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.

Traumatic complete outer ear amputation by human bite, a forensic case report and review of the literature.

We present a case of a complete external ear amputation, caused by a human bite, that took place during a quarrel in a local farmers' market. The male victim was transferred to the Hospital. After surgical reattachment of the auricle, a forensic clinical examination was performed, as per legal obligation. During examination, the victim was found to have sustained: contusions of the orbital regions (lower eyelids), bilaterally, soft tissue oedema of the forehead (to the left of the middle line), and contusion of the right neck area. He also sustained multiple soft tissue injuries (contusions, abrasions) on the torso and on both upper and lower extremities. Clinical forensic examination of human bite injuries requires thorough description of the wound, proper photography and possibly collection of swabs for DNA identification (in case of unknown perpetrator). Nevertheless, the Forensic Pathologist is often required to perform clinical examination, only after medical care has been provided. Therefore, clinicians should be aware of the need of proper documentation and act accordingly.

Uniqueness of the anterior dentition three-dimensionally assessed for forensic bitemark analysis.

The uniqueness of the human dentition (UHD) is an important concept in the comparative process in bitemark analysis. During this analysis, the incisal edges of the suspects' teeth are matched with the bitemarks collected from the victim's body or crime scenes. Despite playing an essential part to exclude suspects, the UHD contained in the involved incisal tooth edges remains an assumption on bitemark level. The present study was aimed, first, to investigate three-dimensionally (3D) the UHD within different quantities of dental material from the incisal edges; second, to test these outcomes in a bidimensional (2D) simulation. Four-hundred forty-five dental casts were collected to compose 4 study groups: I - randomly-selected subjects, II - orthodontically treated subjects, III - twins and IV - orthodontically treated twins. Additionally, 20 dental casts were included to create threshold groups on subjects from whom the dental impressions were taken at 2 different moments (Group V). All the dental casts were digitalized with an automated motion device (XCAD 3D® (XCADCAM Technology®, São Paulo, SP, Brazil). The digital cast files (DCF) were integrated in Geomagic Studio® (3D Systems®, Rock Hill, SC, USA) software package (GS) for cropping, automated superimposition and pair-wise comparisons. All the DCF were cropped remaining 3 mm (part 1), 2 mm (part 2) and 1 mm (part 3) from the incisal edges of the anterior teeth. For a 2D validation, slices of 1 mm, not including incisal edges (part 4), were also cropped. These procedures were repeated in Group V, creating specific thresholds for each of the study parts. The 4 study groups were compared with its respective threshold using ANOVA test with statistical significance of 5%. Groups I, II and III did not differ from the corresponding threshold (Group V) in all study parts (p > 0.05). Scientific evidence to support the UHD was not observed in the current study. Bitemark analysis should not be disregarded but considered carefully when the suspects present similar dental alignment and morphology, such as in orthodontically treated subjects and twins, respectively.

An analysis of dental intercanine distance for use in court cases involving bite marks.

High levels of crime in South Africa and the resulting court cases requiring bite mark evidence have necessitated continuous research into the prevalence and interrelationship of recognisable dental features present in bite marks. This study represents the largest data set of descriptive statistics related to intercanine distance, in which the means, standard deviations, medians and interquartile ranges across four racial groups were determined. Intercanine distances were also statistically weighted by determining the common, uncommon and very uncommon values for each of the racial groups. The results of this research show that we can consider any maxillary intercanine distance more than 24.1 mm and less than 43.0 mm to represent a human bite mark. Black males had the largest mean (average) intercanine distance of 36.33 mm (standard deviation 2.49 mm) and white females the smallest mean intercanine distance of 33.4 mm (standard deviation 2.13 mm). The analyses showed statistically significant differences between the mean intercanine distances of different race and gender groupings. The authors do not advocate trying to determine the race or gender from intercanine distances determined, but rather the relevance of the intercanine distances in the specific race and gender groupings. This study makes a meaningful scientific contribution to the presentation of bite mark evidence at a time when subjective opinions need to be replaced with scientific data.

Plasty of Human bites induced full thickness large area eyelid defects.

