The evaluation of microstructure and mineral density of the focus of artificial enamel caries using X-ray computer microtomography

The aim of this work was to study the features of microstructure and mineral saturation in the focus of artificially (in vitro) created demineralized tooth enamel with the use of computer microtomography. The method of microtomography implemented with the help of an X-ray computer installation Nikon Metrology XT H 225, provided the possibility of certification of macro- and microstructure of small samples of human teeth in vitro, without breaking the integrity, special preparation and preliminary destruction of objects, in a relatively short time. A multilevel analysis based on visual-instrumental (ICDAS criteria), stereomicroscopes (Olympus SZX-16; Olympus DP-73; Olympus Stream Motion v.1.8) and microtopographical assessment of teeth with artificially (in vitro) created focal demineralization of enamel using original technique (patent of Russian Federation No. 172561 and No. 171409 from 16.12.2016) allowed to obtain three-dimensional information on the nature of simulated lesions of the enamel, confirmed the high sensitivity and specificity of the experimental model of primary caries. The algorithm of qualitative and quantitative analysis of computer tomograms of teeth includes 3D-reconstruction of the tooth and the focus of demineralized enamel with the assessment of volume characteristics, safety of the structure, etc.; morphometric analysis of the linear dimensions and geometric characteristics of the lesions of enamel and their individual zones; determination of mineral density in different areas of the lesion by reference densitometry. Artificial enamel caries clinically corresponded to ICDAS (2), according to the microtomography data represented an X-ray diffuse structural heterogeneous lesion center of triangular shape, with a depth of 423.8 ± 107.4 µm, with a multi-level loss of mineral saturation, most pronounced in its Central zones (1.47-1.86 ± 0.17 g/cm3). The use of the method of computer microtomography and the developed model of artificial enamel caries for the assessment of mineral saturation of the demineralization focus in vitro during the approbation of various means and methods of prevention and treatment of early stages of dental caries is promising.