Apatite crystal deformation around the tooth cemento-dentine junction in roots: nanoXRD mapping and annealing of residual strains in a bioge

The cemento-dentine junction (CDJ) is an astoundingly fatigue-resistant interface between two tissues: tooth root dentine and cementum. It sustains millions of chewing cycles without failure, yet the role of residual strain between collagen protein and nanocrystals is not known. We propose to correlate nanostructure and residual strains around the CDJ by nanobeam XRD mapping, followed by annealing and re-mapping. Annealing will release strains induced by the protein shown to arise during sample drying. By nano XRD+XRF mapping matched with phase contrast enhanced nano-CT (holoCT) imaging, we will identify the relations between deformation fields and key structural elements: fiber bundles, interface, tubules and cementocyte canaliculi. Such data from several samples measured on ID16B will help us reveal nano- and microstructural strategies for the impressive fatigue resistance of this biological interface region.