Large area eyelid defects induced by human biting was rare. A 43-year-old man was bited by a human. His Blepharocoloboma size was 60% percent of the upper eyelid, the horizontal defect length of defect area was 25mm, the vertical height was 5mm,a small mass like lateral eyelid tissue was left on the Lateralis lid margin. The toughness of this lateral eyelid tissue was enough to support the lateral canthus tissue transfered to the same area then the lateral eyelid tissue was sutured with the remaining sclera after which the sclera-conjunctiva was reconstructed. The skin tranfering from lateral canthus was sutured with conjunctiva without exposing. Eyelid defect was effectively repaired. The technique of lateralis cantholysis association with self remaining lateral eyelid tissue version was manifested an alternative and useful procedure for the reconstruction of large area upper full thickness eyelid defects.

Locard's Principle of Exchange, Dental Examination and Fragments of Skin.

The transfer of materials between victim and perpetrator was first reported by Locard in the nineteenth century. While in recent years DNA testing has been very successful in matching biological material from crime scenes to perpetrators, the following cases demonstrate that other more time-honored methods remain useful. Two cases of lethal assault are reported where the victims had bitten their assailants resulting in fragments of the perpetrators' skin being wedged between their teeth which were discovered during post mortem oral examinations. As the fragments were able to be matched to injuries in the perpetrators, identification was established prior to confirmatory DNA testing. In case 1 a criminal conviction for manslaughter resulted, and in case 2 the identity of the assailant was confirmed. Examination of a properly exposed and illuminated oral cavity may provide useful evidence in assault cases. These cases represent an unusual dental variant of Locard's principle.

Effects of skin elasticity on bite mark distortion.

Bite marks have been reported to have an evidentiary value similar to fingerprints. We believed bite mark distortion would impact the accuracy and reliability of bite mark interpretation. Inked denture-stamps were substituted for actual bite marks and were placed onto 40 participating volunteers' shoulders. Four changes in arm position were photographed using an ABFO #2 reference scale. The measurements of individual tooth widths and intercanine distances in each position were compared. The maximum tooth width distortion observed was 53.8%, whereas the maximum intercanine distance distortion was 41.9%. Distortion was found to increase with age and weight and was non-uniform across a dental arch.

Human Bite-induced Cellulitis Due to Streptococcus pyogenes.

The rate of infection after a human bite is 10%-30%. Streptococcus spp. are the most common pathogens that may cause serious infections, such as necrotizing fasciitis. The authors describe a 5-year-old girl admitted to the emergency room with cellulitis due to S. pyogenes after human bites. She presented with fever and pain in her left arm, and her medical history revealed a human bite by her cousin on the arm 3 days prior. The wound culture yielded S. pyogenes. She was successfully treated with intravenous ampicillin-sulbactam regimen. S. pyogenes may cause serious wound infections following human bites. In such cases, the patient should be closely followed. Chemoprophylaxis should be initiated in an appropriate clinical setting to prevent secondary bacterial infections. This case was first reported as cellulitis due to S. pyogenes after a human bite.

The uniqueness of the human dentition as forensic evidence: a systematic review on the technological methodology.

The uniqueness of human dentition is routinely approached as identification evidence in forensic odontology. Specifically in bitemark and human identification cases, positive identifications are obtained under the hypothesis that two individuals do not have the same dental features. The present study compiles methodological information from articles on the uniqueness of human dentition to support investigations into the mentioned hypothesis. In April 2014, three electronic library databases (SciELO®, MEDLINE®/PubMed®, and LILACS®) were systematically searched. In parallel, reference lists of relevant studies were also screened. From the obtained articles (n = 1235), 13 full-text articles were considered eligible. They were examined according to the studied parameters: the sample size, the number of examined teeth, the registration technique for data collection, the methods for data analysis, and the study outcomes. Six combinations of studied data were detected: (1) dental shape, size, angulation, and position (n = 1); (2) dental shape, size, and angulation (n = 4); (3) dental shape and size (n = 5); (4) dental angulation and position (n = 2); (5) dental shape and angulation (n = 1); and (6) dental shape (n = 1). The sample size ranged between 10 and 1099 human dentitions. Ten articles examined the six anterior teeth, while three articles examined more teeth. Four articles exclusively addressed three-dimensional (3D) data registration, while six articles used two-dimensional (2D) imaging. In three articles, both imaging registrations were combined. Most articles (n = 9) explored the data using landmark placement. The other articles (n = 4) comprised digital comparison of superimposed dental contours. Although there were large methodological variations within the investigated articles, the uniqueness of human dentition remains unproved.

