Dentine Occlusion Studied Using FIB SEM and Nano X-Ray Tomography

Methods: A 30 µm3 size cube was cut out using a FIB/SEM system from a toothpaste treated dentine disc and was mounted onto a TEM finger support grid using an in situ micromanipulator. After this had been analysed using nano-Xray tomography it was returned to the FIB/SEM system and ‘slice and view' was performed. At 5 µm slicing intervals an energy dispersive (EDS) chemical map was taken over the cut face.

Results: This work showed that, not only did the techniques enable the 3D visualisation of the occluded tubules, but that they both also enabled further information to be obtained such as the percentage volume of the tubules occluded as a function of depth. The two 3D imaging methods have their relative merits. The FIB/SEM ‘slice and view' is a destructive method whereas X-ray tomography is non destructive and enables repeated imaging. However, the FIB/SEM slice and view can have a resolution of the order of 5 nm whereas the X-ray tomography can have a resolution of the order of 50 nm.

Conclusion: Both nano X-ray tomography and FIB/SEM slice and view can provide valuable information on the occlusion of dentine tubules and complementary information to other sample preparation and 2D imaging methods.