Physicochemical markers of thermal exposure in teeth with orthodontic brackets: An integrated forensic analytical...

Dental tissues and orthodontic appliances can persist after fire-related events, constituting relevant evidence for the forensic interpretation of thermally altered remains. This study aimed to characterize the physicochemical, structural, morphological, and elemental changes in human teeth with cemented brackets subjected to high temperatures and to assess their potential forensic relevance. Fifteen extracted teeth were analyzed: ten with brackets and five controls, exposed to temperatures between 200 and 1000 °C. SEM-EDX was performed starting at 200 °C, while XRD, FTIR, and XRF were applied starting at 400 °C, as the samples treated at 200 °C could not be adequately pulverized. Apatite remained the dominant crystalline phase throughout the analyzed range. With increasing temperature, XRD showed greater definition of apatite reflections, while FTIR showed a progressive reduction in carbonates and organic-related signals, particularly at 800-1000 °C. The Ca/P atomic ratio determined by EDX showed compositional changes with temperature: in the control group, it increased from 1.21 at 400 °C to 1.93 at 1000 °C, while in teeth with brackets, mean values ranged from approximately 1.43-1.67, with fluctuations across the temperatures. Although the main mineralogical and spectroscopic trends were comparable between groups, localized morphological and elemental differences were observed in the presence of the orthodontic system. The multimodal integration of SEM-EDX, XRD, FTIR, and XRF provided complementary physicochemical markers of thermal transformation, contributing to a more robust forensic characterization of relative levels of alteration and broad thermal exposure ranges in dental remains affected by high temperatures.