Lessons learned from large-scale comparative dental analysis following the South Asian tsunami of 2004

The aim of this study was to examine the quality of the ante-(AM) and postmortem (PM) dental data that were submitted for entry into the PLASS data system in Phuket, Thailand, following the Boxing Day (December 26) Tsunami, 2004. The investigators were two forensic odontologists who were part of the New Zealand Disaster Victim Identification team that worked at Wat Yang Yao morgue and at the Information Management Center in Phuket. Our findings underline the usefulness of dental data in human identification, but point to a number of significant sources of error. Of the 78 PM records received, only 68% of radiographs and 49% of photos confirmed the accompanying dental charting. This underlines the value, particularly of photographs of the dental arches, in quality control. It also points to a large error component, which may have been due to inexperience of the operators, fatigue, poor conditions in the temporary morgue, or the problem of tooth-colored fillings. Of the 106 AM records received, 62% were of unacceptable quality and 64% were either not accompanied by radiographs or had poor quality radiographs. These results indicate that AM data collection ideally needs to be collated and checked by a forensically trained dentist(s) in the country of origin.     

Development of a Computer‐Assisted Forensic Radiographic Identification Method Using the Lateral Cervical and Lumbar Spine

Medical examiners and coroners (ME/C) in the United States hold statutory responsibility to identify deceased individuals who fall under their jurisdiction. The computer‐assisted decedent identification (CADI) project was designed to modify software used in diagnosis and treatment of spinal injuries into a mathematically validated tool for ME/C identification of fleshed decedents. CADI software analyzes the shapes of targeted vertebral bodies imaged in an array of standard radiographs and quantifies the likelihood that any two of the radiographs contain matching vertebral bodies. Six validation tests measured the repeatability, reliability, and sensitivity of the method, and the effects of age, sex, and number of radiographs in array composition. CADI returned a 92–100% success rate in identifying the true matching pair of vertebrae within arrays of five to 30 radiographs. Further development of CADI is expected to produce a novel identification method for use in ME/C offices that is reliable, timely, and cost‐effective.     

Morphometric Comparison of Clavicle Outlines from 3D Bone Scans and 2D Chest Radiographs: A Shortlisting Tool to Assist Radiographic Identification of Human Skeletons

This paper describes a computerized clavicle identification system primarily designed to resolve the identities of unaccounted‐for U.S. soldiers who fought in the Korean War. Elliptical Fourier analysis is used to quantify the clavicle outline shape from skeletons and postero‐anterior antemortem chest radiographs to rank individuals in terms of metric distance. Similar to leading fingerprint identification systems, shortlists of the top matching candidates are extracted for subsequent human visual assessment. Two independent tests of the computerized system using 17 field‐recovered skeletons and 409 chest radiographs demonstrate that true‐positive matches are captured within the top 5% of the sample 75% of the time. These results are outstanding given the eroded state of some field‐recovered skeletons and the faintness of the 1950's photofluorographs. These methods enhance the capability to resolve several hundred cold cases for which little circumstantial information exists and current DNA and dental record technologies cannot be applied.     

Root Morphology and Anatomical Patterns in Forensic Dental Identification: A Comparison of Computer‐Aided Identification with Traditional Forensic Dental Identification*

Abstract: An online forensic dental identification exercise was conducted involving 24 antemortem–postmortem (AM–PM) dental radiograph pairs from actual forensic identification cases. Images had been digitally cropped to remove coronal tooth structure and dental restorations. Volunteer forensic odontologists were passively recruited to compare the AM–PM dental radiographs online and conclude identification status using the guidelines for identification from the American Board of Forensic Odontology. The mean accuracy rate for identification was 86.0% (standard deviation 9.2%). The same radiograph pairs were compared using a digital imaging software algorithm, which generated a normalized coefficient of similarity for each pair. Twenty of the radiograph pairs generated a mean accuracy of 85.0%. Four of the pairs could not be used to generate a coefficient of similarity. Receiver operator curve and area under the curve statistical analysis confirmed good discrimination abilities of both methods (online exercise = 0.978; UT‐ID index = 0.923) and Spearman’s rank correlation coefficient analysis (0.683) indicated good correlation between the results of both methods. Computer‐aided dental identification allows for an objective comparison of AM–PM radiographs and can be a useful tool to support a forensic dental identification conclusion.     