Accuracy of 3D scanners in tooth mark analysis.

The objective of this study was to compare the accuracy of contact and laser 3D scanners in tooth mark analysis. Ten dental casts were scanned with both 3D scanners. Seven linear measurements were made from the 3D images of dental casts and biting edges generated with DentalPrint© software (University of Granada, Granada, Spain). The uncertainty value for contact 3D scanning was 0.833 for the upper dental cast and 0.660 mm for the lower cast; similar uncertainty values were found for 3D-laser scanning. Slightly higher uncertainty values were obtained for the 3D biting edges generated. The uncertainty values for single measurements ranged from 0.1 to 0.3 mm with the exception of the intercanine distance, in which higher values were obtained. Knowledge of the error rate in the 3D scanning of dental casts and biting edges is especially relevant to be applied in practical forensic cases.

Auricular reconstruction after human bite amputation using the Baudet technique.

OBJECTIVE: This study aimed to present a case of a successful re-implantation of an amputated auricle following a human bite using the Baudet technique. METHODS: Case report and review of the literature. RESULTS: The patient had a very satisfactory postoperative result in terms of appearance and function of the reattached auricle. Cartilage loss was minimal. CONCLUSION: Reattachment of an amputated auricle as a composite graft following a traumatic human bite is feasible. The Baudet technique is a simple alternative that avoids the complexity of microsurgical anastomosis while improving upon the high failure rate associated with simple reattachment.

[Love bite on the neck resulted in an embolic stroke].

A 35-year-old woman experienced sudden onset of right-sided weakness due to a left middle cerebral artery stroke 12 hours after she had obtained a love bite on the left side of her neck. Duplex ultrasonography showed a near-occlusion of the left internal carotid artery (ICA) and CT angiography revealed a mural thrombus at the same location. This case report shows that love bites on the neck are a rare cause of embolic stroke. The most likely aetiology is embolization of thrombus material from a local intimal lesion of the ICA.

Using an unconventional perfusion pattern in ear replantation-arterialization of the venous system.

Ear amputation is a devastating injury characterized by a conspicuous deformity that is not easily concealed and can result in tremendous psychological trauma in addition to the physical insult. While numerous different approaches have been proposed, microvascular replantation is widely considered to deliver the best esthetic outcome. In this article, the authors report a case in which an unconventional perfusion pattern (i.e., arterialization of the venous system) was chosen, as intraoperative anatomic conditions precluded conventional vascular reconstruction. A 25-year-old male patient sustained a human bite resulting in subtotal amputation of his left ear. In the setting of an adequate arterial donor vessel, that is, branch of the posterior auricular artery, and a single suitable recipient vein (0.4 mm), the decision was made to perform an end-to-end arterio-venous anastomosis without the use of vein grafts. Medicinal leeches were applied postoperatively to provide for venous drainage. The ear survived and the patient was discharged after 14 days. To the best of our knowledge, this is first case of a subtotal ear amputation that was successfully replanted by arterialization of the venous system without the use of vein grafts and with preservation of the superficial temporal vessels.

Does contextual information bias bitemark comparisons?

A growing body of research suggests that the interpretation of fingerprint evidence is open to contextual bias. While there has been suggestion in the literature that the same might apply to bitemarks - a form of identification evidence in which a degree of contextual information during the comparison phase is generally unavoidable - there have so far been no empirical studies to test this assertion. We explored dental and non-dental students' ability to state whether two bitemarks matched, while manipulating task ambiguity and the presence and emotional intensity of additional contextual information. Provision of the contextual information influenced participants' decisions on the ambiguous bitemarks. Interestingly, when participants were presented with highly emotional images and subliminally primed with the words 'same' and 'guilty', they made fewer matches relative to our control condition. Dental experience also played a role in decision-making, with dental students making more matches as the experiment progressed, regardless of context or task ambiguity. We discuss ways that this exploratory research can be extended in future studies.

