventions, abbreviations, or symbols. The examiner must translate that work into a standardised chart before comparison begins. This translation step is where many ambiguities enter the process, and it deserves its own attention, covered in the next topic on obtaining AM records.

The postmortem dental examination must be systematic and complete, because whatever is missed now cannot be recovered later. The odontologist works tooth by tooth using a standardised notation system, recording restorations, their surfaces and materials, missing teeth, root morphology where visible on radiographs, anomalies of number or position, and the condition of any prosthetics.

• Notation systems: the FDI (Fédération Dentaire Internationale) two-digit system is the international standard (ISO 3950), but the Universal (ADA) numbering system is common in North American casework, and the Palmer notation persists in parts of Europe and South Asia. The odontologist must be fluent in all three and note which one they used.
• Restorations: each restoration is recorded by tooth, surface (mesial, distal, occlusal, buccal, lingual), and material (amalgam, composite, gold, ceramic, glass ionomer). Surface codes vary by notation system; consistent use prevents misinterpretation.
• Missing teeth: a missing tooth in a PM chart can mean extraction before death, avulsion during the incident, loss during decomposition, or a congenitally absent tooth. The odontologist notes whether an alveolar socket is present and what stage of healing it shows, which distinguishes antemortem from perimortem extraction.
• Unique features: supernumerary teeth, rotations, taurodontism, dens invaginatus, root dilaceration, and unusual crown morphology all carry high identification value because they are rare and distinctive.

With both charts in hand, the odontologist goes through the dentition systematically, tooth by tooth and surface by surface, identifying features that match and features that differ. This is concordance analysis, and it is the analytical core of dental identification.

Not all concordances are equal. A single restored molar is a concordance, but it is one shared by a significant fraction of any adult population. A full-mouth series with seven specific multi-surface restorations, an extracted lower-left second premolar, and a porcelain crown on an upper first molar with a particular porcelain-to-metal margin position is a concordance that is vanishingly unlikely to repeat in a second person. The more unique and numerous the matching features, the stronger the identification support.

Some jurisdictions and professional bodies have proposed minimum feature thresholds for positive identification, but there is no universal fixed number. The American Board of Forensic Odontology (ABFO) guidelines acknowledge that two unusual and uniquely matching features can support a positive identification, whereas ten common matching features in an otherwise undocumented dentition may not. Uniqueness, not quantity alone, drives the conclusion.

The presence of a discordant feature, something in the PM findings that does not match the AM record, does not automatically exclude an identification. The odontologist must first ask whether the discordance has a plausible explanation before treating it as a genuine mismatch.

• New dental work: if the AM record is five years old, several new restorations or an extraction may have occurred since the last dental visit. PM evidence of a restoration where the AM chart showed an intact tooth is consistent with identification as long as it is explainable by the passage of time.
• Postmortem damage: fire, trauma, and advanced decomposition can fracture crowns, displace teeth, and alter restorations. A discordance arising from heat fracture or impact is not the same as a biological difference.
• Charting errors in the AM record: a transposition error in the AM chart (noting a restoration on the wrong surface or the wrong tooth number) is common. If a discordance can be explained by a plausible charting convention mismatch, it does not exclude the identification, but it should be noted.
• Unexplained discordance: if a PM tooth shows a root morphology or a developmental anomaly that is absent from the AM radiographs and cannot be attributed to subsequent treatment or damage, the discordance is genuine. A single unexplained discordance is sufficient to trigger exclusion.

The ABFO and most international forensic odontology bodies recognise four conclusion categories for dental identification. These are not arbitrary; they map directly onto the logical states of the evidence and carry legal consequences when the identification is used in death certification, criminal prosecution, or disaster victim management.

1. Positive identification
   The AM and PM data match in sufficient detail to conclude that the remains are those of the named individual, to the exclusion of all others. No unexplained discordances exist. This is the standard required for official identification in most legal and administrative systems.
2. Possible identification
   The available data are consistent with the proposed identity but are insufficient to reach positive identification. This may be because there is too little data (few teeth, limited AM records), or because the matching features are common rather than distinctive. The odontologist reports what is consistent without overclaiming.
3. Insufficient evidence
   The available data are so limited that no meaningful conclusion can be reached in either direction. This may arise from severely fragmented remains, minimal AM records, or a dentition with no restorations and no distinctive features to compare. Additional records or specialist techniques may resolve the case later.
4. Exclusion
   The AM and PM data are sufficiently different that the remains cannot be those of the proposed individual. A single unexplained, unrepairable discordance is grounds for exclusion. This conclusion is protective: it prevents misidentification and directs the investigation to the correct identity.

Most professional standards bodies for forensic odontology, including the ABFO and the British Association of Forensic Odontology (BAFO), recommend that identifications be reviewed by a second qualified odontologist before they are finalised. This is not distrust of the primary examiner. It reflects the reality that ambiguous charting, unusual notation systems, and high-stakes pressure can produce errors that a fresh reading catches easily.

At major mass casualty incidents, quality-control teams work alongside primary examiners. Each positive identification is checked by a second odontologist working independently. Where the two examiners reach different conclusions, the case is escalated to a third reviewer and the disagreement is documented. This peer-review structure is also increasingly required in single-body cases in many jurisdictions before a formal identification is transmitted to the coroner or registrar.