Fire victim identification by post-mortem dental CT: Radiologic evaluation of restorative materials after exposure to high temperatures

An overview of the heat-induced changes of the chemical composition of bone from fresh to calcined

When bone is exposed to thermal stress, the chemical composition changes. This affects bone tissue regeneration after surgery, and these changes can also aid in reconstructing ante-, peri-, and post-mortem events in forensic investigations and past activities on cremation practices in archaeology. However, to date, no complete overview exists on the chemical composition of both fresh and thermally altered bone. Therefore, we aimed (i) to present the chemical composition of fresh bone and (ii) to present an overview of heat-induced chemical changes in bone under both reducing and oxidizing conditions. From the overview, it became clear that some chemical changes occur at a consistent temperature, independent of exposure duration, meaning there is a temperature threshold. However, the occurrence of other chemical changes appeared to be more inter-experimentally variable, and therefore, it is recommended to further investigate these changes.

The effect of burning on dental tissue: A macroscopic and microscopic investigation

Teeth are considered unique as fingerprints for identification purposes. Their structure and resilience mean they can remain for thousands and millions of years withstanding extreme conditions, including burning. During burning, bones undergo carbonization at approximately 400°C and calcination at approximately 700°C. This study aimed to investigate the effects of carbonization and calcination on dental tissue. It involved nondestructive analyses of 58 extracted human teeth before and after burning, using x-ray diffraction, micro-CT, and high-resolution confocal microscopy. The results revealed that during carbonization, dentin volume decreased in two thirds of the sample, accompanied by crack formation and significant reduction in hydroxyapatite crystal size (p<0.001). During calcination, dentin volume decreased in all teeth, along with a significant deepening of the cracks (p<0.001), while enamel crystal size increased slightly. Initial changes in teeth occurred at lower temperatures than had once been assumed, as indicated by the cracks during carbonization, and there was up to a 36% decrease in dentin volume during calcination, which should be considered when measuring burnt teeth. The results of this research provide new insight into understanding dental tissue response to burning. Thus, dental remains may contribute to the knowledge needed to reconstruct anthropological and forensic scenarios involving burning.

Forensic exploration of endodontic cements: Unveiling macroscopic and radiographic changes under high temperatures

OBJECTIVE

To evaluate macroscopically and radiographically the behavior of four endodontic sealers submitted to high temperatures, with forensic purposes.

METHODS

Sixty-four lower anterior teeth were included. All teeth were endodontically treated, and simulation of external cervical resorption (ECR) was performed. Half of the sample was filled with AH-Plus™ cement and had ECR sealed with Bio-C-Repair™. The other 32 teeth were filled with Bio-C-Sealer™ cement and had their respective ECR sealed with MTA-Repair™. Then, all teeth were introduced into a bovine bone block to simulate the alveolar bone. The teeth were submitted to incineration at temperatures of 600, 800, 1000, and 1140 °C. All teeth were radiographed before and after incineration. The pre-and post-incineration radiopacity of cements and dentin were evaluated using the ImageJ™ software and compared using a t-test for paired samples.

RESULTS

It was possible to confirm color change and appearance of cracks in the tissues and dental materials tested, varying according to the temperature. Radiographically, it was observed that the dental crowns completely detached at 1000 ° and 1140 °C, and, only at 1140 °C, the roots showed cracks. Regarding the radiopacity, there was a significant difference in the shades of gray in AH-Plus™ when subjected to 1000 ° and 1140 °C, and at 600 ° and 1000 °C in Bio-C-Sealer™. In Bio-C-Repair™ and MTA-Repair™, a difference was observed at 600 ° and 1140 °C.

CONCLUSIONS

There were macroscopic and radiographic alterations of the materials. This data is important in Forensic Dentistry and may contribute to identifying carbonized victims.

Dual-energy index variation when evaluating the potential ferromagnetism of ex vivo bullets

Background

An MRI is potentially hazardous for patients with retained ferromagnetic bullets. Recent studies have aimed to develop dual-energy computed tomography (DECT) as a screening tool for recognising highly ferromagnetic bullets. Inconsistent findings have been ascribed to inherent CT technology differences. Previous research demonstrated significant Hounsfield unit (HU) measurement variation among single-source CT machines.

