3D analysis of enamel demineralisation in human dental caries using high-resolution, large field of view synchrotron X-ray micro-computed tomography

Synchrotron X-ray Studies of the Structural and Functional Hierarchies in Mineralised Human Dental Enamel: A State-of-the-Art Review

“…Multiple HAp crystallites are bundled together and arranged in ‘rods’ [ 52 ] of about 5 μm diameter with a cross-section shaped as a ‘keyhole’. These rods are separated by an inter-rod substance of around 2 μm thickness [ 39 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ], Figure 2 b. The bulk of the enamel is prismatic in nature; however, a prism-less region (referred to as ‘aprismatic enamel’) at the surface of the tooth can sometimes be found [ 62 , 63 , 64 , 65 ].…”

“…Retzius striae arise from temporal variations in the secretory activity of ameloblasts during enamel formation [ 23 , 95 , 96 , 97 ], while Hunter–Schreger bands [ 98 , 99 ] arise as an optical effect on sections of enamel, due to changes in the direction of the enamel rods across the tissue thickness from the surface to the DEJ, which results in a weaving into other rods, which is thought to improve the mechanical properties of enamel [ 100 , 101 ]. The Hunter–Schreger bands can be visualised using optical microscopy and scanning electron microscopy (SEM) [ 102 , 103 , 104 , 105 , 106 ] (they are also present in animal enamel, e.g., bear [ 107 ], dog [ 108 ], and rhinoceros [ 109 ]), where the wavy pattern can be visualised using tomography [ 39 , 57 , 109 ]. The distribution of the striae of Retzius and their width are not homogeneous, e.g., their spacing increases with enamel depth [ 62 , 95 ].…”

“…( d6,d7 ) Virtual slices from synchrotron tomography data showing a carious lesion in enamel (adapted from [ 39 ], license accessed on 30 March 2023). ( d8 ) 3D rendering of carious enamel and details of the spacing between rods (adapted from [ 57 ] with permission. Copyright 2021, Elsevier).…”

Development of a Visualisation Approach for Analysing Incipient and Clinically Unrecorded Enamel Fissure Caries Using Laser-Induced Contrast Imaging, MicroRaman Spectroscopy and Biomimetic Composites: A Pilot Study

“…Although some modern achievements in therapeutic dentistry have shown progress in this area [ 15 ], early and precise diagnostics of carious lesions remains a top priority. Spatial spectroscopic visualisation [ 16 ] with a high resolution within the regions of caries development at the micro- and nanoscale is a key challenge in the search for new methods in caries prevention and treatment [ 17 , 18 ].…”

“…Some recent works have demonstrated an unprecedented combination of resolution and contrast during caries visualisation in vitro, i.e., with the use of synchrotron microtomography [ 16 ]. However, applying such approaches in clinical practice can be complicated and sometimes even inappropriate.…”