Analytical survey of restorative resins by SEM/EDS and XRF: databases for forensic purposes

Frequently in forensic cases, unknown substances must be identified. Automated databases can ease the burden of comparison as materials may be compared against many known standards in a relatively short period of time. It has been shown that dental resins can be named according to brand or brand group even in conditions as harsh as cremation. Databases are already in use for many materials, but no such database exists for dental resins. Thus, two databases were generated. One utilized a laboratory-based method, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), in conjunction with the Spectral Library Identification and Classification Explorer (SLICE) software. The other was based on portable X-ray fluorescence (XRF). The ability to perform database comparison with portable instrumentation can thus be brought directly to the field. Both the SLICE and XRF databases were evaluated by testing unknown resins. EDS is a well-established technique and the SLICE program was demonstrated to be a good tool for unknown resin identification. Portable XRF is a relatively new instrument in this regard and its databases have been constructed mostly for metal alloy comparison and environmental soil testing. However, by creation of a custom spectral library, it was possible to distinguish resin brand and bone and tooth from other substances.