The Reliability of Visually Comparing Small Frontal Sinuses*

Abstract: Several studies have investigated frontal sinus comparison for personal identification. One study addressed the statistical reliability of correct identification using automated digital methods and resulted in a 96% accuracy rate. Missed matches with the digital methods generally involved small, less featured sinuses. This study investigates the hypothesis that human examiners may be able to more accurately identify correct matches than digital methods, even when the comparisons involve small frontal sinuses. Participants were provided two sets of 28 radiographs and were instructed to identify matching radiographs and list the radiographs that did not have a corresponding match. Overall, error rates were low, with correct associations identified at a rate of 0.983. No incorrect associations (“false positives”) were made. Correct association rates were highest among participants “experienced” examining radiographs. Results support previous assertions that frontal sinus radiographs are a reliable means of personal identification even when the frontal sinuses are small.     

A Large‐Sample Test of a Semi‐Automated Clavicle Search Engine to Assist Skeletal Identification by Radiograph Comparison

In 2014, a morphometric capability to search chest radiograph databases by quantified clavicle shape was published to assist skeletal identification. Here, we extend the validation tests conducted by increasing the search universe 18‐fold, from 409 to 7361 individuals to determine whether there is any associated decrease in performance under these more challenging circumstances. The number of trials and analysts were also increased, respectively, from 17 to 30 skeletons, and two to four examiners. Elliptical Fourier analysis was conducted on clavicles from each skeleton by each analyst (shadowgrams trimmed from scratch in every instance) and compared to the search universe. Correctly matching individuals were found in shortlists of 10% of the sample 70% of the time. This rate is similar to, although slightly lower than, rates previously found for much smaller samples (80%). Accuracy and reliability are thereby maintained, even when the comparison system is challenged by much larger search universes.     

Radiographic comparison of a fractured clavicle exhibiting a pseudo-arthrosis

Bone remodeling is a natural process that is potentially problematic for radiographic comparisons because it can occur after antemortem (AM) imaging, thus interfering with the comparability of AM and postmortem (PM) radiographs from the same individual. While the effects of age-related remodeling have been studied, limited attention has been given to trauma-related remodeling with respect to radiographic comparisons. This report adds to the latter topic by presenting a case of AM clavicle fracture that developed into a pseudo-arthrosis over a 12-month period prior to the individual's death. Even though remodeling was discernable along the fracture margins, adjacent skeletal features on the PM radiograph remained unaltered and constituted compelling evidence for the identification. This case illustrates the potential of using both normal and pathological anatomy concurrently to maximize the surety of findings from radiographic comparisons.     

Development and Validation of a Virtual Examination Tool for Firearm Forensics, ,

The transition from 2D imaging to 3D scanning in the discipline of firearms and toolmark analysis is likely to provide examiners an unprecedented view of microscopic surface topography. The digital examination of measured 3D surface topographies has been referred to as virtual microscopy (VM). The approach offers several potential advantages over traditional comparison microscopy. Like any new analytic method, VM must be validated prior to its use in a crime laboratory. This paper describes one of the first validation studies of virtual microscopy. Fifty‐six participants at fifteen laboratories used virtual microscopic tools to complete two proficiency‐style tests for cartridge case identification. All participating trained examiners correctly reported 100% of the identifications (known matches) while reporting no false positives. The VM tools also allowed examiners to annotate compared surfaces. These annotations provide insight into the types of marked utilized in comparative analysis. Overall, the results of the study demonstrate that trained examiners can successfully use virtual microscopy to conduct firearms toolmark examination and support the use of the technology in the crime laboratory.     

Identification of the Edentulous Individual: An Investigation into the Accuracy of Radiographic Identifications*

Abstract: The dental identification of edentulous individuals can be challenging based on the lack of antemortem materials and unique features visible on radiographs. The constant resorption of the alveolar ridges further complicates the process. The purpose of this study was to quantify the error rate and reliability of dental identifications based on a comparison of synthesized antemortem and postmortem radiographs of edentulous individuals. Ten observers examined ten cases on two occasions and reported dichotomous and conclusion level decisions. These were analyzed using Kappa and Receiver Operator Characteristics. The mean area under the curve was 0.75 and the mean sensitivity was 0.57 and specificity was 0.83. These results suggest that dental identifications of edentulous individuals using radiographs alone have a high error rate and should be dual reported. These data add further weight to the argument that all dental prostheses should be labeled.     

