Bite marks: To opine or not to opine?

Much has been written about bite mark comparisons and bite mark analysis. It has largely been written for, and remained within the domain of, the forensic odontologist despite the limited number of such specialists and the even smaller subset who have expertise in this area. For those health professionals who work in the field of clinical forensic medicine, most will not have access to a forensic odontologist. Courts can be reticent about the costs involved in obtaining another expert opinion. For health professionals, who will likely encounter more bite marks in their career than forensic odontologists, the difficulty is knowing what can legitimately be opined about such injuries.

Influence of the amount of saliva deposition and time elapsed after deposition on bite mark analysis.

Bite mark analysis is among the most interesting research fields in forensic odontology; however, it is limited by its dependence on the employed method as well as assessor subjectivity, particularly when using morphological analysis or DNA profiling. These limitations are due to differences in DNA collected from saliva adhering to a living or inanimate body, as well as differences in exocrine fluid secretion and deposition amount among individuals. This study aimed to analyze the effectiveness of DNA profiling when there are differences in the amount of saliva adhering to a living body and when time has elapsed since deposition. Most allele peaks could be identified in 1 µl of saliva, even 9 h after saliva deposition and examination. Consistent results were obtained following saliva deposition in an individual who had engaged in up to 9 h of free activity. The results of this study demonstrate the validity and reliability of DNA profiling for bite mark analysis and are extremely important as they can demonstrate the usefulness of the little information left by a suspect on a victim's body.

Medico-legal implications of dog bite injuries: A systematic review.

Dog bites pose a significant global public health issue and are the most common type of injury caused by animals. While most dog bites result in minor harm, they can also lead to severe or even fatal consequences. In cases involving serious injury or death, forensic pathologists investigate various aspects, including the crime scene, the injuries sustained by the victim, and the characteristics of the dog suspected to have caused the bite. The aim of this study is to provide a systematic review of the literature on the medical-legal implications of dog bites in forensic practice, in order to recognize the dog bite victim features, the injuries and their consequences related to, and to identify the offending dogs. The literature search was performed using PubMed, Scopus and Web of Science from January 1980 to March 2023. Eligible studies have investigated issues of interest to forensic medicine about dog bites to humans. A total of 116 studies met the inclusion criteria and were included in the review and they were organized and discussed by issue of interest (biting dog features, dog bite victim features, anatomical distribution of dog bites, injuries related to dog bites, cause of death, bite features, dog identification and post-mortem dog depredation). The findings of this systematic review highlight the importance of bite mark analysis in reconstructing the events leading to the attack and identifying the dog responsible. In medical forensic evaluations of dog bite cases, a multidisciplinary approach is crucial. This approach involves thorough analysis of the crime scene, identification of risk factors, examination of dog characteristics, and assessment of the victim's injuries. By combining expertise from both human and veterinary forensic fields, a comprehensive understanding can be achieved in dog bite cases.

Forensic odontology: Wrong convictions, "bad apples" and "the innocence files".

Forensic odontology (FO) provides expert testimony; however, new criticism has identified FO as one of the fields that must strengthen its scientific foundations. The recent Netflix documentary titled "The Innocence Files", featuring wrongful convictions, dedicates three of its nine episodes almost exclusively to bite mark identification (BMI), one of the most questioned tests performed by FO. Although most of the FO fields have an undoubted utility in forensic and juridical context, only BMI has been questioned in recent years; the derogatory expression "Junk science" is used continuously in the documentary almost as a synonym for FO. We present a scoping review of cases reported in the US National Registry of Exonerations in which FO was false or misleading forensic evidence (F/MFE) leading to wrongful convictions. Although in the 26 cases identified the only declared F/MFE was the BMI (excluding any other type of dental expertise), only in 2 cases (7.69%) was F/MFE the sole contributing factor, and in 4 cases (15.38%) there was F/MFE plus three additional factors. Official misconduct was detected in 19 cases (73.08%) and perjury or false accusation in 16 cases (61.54%). It has already been mentioned how dangerous it is to consider FO as synonymous with "bite mark identification", or even to publicly provide incorrect or decontextualized information. This review shows that erroneous convictions have been exclusively in the field of BMI, and that FO encompasses much more than just BMI. The relationship between the media and forensic sciences has been strained. The perspective of the new culture of risk management in forensics is also discussed.