Objectives

This study investigated the theoretical dual-energy index (DEI) variation between DECT machines when evaluating the potential ferromagnetic properties within the same sample of ex vivo bullets and metal phantoms.

Method

An experimental ex vivo study was conducted on eight metal phantoms and 10 unused bullets individually positioned in the same Perspex head phantom and scanned on two DECT machines. Two senior radiology registrars independently recorded the HU readings, and DEI values were calculated. Statistical analysis was performed using non-parametric methods for paired data, namely the Signed Rank Test. The DEI values based on mean HU readings between the DECT machines were compared.

Results

Inter- and intra-reader agreement was not statistically significant. The metal phantoms had poor interscanner agreement, with an overlap of the ferromagnetic and non-ferromagnetic ranges. The bullets had good interscanner agreement, with a similar ferromagnetic to non-ferromagnetic relationship.

Conclusion

The use of DEI values negates the previous assumption that significant interscanner variability exists among different DECT technologies while assessing highly attenuative ex vivo bullets.

Contribution

This investigation demonstrated that even though HU readings may be variable, the implementation of the DEI equation translates this into comparable values with good interscanner agreement.

Color change in teeth due to burning: Spectrophotometric analysis

Teeth are one of the most common skeletal elements for forensic identification purposes and also the strongest human tissue, making them resistant to high temperatures. Over the course of burning as temperature increases, teeth go through a process of structural change characterized by a carbonization phase (at approx. 400 °C) and calcination phase (at approx. 700 °C) that might result in complete enamel loss. The aim of the study was to quantify color change of enamel and dentin and to determine whether both tissues can be used for estimating burn temperature as well as to evaluate the whether these changes are visually perceptible. 58 human, permanent maxillary molars without restorations were burned for 60 min at either 400 °C or 700 °C in a Cole-Parmer StableTemp Box Furnace. The change in color was measured for the crown and root using a SpectroShade Micro II spectrophotometer to determine lightness (L*), green-red color (a*), and blue-yellow color (b*). Statistical analysis was performed using SPSS version 22. There is a significant difference between the L*, a*, and b* values of pre-burned enamel and dentin at 400 °C (p < 0.001). In addition, differences in dentin measures between 400 °C and 700 °C (p < 0.001), as well as pre-burned teeth and 700 °C (p < 0.001). The mean L*a*b* values were used to calculate a measure of the perceptible difference between colors (ΔE) revealing a highly perceptible color difference between the pre- and post-burn teeth for both enamel and dentin. There is a low perceptible difference between burned enamel and dentin was found. During the carbonization phase the tooth gets darker and redder and as temperature increases, teeth become bluer. Overall, as calcination occurs the tooth root color gets closer to a neutral gray palette. The results showed a highly perceptible difference indicating that for forensic purposes simple visual color evaluation can provide reliable information, and dentin color evaluation can be used in cases when enamel is missing. However, the spectrophotometer allows an accurate replicable measure of tooth color across various stages of the burning process. This has practical applications in forensic anthropology as a portable and nondestructive technique that can be used in the field regardless of the practitioner's level of experience.

Effects of high temperature on dental restorative materials for forensic purposes

This study aimed to observe the effects of high temperature on different restorative dental materials by detecting changes in their microstructural and elemental composition. Disk shaped samples (10 mm diameter, 2 mm depth) were prepared from 8 dental materials (compomer, glass carbomer, ormocer, giomer, zinc reinforced glass ionomer (GI), silver-alloy reinforced GI, zirconia reinforced GI, and conventional GI). Scanning electron microscopy/Energy dispersive X-ray spectroscopy (SEM/EDS) was used to characterize sample surface structures and elemental composition. The same samples were also analyzed using X-ray fluorescence (XRF) to determine the trace element content. Each sample was placed in a porcelain furnace and exposed to 900 °C for 30 min. Observations of macroscopic changes in samples after exposure high temperature were recorded. The microstructural changes in sample surfaces after incineration were detected by SEM. The elemental compositions obtained before and after the incineration were compared after repeating the XRF and EDS analyses. Dental materials demonstrated specific macroscopic changes and microstructural deteriorations detected by SEM images after exposure to high temperature. While several changes occurred in the elemental content of materials in terms of amount, the original elemental composition was preserved. The ability to distinguish dental materials by elemental analyses has had an important impact on the identification process.

