Forensic Dentistry: A Review of its Scope and Application

Artificial neural networks reconstruct missing perikymata in worn teeth

Dental evolutionary studies in hominins are key to understanding how our ancestors and close fossil relatives grew from the early stages of embryogenesis into adults. In a sense, teeth are like an airplane's 'black box' as they record important variables for assessing developmental timing, enabling comparisons within and between populations, species, and genera. The ability to discern this type of nuanced information is embedded in the nature of how tooth enamel and dentin form: incrementally and over years. This incremental growth leaves chronological indicators in the histological structure of enamel, visible on the crown surface as perikymata. These structures are used in the process of reconstructing the rate and timing of tooth formation. Unfortunately, the developmentally earliest growth lines in lateral enamel are quickly lost to wear once the tooth crown erupts. We developed a method to reconstruct these earliest, missing perilymata from worn teeth through knowledge of the later-developed, visible perikymata for all tooth types (incisors, canines, premolars, and molars) using a modern human dataset. Building on our previous research using polynomial regressions, here we describe an artificial neural networks (ANN) method. This new ANN method mostly predicts within 2 counts the number of perikymata present in each of the first three deciles of the crown height for all tooth types. Our ANN method for estimating perikymata lost through wear has two immediate benefits: more accurate values can be produced and worn teeth can be included in dental research. This tool is available on the open-source platform R within the package teethR released under GPL v3.0 license, enabling other researchers the opportunity to expand their datasets for studies of periodicity in histological growth, dental development, and evolution.

Forensic applications: Fluorescence properties of tooth-coloured restorative materials using a fluorescence DSLR camera

The objective of this study was to compare the fluorescence properties of dry and wet samples of contemporary tooth-coloured restorative materials using a fluorescence based DSLR camera and a variety of LEDs emitting different wavelengths of visible light as excitation sources. The materials examined included resin composites; ceramics and hybrid restorative materials such as ormocers, Vita Enamic™ and resin reinforced glass-ionomer cements. The levels of fluorescence for each sample under different combinations of incident light wavelengths and filters was analysed by using histogram data for colour channels from Adobe Photoshop software. Fluorescence patterns were influenced by water sorption of the materials. UV-A/Violet light (405±nm) produced the greatest range of luminosity values (10-204) amongst the tooth-coloured restorative materials, and showed the greatest differences between restorations and tooth structure. The best filter combinations with violet light were orange or yellow filters. Under ultraviolet excitation, Fuji VIII A2 exhibited a unique bright pink fluorescence emission, while VitaEnamic™, ormocer and glass-ionomer cements emitted bluish-pink fluorescence emissions. In conclusion, restorative materials exhibited varied emission pattern under UV-A (405nm) light, which enables their detection and differentiation from natural tooth structure.

Antemortem and postmortem nonapposite data--a multidisciplinary identification strategy

Identification of human remains is often achieved by comparing documented reference data with the same type of evidence obtained from the remains. We present a case of a decomposed unidentified body, whose identity was presumed but because of the low validity range of the available data, the identification process could not be completed. Antemortem radiographs of the teeth found in the house of the reputed victim could not be compared to the edentulous cadaver and the kinship between the victim and the only living relative that could provide DNA for comparison was too tenuous. Isolated teeth found at the scene, were neither a source of DNA reference information nor questioned data to be compared to the antemortem radiographs. The strategy implemented by the investigators to reallocate the status of the isolated teeth from the questioned source to the reference source of DNA to be compared with the cadaver is presented.

Forensic dental identification

Identification of deceased persons is the most common role of the forensic dentist. Forensic physical comparison of antemortem and postmortem dental data is used to establish that a found body and a missing person are one and the same to a high degree of certainty. An overview of this role is presented as a review of dental identification.