Forensic odontology and dental age estimation research: a scoping review a decade after the NAS report on strengthening forensic science.

Dental age estimation (DAE) is one of the most reliable and useful scientific methods employed by forensic odontology (FO) for human identification. In 2009, the US National Academy of Sciences (NAS) report highlighted the need to deepen research in many disciplines, among which FO received strong criticism for specific expertise. The aim of this review is to provide a comprehensive overview in order to systematically map the latest original research done in FO, as well as identify DAE within this field. A systematic search was performed from 2014 to 2019. In total, 644 studies were identified for qualitative analysis: DAE was the most studied topic (41.30%). Asia was the most productive continent with 58.27% of the global production on DAE; India was the most productive Asian country, with 32.33% and 55.48% of global and Asian production, respectively. The University of Macerata (Italy), KU Leuven (Belgium), University of Split (Croatia), and University of São Paulo (Brazil) led DAE research. Authors from leading countries on DAE research demonstrated great individual productivity, which is evidence of their scientific efforts, but also possible risks if the continuity of this line of research depends on them. Although FO has significantly focused its research on DAE, the absence of publications on controversial topics but necessary for research according to the NAS report shows the possible lack of interest of authors or journals to address them.

Post-Mortem Dental Profile as a Powerful Tool in Animal Forensic Investigations-A Review.

Veterinary forensics is becoming more important in our society as a result of the growing demand for investigations related to crimes against animals or investigations of criminal deaths caused by animals. A veterinarian may participate as an expert witness or may be required to give forensic assistance, by providing knowledge of the specialty to establish a complete picture of the involvement of an animal and allowing the Courts to reach a verdict. By applying diverse dental profiling techniques, not only can species, sex, age-at-death, and body size of an animal be estimated, but also data about their geographical origin (provenance) and the post-mortem interval. This review concentrates on the dental techniques that use the characteristics of teeth as a means of identification of freshly deceased and skeletonised animals. Furthermore, this highlights the information that can be extracted about the animal from the post-mortem dental profile.

Eye healing in a free-ranging whitespotted eagle ray (Aetobatus narinari) following shark-inflicted bite injuries.

Here we provide the first photographic records of the eye healing of a free-ranging whitespotted eagle ray (Aetobatus narinari) following shark-inflicted bite injuries on the cephalic region. The whitespotted eagle ray with fresh wounds on the cephalic region close to its right orbit, upper jaw and the anterior margin of its right pectoral fin was photographed on 19 July 2017 at the Fernando de Noronha Archipelago. Two subsequent photographs of the whitespotted eagle ray with a blind right eye were taken on 29 March 2018 and 18 April 2018. These records show the whitespotted eagle ray had the capacity to recover from the wounds, although they have led to the blindness of the eye. These findings also demonstrate this individual was able to survive for at least 9 months with a nonfunctional eye.

Rare evidence for 'gnawing-like' behavior in a small-bodied theropod dinosaur.

Mammalian carnivores show a higher degree of prey bone utilization relative to non-avian theropod dinosaurs, with this major ecological difference reflected in the frequency and morphology of tooth marks in modern and Cenozoic assemblages relative to Mesozoic ones. As such, prey bone utilization (i.e., gnawing, bone-breaking, osteophagy) may represent a key ecological strategy repeatedly exploited by mammalian carnivores but rarely in theropod dinosaurs. Here we describe an isolated adult-sized hadrosaurid pedal ungual (III-4) from the Dinosaur Park Formation (Campanian) of southern Alberta which shows a unique pattern of bite marks from a small- to medium-sized theropod dinosaur. Thirteen distinct tooth marks occur in a restricted area of the ungual, and the pattern suggests up to six repeated, high-power bites delivered to the bone. The tracemaker cannot be definitively identified, but was likely a dromaeosaurid or very young tyrannosaurid. Tooth marks on at least four other Dinosaur Park Formation hadrosaur pedal unguals are reported, but the overall frequency of occurrence in unguals (< 1%) is much lower than that reported for other bones. The pattern of tooth marks on this specimen deviates from most described theropods tooth marks, and given the low volume of meat associated with the ungual, may represent theropod prey bone utilization as part of late-stage carcass consumption, and a behavior similar to mammalian gnawing.

