Toward the adoption of cementochronology in forensic context.

Because acellular dental cementum is considered to be formed continually throughout life and to not undergo remodeling processes, cementochronology is considered to be a method with the potential for directly assessing chronological age. Considering that most previous studies on humans have assumed the superior performance of this method, it is surprising that this technique is not more widely adopted in anthropology. To understand this controversy, we highlight that there is no standardized procedure for sample preparation. The numerous technical approaches that exist impact the reliability of the method, and the recent creation of an international work group (Cementochronology Research Program) demonstrates the need for researchers to share their experience to overcome these obstacles. This paper aims to address this paradox by debating the aspects that contribute to the limited use of this method and by illustrating its potential through an application on forensic cases. A protocol, which was recently certified according to the ISO-9001, was applied to nine anthropological cases from the Forensic Medicine Institute of Lille (northern France) and compared with routine osteological and dental methods. The results show that traditional methods matched the known age due to the wide extent of their range, while the accuracy and precision of cementochronological estimates was also notable. This paper establishes that cementochronology may serve as a particularly important tool for age estimation for forensic anthropologists and should, at least, be used in addition to other methods.

Age-at-death estimation of pathological individuals: A complementary approach using teeth cementum annulations.

Bioarchaeologists rely on accurate estimations of age-at-death. Clearly, some pathological conditions are associated with gross morphological changes in the skeleton that could impact the effectiveness of age-at-death estimation (i.e. methods based on the pelvis, fourth rib, dental attrition, and cranial stenosis). The magnitude of this problem has not been widely studied due to a paucity of pathological skeletons of known age. We assessed age-at death for three individuals affected by bone dysplasias (achondroplasia, residual rickets, osteogenesis imperfecta) using cementum annulations and several osseous age indicators. We predicted osseous indicators that are based on gross morphological changes would yield age estimates discrepant from the cementochronology. Results demonstrated considerable differences in age estimates between morphological and histological techniques suggesting a need for additional research on the effects of pathology on the accuracy of morphological methods. Conversely, we addressed the proposition that cementum annulations will be inappropriate for age estimation in cases of chronic and severe rhino-maxillary infection and periodontitis. We assessed age-at-death for one individual with leprosy and found no indication the disease process affected cementum formation or preservation. The results of this research indicate the potential value of cementochronology in cases where skeletal pathological conditions constrain the usefulness of traditional age estimation approaches.

Use of larder beetles (Coleoptera: Dermestidae) to deflesh human jaws.

We describe new experimental data for the defleshing of human bones using larder beetles (Dermestes haemorrhoidalis) (Küster, 1852). Although the ability of larder beetles to feed on vertebrate remains has been, and still is, used by taxidermists to deflesh skulls and bones, this method has never been documented from a quantitative perspective and has over time become ignored in most forensic anthropology or odontology laboratories. To promote the rational and efficient use of this method, we performed experiments to estimate the quantity of food consumed by larvae. From the 2nd instar to nymphosis, each larva consumed a mean of 0.13±0.03 g of dry beef muscle. We then used 100±50 D. haemorrhoidalis adults and 100±50 larvae to deflesh human maxillae and mandibles sampled within a forensic context (victim identification). Each sample was weighed and photographed before, during and after the experiment. According to our experiments, 20-25 days were sufficient to completely deflesh all of the samples. We concluded that a small number of larder beetles can be used to efficiently deflesh human jaws. According to this result, the use of larder beetles appears to be an inexpensive, simple and efficient way to clean mandibles and maxillae. Furthermore, this method is DNA-safe (compared to usual maceration techniques) and thus allows the samples to be used for subsequent DNA and drug analyses.

3D-MSCT imaging of bullet trajectory in 3D crime scene reconstruction: two case reports.

