Dental calculus, which is mineralised dental plaque that preserves well in archaeological contexts, is increasingly of interest for researchers for several reasons. One of them is its potential to...Show moreDental calculus, which is mineralised dental plaque that preserves well in archaeological contexts, is increasingly of interest for researchers for several reasons. One of them is its potential to preserve plant micro-remains which can be used to infer information about diets in the past. These microscopic plant parts may exhibit taxon-specific morphologies, and their integration into dental calculus provides strong evidence in support of food consumption. However, traditional methods used to extract plant micro-remains from dental calculus are destructive, which can be a concern depending on the availability of the material. Therefore, this study aimed to test non-destructive micro-CT scanning as a method to examine plant micro-remains by comparing the results to the findings of destructive light microscopy analysis. Materials and Methods: Three dental calculus samples from the site of Arnhem Jansbeek/Eusebiuskerk (The Netherlands), dating from roughly 1350 to 1829 AD, were scanned using a Phoenix Nanotom micro-CT scanner. The resulting scans revealed the complete structure of the samples in resolutions ranging from 3.5 to 8µm. Aliquots of the scanned samples were then dissolved using EDTA, and the extracted plant micro-remains analysed using an AxioScope microscope at 400x magnification. After identification of some of the plant micro-remains using light microscopy, an effort was made to identify them in the micro-CT scans. Results: Light microscopy was used to identify two starch grains, two potential phytoliths, fungal remains, fibres, and fragments of a mite. None of the inclusions identified under light microscopy could be recognised in the micro-CT scans. Discussion: The two starch grains share affinities with wheat starch, whereas the two phytoliths could not be identified further. This severely limited possibilities for a dietary reconstruction. The fact that none of the organic inclusions from the calculus could be identified in the micro-CT scans suggests that plant micro-remains are either too small to be recognised or are incorporated into the dental calculus matrix in a way that does not reflect their diagnostic morphologies. While the results did not provide material for a dietary reconstruction, and the plant micro-remains could not be identified in the micro-CT scans, testing new applications of non-destructive methods is still important. The micro-CT scans are available for future research on DANS EASY (https://doi.org/10.17026/dans-2av-8agb). Conclusion: This study contributed to the development of non-destructive analysis methods by showing that micro-CT is not a suitable non-destructive method for the identification of plant micro-remains in dental calculus deposits. The fact that, while the research aims were not all fulfilled as expected, the micro-CT scans will be available for other research, underlines the value of non-destructive methods.Show less
