Dr. L. Thomas Johnson

The Quantification of Tooth Displacement

Thomas W. Radmer et al. — Sat, 03 Mar 2012 09:08:13 PST

By using reference points from a single pixel marker placed at the center point of the cuspid teeth and the center point on each of the incisor teeth, a polynomial curve was generated as a native curve for each dental arch studied. The polynomial curve generated from actual tooth position in each arch provides the forensic odontologist with another reference point that is quantifiable. The study represents that individual characteristics, such as tooth displacement, can be quantified in a simple, reliable, and repeatable format.

A Methodology for Three-Dimensional Quantification of Anterior Tooth Width

L Thomas Johnson et al. — Sat, 03 Mar 2012 09:08:12 PST

The use of cone-beam computed tomography (CBCT) technology has been shown to be more accurate in measuring individual incisor tooth widths than the use of wax exemplars. There were fewer differences by investigators using CBCT than others using an F-test in a mixed model of the measurement differences of investigators, wax type, and which tooth was measured. In addition, the frequency of outliers was less in the CBCT method (a total of 5) as compared to the two-dimensional measurements in ether Aluwax (a total of 8) or Coprwax (a total of 12). Both results indicate that CBCT measurements accounted more precisely for tooth width and level of eruption.

Quantification of the Individual Characterstics of the Human Dentition: Methodology

L Thomas Johnson et al. — Sat, 03 Mar 2012 09:08:11 PST

This study provides a method for comparing six individual human dentition characteristics using the standard measuring tool in Adobe Photoshop CS2 as compared to measuring individual characteristics with an automated software program under development at Marquette University, which has been adapted for bitemark analysis. The algorithm identifies color-specific pixels and automatically calculates the measurements.

The Correlation of Dental Arch Width and Ethnicity

Thomas W. Radmer et al. — Sat, 03 Mar 2012 09:08:10 PST

This study sought to demonstrate a correlation between arch width, ethnic background, individual height, weight, and whether orthodontic treatment had been rendered. Conclusions revealed that arch widths were significantly larger (p= 0.002 for the mandible and p= 0.008 for the maxilla) in non-Whites than in Whites. In addition, arch widths of the mandible were significantly larger in individuals who had had orthodontic treatment compared to those who had not (p=0.005). This did not carry through to those arch widths in the maxilla of orthodontic versus nonorthodontic care (p=0.258).

Quantification of the Individual Characteristics of the Human Dentition

L Thomas Johnson et al. — Sat, 03 Mar 2012 09:08:09 PST

The considerations for admissibility suggested by the Daubert trilogy challenge forensic experts to provide scientific support for opinion testimony. The defense bar has questioned the reliability of bitemark analysis. Under an award from the U. S. Department of Justice, via the Midwest Forensic Resource Center, a two-year feasibility study was undertaken to quantify six dental characteristics. Using two computer programs, the exemplars of 419 volunteers were digitally scanned, characteristics were measured, and frequency was calculated. The study demonstrates that there were outliers or rare dental characteristics in measurements. An analysis of the intra-observer and inter-observer consistency demonstrated a high degree of agreement. Expansion of the sample size through collaboration with other academic researchers will be necessary to be able to quantify the occurrence of these characteristics in the general population. The automated software application, Tom's Toolbox, developed specifically for this research project, could also provide a template for precisely quantifying other pattern evidence.