Virtual Tool Mark Generation for Efficient Striation Analysis,

This study introduces a tool mark analysis approach based upon 3D scans of screwdriver tip and marked plate surfaces at the micrometer scale from an optical microscope. An open‐source 3D graphics software package is utilized to simulate the marking process as the projection of the tip's geometry in the direction of tool travel. The edge of this projection becomes a virtual tool mark that is compared to cross‐sections of the marked plate geometry using the statistical likelihood algorithm introduced by Chumbley et al. In a study with both sides of six screwdriver tips and 34 corresponding marks, the method distinguished known matches from known nonmatches with zero false‐positive matches and two false‐negative matches. For matches, it could predict the correct marking angle within ±5–10°. Individual comparisons could be made in seconds on a desktop computer, suggesting that the method could save time for examiners.     

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.     

Personal Identification by Morphometric Analyses of Intra‐Oral Radiographs of Unrestored Teeth*

Abstract: The aim of this study was to work out a biometric method for personal identification by comparing simulated antemortem and postmortem digital radiographs of unrestored teeth. Intra‐oral radiographs of the inferior right first molar, without restorations, were acquired at two different times in 70 subjects using a standardized technique followed by a morphometric analysis. The program automatically supplied values of the absolute distances, relative distances, shape factors, moments, perimeter values, and the areas of the triangles, which were obtained by joining key reference points. The values for the homologous samples were compared with the heterologous samples. Statistical analysis was then carried out, resulting in a section point value of 0.9992. Higher correlation coefficients indicate positive identification, with less than 2% risk of false positives, and approximately 3% of false negatives. We have also tested the method on dental records from 30 patients in order to demonstrate the specificity and sensitivity of the system.     

Dental CT imaging as a screening tool for dental profiling: advantages and limitations

The use of dental processing software for computed tomography (CT) data (Dentascan) is described on postmortem (pm) CT data for the purpose of pm identification. The software allows reconstructing reformatted images comparable to conventional panoramic dental radiographs by defining a curved reconstruction line along the teeth on oblique images. Three corpses that have been scanned within the virtopsy project were used to test the software for the purpose of dental identification. In every case, dental panoramic images could be reconstructed and compared to antemortem radiographs. The images showed the basic component of teeth (enamel, dentin, and pulp), the anatomic structure of the alveolar bone, missing or unerupted teeth as well as restorations of the teeth that could be used for identification. When streak artifacts due to metal-containing dental work reduced image quality, it was still necessary to perform pm conventional radiographs for comparison of the detailed shape of the restoration. Dental identification or a dental profiling seems to become possible in a noninvasive manner using the Dentascan software.     

Positive Dental Identification Using Tooth Anatomy and Digital Superimposition

Dental identification of unknown human remains continues to be a relevant and reliable adjunct to forensic investigations. The advent of genomic and mitochondrial DNA procedures has not displaced the practical use of dental and related osseous structures remaining after destructive incidents that can render human remains unrecognizable, severely burned, and fragmented. The ability to conclusively identify victims of accident and homicide is based on the availability of antemortem records containing substantial and unambiguous proof of dental and related osseous characteristics. This case report documents the use of digital comparative analysis of antemortem dental models and postmortem dentition, to determine a dental identification. Images of dental models were digitally analyzed using Adobe Photoshop^TM software. Individual tooth anatomy was compared between the antemortem and postmortem images. Digital superimposition techniques were also used for the comparison. With the absence of antemortem radiographs, this method proved useful to reach a positive identification in this case.     

Forensic dental training in the dental school curriculum

This article reviews the literature regarding forensic education in the dental school curriculum and describes an exercise in forensic identification of victims of a mass casualty. Radiographs were made of dentate human cadavers in the gross anatomy laboratory at the Southern Illinois School of Dental Medicine. The jaws were then removed to provide "wet specimens" for the exercise. Several restorations were performed on the cadaver teeth, after which radiographs of the dissected jaws were made. One author wrote up mock dental records for each of the victims. These records included the first set or "premortem" radiographs. Students participating in the exercise were provided with a plane crash scenario, the dental records of the passengers on the manifest, the dissected jaws, and the second set or "postmortem" radiographs. Students were expected to form three teams. The first two teams evaluated the ante-mortem and postmortem dental records. The third team compared the ante-mortem and postmortem records to arrive at identification. The purpose of the exercise was twofold. It introduced dental students to forensic dentistry and emphasized the need for complete and accurate record keeping in the dental office. Several factors lessened the realism of the exercise and made it difficult to reproduce in the future. These included the uniformity of the dental records and the destruction of cadaver material following the exercise.     

