Reality bites--A ten-year retrospective analysis of bitemark casework in Australia

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.

Benchmarking forensic rulers and photographic techniques

Measuring various items (evidence) at the scene of an investigation, exposed to the elements, is an instrumental part of systematic forensic science. The key to these measurements often rest on rulers, and a knowledge of their limitations is vital to their appropriate application. The aim of this study was to test forensic ruler accuracy and photographic distortion under conditions that simulate common use to provide a foundational basis for baseline accuracy of their use. A series of ABFO rulers from 2 anonymous manufactures were tested against gold standards for accuracy at various temperatures (-14, 0, 25 and 40 °C). At the same time a series of rulers were photographed at different angulations to test reproducibility and angular distortion. At room temperature a variation of 0.28% in the dimensions of the rulers were found with larger distortions at colder temperatures. Photographs taken with the camera above the rulers suffered the least distortion (approximately 6-10°) and there was no difference over time, nor with ruler background colour. The results from this study show that further investigation is required into preventing angular distortion, and show the need for increased training to those who would be in a situation requiring them to document the scene of a crime.

Envelopment technique and topographic overlays in bite mark analysis

Aims and Objectives:

The aims and objectives of our study were to compare four sequential overlays generated using the envelopment technique and to evaluate inter- and intraoperator reliability of the overlays obtained by the envelopment technique.

Materials and Methods:

Dental stone models were prepared from impressions made from healthy individuals; photographs were taken and computer-assisted overlays were generated. The models were then enveloped in a different-color dental stone. After this, four sequential cuts were made at a thickness of 1mm each. Each sectional cut was photographed and overlays were generated. Thus, 125 overlays were generated and compared.

Results:

The scoring was done based on matching accuracy and the data were analyzed. The Kruskal-Wallis one-way analysis of variance (ANOVA) test was used to compare four sequential overlays and Spearman's rank correlation tests were used to evaluate the inter- and intraoperator reliability of the overlays obtained by the envelopment technique.

Conclusion:

Through our study, we conclude that the third and fourth cuts were the best among the four cuts and inter- and intraoperator reliability were found to be statistically significant at 5% level that is 95% confidence interval (P < 0.05).