Dental hygiene students' matching accuracy when comparing antemortem dental radiographs and oral photographs to simulated postmortem WinID3® odontograms

Matching dental antemortem (AM) and postmortem (PM) data for human identification is especially challenging when the workforce is limited. Dental hygienists have served mass fatality incidents (MFIs) due to dental-related expertise. However, forensics within dental hygiene education and research on transferable skills is limited. This qualitative balance design study assessed senior dental hygiene students' match accuracy of simulated cases varying in dental identifiers based on AM full mouth series (FMS) radiographs and oral photographs to PM WinID3^® odontograms to demonstrate possible disaster victim identification (DVI) transferable skills gained during formal education. A convenience sample of senior dental hygiene students (n = 31) was presented information on WinID3^® interpretation, then presented with 5 mismatched cases and asked to visually interpret each to make 10 total matches; five based on AM FMS with simulated PM WinID3^® odontograms and five based on AM photographs with PM WinID3^® odontograms. Match accuracy scores ranged from 41.9% to 58.1% for cases with 1–10 identifiers, and 77.4% to 93.5% for cases with 11–40 identifiers. Accuracy when matching AM radiographs to PM odontograms versus AM photographs to PM odontograms was compared and revealed no statistical differences in match accuracy depending on image type (p = 0.388 to 1.000). Results of this pilot study suggests transferable match accuracy skills resulted from the participants' dental hygiene formal education. These baseline skills with additional specialized training support the rationale for dental hygienists serving on DVI teams. More research is needed in education and practice when preparing dental hygienists for forensic-based service.     

Frontal sinus accuracy in identification as measured by false positives in kin groups

The aims of this study were to verify if frontal sinuses can uniquely identify individuals belonging to family groups using Cameriere methods and to test if kinship can affect the proportion of erroneous identifications. For this purpose, we compared the proportion of false-positive identifications in a sample of 99 individuals within 20 families with a control sample of 98 other individuals without kinship. The results show that the combined use of SOR and the Yoshino code number allows personal identification with a small probability of false positives (p < 10(-6)), even when kinship is taken into account. The present research confirms the importance of studying anthropological frameworks for identification, which leads to reliable methods and allows for both quick and economic procedures.     

Novices cannot fill the examiners’ shoes: Evidence of footwear examiners’ expertise in shoe comparisons

The value of a footwear examiner’s opinion centres on their ability to determine whether a particular shoe made an impression with greater accuracy than a novice. However, there has been limited research on the expertise of footwear examiners and the accuracy and reproducibility of their decisions. In the current study, we measured the accuracy and consensus of 31 footwear examiners versus a comparison group of 29 novices. Participants completed 20 ground truth known mock shoe comparisons. Results demonstrated that footwear examiners were more accurate than novices, regardless of comparison difficulty. Overall, on trials where probative decisions were given, examiners made false identifications and false exclusions on a total of 3% and 2% of trials, while novices made false identifications and false exclusions on a total of 19% and 17% of trials. Examiners also demonstrated better consensus in their opinions than novices, although both groups demonstrated low levels of agreement in their responses and variability in their interpretation of the conclusion scale. In summary, these findings support the proposition that footwear examiners show expert-level performance in matching known and unknown footwear impressions. These performance estimates may help the criminal justice system to appropriately value footwear examination evidence.     

