Bite mark documentation and analysis: the forensic 3D/CAD supported photogrammetry approach

Teaching forensic odontology: an opinion on its content and format*

Forensic odontology involves dentists' participation in assisting legal and criminal issues. Formal teaching in forensic odontology has existed for over a 100 years. Over the last century, forensic odontology has evolved and, today, it is an integral part of undergraduate dental training in many countries. Dentists have been trained in the specialty, and dedicated departments established in institutes and universities around the world. A survey undertaken at five universities revealed that these centres have developed detailed curricula in forensic odontology, and a general standard exists in teaching forensic odontology, however, coverage of recent advances in forensic science may be lacking. While recognising that these programmes are not representative of teaching in forensic odontology worldwide, suggestions are made for an alternative approach to teaching the subject. Moreover, it is stressed that teaching be undertaken by qualified forensic odontologists.

Comparison of performance of conventional and minimally invasive surgery acetabular reamers

Acetabular reaming in minimally invasive surgery can be done using a newly designed minimally invasive reamer. The new minimally invasive reamer is narrower and chamfered, which results in two sharp edges. This design may result in acetabular cavities with less ideal spheres than those achieved with conventional reaming. We compared the acetabular shapes in nine pairs of cadaver acetabula. Minimally invasive reaming was performed in one acetabulum of each pair, and conventional reaming was performed on the contralateral side. A new digitizing technique, optical three-dimensional scanning, was applied to the reamed acetabula to determine the reamers' performance. Best-fit spheres were calculated for the reamed cavities, and all reamers were measured for exact dimensions. There were small deviations between the diameters of the reamer and the reamed cavity for the minimally invasive (mean, 0.1 mm; standard deviation, 0.5 mm) and conventional (mean, 0.3 mm; standard deviation, 0.4 mm) reamers. There were no significant differences between minimally invasive and conventional reaming. The mean differences between the reamer domes and the measured values showed a discrepancy of 2.2 mm (standard deviation, 0.08 mm) in the minimally invasive surgery group and 2.8 mm (standard deviation, 0.09 mm) in the conventional group. Although the acetabular reamer design has been modified, there were no significant differences in the acetabular shapes after minimally invasive or conventional reaming.

LEVEL OF EVIDENCE

Therapeutic Study, Level II (prospective comparative study with no statistically significant difference). See the Guidelines for Authors for a complete description of levels of evidence.

3-D imaging and quantitative comparison of human dentitions and simulated bite marks

This study presents a technique developed for 3-D imaging and quantitative comparison of human dentitions and simulated bite marks. A sample of 42 study models and the corresponding bites, made by the same subjects in acrylic dental wax, were digitised by laser scanning. This technique allows image comparison of a 3-D dentition with a 3-D bite mark, eliminating distortion due to perspective as experienced in conventional photography. Cartesian co-ordinates of a series of landmarks were used to describe the dentitions and bite marks, and a matrix was created to compare all possible combinations of matches and non-matches using cross-validation techniques. An algorithm, which estimated the probability of a dentition matching its corresponding bite mark, was developed. A receiver operating characteristic graph illustrated the relationship between values for specificity and sensitivity. This graph also showed for this sample that 15% of non-matches could not be distinguished from the true match, translating to a 15% probability of falsely convicting an innocent person.