Spectrophotometric analysis of color changes in teeth incinerated at increasing temperatures

Color changes produced by histological alterations in burned teeth can provide conclusive forensic information on the temperature of exposure. The objective was to correlate heat-induced color changes in incinerated teeth with increases in temperature (to 1200 °C). Spectrophotometry was used to measure lightness, chromaticity (a* and b*), whiteness, and yellowness in 80 teeth heated at temperatures of 100, 200, 400, 600, 800, 1000, or 1200 °C for 60 min. Chromaticity a* was reduced at 100 °C and lightness at 200 and 400 °C, while chromaticity b* and yellowness were reduced at 400 and 600 °C. Higher temperatures (800, 1000, and 1200 °C) produced progressive increases in lightness and whiteness but reductions in chromaticity b* and yellowness. The accuracy of color values to determine the temperature of exposure was determined by Receiver Operating Characteristic analysis. High accuracy was shown by lightness, chromaticity b* and yellowness values for temperatures between 800° and 1200 °C, by whiteness for temperatures of 1000° and 1200 °C, and by lightness for temperatures of 200° and 400 °C, with sensitivity and specificity values ranging from 90% to 100%. According to these results, colorimetric analysis of incinerated teeth can be used to estimate the temperature of exposure with high accuracy, with lightness being the most useful variable.