Postmortem dental radiography

Comparison of postmortem and antemortem dental radiographic films or digital images is a common procedure for establishing identity of human remains. This article describes some problems with producing postmortem dental radiographs in a medical examiner setting and gives methods for circumventing these difficulties. Resection of the jaws, when permitted, significantly simplifies the postmortem radiographic technique. When producing an actual postmortem panoramic dental radiograph (orthopantomogram) from a dry skull, stabilization of the specimen for exposure by the moving beam source may be accomplished simply by placing the specimen upside down on an anthropologist's skull ring. Image "burnout" in the anterior segment, which results from absence of the tissues of the neck, may be avoided by appropriate placement of radiodense objects such as "zippered" plastic bags filled with water or other fluid material, freezer gel packs, or a block of self-polymerizing acrylic. These methods may increase future postmortem dental radiography efficiency.     

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.     

Probabilistic Classification of Age by Third Molar Development: The Use of Soft Evidence

Abstract: This study introduces a method to classify individuals according to an age threshold, given sex and third molars’ dental maturity measured on the Demirjian scale by expressing uncertainty on dental evidence (soft evidence). We introduced a procedure to learn the parameters of the Naïve Bayes model, and we discussed two classification rules. The model was estimated and tested on 559 Italians aged 16–22. Two experts provided the dental evaluations, and the model was estimated for each of them. We evaluated the coherence of the evidence provided by the experts. Some indexes have been proposed to evaluate the effectiveness of the models, emphasizing how the experts’ ability and the technology affect the results. We introduced two benchmarks, one based on the sample distribution per sex and age: in this case, probability of correct classification increases 22% and the proportion of false adults impressively decreases 80.2%; the other benchmark, obtained by simulating hard evidence, shows how the use of soft evidence increases the proportion of correct classification 3.1% and decreases the crucial proportion of false adults about 20%. Similarly, the proportion of false minors decreases about 5.3%.     

Anthropological and radiographic comparison of vertebrae for identification of decomposed human remains

This case study demonstrates the importance of involving an anthropologist in forensic situations with decomposed remains. Anthropological consultation was used in conjunction with the comparison of antemortem and postmortem radiographs to establish positive identification of unknown, decomposed remains. The remains had no traditional identifying features such as fingerprints or dental. Through anthropological analysis, it was determined the decedent was male, between 20 and 23 years at time of death and c. 5'2' tall. This information allowed for a presumptive identification and a request for antemortem radiographs. The missing person was identified comparing the spinous processes of the cervical and thoracic vertebrae between ante- and postmortem radiographs.     

Role of orthopedic implants and bone morphology in the identification of human remains

When conventional methods of identification, such as visual recognition and dental comparison, cannot be used to identify a deceased person, it becomes necessary to consider alternative methods. The presence of an orthopedic implant in a body may assist identification if ante-mortem medical records are available for comparison. Another method of identification involves comparison of ante-mortem and postmortem radiographs. Eight cases are reported from Forensic Science SA where the presence of orthopedic implants and/or ante-mortem radiographs were used to try to establish identification. In six cases, positive identification was established, and in two cases with upper limb orthopedic implants, the bones remained unidentified. Manufacturers were unable to provide any information about the distribution and use of the implants that could be of use with identification, as there are no requirements in Australia for individual medical implants to be tracked. Such a system has the potential to aid postmortem identification if serial codes were etched onto implants that could then be traced to manufacturers, surgeons, and recipients of these devices.     

