Alex Forrest

Age-related changes in maxillary and mandibular cortical bone thickness in relation to temporary anchorage device placement

BACKGROUND The aim of this study was to investigate the correlation between alveolar bone cortical thickness (ABCT) and age in the maxillae and mandible in humans. This information could then be translated into clinical application with temporary anchorage devices (TADs) in orthdontics. METHODS Samples comprised 82 post-mortem CT datasets (41 males and 41 females) aged between 11 to 50 years, and were divided into five different age groups and gender. Alveolar ABCT was measured in the labial/buccal and palatal/lingual sides of the incisor, canine, premolar, molar and tuberosity/retromolar regions of the maxillae and mandible. Correlations between ABCT and age and gender were analysed with linear regression analysis. RESULTS Strong correlation between ABCT and age was found for the maxilla on the labial side of the maxillary incisor region (p < 0.001). On the palatal aspect, significant correlations between ABCT and age were found in the maxillary incisor and maxillary premolar regions (p = 0.01 and p = 0.047 respectively). Significant correlation between ABCT and gender was found only at the buccal aspect of the maxillary molar region (p = 0.022). In the mandible, a statistically significant correlation between ABCT and age was found in the cortical bone of the labial side of the mandibular incisor region (p = 0.017). However, statistically significant negative correlation between ABCT and age was found in the mandibular canine region (p = 0.033). The only site to demonstrate a significant difference in change in ABCT with age between males and females was the lingual side of the retromolar region, in which female ABCT increased more than in males (slope = 0.015). CONCLUSIONS There is minimal clinically significant correlation between ABCT and age at the alveolar bone level. Although investigations show statistically significant correlations, these may not be clinically significant as those regions are not ideal for anchorage reinforcement with TADs in orthodontic practice.

Collection and recording of radiological information for forensic purposes

Forensic odontology is the application of dental expertise to legal issues. Commonly, it involves the comparison of dental records of a missing person with a deceased individual for the purposes of forensic personal identification, either in a single case, or as part of the response to an event involving multiple simultaneous fatalities (Disaster Victim Identification, or DVI). It may also involve studies to determine the age of an individual, which may be required as part of a forensic identification process, or for another legal purpose such as the determination of legal responsibility, or in connection with immigration. This report examines the types of radiological information currently used in such forensic studies, and discusses how this information may be accessed or recorded, as well as the techniques that are commonly applied to the radiological data to reach a satisfactory outcome for application in forensic casework.

Endodontic imaging as an aid to forensic personal identification.

Identification by dental comparison between records of a missing person and the dentition of a deceased individual depends on recognition of concordant features common to both with no unexplained discrepancies. While written dental records are commonly used for this task, we believe they should not be the preferred basis of comparison because they do not derive directly from an individual and are potentially prone to errors, inaccuracies and misinterpretation. Images, however, are a direct representation of a physical item, and are an objective method of recording information. Radiographs are images that capture the unique morphological features of teeth, surrounding structures and physical detail of past dental treatment resulting in changes to a dentition. Taking post-mortem radiographs in such a way as to duplicate as closely as possible the conditions under which the ante-mortem radiographs were produced, permits demonstrably rigorous methods of comparison, raising the probative value of the outcome. In this context post-treatment endodontic radiographs present a particularly rich source of features on which individuation can be achieved, especially considering that alteration of endodontic restorations happens less frequently than is the case with intra-coronal restorations. We illustrate various techniques with a series of cases and discuss the parameters for success.

Hereditary angioedema: death after a dental extraction

Hereditary angioedema (HAE) is a group of three uncommon and potentially fatal conditions, each of which is transmitted as a somatic dominant trait. A recognized trigger to attacks is dental treatment, with tooth extraction frequently reported in the published work. The clinical symptoms may not manifest for many hours or even days after the procedure. We describe a recent case in Australia in which death resulted from HAE following dental extraction, and we discuss its post-mortem presentation and diagnosis, highlighting the need for dental practitioners to be aware of this condition.

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.

Detection of Tooth‐Colored Restorative Materials for Forensic Purposes Based on Their Optical Properties: An In Vitro Comparative Study

Victim identification using dental records involves antemortem and postmortem comparison of dental charts. Since dental restorations may be part of such records, identifying them accurately is critical. The objective of this study was to compare the diagnostic reliability and validity of two optical methods for identifying tooth‐colored restorations (digital imaging fiber optic transillumination (DiFOTI) using near infrared light, and fluorescence‐aided identification of restorations (FAIR)) with conventional diagnostic methods. Four examiners identified and charted tooth‐colored restorations in three sets of typodonts on the bench using conventional visual and tactile examination, DiFOTI (DIAGNOcam™) and FAIR. All examinations were repeated after 4 weeks. Both the sensitivity (95%) and specificity (97%) of the FAIR method were significantly higher than those for DiFOTI (82% and 82%) and for conventional inspection (71% and 82%). In conclusion, FAIR method performed better than conventional examination and DiFOTI, and was more reliable for identifying tooth‐colored restorations.

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.

The incidence of public sector hospitalisations due to dog bites in Australia 2001–2013

Objective: To estimate the incidence of dog bite‐related injuries requiring public sector hospitalisation in Australia during the period 2001–13.

Death in the dental chair

Patients may die in the dental chair or the operating theatre during dental procedures, or subsequently as a cause of dental treatment. This presentation discusses some of the causes of such deaths and explores their features.