The use of X-ray microtomography (XMT or micro-CT) is well established in many disciplines, including dentistry. It is able to show morphology and, with careful calibration, mineral concentration, allowing quantitative studies of caries and the processes of de- and re-mineralisation. The MuCAT scanners, designed at Queen Mary University of London, have been specifically optimised for high quantitative accuracy and contrast ratio, allowing features with very similar X-ray attenuation properties to be resolved. The use of a time-delay integration readout camera and modelling methodology reduce or eliminate ring and beam hardening artefacts respectively.
Extracted teeth have been scanned for a variety of research projects. These scans have often revealed unexpected features, not related to the original research purpose. The objective here is to make an overview of these features to investigate what this methodology reveals about dental morphology and pathology.
Methods:
Extracted teeth were taken from an anonymised collection (Queen Mary Research Ethics Committee QMREC2008/57). They were scanned at 90kV and 180µA with 15µm voxel size.
Results:
Contrast enhanced images show a region of reduced mineral concentration beginning from around 100µm from the pulp chamber and extending for around 200µm. Mineral concentration drops again towards the enamel-dentine junction. Of particular interest are paths of hyper-mineralisation that can be traced from the pulp to the enamel. These are associated with cracks and lesions in the enamel and often with tertiary dentine deposition in the pulp. Sometimes, these pathways are more visible than the lesions (especially very fine cracks), which may require close scrutiny for discovery. They can also usually be seen between pulp and dentine horns. In the roots, similar pathways can be seen in relation to cementosis.
Conclusion:
The high contrast resolution of the MuCAT XMT scanners is providing key new information in the investigation of dental pathology.