Fire victim identification by post-mortem dental CT: radiologic evaluation of restorative materials after exposure to high temperatures

Objectives: The aim of this study was to evaluate the use of high resolution CT to radiologically define teeth filling material properties in terms of Hounsfield units after high temperature exposure.

Methods: 122 human molars with 10 different filling materials at defined filling diameters were examined. The teeth were CT scanned both before and after the exposure to different temperatures. After image reconstruction, the teeth and filling materials were analyzed regarding their morphology and Hounsfield units (HU) using an extended HU scale.

Results: The majority of filling materials diminished in size at temperatures≥400 °C. HU values were stable for all materials up till 200 °C, and only slightly changed up to 600 °C. Cerec, Dyract and dentin showed only minor changes in HU at all temperatures. The other materials, inclusive enamel, showed specific patterns, either increasing or decreasing in HU with increasing temperatures over 600 °C.

Conclusions: Over 600 °C the filling materials show specific patterns that can be used to discriminate filling materials. Ultra high resolution CT may improve the identification processes in fire victims. Existing 3D visualization presets for the dentition can be used until 600 °C and have to be optimized for bodies exposed to higher temperatures.