Postmortem investigations are increasingly assisted by three-dimensional multi-slice computed tomography (3D-MSCT) and have become more available to forensic pathologists over the past 20years. In cases of ballistic wounds, 3D-MSCT can provide an accurate description of the bullet location, bone fractures and, more interestingly, a clear visual of the intracorporeal trajectory (bullet track). These forensic medical examinations can be combined with tridimensional bullet trajectory reconstructions created by forensic ballistic experts. These case reports present the implementation of tridimensional methods and the results of 3D crime scene reconstruction in two cases. The authors highlight the value of collaborations between police forensic experts and forensic medicine institutes through the incorporation of 3D-MSCT data in a crime scene reconstruction, which is of great interest in forensic science as a clear visual communication tool between experts and the court.

Typical external skull beveling wound unlinked with a gunshot.

Lesions of the cranial vault resulting from firearms are traditionally described in forensic medical literature with many reports illustrating atypical bone lesions carried out to the skull by gunshot wounds. The authors present this report which illustrates an external beveled skull wound, associated with internal beveling damage, caused by a stabbing injury. A partially buried human skeleton was found in a forest. The examining of the skull revealed a hole resembling the exit wound caused by a bullet and two other smaller stab wounds. No typical entering bullet wound and no other bone lesions were found. During the course of the investigation, one of the perpetrators admitted to hitting the victim, using a sickle, and to hiding the body. For this purpose, he dragged the corpse with the sickle still implanted in the skull, using it as a hook. Upon retrieving the sickle, a piece of cranial vault was removed, thus creating an external beveled wound. In order to identify the mechanism which brought about this kind of lesion, experimental work was carried out on a human skull. In this particular case, the tip of the sickle penetrated into the bone, creating a lesion that would typically be produced with a stabbing instrument when applied with vertical force. When the body was dragged, using the sickle as a hook, this was a hand-produced vertical force, which was applied in the opposite direction. It caused the tearing of a piece of bone and the creation of an outer bevel. This atypical lesion should be made known to medical examiners and pathologists in order to help investigating and understanding of the circumstances of injuries.

Experimental study of the expansion dynamic of 9 mm Parabellum hollow point projectiles in ballistic gelatin.

We study in this paper the expanding behaviour of hollow point 9 mm Parabellum projectiles (Hornady XTP(®) and Speer Gold Dot(®)). We defined a deformation rate that takes into account both the diameter increase and the length reduction. We plotted the behaviour of this parameter versus impact velocity (we refer to this curve as the expanding law). This expanding law has been plotted for different gelatin weight ratios and different gelatin block lengths. We completed our experiments with a set of high speed movies in order to correlate the deceleration to the state of expansion and size of the temporary cavity. Our results pointed out that full expansion is reached shortly after the projectile fully penetrates the gelatin. This result shows that the key point to accurately simulate human body interaction with a hollow point projectile is to accurately simulate the interface (skin, skull, clothes thoracic walls). Simulating accurately organs is only an issue if a quantitative comparison between penetration depths is required, but not if we only focus on the state of expansion of the projectile. By varying the gelatin parameters, we discovered that the expanding law exhibits a velocity threshold below which no expansion occurs, followed by a rather linear curve. The parameters of that expanding law (velocity threshold and line slope) vary with the gelatin parameters, but our quantitative results demonstrate that these parameters are not extremely critical. Finally, our experiments demonstrate that the knowledge of the expansion law can be a useful tool to investigate a gunshot in a human body with a semi-jacketed projectile, giving an estimation of the impact velocity and thus the shooting distance.

An original case of tin dental fillings from 18th century northern France.

During the 18th century, France was the leader in the field of dentistry, exemplified by Pierre Fauchard (1678-1761), who was given the title "the father of modern dentistry" for his comprehensive work, Le Chirurgien Dentiste. This paper examines an 18th century dental treatment in a barely 50-year-old male whose body was excavated from Saint Amé's Collegiate Church, Douai, France. This individual had 6 dental restorations, exceptional for that period. All fillings were on the occlusal surfaces of molars and extended at least to the superficial dentin. Panoramic and retro-alveolar radiography confirmed the presence of a radio-opaque filling material, and x-ray fluorescence (XRF) and x-ray diffraction analyses demonstrated the exclusive presence of tin in these restorations.