Forensic study of mechanical properties of dental restoration after burial in mangrove environment

Conducting research in the field of forensic sciences with methodologies that simulate situations found in the day-to-day practice of a given field of expertise is relevant insofar as this approach can produce results that are as close as possible to reality. In this context, the present study provided situations based on burial in a mangrove environment to estimate the changes in the mechanical properties (Knoop microhardness, roughness and color) of dental restorations utilizing silver amalgam, composite resin and glass ionomer cement over the time of burial. The silver amalgam showed a significant increase in surface roughness and a reduction in Knoop microhardness. Composite resin showed a statistically significant increase in color variation, and the glass ionomer cement showed significant increases in color variation and Knoop microhardness. These results allowed us to conclude that teeth restored with silver amalgam, composite resin and glass ionomer cement submitted to burial in mangrove environments produce different changes in surface roughness, Knoop microhardness and color properties depending on the time of burial to which the victims were submitted. These proprieties could help the forensic sciences to estimate time intervals for burial in mangrove environments.

Comparing dental identifier charting in cone beam computed tomography scans and panoramic radiographs using INTERPOL coding for human identification

According to INTERPOL, the comparison of antemortem and postmortem dental identifiers is a scientifically reliable approach for human identification. This study aimed to quantify the prevalence of corresponding INTERPOL coded dental identifiers in cone beam computed tomography (CBCT) scans and panoramic radiographs (PR). The sample consisted of 100 CBCT scans and 100 PR taken the same day from the same patients (35 males and 65 females). Randomly and independently, forty-one INTERPOL coded dental identifiers were searched in each image. Wilcoxon test compared the prevalence of codes in CBCT scans and PR, Chi-square tested the dependence between codes and teeth; and multiple correspondence analyses (MCA) explored the association between codes and teeth in color maps for CBCT scans and PR. No statistically significant differences between the prevalence of identifiers in CBCT scans and PR were detected (p=0.693). In CBCT scans and PR, dependence between teeth and codes was detected (p<0.05). In the study sample, the strongest associations were found between the codes unerupted (UNE), partially erupted (ERU) and impacted (IMV) and third molars, both in CBCT scans and PR. INTERPOL coded dental identifiers registered on CBCT scans and PR can be exchanged during human identification.

Color stability of dental restorative materials submitted to cold temperatures for forensic purposes

In the post-mortem examination of the dental arches of accident victims in cold locations, dental restorative materials can be found. Cold temperatures can be capable of causing color changes of aesthetic materials, such as composite resin (CR) and glass ionomer cement (GIC). The aim of this study was to evaluate the effect of the cold action on the color stability of CR and GIC restorations, in order to discriminate them and enable the adequate comparison between antemortem and post-mortem data. Sixty bovine teeth (30 CR and 30 GIC) were prepared (6 × 6 × 2 mm) and separated into groups (n = 10). The color readouts were taken by a portable spectrophotometer, before and after of cold action (2.5 °C, -20 °C, -80 °C) inside of freezers. There were color alterations in the coordinates (ΔE, ΔL^∗, Δa^∗ e Δb^∗) for both materials. The authors concluded that cold was capable of producing changes in color in the two esthetic materials, with similar intensities between the two, at all the temperatures studied, when analyzed at 7 days. After being submitted to cold for 30 days, the changes were more significant for CR, allowing it to be differentiated from GIC after 30 days, at all the temperatures tested. Therefore, the test proposed in the study was shown to be practical, feasible and capable of helping Forensic Odontology with the identification of victims.

The use of incinerated pig head in dental identification simulation

PURPOSE

The aim of this exercise was to simulate a disaster victim identification scenario to allow training in documentation of postmortem incinerated remains and reconciliation of dental data.

METHOD

Varying number of restorations were placed in ten pig heads. The teeth and restorations were charted, with the restorations radiographed and documented, creating an ante-mortem data set. The following day the heads were cremated. Following cooling and recording they were transported for a post-mortem examination by trained specialist odontologists who were not involved in the initial antemortem phase. Recordings included the charting of teeth, restorations, lost teeth, and radiographs to simulate a post-mortem examination. A reconciliation of postmortem to antemortem information was attempted.

