Search

Abstract In forensic commingled contexts, when the disarticulation occurs uniquely at the atlantoaxial joint, the correct match of atlas and axis may lead to the desirable assembly of the entire body. Notwithstanding the importance of this joint in such scenarios, no study has so far explored three-dimensional (3D) methodologies to match these two adjoining bones. In the present study, we investigated the potential of re-associating atlas and axis through 3D–3D superimposition by testing their articular surfaces congruency in terms of point-to-point distance (Root Mean Square, RMS). We analysed vertebrae either from the same individual (match) and from different individuals (mismatch). The RMS distance values were assessed for both groups (matches and mismatches) and a threshold value was determined to discriminate matches with a sensitivity of 100%. The atlas and the corresponding axis from 41 documented skeletons (18 males and 23 females), in addition to unpaired elements (the atlas or the axis) from 5 individuals, were superimposed, resulting in 41 matches and 1851 mismatches (joining and non-joining elements). No sex-related significant differences were found in matches and mismatches (p = 0.270 and p = 0.210, respectively), allowing to pool together the two sexes in each group. RMS values ranged between 0.41 to 0.77 mm for matches and between 0.37 and 2.18 mm for mismatches. Significant differences were found comparing the two groups (p

Abstract Forensic anthropologists dealing with personal identification (PI) of human remains have recently stressed the need to explore the potential of “secondary identifiers” for identifying victims who died in particular events for whom images often represent the main antemortem data available. Being the face the part most exposed in images, characteristics as pigmented skin lesions (PSLs), can be crucial if combined with other input. Since no data is available on frequencies and distribution of facial PSLs in the general population, this study aims at systematically collecting such data to verify their potential in PI and to open a debate on the aid that “secondary identifiers”, regardless of their specific nature, can give to the identification of the deceased in specific forensic contexts. A retrospective analysis on three-dimensional facial models of 1039 Italian subjects (from 4 to 84 years old) was conducted to examine the incidence of PSLs discriminated according to size and position in well-defined facial areas. From the collected data we developed a probabilistic approach providing the likelihood ratio (LR) for two settings: (1) the relative frequencies of nevi in the various facial areas, providing the deriving compound probability of owning a certain facial PSLs pattern; and (2) codes describing the facial nevi pattern of each individual of our population, thus testing their uniqueness and so their potential in PI. The calculated LRs mostly proved high identifying strength, particularly when provided by the compound probability-based approach. Data on incidence and position of facial nevi, their generated codes, and the probabilistic approach here presented, all constitute a starting point for advancing secondary identifiers. Nonetheless, although this preliminary study proved facial PSLs as valuable and potentially useful for identification, their significance and validity should be interpreted with caution as we are still at the first theoretical step clearly based on ideal conditions, and thus further investigations are due on the limitations of their use in practical identifying settings. Therefore, being this systematic study only a preliminary one in its nature, it is recommended not to use this kind of approach until further studies will test its validity in several practical conditions.

Reference data on the asymmetry of facial thirds of children is still scarce, although it can offer meaningful comparative information for clinical studies. This study aims to provide reference data on the facial asymmetry of Italian children using a 3D analysis of facial thirds divided according to the trigeminal nerve distribution (upper, middle, and lower). A 3D surface-based approach was conducted on the digital models of the faces of 135 children (74 M, 61 F), acquired by stereophotogrammetry. In addition to sex, two different age classes were analyzed (4–8 years and 9–12 years). For each facial third, the asymmetry was expressed as root-mean-square distance (RMS) by calculating the point-to-point distances between the original and the reflected 3D models. A 3-way ANOVA test verified significant differences between the two sexes, the two age classes, and the three facial thirds (p-value < 0.05), and also their interaction. Significant differences were found between the sexes (females were more symmetric, p = 0.005) and the two age groups (younger were more symmetric p < 0.001). According to Tukey’s HSD post-hoc test, among the thirds, the middle one proved to be significantly more symmetrical (p < 0.001). No significant interaction impacting the asymmetry was found when the main factors were considered in any combination. Reference data on the “normal” facial asymmetry of Italian children was provided for further clinical purposes. Normal children have low average RMS values (0.30–0.51 mm) and younger, in particular females, proved more symmetrical than older children, while among the facial surfaces, the middle proved most symmetrical in both sexes, although with little clinical relevance. Since there is no consensus on the amount of symmetry deemed clinically acceptable, further studies on larger randomized samples are auspicial.