Plaque and archeological research

Dental plaque is often considered an obstacle to oral health and a reason to schedule a cleaning with your dentist. We agree, but we also celebrate the utility of dental plaque in historic research! A student analyzing dental calculus from ancient teeth is helping resolve the question of what plant foods Easter Islanders relied on before European contact.

A common hypothesis has been that inhabitants survived on palms, yet researchers know that the palms were destroyed shortly after colonization of the island. After removing and decalcifying the plaque from tooth fossils, however, researchers identified starch grains that were consistent with modern sweet potato. None of the recovered grains showed any similarities to banana, taro or yam, other starchy plants that are hypothesised to be part of the diet.

The researchers went on to test modern sweet potato skins grown in sediment similar to that of Easter Island’s and found that as tubers grow, their skins seem to incorporate palm phytoliths from the soil.

Thus, the presence of calcified plaque has helped solve the mystery of what Easter Island inhabitants may have eaten, and all calcified signs point toward the sweet potato. If you’d like to ensure that your dental plaque doesn’t become the object of research, book your next cleaning today!


University of Otago. (2014, December 15). Dental plaque reveals key plant in prehistoric Easter Island diet. ScienceDaily. Retrieved February 16, 2015 from


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