Oral bacterial DNA-based discrimination of human and canine saliva for the analysis of indistinct bite marks.

Analyzing ambiguous bite marks using conventional morphological approaches to identify attackers is difficult; thus, applying molecular biological methods for identifying an attacker from their saliva is a possible approach in a forensic investigation. This study aimed to establish oral bacterial DNA-based human and canine saliva markers and develop a practical method for their discrimination. We considered Streptococcus oralis and Pasteurella canis as human and canine saliva marker candidates, respectively. Duplex bacterial DNA detection using melting curve analysis was designed and evaluated for forensic applicability using proof-of-concept experiments. S. oralis DNA was detected from human saliva samples from 30 out of 30 individuals, and P. canis DNA was detected from canine saliva samples from 73 out of 77 individuals (26 dog breeds). Additionally, both bacterial DNA markers were accurately detected from human blood-contaminated saliva samples and mock indistinct bite marks. Our results indicate that both bacterial DNA markers were sensitive, robust, and discriminating saliva markers. We consider that our duplex bacterial DNA examination is a simple, practical, and useful method for the detection of saliva from indistinct bite marks and discrimination between human and canine saliva.

Multidisciplinary analysis of bite marks in a fatal human dog attack: A case report.

INTRODUCTION: Lethal injuries by animal attacks are a matter of concern for the forensic pathologist; the presented case illustrates a two dogs attack on a 61-year-old man. The authors have focused on a multidisciplinary approach involving forensic pathologists and veterinarians. MATERIALS AND METHODS: The victim was cycling in the countryside when he was attacked by two dogs that came out of a large house. He was found lying in the street by the homeowners who called for help. The victim was transported to the hospital where he died five days later. According to recovery data and medico-legal autopsy findings the cause of death was septic shock. RESULTS: Forensic pathologists and veterinarians multidisciplinary evaluation revealed lacerations, abrasions, and multiple small punctures constituting bite marks over the entire body. Six skin dowels with bite marks were taken and compared with the dental cast of the dogs. CONCLUSION: A comparison of the dog dental casts and the bite marks on the victim's body allowed the identification of the animals involved in the attack.

Application Status and Prospect of Bite Mark Evidence in Forensic Odontology.

ABSTRACT: Bite marks are increasingly common in violent cases such as child abuse and sex crimes. Bite marks are often the result of a suspect's attack or a victim's self-defense. Because human teeth vary in size, shape and arrangement, bite marks on objects such as skin and food are characteristic. By using this principle, forensic odontology can identify or exclude suspects by comparing actual bite marks with the teeth marks in the mouth. In this paper, the practical application of bite mark evidence, the research status and problems of bite mark analysis are briefly reviewed, and the prospect of bite mark analysis is also discussed.

Characterisation of an unexplored group of microplastics from the South China Sea: Can they be caused by macrofaunal fragmentation?

Research on plastics fragmentation is important for the estimation of amount of microplastics but the biological causes for fragmentation have not been acknowledged. From microplastics collected in the beaches of Hong Kong, we revealed an abnormal type of fragment which has not been reported before. These fragments, composing about 6% of the microplastics (pellet, foam, bead, fragment) collected, were interestingly triangular in shape with at least two of the three sides being characteristically straight and resembling a cut made by compression. Objective observations have distinguished these "trimmed triangular fragments" to those triangular fragments that were fractured randomly. By comparing with additional evidence, we proposed that these trimmed fragments were the daughter pieces of macrofaunal biting. If this was so, there would be wide implications on fragmentation modeling studies for microplastics since active biting of large plastic debris has generally not been considered as a factor of plastics fragmentation.

Exploring the degrees of distortion in simulated human bite marks.

