Extended CT scale overcomes restoration caused streak artifacts for dental identification in CT--3D color encoded automatic discrimination of dental restorations

OBJECTIVE: Besides DNA, dental radiographs play a major role in the identification of victims in mass casualties or in corpses with major postmortem alterations. Computed tomography (CT) is increasingly applied in forensic investigations and is used to scan the dentition of deceased persons within minutes. We investigated different restoration materials concerning their radiopacity in CT for dental identification purposes. METHODS: Extracted teeth with different filling materials (composite, amalgam, ceramic, temporary fillings) were CT scanned. Radiopacities of the filling materials were analyzed in extended CT scale images. RESULTS: Radiopacity values ranged from 6000-8500HU (temporary fillings), 4500-17000HU (composite fillings) and >30710HU (Amalgam and Gold). The values were used to define presets for a 3D colored volume rendering software. CONCLUSIONS: The effects of filling material caused streak artifacts could be distinctively reduced for the assessment of the dental status and a postprocessing algorithm was introduced that allows for 3D color encoded visualization and discrimination of different dental restorations based on postmortem CT data.     

Dental orthopantomogram biometrics system for human identification

Fingerprinting is the most widely accepted method of identification of people. But in cases of disfigured, decomposed, burnt or fragmented bodies, it is of limited value. Teeth and dental restorations on the other hand are extremely resistant to destruction by fire. They retain a number of their original characteristics, which are often unique and hence offer a possibility of rather accurate and legally acceptable identification of such remains. This study was undertaken to evaluate the utility of orthopantomography for human identification and propose a coding system for orthopantomogram (OPG), which can be utilized as an identification tool in forensic sciences.     

Zur Personenidentifikation mittels Zahnstatus

The forensic value of postmortem dental charts for identification purposes depends on the quantity and quality of premortem dental documentation. A survey of 143 dentists from Mittelfranken showed that in 65% dental records only comprised features according to contractual obligation (“minimal record”). In 19.5% additional own restorations (“continuously updated record”) and in 15.5% all odontological features were recorded (“ideal record”). The rate of failures ascertained by subsequent examination of 61 patients was between 21.3% (“ideal record”) and 55.6% (“minimal record”).     

Dentine and cementum as sources of nuclear DNA for use in human identification

Teeth are increasingly utilized as a source of nuclear DNA to aid identification of human remains. DNA extraction and the results of genetic analysis from these tissues are extremely variable and to some extent unpredictable. This study examines the availability of nuclear DNA in different areas of the dental hard tissues and explores the extent and nature of the variation within and between individuals. Results of this study indicate that nuclear DNA is available in widely variable quantities in dentine and cementum. This variation exists within teeth and between teeth, even between comparable teeth from the same individual. The quantity of DNA available in dentine is affected by age and dental disease, whereas that in cementum is not. Forensically useful genetic profiles were obtained from as little as 20 mg of tooth powder, thus avoiding the necessity for complete destruction of the tooth. A better understanding of why there is more DNA in one tooth tissue or region compared with another, and of the effects of disease and age, will aid in the selection of which tooth and tissue to sample and will increase the validity of the use of teeth as a source of nuclear DNA for human identification.     

Dental identification in routine forensic casework: clinical and postmortem investigations

The aim of this study was to examine the factors which may disturb dental identification of unknown human remains and the practical value of dental evidence in routine forensic casework, including the changes due to dental treatment and postmortem interference. In the investigation of changes due to dental treatment on 696 patients' dental history at two clinics, increase of the number of dental restorations was the greatest in the initial 1-2 years. This finding suggests that dental treatments performed in early period after initial examination contributes more to forensic dental identification than those performed afterwards. The lower anterior teeth (incisors and canines) remained relatively unchanged for years compared with other teeth. The molars appeared to be more frequently restored at a relatively younger age and more frequently missing in the elderly. The investigation of 260 unknown remains in 971 forensic autopsy cases during a period of seven years (1992-1998) at our institute indicated the particular usefulness of dental evidence in cases where the candidates were identified from some other evidence, and usually in cases having a postmortem period corresponding to the obligatory preservation term for the clinical dental records and radiographic films. There were non-identity in the status of dental treatments between ante-mortem dental findings due to additional treatments received after the last day of examination recorded in the corresponding clinical dental records. Postmortem damage from decomposition and fire was more frequently observed in the anterior teeth. These observations indicate that precise documentation of dental evidence including postmortem deterioration and the establishment of a well-organized dental database of missing persons together with a suitable screening system is required to more effectively utilize dental evidence in routine forensic casework.     