Skeletal identification by radiographic comparison: blind tests of a morphoscopic method using antemortem chest radiographs

This study investigated the value of antemortem (AM) and postmortem (PM) radiographs of the claviculae and C3-T4 vertebrae to identify skeletons of missing U.S. soldiers from past military operations. In total, 12 field-recovered skeletons and AM chest radiographs of 1460 individuals were used. For each skeleton, examiners analyzed an array of AM chest radiographs (up to 1000 individuals) and attempted to identify the correct PM/AM radiographic match. When examiners were able to compare all images within a single test, only true-positive identifications were made. When AM radiographs were presented one-at-a-time, in sequential order, and without examiners having knowledge of array size, erroneous identifications resulted but they were almost exclusively made by untrained examiners (accuracy = 35% vs. 90% for trained examiners). This study demonstrates the value of chest radiographs for the identification of disarticulated and even eroded skeletons, but only when methods are wielded by trained examiners.     

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.     

Measurement of Postmortem Pupil Size: A New Method with Excellent Reliability and Its Application to Pupil Changes in the Early Postmortem Period

Measurement of postmortem pupil width is a potential component of death time estimation. However, no standardized measurement method has been described. We analyzed a total of 71 digital images for pupil–iris ratio using the software ImageJ. Images were analyzed three times by four different examiners. In addition, serial images from 10 cases were taken between 2 and 50 h postmortem to detect spontaneous pupil changes. Intra‐ and inter‐rater reliability of the method was excellent (ICC > 0.95). The method is observer independent and yields consistent results, and images can be digitally stored and re‐evaluated. The method seems highly eligible for forensic and scientific purposes. While statistical analysis of spontaneous pupil changes revealed a significant polynomial of quartic degree for postmortem time (p = 0.001), an obvious pattern was not detected. These results do not indicate suitability of spontaneous pupil changes for forensic death time estimation, as formerly suggested.     

Using PMCT of Individuals of Known Age to Test the Suchey–Brooks Method of Aging in Victoria,Australia

The estimation of an individual's age at death plays a critical role in the investigation of unidentified human remains. The Suchey–Brooks method, which involves the analysis of degenerative morphological changes in the pubic symphysis, is currently widely used to estimate age in adults. This study tested the applicability of the Suchey–Brooks method on a contemporary adult Australian (Victorian) subpopulation by observing three‐dimensional volume‐rendered postmortem computed tomographic (PMCT) reconstructions of the pubic symphysis of 204 individuals aged 15–100 years. Results showed the method was reliable for females (85% correct allocations) but not for males (67% correct allocations). It is therefore recommended that extreme caution be used when applying the Suchey–Brooks method for estimating age at death of an individual in this subpopulation from PMCT images. The results suggest further investigation into alternate age estimation methods is required.     

A Test of Age Estimation Methods on Impacted Third Molars in Males

This study tests the relationship between third molar impaction and its concomitant effect on age estimation methods. Data were collected on radiographs of males analyzed in the Defense POW/MIA Accounting Agency Laboratory (n = 114). Radiographs of skeletonized individuals were scored for dental development, and age was assigned based on the appropriate ancestry‐based method. Differences between identified age and estimated dental age were assessed to determine whether molar impaction affected root development and age estimations. Results indicate that impacted teeth tend to be underdeveloped and result in age estimates that are too low. While these results are of note to anthropologists and odontologists performing dental age estimates, more work is needed to explore the effect of impaction on development among a more diverse sample.     

Comparative dental radiographic identification using flat panel CT

A skull without lower jaw was found and brought in for identification. It was suspected to be that of a man reported missing five years ago. An undated antemortal dental chart and two dental films of the 1st and 2nd dental quadrants, both taken about 4 years before the man went missing, were available for comparison. The method of choice in solving the identity question was comparative dental radiography. Despite numerous attempts, it was not possible to obtain radiographs of the upper jaw that duplicated the X-ray beam angulation of the antemortem dental films. The skull was thus scanned with a multislice computed tomography (MSCT) scanner, and virtual radiographs with the desired angulation were generated from the data with the maximum intensity projection (MIP) technique. The resulting virtual radiographs could, however, not be used for superimposition with the antemortem radiographs because of their poor resolution and the occurrence of artifacts caused by metallic dental fillings. The upper jaw was therefore scanned again, this time with a high resolution eLU-CT (eXplore Locus Ultra flat panel CT). The resulting eLU-CT datasets were visualized with the MIP technique and yielded virtual radiographs that could be compared with the antemortem radiographs. Positive identification could be assumed with near certainty after dental features could be matched in the superimposition of antemortem and postmortem radiographs. In the presented case, eLU-CT was used for the first time for a comparative dental radiographic identification.     

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.     

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.