The properties of the skin and the posture of the body during photographic recording are factors that cause distortion in the bite mark injury. This study aimed to explore the degree of distortion between a 'touch mark' (method 1) and a 'bite mark' (method 2) on the left upper arm at three different positions (arm relaxed; arm flexed in two different positions). A pair of dental casts with biting edges coated in ink was used to create a mark in 30 subjects (6 ♂, 24 ♀) aged 20-50 years old. Photographs were taken using a Nikon DX digital camera (D5000). The mesiodistal widths and angle of rotations of both upper right central incisor and lower right central incisor and the inter-canine distances were analysed and compared with the true measurements using Adobe Photoshop CC 2017. Statistical analysis was carried out using SPSS Statistics 22 applying a 2 (mark type) × 3 (position) repeated measures ANOVA. For all measures studied, there was a statistically significant difference between mark types and positions. In the case of bite marks, a great degree of distortion was detected, and this increased further when changing the position of the arm. The findings demonstrated that skin properties and posture influence distortion. This could lead to inaccurate measurements and misleading pattern interpretation of bite mark injuries.

Exploring bite marks on different types of skin tones / Explorando as marcas de mordida em diferentes tipos de tons de pele

The analysis of bite marks is a challenging and convoluted part of Forensic Odontology. Various interrelated factors such as location of the bite and skin elasticity complicate the bite mark analysis. The relationship between the bite mark and the biochemical properties of skin has been well-documented but there is need to consider the variety of skin tones as a factor to explore. The aim of this pilot study was to analyse the appearance of bite marks on 5 different types of skin tones of 15 subjects (6 males and 9 females) from 11 nationalities and age ranged from 21 to 46 years. A pair of 3D printed dental cast was transferred onto a mechanical apparatus for production of experimental bitemarks by using 12.5 kg of weight. Common imaging modalities including conventional, infrared and ultraviolet light were used to record the bite mark images for following visual assessment. The different skin tones were categorized using Fitzpatrick scale (1975) and a colour chart was used to compare the changes on skin after 15 minutes of bite registration. According to the results, the force was well tolerated by the subjects producing a well-defined bite mark, although males showed a less prominent mark than females irrespective of the skin tone and nationality. Neither bruises nor significant changes in the colour of bite mark could be appreciated among the subjects. The different types of skin tones did not affect the registration of bite mark applying a force of 122.5.N for 15 seconds in this sample

A análise das marcas de mordida é a parte mais desafiadora e complicada da Odontologia Forense. Vários fatores inter-relacionados, como a localização da mordida e a elasticidade da pele, complicam a análise da marca de mordida. A relação entre a marca de mordida e as propriedades bioquímicas da pele tem sido bem documentada, mas é preciso considerar a variedade de tons de pele como um fator a ser explorado. O objetivo deste estudo piloto foi analisar o aparecimento de marcas de mordida em 5 tipos diferentes de tons de pele de 15 indivíduos (6 homens e 9 mulheres) de 11 nacionalidades e idades entre 21 a 46 anos. Um par de modelos dentários impressos em 3D foi transferido para um aparelho mecânico para a produção de marcas de mordida experimentais usando 12,5 kg de peso. Modalidades de imagem digital como convencional, infravermelha e ultravioleta foram usadas para registrar as imagens da marca de mordida para posterior avaliação visual. Os diferentes tons de pele foram categorizados usando a escala de Fitzpatrick e uma cartela de cores foi usada para comparar as alterações na pele após 15 minutos de registro da mordida. De acordo com os resultados a força foi bem tolerada pelos sujeitos, produzindo uma marca de mordida bem definida, embora os homens mostraram uma marca menos proeminente do que as mulheres, independentemente do tom da pele e da nacionalidade. Nenhum hematoma ou mudanças significativas nas cores das marcas de mordida foram encontrados entre os indivíduos. Os diferentes tipos de tons de pele não afetaram o registro da marca de mordida aplicando uma força de 122,5 N por 15 segundos nesta amostra.

Forensic odontology in the 21st century - Identifying the opinions of those behind the teaching.

