Use of high resolution computed tomography to diagnose ante-mortem dental root fractures in archaeological samples

Dental root fractures are rarely documented in past human populations, but when they are observed, diagnosing ante-mortem events as causal factors can be difficult due to postmortem alteration. Can high resolution X-ray computed tomography (CT) improve our ability to diagnose if a dental fracture was caused ante- or post-mortem? To test this, a case study of two individuals with previously diagnosed dental root fractures were re-examined with high resolution CT to confirm or refute the original diagnoses. For individual 4170, use of high resolution CT supported the original diagnosis of an ante-mortem root fracture on the right mandibular central incisor that was made based on planar X-ray. With the new analyses, the root fracture was found to be associated with evidence of calcification, and with radicular and alveolar bone resorption, which are positive correlates of an ante-mortem origin. Resolving this level of detail of bone modification was not possible without using high resolution CT. For individual 4172, the use of high resolution CT enabled visualisation of fracturing and cracking throughout several molars and crowns of other teeth that were not evident in planar X-ray, suggesting that these fractures were likely produced by post-mortem taphonomic processes rather than ante-mortem events as originally diagnosed. In this case study, high resolution CT offered critical advantages compared to a planar X-ray approach, such as using 3D multiple slice views without superimposing alveolar bone and teeth as in planar X-ray imaging. This study demonstrates the potential of high resolution CT in confirming and refuting ante-mortem processes, and that visualisation of 3D structures is crucial for arriving at definitive diagnoses.