Self inflicted human teeth bites: a case report.

Human infighting has been a part of our civilization since times immemorial. These incidences may go unnoticed or may attract attention of law enforcing agencies depending upon the severity of the offence. Though weapons are generally employed to inflict injuries, rare cases have been reported in literature where human teeth have been used to serve this purpose. Human bites may be self inflicted or self suffered in connivance with others to level an allegation against an adversary. We are presenting here such a case where such injuries were produced to bring a false charge against a neighbor.

Development of a methodology for the standardisation and improvement of 'Smartphone' photography of patterned bruises and other cutaneous injuries.

Human bite-mark analyses can play a prominent role in forensic case investigations, including those involving sexual assault. High-quality photographs routinely secure a link between a bite-mark and an individual's dentition. Access to around the clock forensic photography, however, is often limited, resulting in delay and/or missed opportunities to record valuable evidence. The emergence of Smartphone high-quality photographic technology now provides a previously unimagined opportunity to gather timely forensic photographic evidence. Problems can arise, however, due to the relatively poor quality of the photographs, as a result of many of those taking photographs having received little or no forensic photography training. This study compares unassisted photography with assisted photography, by a specifically developed camera application (App), to provide a standardised method for taking forensic photographs. An App, written in Java, was hosted on the Google Android Operating System, on a Samsung Galaxy SII Smartphone. Twenty-four volunteers participated in a study to photograph a pseudo bite-mark using three methods, (1) unassisted (as a control), (2) assisted by an ABFO No.2 right-angled photographic reference scale and (3) assisted by the App. The App, method (3), was shown to consistently outperform methods (1) and (2), demonstrating greater standardisation and precision (p<0.001). Analysis of the data showed the extent to which acquiring an accurate photograph depends on the image being orthogonal to the camera. It appears likely that the relatively inaccurate photographs acquired by methods (1) and (2), were as a result of deviation from the plane, orthogonal to the bite-mark. Therefore, the App was successful in ensuring that the camera was both orthogonal and at an appropriate distance, relative to the bite-mark. Thus, the App enhanced the abilities of non-experts to acquire more accurate photographs and created the potential to significantly improve the quality of forensic photographs.

Effect of systematic dental shape modification in bitemarks.

Studies on human cadaver models have reported significant levels of distortion of bitemarks in skin, indicating that tooth characteristics are not reliably transferred and recorded in the bitten subject. Moreover, matches among the anterior biting dentition in open population studies have been found. This prompts the question as to what degree of difference in shape will distinguish one dentition from another as reflected in a bitemark. In order to understand how these variables appear on skin, 10 dental casts with systematic variations in tooth positions were produced. The height of the lateral incisors was systematically altered in 1mm increments up to 3mm and lateral incisor/canines were altered in facial/lingual displacement in 1mm increments up to 5mm. Each of the models was used to produce a series of 10 repeated bites, distributed over arms and legs of un-embalmed cadavers. Landmark-based geometric morphometrics were used for analysis of digital images of the bitemarks. Results indicate that alterations of height and displacement of particular teeth affected the position of impressions created by the adjacent teeth. Displacement of one lateral incisor/canine led to a relative shift in impressions of the central incisors and unaltered canines, while height alteration of the lateral incisors led to a shift in relative position of central incisors as recorded in the bitemark. The prominence of displacements was more pronounced in the bitemarks than in images of the dentition used to make the bites, thus the bitemarks tended to exaggerate the differences. It was found that a displacement of 5mm between teeth allowed for reliable distinction between bitemarks. No such threshold of distinction could be established for differences in height of teeth under these experimental conditions. The effect of distortion was more significant in the mandibular than maxillary arch, suggesting that the mandible exhibits higher variation than the maxilla, as impressed in skin. Numerous bitemarks also exhibited arch flattening, consistent with recent studies showing arch width as the principal variable in a bitemark.