From the 19th century, society has been aided by Forensic Odontology and the teaching practice has rapidly expanded in the last 30 years. Information about academics and teaching topics can be found in literature but any research has never investigated the basic profile of lecturers by survey. The aim of this study was to explore the lecturers' opinions on teaching the subject in the 21st century and its current standing. Even though the number of forensic dentists is not low worldwide, not all are involved with teaching. A total of 36 dentists (26 males, 10 females) from 19 countries answered to a survey of eight-questions. Results showed a high prevalence of males (84.6% postgraduate) as opposed of 100% of women postgraduate. Forensic 'dental identification', 'overview of forensic dentistry' and 'DVI' were topics widely taught and 'bite mark analysis' was considered the most difficult one. The 'lack of funding' was the greatest limitation (36.1%) followed by 'lack of recognition and case work' (equally 30.6%). Past problems continue to jeopardize this field and forensic dental bodies should formally liaise with universities and dental councils for the complete expansion of it.

How Cross-Examination on Subjectivity and Bias Affects Jurors' Evaluations of Forensic Science Evidence.

Contextual bias has been widely discussed as a possible problem in forensic science. The trial simulation experiment reported here examined reactions of jurors at a county courthouse to cross-examination and arguments about contextual bias in a hypothetical case. We varied whether the key prosecution witness (a forensic odontologist) was cross-examined about the subjectivity of his interpretations and about his exposure to potentially biasing task-irrelevant information. Jurors found the expert less credible and were less likely to convict when the expert admitted that his interpretation rested on subjective judgment, and when he admitted having been exposed to potentially biasing task-irrelevant contextual information (relative to when these issues were not raised by the lawyers). The findings suggest, however, that forensic scientists can immunize themselves against such challenges and maximize the weight jurors give their evidence by adopting context management procedures that blind them to task-irrelevant information.

Correlation between bizygomatic and maxillary central incisor width for gender identification / Correlação entre a distância bizigomática e a espessura de incisivo central maxilar para identificação de gênero

Objective: The aim of the present study is to analyze and evaluate the applicability of bizygomatic and maxillary central incisor width in identifying the sex of an individual for anthropological studies. Material and Methods: The study was conducted on 100 individuals in a private dental institution. The width of the central incisor was measured by requesting the subject to bite onto a sheet of modelling wax. The bizygomatic width was calculated with the help of a divider by taking the most prominent area of the zygomatic arch as the reference point bilaterally. Berry's formula was used to calculate the width of the maxillary central incisor from the bizygomatic width. Berry's Formula "Width of the maxillary central incisor = Bizygomatic width / 16." The data obtained was tabulated and analyzed statistically. Results: The results in our study indicated that the widths of both maxillary central incisors and the bizygomatic width were found to be higher in males when compared to females with a positive strong correlation. Conclusion: The Berry's index can be used for identifying the gender and can also be used for facial reconstruction. (AU)

Objetivo: O objetivo do presente estudo é analisar e avaliar a aplicabilidade da distância bizigomática e espessura de incisivos centrais maxilares na identificação do sexo de um indivíduo para estudos antropológicos. Material e métodos: O estudo foi conduzido com 100 indivíduos de uma instituição odontológica privada. A espessura do incisivo central foi medida pedindo ao sujeito que mordesse em uma folha de cera. A espessura bizigomática foi calculada com o auxílio de uma régua pegando a área mais proeminente do arco zigomático como ponto de referência bilateralmente. A fórmula de Berry foi usada para calcular a espessura do incisivo central maxilar da espessura zigomática. Fórmula de Berry: "Espessura do incisivo central maxial = Espessura bizigomática / 16". Os dados obtidos foram tabulados e analisados estatisticamente. Resultados: Os resultados em nosso estudo indicaram que as espessuras de ambos os incisivos centrais maxilares como as espessuras bizigomáticas foram maiores no sexo masculino do que no sexo feminino, com uma correlação positiva forte. Conclusão: O índice de Berry pode ser usado para identificação de gênero e também pode ser usado para reconstrução facial. (AU)

A comparative study to investigate the effect of orthodontic treatment on the uniqueness of the human anterior dentition.

