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.

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.

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.

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.

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.

DNA persistence of bite marks on food and its relevance for STR typing.

In forensic DNA analysis, salivary traces at crime scenes are a promising way to identify a person. However, crime scenes are oftentimes investigated a while after the crime and recovered samples might have been degraded leading to poor PCR amplification. Probably due to decomposition and negative visual impression of spoiled food, bite mark samples make up only a small part of our casework routine. In this study, bite marks on apples and chocolate bars as well as on an inert surface (microscope slide) were stored up to 3 weeks indoors and outdoors during different seasons and analyzed for amylase activity and DNA quantity and quality. The results underlined the stability of human nuclear DNA not only on inert but also on biological surfaces and their forensic usefulness even when bite marks are stored 21 days under adverse but realistic conditions at a crime scene. Overall, amylase activity as well as DNA quantity decreased over time depending on storage environment with a certain inter- and intrapersonal variation. But amylase activity testing was not found to be an appropriate screening tool for further analysis. Apple bite marks resulted in generally higher DNA amounts than chocolate bars and microscope slides. Although mold reduced the DNA quantity, complete STR profiles could be analyzed. High air humidity and cold temperatures were found to act preservative on raw food with high water content but caused loss of information over time for smooth inert surfaces and hygroscopic foods like sweets. Many factors are involved in the stability of DNA in bite marks and its resulting quality and quantity available for an STR analysis. However, since there was a substantial proportion of informative STR profiles even from bite marks stored for 21 days, the results encourage the analysis of those even if their visual appearance seems unfavorable.

[Double homicide with a damning bite mark on the offender´s body - case report]. / Dvojnásobná vrazda s usvedcujícím kousnutím na tele pachatele - kazuistika.

The authors deal with a case of a double homicide, the parental murder made by their older son, which was committed by a combination of stabbing and cutting wounds. The perpetra-tor tried to hide the bodies, so he doused them with gasoline and set fire to them on a lonely forest road. Then he ran over the remains by his car. The cause of death was in both cases open wound of the neck - autopsy findings of the woman´s body testified for a blood aspi-ration, on the man´s body it was not clear for a partial charring, so the possibilities were blood aspiration, air embolism or external bleeding with haemorrhagic shock. There were also many other injuries on the bodies, especially of the post-mortem origin. During the combat, one of the victims - the mother - bit the assailant´s left forearm. So a few days after creation the injury on murderer´s left upper extremity, the police technicians took photos and during the forensic autopsies of both bodies, authors created the impressions of the teeth. The utilities were loaned from Department of Stomatology of University Hospital Královské Vinohrady in Prague and they were designed for the general adult population. The work was more difficult for the state of mortal remains, which were damaged by combination of fire and blunt violence. However finally the impressions of each arch were made, and they were given to the experts from Institute of Criminalistic Prague, who compared them with pictures of the bite mark. The results of this analysis were used in a court as evidence against the perpetrator.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Forensic bitemark identification: weak foundations, exaggerated claims.

Several forensic sciences, especially of the pattern-matching kind, are increasingly seen to lack the scientific foundation needed to justify continuing admission as trial evidence. Indeed, several have been abolished in the recent past. A likely next candidate for elimination is bitemark identification. A number of DNA exonerations have occurred in recent years for individuals convicted based on erroneous bitemark identifications. Intense scientific and legal scrutiny has resulted. An important National Academies review found little scientific support for the field. The Texas Forensic Science Commission recently recommended a moratorium on the admission of bitemark expert testimony. The California Supreme Court has a case before it that could start a national dismantling of forensic odontology. This article describes the (legal) basis for the rise of bitemark identification and the (scientific) basis for its impending fall. The article explains the general logic of forensic identification, the claims of bitemark identification, and reviews relevant empirical research on bitemark identification-highlighting both the lack of research and the lack of support provided by what research does exist. The rise and possible fall of bitemark identification evidence has broader implications-highlighting the weak scientific culture of forensic science and the law's difficulty in evaluating and responding to unreliable and unscientific evidence.

Inconsistency in opinions of forensic odontologists when considering bite mark evidence.

There has been controversy surrounding the principles of bite mark analysis, and also the opinions reached by forensic odontologists. The purpose of this study was to assess the consistency of opinions formed by forensic odontologists, both for individual odontologists after a period of time, and between odontologists. 23 forensic odontologists participated, and opinions on 4 cases per member were requested. The request was then repeated after a 8 week period. Results highlighted an inconsistency in opinions between odontologists, and also an inconsistency in opinion for individual members over time, even for experienced odontologists. Inconsistencies varied from whether the mark could be from human or animal, and also from adult or child. In conclusion, the authors recommend that bite mark evidence should be treated with caution.