Thermal effects on the optical properties of dental composite resins and glass ionomer cements in forensic contexts

This study investigated the fluorescence intensity and color changes of tooth-colored dental materials under experimental conditions similar to those of charred bodies, from which dental evidence can be obtained. Among 160 composite resin (CR) and glass ionomer cement samples, the fluorescence intensity was measured using a spectrofluorometer. CIELAB color space (L*a*b*), difference in lightness (ΔL*), and CIEDE2000 color difference (ΔE00) were calculated for all samples. The fluorescence intensity of CR was significantly higher in the flow type than in the paste type, and the A1 shade showed significantly higher intensity than the A3 before and after heating. The flow and paste type of the universal shade type CRs showed similar fluorescence to the A1 of conventional CRs before heating and tended to lose its fluorescence and transparency upon heating more easily than the conventional CRs. CR fluorescence intensity decreased significantly after 10 min of heating at 300°C, and many samples lost their fluorescence after 30 min. In contrast, glass ionomer cement fluorescence intensity increased with heating. ΔL* and ΔE00 were consistent with the macroscopic findings. The findings of this study provide updated information on tooth-colored dental materials and help us understand the circumstances in charred cases.