AIM: The human dentition contains many features which can be used to identify an individual from the dentition or from bite marks created and bite mark evidence may be used to link a suspect to a crime. The aim of this research was to investigate the effect of orthodontic treatment on the uniqueness of the human anterior dentition by comparison of the number of dental shape matches between pre- and post-treatment dental casts for a group of patients who have undergone orthodontic treatment (dental braces) to improve the alignment of their teeth. METHOD: This comparative study utilised pre- and post-orthodontic treatment dental casts from 36 patients. The dental casts were scanned and the anterior 6 teeth landmarked with 24 landmarks in total. The dental casts were divided into 4 groups: pre-orthodontic upper jaw (maxillary) and lower jaw (mandibular) and post-orthodontic maxillary and mandibular. Partial and full Procrustes analyses were undertaken to investigate the similarity between dental casts within each group and whether any of the comparisons were similar enough to be classified as a match. A landmarking repeatability study performed on a set of digitised dental casts determined the error of the landmarking procedure and allowed a proposed match threshold to be established. RESULTS: Orthodontic treatment reduced the uniqueness, and increased the similarity, between dentitions, as evidenced by a reduction in the maximum partial Procrustes distances in the post-orthodontic dental cast groups. None of the dental cast comparisons in the pre- or post-orthodontic maxillary or mandibular groups were classified as a match with the partial Procrustes analysis. However, many false positive matches (between 35 and 61) were identified within the post-orthodontic maxillary and mandibular groups using the full Procrustes analysis. CONCLUSIONS: Orthodontic treatment reduced the uniqueness of the human anterior dentition between different patients. There were no matches identified with the partial Procrustes analysis, but a large number of false positive matches were identified using the full Procrustes analysis. It is therefore proposed that full Procrustes analysis is unsuitable for this type of work and that only partial Procrustes analysis should be utilised.

Injury patterns of fatal bear attacks in Japan: A description of seven cases.

In recent years, the number of bear attacks has risen in Akita prefecture, Japan. Here, we present the injury patterns of seven fatal bear attacks, and discuss the implication of these findings. We included five cases of Asiatic black bear attacks and two cases of Ezo brown bear attacks. In all cases, the injuries, 2-5 parallel linear lacerations with severe hemorrhaging and decollement, were mainly located on the upper body. These injuries were thought to be fatal as, upon a first encounter, bears often stand and first attack the victim's head and face using their claws. Four lacerations were located at the vertex of the trapezoid in all cases, without severe hemorrhaging on the neck, extremities, or around the antemortem injuries. These injuries were thought to be bite marks incurred by the bears' four large canines, mainly occurring postmortem during the process of predation. These findings differed from those of fatal biting around the neck by other animals such as lions, mountain lions, or large-sized dogs. Further, laceration with avulsion of the skin was found in the inguinal region, without severe hemorrhaging. In some cases, the intestine had been removed from the inguinal injury for predation. In conclusion, the injuries of bear attacks are different from those caused by other animals, owing to the characteristics of bears. By investigating the injuries caused by fatal bear attacks, we can better understand the patterns of such injuries. Especially, the diameter between the canines is sometimes useful to estimate the size and the number of offending bears.

The reliability and validity of measurements of human dental casts made by an intra-oral 3D scanner, with conventional hand-held digital callipers as the comparison measure.

AIM: Intra-oral 3D scanning of dentitions has the potential to provide a fast, accurate and non-invasive method of recording dental information. The aim of this study was to assess the reliability of measurements of human dental casts made using a portable intra-oral 3D scanner appropriate for field use. METHOD: Two examiners each measured 84 tooth and 26 arch features of 50 sets of upper and lower human dental casts using digital hand-held callipers, and secondly using the measuring tool provided with the Zfx IntraScan intraoral 3D scanner applied to the virtual dental casts. The measurements were repeated at least one week later. Reliability and validity were quantified concurrently by calculation of intra-class correlation coefficients (ICC) and standard errors of measurement (SEM). RESULTS: The measurements of the 110 landmark features of human dental casts made using the intra-oral 3D scanner were virtually indistinguishable from measurements of the same features made using conventional hand-held callipers. The difference of means as a percentage of the average of the measurements by each method ranged between 0.030% and 1.134%. The intermethod SEMs ranged between 0.037% and 0.535%, and the inter-method ICCs ranged between 0.904 and 0.999, for both the upper and the lower arches. The inter-rater SEMs were one-half and the intra-method/rater SEMs were one-third of the inter-method values. CONCLUSION: This study demonstrates that the Zfx IntraScan intra-oral 3D scanner with its virtual on-screen measuring tool is a reliable and valid method for measuring the key features of dental casts.