Background. In prosthetic dentistry, the replacement of a damaged tooth structure with ceramics has become increasingly common today. The possibility of achieving a high level of aesthetics, durability and cost-effectiveness in the restoration of the coronal part of the teeth with all-ceramic inlays by the method of indirect restoration is one of the topical issues for dentists. Objectives. This article gives an idea of the possibilities of modern technology in orthopedic dentistry. The aim of the work is to identify the quality of the restoration result as compared to fillings in cavities with a degree of destruction according to TOSFI (Tooth Occlusal Surface Failure Index offered by V.Y. Milikevich) -0.3- 0.6 in the teeth of the chewing group. Methods. The article deals with the clinical cases of the replacement of insolvent fillings made of a light-cured composite with cast ceramic microprostheses. For the restoration of the molars, 2 all-ceramic inlays were made on a 5-axis open-type milling system Wieland dental zenotec select hybrid. Results. Based on dental microscopic examination and a comparative analysis of the properties and behavior of the composite fillings and ceramic inlays, one can be sure that the restoration with ceramics is much superior to the composite filling, as it represents a more reliable, durable and aesthetic option for restoring the destroyed tissues of the crowns of chewing teeth. Conclusions. In the modern world, various technologies are being created for prosthetics of hard dental tissues that could create more and more perfect restorations. Looking at the investigated examples of clinical cases and relying on the statements of many authors of works on orthopedic dentistry, we can conclude that tabs are the best alternative to fillings. The practical significance of the work consists in identifying the greater efficacy of treatment for people with significant dental defects due to microprosthetics with ceramic inserts as compared with classical treatment with composite materials.

.4 mathematical model for determining the effective elastic properties and describing the processes of inelastic deformation and damage accumulation of unidirectional fiber-reinforced composites with tetragonal and hexagonalModels with a periodic structure serve as good approximations in modeling the mechanical behavior of composite materials. It is assumed that, in an elementary macrovolume of such media, the strain fields are periodic, i.e., during calculation of structural stresses and strains and evaluation of the effective properties, periodic problems can be considered, taking into account that the stresses averaged over the periodicity cells must be equal to the given macroscopic stresses. Efficient methods have recently been developed for the solution of periodic problems [1][2][3] in the mechanics of composites.This study deals with investigation of nonlinear stress and strain fields, modeling of failure processes in the matrix and fibers, and calculation of the effective characteristics of unidirectional composites with tetragonal and hexagonal layout of fibers in the matrix (Fig. 1). The tetragonal model is employed because of the minimum distances between the fibers at a given volume fraction [1]. Thus, we can expect that the strength properties of a composite predicted according to this model provide the lower estimates of the actual characteristics. However, the structure of an actual composite can differ considerably from the model representations. In creating struCaLreS from fibrous composites, there exists a tendency to increase the volume fraction of fibers in these materials. In this case, the geometry of the structure approaches the hexagonal model, which ensures the highest theoretically possible degree of packing for fibers of identical radius in a unidirectional fibrous composite. Therefore, along with examination of a material with a tetragonal packing of fibers, investigation of the behavior of a composite with a hexagonal structure is also of importance.To calculate the fields of structural stresses and strains in a composite, the method of local approximation, described in detail in [4][5][6], is applied. According to this method, the problem ofmicromechanics is solved using the structural fragments shown in Fig. 2. For a composite material with a tetragonal structure, such a fragment consists of nine cells, while for that with a hexagonal structure--of seven cells. The boundary conditions on the contour of the fragment, 8#, are chosen so that the stresses averaged over the central periodicity cell be equal to the given macroscopic stresses ,.~.The mathematical statement of the problem on the generalized plane deformation is described by the following system of equations:

In the present study, an important property of elastic microheterogeneous deformable solids is established. If a microheterogeneous medium is macroscopically homogeneous and macroAnl.qotropic, displacements of the boundary of a body having finite dimensions are determinate, dispersions of the physical properties of the solid are finite, and microdeformations of the regular medium within the structural element are smooth functions of coordinates, there exists a random functional ~)(P)(0), which does not depend on the boundary conditions, such that pulsations of the structural deformations ~ are connected with the structural deformations r in the regular medium by the relation ~ = r 9 9 ~ff).(1)To prove formula (1), we consider a stochastic boundary-value problem of the mechanics of microheterogeneous solids in the absence of volumetric forces V. a(r-) = 0, s(r-) = clef u(D, o~r) = e(r-}., s(r-)with boundary conditions

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