Fluorescence imaging of dental restorations using the VistaCam intra-oral camera

Optical fluorescence imaging methods have a range of forensic applications. The VistaCam system (Dürr Dental) is an existing intra-oral fluorescence camera, which was designed to aid detection of dental caries using 405 nm wavelength light generated by light emitting diodes (LEDs). This study assessed whether this fluorescence imaging device could also be used to recognize dental restorative materials, which is essential for accurate dental charting of deceased persons who are unidentified. The effect of body fluids (saliva and blood) on performance was also assessed. The VistaCam was used on the bench to assess 55 extracted human teeth with restorations, and samples of restorative materials. Readings were first taken in the moist state and then after the application of human saliva or venous blood. Fluorescence scores were compared using one-way ANOVA. Human enamel gave lower fluorescence than restorations. Different tooth-coloured restorative materials gave similar strong fluorescence scores, without statistically significant differences between them. Fluorescence scores were not affected by the presence of ambient fluids (saliva or blood). Using violet 405 nm light to elicit fluorescence may aid in the recognition of dental restorative materials.     

How to do identify single cases according to the quality assurance from IOFOS. The positive identification of an unidentified body by dental parameters: A case of homicide

The positive identification of skeletal by individual dental parameters is one of the objectives of the criminal investigation. The intervention of Forensic Dentistry in some circumstances may represent the only way to obtaining a positive identification of an unidentified bodies. The teeth constitute a scientific method in forensic identification, principally due to the great resistance to the agents who provoke the destruction of the soft tissues in the corpses (putrefaction, traumatic, physical and chemical agents) and to the high morphological variability of the human teeth. The human identification in Forensic Dentistry is made by two ways: comparative and reconstructive. The identification allows to determine several parameters of forensic interest: specimen, population affinity, sex, age, stature and individualization's factors. The Forensic Dentistry is one of the most important fields in individual identification, because teeth have less variability in the chronology of events in terms of the reconstructive way. On the other side, in terms of the comparative way, this area is also important, because of the individualization's factors: positive identification in individual cases and in mass disasters. In this forensic case report, a homicide case, the objective of the medico-legal investigation was a positive identification of the unidentified corpse found one year after the crime, July 2010. The Portuguese Criminal Police of Lisbon, Homicide Group, requested to South Branch of the Portuguese National Institute of Forensic Medicine, a forensic examination by a Forensic Odontologist for dental positive identification. The objectives were: 1) post mortem reconstruction of the dental status of the victim; 2) obtain the ante mortem information of the presumable victims; 3) comparison of the post mortem information with the ante mortem information, for a positive identification of the presumable homicide victim. Materials and methods: in this field of dental investigation, the guidelines of the International Organization of Forensic Odontology were used for reconstruction of the post mortem dental profile, to register ante mortem information of the presumable victims and to compared for individualized dental factors, by using Interpol DVI Forms for Individual Case, post mortem and ante mortem forms F1 and F2. Results: the unidentified victim of homicide was positive identified where it was established the identity by more than 12 individual dental characteristics. Conclusion: the Forensic Dentistry is a very important and simple field for individual identification of unidentified corpses for application of the criminal law.     

Odontological identification of human remains from mass graves in Croatia

This paper reports the results and methods of dental identification of 1000 human remains exhumed from mass graves in Croatia up to July 1998. Personal identification of the victims was performed at the Department of Forensic Medicine and Criminology at the School of Medicine in Zagreb. A forensic odontologist participated in the identification process by carrying out the dental identification. A total of 824 victims were positively identified, while 176 victims remained unidentified. Dental identification based on available dental antemortem data was achieved in 25% of the cases. Dental identification based on dental charts was achieved in 35%, on x-rays in 15%, on photographs of teeth in 22%, on interviews in 18%, and on confirmation by odontologists in 10% of the cases. Teeth, in combination with anthropological parameters, age, sex and height, as well as other specific characteristics such as tattoos, personal identification cards, clothes, jewellery and DNA, were helpful for identification of 64% of the victims, but the significance for the identification was not dominant. Only in 11% of the cases was identification achieved by other relevant means and teeth not used at all. Identification procedures in Croatia will continue until another 1700 people who are still missing or kept as prisoners of war since the aggression on Croatia in 1991 are found and/or identified. Received: 6 August 1999 / Received in revised form: 9 November 1999     