Computer‐aided Dental Identification: An Objective Method for Assessment of Radiographic Image Similarity*

Abstract: A pilot study evaluated a computer‐based method for comparing digital dental images, utilizing a registration algorithm to correct for variations in projection geometry between images prior to a subtraction analysis. A numerical assessment of similarity was generated for pairs of images. Using well‐controlled laboratory settings, the method was evaluated as to its ability to identify the correct specimen with positive results. A subsequent clinical study examined longitudinal radiographic examinations of selected anatomical areas on 47 patients, analyzing the computer‐based method in making the correct identification based upon a threshold level of similarity. The results showed that at a threshold of 0.855, there were two false negative and two false positive identifications out of 957 analyses. Based on these initial findings, 25 dental records having two sets of full mouth series of radiographs were selected. The radiographs were digitized and grouped into six anatomical regions. The more recent set of films served as postmortem images. Each postmortem image was analyzed against all other images within the region. Images were registered to correct for differences in projection geometry prior to analysis. An area of interest was selected to assess image similarity. Analysis of variance was used to determine that there was a significant difference between images from the same individual and those from different individuals. Results showed that the threshold level of concordance will vary with the anatomical region of the mouth examined. This method may provide the most objective and reliable method for postmortem dental identification using intra‐oral images.     

Microscopical discrimination of human head hairs sharing a mitochondrial haplogroup

In forensic analyses, determining the level of consensus among examiners for hair comparison conclusions and ancestry identifications is important for assessing the scientific validity of microscopical hair examinations. Here, we present data from an interlaboratory study on the accuracy of microscopical hair comparisons among a subset of experienced hair examiners currently analyzing hair in forensic laboratories across the United States. We examined how well microscopical analysis of hair can reliably be used to differentiate hair samples, many of which were macroscopically similar. Using cut hair samples, many sharing similar macroscopic and microscopic features, collected from individuals who share the same mitochondrial haplogroup as an indication of genetic relatedness, we tested multiple aspects that could impact hair comparisons. This research tested the extent to which morphological features related to ancestry and hair length influence conclusions. Microscopical hair examinations yielded accurate assessments of inclusion/exclusion relative to the reference samples among 85% of the pairwise comparisons. We found shorter hairs had reduced levels of accuracy and hairs from populations examiners were not familiar with may have impacted their ability to resolve features. The reliability of ancestry determinations is not yet clear, but we found indications that the existing categories are only somewhat related to current ethnic and genetic variation. Our results provide support for the continued utility of microscopical comparison of hairs within forensic laboratories and to advocate for a combined analytical approach using both microscopical analysis and mtDNA data on all forensic analyses of hair.     

The reliability of digitized radiographs for dental identification: a Web-based study

In the era of Daubert and other judicial rulings pertaining to the acceptability of forensic evidence, it is increasingly important that experts are able to testify that their methods have been scientifically tested and that error rates and other factors relating to reliability have been published. The purpose of this study was to determine the reliability of digitized radiographic comparisons for the purposes of dental identification. Participants with various forensic backgrounds and experience levels were passively recruited to the website. Ten forensic identification cases composed of antemortem and postmortem dental radiographs were supplied to examiners using a bespoke website. Participants responded to the cases on two occasions after a one-month washout interval using the ABFO conclusion levels for forensic identifications. A total of 115 first attempts and 87 matched second attempts were received. Of the total responses, 72% were dentally trained respondents who had completed at least one forensic identification case; of these, 38% were experienced forensic dentists who had completed more than 25 identifications. Data relating to accuracy, intra- and inter-examiner agreement, and the effect of case difficulty are presented. Mean accuracy was 85.5% for all cases, with the experienced forensic dentists obtaining a 91% success rate. The inter-examiner agreement on the negative identification cases was classified as poor. The data suggest that dental identifications resulting from the comparison of postmortem and antemortem radiographs are valid, accurate, and reliable when undertaken by experienced odontologists.     

A Radiographic Study on the Utility of Cranial Vault Outlines for Positive Identifications

A standard method for positive identification is the use of antemortem and postmortem radiographic comparisons. The purpose of this research is to test the visual accuracy of antemortem and postmortem radiographic comparisons of cranial vault outlines and to evaluate their uniqueness using geometric morphometric methods. A sample of 106 individuals with varying levels of education and forensic case experience participated in a visual accuracy test. Of the 106 individuals, only 42% correctly assigned all of the radiographs, with accuracy rates ranging from 70 to 93% for each radiographic comparison. Vault shape was further examined using elliptic Fourier analysis, and paired t‐tests were computed on the first 10 principal components accounting for 100% of the variance, which found no significant differences. The visual accuracy test and elliptic Fourier analysis shows that vault outlines may not be unique enough for positive identifications when used as a sole indicator.     

