The aim of the paper is to study phase transformations in solid tissues of the human teeth during the development of fissure caries by Raman and fluorescence microspectroscopy. The study of the areas with fissure caries confirmed the assumption of the formation of a weak interaction between phosphate apatite enamel and organic acids (products of microorganisms). The experimental results obtained with by Raman microspectroscopy showed the formation of dicalcium phosphate dihydrate - CaHPO₄-2H₂O in the area of mural demineralization of carious fissure. A comparative analysis of structural and spectroscopic data for the intact and carious enamel shows that emergence of a more soluble phase - carbonate-substituted hydroxyapatite - is typical for the initial stage of caries. It is shown that microareas of dental hard tissues in the carious fissure due to an emerging misorientation of apatite crystals have a higher fluorescence yield than the area of the intact enamel. These areas can be easily detected even prior to a deep demineralization (white spot stage) for the case of irreversibly changed organomineral complex and intensive removal of the mineral component.

This study investigated the luminescence characteristics of synthesized biocomposites similar in organic and mineral composition to native dental tissues, enamel and dentine. It was found that the luminescence spectrum of intact enamel is similar to that of calcium hydroxyapatite (HAP) used to synthesize biomimetic materials. Despite the morphological differences between the synthesized biocomposite and native tissue, their luminescence spectra suggest that the shape of the luminescence spectrum is more influenced by defects in the crystal structure of the employed hydroxyapatite than by the structure and order of the apatite nanocrystals typical of native dental tissues. The spectrum of intact human dentine possessed a wider luminescence band, unlike that of enamel, with a maximum typical of intact dentine. Analysis of the spectra of biomimetic material modelling the properties of dentine indicated that both the organic and non-organic components contribute to their luminescence

The results of the X-ray diffraction analysis (XRD) and optical (IR) investigations of hydroxyapatite (HAP) produced from the egg-shell of birds and biogenic HAP (a slice of tooth enamel) are presented. The synthesized material is a nanocrystalline hydroxyapatite with an average crystal size ∼35 nm. The outer and inner sides of the tooth enamel slice include HAPs with a different structural organization. The inner side of the tooth slice containing HAP nanocrystals, with an average size of ∼15 nm, demonstrates the most similarity with the synthesized material. Hydroxyapatite of the outer enamel consists of hydroxyapatite with a strong texture organization whose common elements, namely hexagonal prisms, are predominantly oriented along the [001] crystallographic direction. The IR spectra of the tooth enamel (in addition to fundamental HAP vibration modes) revealed the vibration modes of the collagen protein. The comparison of the characteristics of the synthesized and biogenic HAP show that synthesized HAP is a promising candidate for medical applications, e.g., for improving the adhesion properties of dental cement pastes.

The purpose of this study is the deposition of nanodimensional Al²O³ films on the surface of nanoporous silicon and also fundamental investigations of the structural, optical, and morphological properties of these materials. Analyzing the results obtained here, it is possible to state that ultrathin nanostructured Al²O³ films can be obtained in the form of threads oriented in one direction and located at a distance of 300–500 nm from each other using ion-plasma sputtering on a layer of porous silicon. Such a mechanism of aluminum-oxide growth is conditioned by the crystallographic orientation of the initial single-crystalline silicon wafer used to fabricate the porous layer. The results of optical spectroscopy show that the Al²O³/por-Si/Si(111) heterophase structure perfectly transmits electromagnetic radiation in the range of 190–900 nm. The maximum in the dispersion of the refractive index obtained for the Al²O³ film grown on por-Si coincides with the optical-absorption edge for aluminum oxide and is located in the region of ~5.60 eV. This fact is confirmed by the results of calculations of the optical-absorption spectrum of the Al²O³/por-Si/Si(lll) heterophase structure. The Al²O³ films formed on the heterophase-structure surface in the form of nanodimensional structured threads can serve as channels of optical conduction and can be rather efficiently introduced into conventional technologies, which are of great importance in microelectronics and optoelectronics.

The objective of this study was to investigate the efficiency of the saturation of mixed saliva by mineral complexes and groups necessary for the remineralisation of tooth enamel using exogenous and endogenous methods of caries prevention.Using IR spectroscopy and high-intensity synchrotron radiation, changes in the composition of the human mixed saliva were identified when exogenous and endogenous methods of caries prevention are employed. Based on the calculations of mineral/organic and carbon/phosphate ratios, changes in the composition of the human mixed saliva depending on a certain type of prevention were identified.It is shown that the use of a toothpaste (exogenous prevention) alone based on a multi-mineral complex including calcium glycerophosphate provides only a short-term effect of saturating the oral cavity with mineral complexes and groups. Rinsing of the oral cavity with water following the preventive use of a toothpaste completely removes the effect of the saturation of the mixed saliva with mineral groups and complexes.The use of tablets of a multi-mineral complex with calcium glycerophosphate (endogenous prevention) in combination with exogenous prevention causes an average increase of ∼10% in the content of mineral groups and complexes in the mixed saliva and allows long-term saturation of the oral fluid by them. This method outperforms the exogenous one owing to a long-term effect of optimal concentrations of endogenous and biologically available derivatives of phosphates on the enamel surface