Forensisch-odontologische Identifizierung der Opfer des Flugunfalls Zell am See

In 2007 the most serious aircraft accident in Austria since the Second World War occurred. The collision between a cargo helicopter and a light aircraft at a height of 800 m in the area of Zell am See near Salzburg resulted in 8 victims. The victims and the wreckage were spread over an area of approximately 20 hectares. The victim’s bodies were sent to the department of forensic medicine in Salzburg for autopsy and identification. The identification was carried out according to the Interpol guidelines for victim identification and involved the three primary identification markers fingerprints, DNA analysis and dental status. Of the eight victims six could be successfully identified by the dental status on the basis of antemortem (AM) dental charts. All victims could be identified by fingerprints and DNA analysis.     

Incorrect identification of a military pilot with international implications

The case is reported of a military pilot shot down in 1986 during a mission whose body was recovered in an advanced state of decomposition and delivered to Italian police in 1989. The first autopsy led to an incorrect identification of the corpse. Because of the advanced decomposed state of the corpse, a correct identification was made only through evaluation of the dental status and radiological examination. The correct evaluation of the specific shape of the amalgam restorations, particularly of those of the first and second inferior right molars, showed agreement with those of the pilot of the plane and not of the co-pilot as was initially stated. Received: 26 April 1996 / Received in revised form: 21 January 1997     

Feasibility and validation of virtual autopsy for dental identification using the Interpol dental codes

Virtual autopsy is a medical imaging technique, using full body computed tomography (CT), allowing for a noninvasive and permanent observation of all body parts. For dental identification clinically and radiologically observed ante-mortem (AM) and post-mortem (PM) oral identifiers are compared. The study aimed to verify if a PM dental charting can be performed on virtual reconstructions of full-body CT’s using the Interpol dental codes. A sample of 103 PM full-body CT’s was collected from the forensic autopsy files of the Department of Forensic Medicine University Hospitals, KU Leuven, Belgium. For validation purposes, 3 of these bodies underwent a complete dental autopsy, a dental radiological and a full-body CT examination. The bodies were scanned in a Siemens Definition Flash CT Scanner (Siemens Medical Solutions, Germany). The images were examined on 8- and 12-bit screen resolution as three-dimensional (3D) reconstructions and as axial, coronal and sagittal slices. InSpace^® (Siemens Medical Solutions, Germany) software was used for 3D reconstruction. The dental identifiers were charted on pink PM Interpol forms (F1, F2), using the related dental codes. Optimal dental charting was obtained by combining observations on 3D reconstructions and CT slices. It was not feasible to differentiate between different kinds of dental restoration materials. The 12-bit resolution enabled to collect more detailed evidences, mainly related to positions within a tooth. Oral identifiers, not implemented in the Interpol dental coding were observed. Amongst these, the observed (3D) morphological features of dental and maxillofacial structures are important identifiers. The latter can become particularly more relevant towards the future, not only because of the inherent spatial features, yet also because of the increasing preventive dental treatment, and the decreasing application of dental restorations. In conclusion, PM full-body CT examinations need to be implemented in the PM dental charting protocols and the Interpol dental codes should be adapted accordingly.     

Human identification and sex determination of dental pulp,bone marrow and blood stains with a recombinant DNA probe

Summary Recombinant DNA hybridizing specifically to a 300 nucleotide repeat DNA sequence (BLUR8) of human specificity and to human repeat DNA sequence (pHY10) on the Y chromosome was used for human identification and sex determination of degraded DNA samples of blood stains, dental pulp, and bone marrow. This radioactive technique enabled reliable and sensitive human and sex determination from blood stains that were more than 80 years old. Less than 1 piece of 0.5 cm length thread of blood stain was enough for both tests. DNA from relatively fresh dental pulp and bone marrow was clearly identified. The human identification test, which could recognize up to 0.3 ng DNA correctly, was 3 to 5 times more sensitive than the sex determination test.     