A post-processing technique for cranial CT image identification

Objective: A major challenge in radiographic identification is the inconsistent orientation between clinical (ante-mortem, AM) and post-mortem (PM) radiographs. The objectivity and accuracy of radiological identification would be greatly enhanced by post-processing techniques that allow quantitative comparison of PM CT data in the same orientation as the AM CT data. Methods: We applied a post-processing technique to reposition a multislice computed tomography (MSCT) scan for spatial registration with a CT radiograph from the same patient. A second set of MSCT images from different individuals served as the non-matched control group. The consistency in radiographic positioning eliminated subjectivity in the comparison and identification process because the radiograph superposition provided objective evidence that confirmed the identification with fine detail. Results: A quantitative comparison with statistical validation was achieved by measuring a set of 14 landmarks from the images. Discrimination of identity based on logistic regression analysis of the earlier CT patient scans (the AM group) versus subsequent MSCT scans (the PM group) was objective and reliable. Conclusion: This quantitative comparison depends less on subjective judgment and the experience of the examiner, and so may meet legal standards.     

Clinically Detectable Dental Identifiers Observed in Intra‐oral Photographs and Extra‐oral Radiographs,Validated for Human Identification Purposes

Screening the prevalence and pattern of dental identifiers contributes toward the process of human identification. This research investigated the uniqueness of clinical dental identifiers in photographs and radiographs. Panoramic and lateral cephalometric radiographs and five intra‐oral photographs of 1727 subjects were used. In a target set, two observers examined different subjects. In a subset, both observers examined the same subjects (source set). The distance between source and target subjects was quantified for each identifier. The percentage of subjects in the target set being at least as close as the correct subject was assessed. The number of molars (34.6%), missing teeth (42%), and displaced teeth (59.9%) were the most unique identifiers in photographs and panoramic and lateral cephalometric radiographs, respectively. The pattern of rotated teeth (14.9%) was the most unique in photographs, while displaced teeth was in panoramic (37.6%) and lateral cephalometric (54.8%) radiographs. Morphological identifiers were the most unique, highlighting their importance for human identifications.     

Metacarpal sexual determination in a Spanish population

Anthropologists and forensic pathologist determine the sex of skeletons by analyzing quantitative and qualitative characters in the bone remains. Generally, the skull and os coxae are the elements most used, but they are not always preserved. In such cases, the investigator needs to have available other techniques based on different remains. The aim of the present work is to develop and describe discriminating functions for sex determination in a recent Spanish population using metacarpal morphology. A sample of bones corresponding to a contemporary Spanish population deposited at the Complutense University of Madrid (UCM) was analyzed. This sample comprised 697 metacarpals, corresponding to 79 adult individuals (37 men and 42 women). These allowed us to obtain 120 unifactorial discriminant functions. We selected the 10 equations, one for each metacarpal from both hands, that provided the best sexual discrimination. The correct sex classification rank progressed from 81%, for right (R) metacarpals IV and V, to 91%, for left (L) metacarpal II. The results suggest that metacarpals are structures that can be used for sex determination in paleoanthropological and forensic identifications.     

A Retrospective Review of Forensic Odontology Reports Written by the Joint POW/MIA Accounting Command Central Identification Laboratory for Remains Identified from the Korean War

As of August 2014, the Joint POW/MIA Accounting Command has identified the remains of 1980 previously unknown U.S. service members; 280 were from the Korean War. To determine the accuracy and completeness of the available antemortem (AM) dental records, a review of the AM/postmortem (AM/PM) dental record comparisons from 233 Forensic Odontology Reports written in support of remains identified from the Korean War was performed. Seventy‐two AM/PM comparisons resulted in exact dental chartings while 161 contained discrepancies which were explainable. Explainable discrepancies include undocumented treatment (103), incorrectly charted third molars as missing (82), differing opinions of specific molars present/missing (20), and erroneous treatment documentation and/or misidentification of teeth present/missing (22, other than molars). Reassessment has revealed varying levels of completeness for our available AM dental records, the need to thoroughly review our computerized comparisons, adjust our comparisons to include molar pattern variations/third molars, and updating our database comparison program.