Massé, Léa, d'Incau, Emmanuel, Souron, Antoine, Vanderesse, Nicolas, Santos, Frédéric, Maureille, Bruno, and Le Cabec, Adeline
Simple Summary: In past populations, some individuals used their front teeth as tools for purposes other than eating, such as making tools or preparing food. These activities have an impact on both the visible part of the tooth (crown) through wear, as well as the part anchored deep in the gum (tooth root) by causing excessive production of a mineralized tissue called 'cementum'. Cementum surrounds the tooth root and forms throughout an individual's life. It records information about the individual's oral health, physiology, and chewing activities. Under certain conditions (e.g., significant mechanical stress or infection), cementum production becomes excessive and exceeds normal physiological limits, resulting in 'hypercementosis'. The present study aims to identify different patterns of cementum apposition and to propose probable causes. We examined a sample of 35 teeth (Sains-en-Gohelle, France, 7th–17th century) and identified four groups of cementum apposition: (i) impacted teeth that never erupted in the mouth, (ii) infected teeth, with caries or gum disease, (iii) hyperfunctional teeth subjected to high mechanical stress, and (iv) hypofunctional teeth that were not used in chewing due to the loss of opposing teeth. We conclude that hypercementosis could provide information on the life history of archeological specimens, even based on isolated teeth. The "teeth-as-tools" hypothesis posits that Neanderthals used their anterior teeth as a tool or a third hand for non-dietary purposes. These non- or para-masticatory activities (e.g., tool-making or food preparation prior to ingestion) have also been described in other past and extant human populations, and other Primates. Cementum is the mineralized tissue that covers the tooth root surface and anchors it to the alveolar bone. Under certain conditions (e.g., mechanical stress, infection), its production becomes excessive (i.e., beyond the physiological state) and is called 'hypercementosis'. Several studies in dental anthropology have established a correlation between the teeth-as-tools and hypercementosis. The present work aims to characterize the different patterns of cementum apposition on archeological teeth and discuss their supposed etiology. Using microtomography and confocal microscopy, the patterns of cementum apposition (i.e., thickness, location, and surface characteristics) were analyzed in 35 hypercementotic teeth (Sains-en-Gohelle, France; 7th–17th c. A.D.). Four groups were identified with distinct hypercementosis patterns: (1) impacted, (2) infected, (3) hypofunctional, and (4) hyperfunctional teeth. Characterizing hypercementosis can contribute to documenting the oral health status (paleopathology) and/or masticatory activity of individuals, even from isolated teeth. This has implications for the study of fossil hominins, particularly Neanderthals, known for their use of anterior teeth as tools and frequent and substantial occurrence of hypercementosis. [ABSTRACT FROM AUTHOR]