Is post-mortem CT of the dentition adequate for correct forensic identification?: comparison of dental computed tomograpy and visual dental record

The gold standard for identification of the dead is the visual dental record. In this context, several authors emphasize computed tomography (CT) as valuable supportive tool for forensic medicine. However, studies focusing on diagnostic accuracy of post-mortem computed tomography (PMCT) are still missing. Therefore, the aim of this study was to compare diagnostic accuracy of the visual dental record and post-mortem computed tomography (PMCT) of the dentition for identification of the dead. Ten whole skulls were included into the study. The entire dentition of each skull was first examined with the visual dental record as a gold standard and second using dental PMCT scans, performed on a 64-multi-detector CT (MDCT). 3D reformations, multi-planar reformations (MPR), and CT–orthopantomography (OPG) were performed in the post-processing. All examinations were analyzed by three independent investigators regarding the criteria for identification of the dead, e.g., in case of disaster. PMCT for the dental identification of the dead was difficult to perform and time consuming. Due to dental overlays and corresponding artifacts, the definite periphery of the dental fillings/inlays was not accurately defined resulting in 2.9% incorrect and 64.1% false negative findings, especially synthetic inlays were hardly or not recognizable at all. For the identification of the dead especially in case of disasters with large numbers of victims, the visual dental record is still to be considered the gold standard. In the identification process itself, there is no room for error at all, although some non-concordant information may occur. Thus, PMCT should only be performed for identification in individual cases due to the relatively high error rate. S. Kirchhoff and F. Fischer contributed equally to this work.     

Soft tissue removal by maceration and feeding of <Emphasis Type="Italic">Dermestes</Emphasis> sp.: impact on morphological and biomolecular analyses of dental tissues in forensic medicine

Maceration techniques remove soft tissue by the destruction of biomolecules, but the applied techniques may also affect the morphology and the molecular integrity of the hard tissue itself. The impact of seven different techniques for soft tissue removal on morphological and biomolecular parameters of teeth and dental tissues was systematically examined. All methods tested showed significant changes in dental morphology and in the molecular integrity of DNA and the dental proteins, as revealed by aspartic acid racemisation (AAR). In forensic casework this may have severe impacts on the results of morphological methods (e.g. age estimation based on root translucency) and of biomolecular analyses (e.g. age estimation based on AAR and DNA analysis). Therefore, age estimation based on AAR should not be applied to tissue treated in such a manner, and it is recommended that teeth for analysis should be extracted before soft tissue removal. DNA in the hard tissue seems to be less susceptible to soft tissue removal than proteins, and several of the tested maceration techniques appear not to have a damaging effect on DNA. Generally, the indication for soft tissue removal demands a careful case management to avoid methodological collisions.     

Influence of metal-ceramic fixed dental restorations on the occurrence of discoloration of gingiva

BACKGROUND: Adverse effects of dental cast alloys on the health of patients are the problem in clinical practice. The aim of this paper was to describe the case of a patient with discolorated gingivae in the presence of fixed dental restorations and used diagnostic and therapeutic procedures. CASE REPORT: A 30-year old pacient, presented with the complaints about unsatisfactory esthetic of his fixed dental restorations. He complained about the greyish discoloration of gingivae, inappropriate color of the crowns, and a larger space between the central incisors. Both discolorated and normal gingivae around the fixed dental restorations were taken by excision and the samples of gingivae were examined histopathologically, and by using the Atomic Absorption Spectrophotometry test (AAS). Histopathological examination of the discolorated gingivae showed the presence of non-specific inflammation with a foreign body. AAS revealed the presence of various metals in the samples and the higher metal contents in the samples of discolorated gingivae as compared with the samples of normal gingivae. New metal-ceramic crowns were made for the patient. CONCLUSION: A main cause of greyish discoloration of gingivae was presence of a metal in gingival tissue. After the excision of discolorated gingivae old metal-ceramic crowns should be replaced with new crowns.     