RESULTS

There was an unacceptable amount of error in the postmortem examination of the heads. The errors related mainly to avulsed teeth and incorrect opinion of which charted surfaces the restorations were placed upon. Also noted were a considerable number of root fractures occurring beneath the crestal bone. This observation does not mimic the evidence observed in human incinerated teeth where the crowns tend to fracture off the roots at the dentin-enamel junction.

CONCLUSION

The use of incinerated pig (Sus Scrofa) heads is not an ideal model for forensic odontology training in disaster victim identification. Differences in both anatomy and behavior following exposure to heat were shown to hamper documentation and subsequent comparison to antemortem data.

A study of osseointegrated dental implants following cremation

BACKGROUND

The comparison of dental morphology and restorative work for human identification has been well documented. This case study involved documentation of osseointegrated and clinically restored dental implants following cremation.

METHODS

The mandible and the maxilla were excised from a head containing implants and cremated. The remains were retrieved, digital and radiographic images were taken and elemental analysis undertaken. The brand of implants was identified utilizing web based search engines. A prosthodontist, known to commonly use this implant system, was approached to ascertain possibilities that matched the data given.

RESULTS

Following cremation the implants were identified and a prosthodontist was able to identify the deceased. Two implants in the maxilla had dehiscences on their buccal surfaces, which could not be detected by periapical radiographs.

CONCLUSIONS

Dental implants osseointegrated and restored with a prosthetic superstructure were recognizable following severe incineration. It was possible to trace back the identity of the unknown victim to a prosthodontist. Bone dehiscences discovered in this study highlighted how two-dimensional radiographs may not reveal lack of bone support.

Forensic imaging for causal investigation of death

A 63-year-old man was found in the street after overrun by a car. Postmortem CT revealed multiple bone fractures, but surprisingly all without any relevant hemorrhage which would have been expected under such circumstances. A round radiopaque formation was found in the duodenum, which was reminiscent of ingested tablets. The toxicological analysis revealed high concentrations of zopiclone and alcohol. By combining radiologic and forensic results, zopiclone and alcohol intoxication were concluded as the cause of death, followed by a postmortem overrun accident.

Maximizing postmortem oral-facial data to assist identification following severe incineration

PURPOSE

This paper reviews the literature for methods of maximizing the postmortem oral-facial information available for a comparison to be made for identification following an incident resulting in incineration.

METHOD

A search was initially instigated utilizing PubMed, Scopus, and Google Scholar, with further library searches and correspondences among peers around the world leading to a comprehensive review of the literature.

CONCLUSION

Maximizing postmortem dental evidence in a severe incineration event requires correct recognition and recording of dental data. Odontologists should attend the scene to facilitate this recognition. The information should be documented, photographed, and stabilized before retrieval. Wrapping, padding, and further support of the remains during transportation to the examination mortuary will aid this process. Examination at the mortuary requires further photography, complete charting, and radiographic examination of any dental material available, as well as awareness of other possible medical evidence, to enable identification of the human remains.

Material differentiation in forensic radiology with single-source dual-energy computed tomography

The goal of this study was to investigate the use of dual-energy computed tomography (CT) in differentiating frequently encountered foreign material on CT images using a standard single-source CT scanner. We scanned 20 different, forensically relevant materials at two X-Ray energy levels (80 and 130 kVp) on CT. CT values were measured in each object at both energy levels. Intraclass correlation coefficient (ICC) was used to determine intra-reader reliability. Analysis of variance (ANOVA) was performed to assess significance levels between X-Ray attenuation at 80 and 130 kVp. T test was used to investigate significance levels between mean HU values of individual object pairings at single energy levels of 80 and 130 kVp, respectively. ANOVA revealed that the difference in attenuation between beam energies of 80 kVp compared to 130 kVp was statistically significant (p < 0.005) for all materials except brass and lead. ICC was excellent at 80 kVp (0.999, p < 0.001) and at 130 kVp (0.998, p < 0.001). T test showed that using single energy levels of 80 and 130 kVp respectively 181/190 objects pairs could be differentiated from one another based on HU measurements. Using the combined information from both energy levels, 189/190 object pairs could be differentiated. Scanning with different energy levels is a simple way to apply dual-energy technique on a regular single-energy CT and improves the ability to differentiate foreign bodies with CT, based on their attenuation values.