Stabilisation of dental structures of severely incinerated victims at disaster scenes to facilitate human identification

Dental damage: Creating 3D anatomical models to illustrate destructive effects on human teeth

Forensic odontologists often must identify human remains with damaged teeth. This damage is due to high-impact accidents, violence, or disasters. This 2-part study aimed to create two 3D digital models. They should show the destructive effects of physical and chemical agents on human teeth and popular dental materials. Researchers created an e-survey to investigate how digital models are perceived as an educational tool for Forensic Odontology. Also, a systematic review assessed experimental studies on the effects of high temperature on various prosthodontic materials. According to the results of the survey, most participants (n=69; 79%) agreed that they would find a 3D model useful for training. Participants misidentify images of burned and broken teeth under Ellis and Davey system (1970). The systematic review identified dental implant and dental crown as the most studied prosthodontic materials exposed to heat. The researchers designed dental damage model 1 to represent restored and unrestored burnt teeth, postmortem pink teeth, and traumatic injuries. The dental damage model 2 was created to demonstrate the effects of various types of damage to different prosthetic and restorative dental materials, as well as the impact of acid, water, and burial on restorative materials as additional information. Both models were edited, sculpted and painted using 3D modelling software ZBrush (2020. 1.4) and Blender (version 3.6.2). The dental damage models were uploaded and labelled on Sketchfab (Cédric Pinson, Paris, France). The study's materials could transform the teaching of complex tooth changes.

The evidential value of dental calculus in the identification process

DNA analysis-based identification is by far the gold standard in forensic genetics and it should be performed in every case involving human remains or unidentified bodies. Bones and teeth are the preferred source of human DNA for genetic analysis. However, there are cases where the nature of the proceedings and historical significance prevent the disruption of skeletal structure. The remains may also be heavily degraded. In such situations, forensic geneticists seek alternative sources of human DNA. Teeth calculus has proven to be a viable source of DNA for identification purposes. The aim of this study was to assess the concentration of human DNA in teeth calculus and evaluate the usefulness of teeth calculus as a DNA source in the identification process. Teeth calculus was collected from skeletons exhumed between 2021 and 2022 by the PBGOT (Polish Genetic Database of Victims of Totalitarianism) team from the former Stalag IID prisoner-of-war camp in Stargard. Genetic analyses included the determination of autosomal and Y-STR markers. The total concentration of human DNA was also evaluated in samples from teeth calculus and teeth taken from the same individuals. The pilot study included 22 skeletons with a sufficient amount of calculus for isolation (specified in the protocol). Samples were taken from the largest areas of calculus deposited on lingual surfaces of mandibular incisors. The prepared samples underwent DNA extraction. Our study demonstrated that teeth calculus is a source of human DNA for remains from the World War II period. The obtained DNA concentration allowed for the determination of STR markers. It was shown that teeth calculus contains human DNA in an amount suitable for preliminary identification analyses.

The use of gelling agents to preserve burnt teeth within the dental alveoli for dental human identification - a study utilising sheep mandibles

Dental comparison is one of the primary methods of scientific identification of severely incinerated human remains. However, due to the fragile nature of the remains dental structures may be lost or damaged during recovery and transportation, limiting the amount of evidence available for examination. In addition to protecting the head, stabilization of the oral structures with an adhesive substance that will not interfere with the dental examination is ideal. A number of materials have been described in previous studies, however, no optimal method has yet to be indicated. Many of these materials contain petrochemicals, which have been shown to be a contamination risk. Wheatpaste solution has been demonstrated to be a viable alternative but has demonstrated handling issues and is not optimal in some environments. This study explores the stabilization of burnt teeth utilizing gelatin and agar solutions as alternatives to wheatpaste. Like wheatpaste solution, these materials are inexpensive, simple to use and are free from petrochemicals. Anterior sections of sheep mandibles were incinerated and subsequently solutions of agar, gelatin or wheatpaste were applied. The jaw fragments were then subjected to vibration and the number of teeth retained within the bone was recorded and compared to untreated incinerated jaw fragments. Although agar solution demonstrated serious handling issues, gelatin solution provided stabilization equivalent to that of wheatpaste. Gelatin also performed well at lower temperature conditions under which wheatpaste has been shown to perform poorly.

A comparative assessment of consolidation materials applied to burned bone

Fire-altered or fragmentary bone presents a challenge to forensic anthropologists and bioarchaeologists due to its characteristic friability. A potential solution to this problem is the use of consolidant materials on fragile osteological material, including burned remains. Although anthropologists and odontologists employ a variety of consolidant materials, there is no consensus regarding which material is most appropriate. Four easily obtained and commonly used consolidants, Acryloid™ B-72, Acrysol™ WS-24, Rhoplex™ B-60A, and Butvar® B-98, were compared to assess ease of material application and ability to stabilize burned bone. Each consolidant was applied to a subgroup of the study population at a 10% concentration. Total dry time per specimen, ease of solution preparation and application, and any alteration to the bone's appearance were recorded to assess the practical use of each material in field recovery settings. Nanoindentation, drop weight impact, and forced vibration tests were then performed to assess degree of stabilization. These tests were chosen to mimic possible real-world scenarios where burned bone may undergo damage during and after recovery, including repeated handling and transportation from the fire scene to the lab. Based on both qualitative and quantitative data collected, Acryloid™ B-72 is the most suitable consolidant tested to stabilize burned or fragmentary bone during recovery efforts. If the dry time for Rhoplex™ B-60A could be reduced by using a different solvent, such as acetone, Rhoplex™ B-60A would also be appropriate. Highly calcined areas, and targeted structures that could be utilized for positive identification, including teeth and the frontal sinus, should preferentially be consolidated with Acryloid™ B-72 in the field prior to recovery.