Enhancing accurate data collection in mass fatality kinship identifications: Lessons learned from Hurricane Katrina

A mass fatality DNA identification effort is a complex process in which direct matching and kinship analysis is used for identifying human remains. Kinship DNA identification is an important tool in the identification process in which victim's DNA profiles are compared to the profiles of “known” biologically related reference samples. Experience from the 9/11 World Trade Center DNA identification efforts showed that forms used to record biological relationships are important and that inaccurately documented information may hamper the kinship analysis and DNA identification process. In the identification efforts following Hurricane Katrina, a Family and/or Donor Reference Collection (FDRC) form was used as a means to document the reported relationship between the reference DNA donor and the purported missing individual. This FDRC form was developed based upon lessons learned from 9/11 and the Tsunami identification efforts. This paper analyses the effectiveness of the FDRC form used in the Hurricane Katrina kinship DNA identification efforts and proposes an improved sample collection form for kinship and other donor reference samples. The data presented can be used to enhance the accuracy of the data collection process through an improved sample collection form, streamlining the DNA kinship identification process and decreasing the burden on valuable resources.     

Tsunami 2004

Disaster victim identification following the Tsunami 2004 in southeast Asia has developed into a long lasting multinational project. Post-mortem procedures for identification included a general external and a selective internal examination, photographic documentation, dental examination, dental radiographs and collection of DNA samples. The majority of identifications in Thailand rely on forensic odontological findings, however, physical examinations are essential for the identification process. The major problem was the advanced putrefaction of most of the bodies. Development of advanced standards and a harmonisation of medico-legal procedures for international cooperations are needed.     

Odontological identification of fire victims —potentialities and limitations

A retrospective study was performed to analyse the power of odontological evidence in burn victims. The material comprised 292 single fire cases registered at 4 centers of forensic odontology in Scandinavia (DK: Aarhus, Copenhagen; N: Oslo; S: Goteborg) covering a 10-year period. Filed antemortem (am) and postmortem (pm) data were critically reviewed and registered. New systems for classification of the degree of injuries to the teeth and jaws and of the quality of dental records were developed. Matching dental am-pm units/features were recorded using the tooth as unit. Units were scored as either ordinary or extraordinary if the frequency of occurrence in a Danish reference population was 10% or < 10%, respectively. The ID conclusion of a single case was classified into one of the categories: no conclusion, ID possible, ID probable or ID established, depending on the number of ordinary/extraordinary matching units. All age groups were represented. Most fatal burns occurred in house fires (62%) and there was a preponderance of males (71%). Detailed written records supplied by single or by systematic radiographs were available in 71% of cases. About 50% of burn victims were classified into the no-injury group and approximately 25% of cases showed injuries to the anterior teeth only. The number and complexity of dental restorations increased with age. The dental examination was a powerful tool in identification of burn victims. Thus, dental identity (ID) was established in 61% of burn victims and dental evidence assisted the identification in another 31% (ID possible 19%; ID probable 12%). The improvement in dental health status seems to interfere with the discriminating potential of dental restoration as reflected in a lower fraction of established dental ID among fire victims younger than 20 years old. General use of denture marking would improve the proportion of established dental ID. Oral radiographs play an important role in personal identification and systematic exposures are therefore valuable tools.     

Discoloration of gingiva in the presence of fixed dental restorations

AIM: To investigate the frequency of discoloration of gingiva in the presence of fixed dental restorations, regarding the type of alloy of which restorations were made, and to show histopathological changes of discolored gingiva. METHODS: One hundred and eighty four patients of both sexes were examined. The average age of the examinees was 52. They were divided into four groups according to the alloys from which their restorations were made. Standardized history questionnaires and clinical examination procedures were developed for this study. In ten examinees, whose teeth were indicated for extraction and who had a discoloration of gingiva, the samples of tissue were taken from the discolored gingiva for histopathological examination. RESULTS: Our results showed the presence of discolored gingiva in all four groups. It was most frequent in the examinees with fixed restorations made of Ni-Cr alloy (43,5%) and less frequent in those with fixed dental restorations made of gold alloy (26,5%). Histopathological examination showed the presence of tissue foreign body granulomas with giant cells in which the metal particles were found, partially as small and partially as large particles. CONCLUSION: Results suggested that grayish discoloration of gingiva was present in all four groups of examinees. The highest number of examinees with discolored gingiva was in the group with restorations made of Ni-Cr alloy. Grayish discoloration of gingiva was a consequence of incorporation of metal particles into gingival tissue.