New fluorescence and reflectance analyses to aid dental material detection in human identification

The identification of aesthetic dental materials during clinical dental examination can be challenging especially as patients and dental manufacturers place great emphasis on filling materials being as close as possible in appearance to the natural tooth. This makes dental identification in a forensic setting even more complicated.

The aim of this study was to develop a simple method using photographic analyses to determine differences in fluorescence and reflectance between brands and shades.

Three discs of 95 shades of resin composites (n = 285) were produced. Photographs were taken using a digital single-lens reflex (DSLR) camera attached to a dark box illuminated by an ultraviolet (UV) flashlight (wavelength 385 ± 10 nm) in a standardised manner. Images were analysed using an image software. The lightness (L) component according to the CIELAB was recorded. Kruskal-Wallis test was used to compare the mean lightness of the different samples followed by Dunn's test for multiple comparisons. The level of significance was set at P < 0.05.

L values ranged from 238.81 to 49.74. Fluorescence and reflectance were categorized according to crescent L values into 5 categories and organized into a Fluorescence and Reflectance Scale. Overall, dentin shades showed similar L values when compared to the same enamel shade from the same manufacturer. Comparison of L values for shades A1E and A3.5E demonstrated that darker shades had lower L values.

UV light allowed the recording of the Lightness component of CIELAB of a composite with little variation between images. The Fluorescence and Reflectance Scale allows the examiner to identify a specific brand or restrict the possibilities down to two brands. This information could help in cases of identification especially when ante-mortem data is limited.