Atlas-based radiographic classification of mandibular molar root morphology for forensic dental identification.

BACKGROUND: Forensic dental identification relies on the comparison of antemortem (AM) and post-mortem (PM) records. In the absence of restorative features, identification depends on inherent anatomical structures, such as root morphology, for which no standardized descriptive framework exists. OBJECTIVES: To propose a structured, atlas-based radiographic classification of mandibular molar root morphology specifically designed for forensic dental identification, and to evaluate its reproducibility among observers with varying levels of forensic experience. METHODS: A radiographic classification comprising six morphological parameters was applied to 512 molars depicted in 22 panoramic radiographs. Sixteen observers (three forensic odontologists, 13 prosthodontic residents) independently classified all cases. Additional real forensic cases including 56 mandibular molars were evaluated by four forensic odontologists. Inter-observer agreement was assessed using average pairwise agreement, Fleiss' Kappa, and Gwet's AC1 coefficient. RESULTS: Inter-observer agreement ranged from 75% to 91% among experts and 77%-89% among residents. Gwet's AC1 demonstrated substantial to almost perfect agreement (0.62-0.88). Lower agreement was observed in third molars with atypical morphology. In the real forensic cases, inter-rater agreement was 89.1% (Gwet's AC1 = 0.878) and intra-rater agreement was 95.7% (Gwet's AC1 = 0.952). A pairwise AM-PM identification analysis correctly ranked the true match first in 71.4% of cases and within the top two candidates in 100% of cases. CONCLUSIONS: The proposed classification provides a reproducible and standardized framework for describing mandibular molar root morphology in a forensic context. Substantial inter-observer agreement across experience levels, supports its use in AM-PM radiographic comparison and potential future computational applications in automated forensic radiographic comparison.