Russian Journal of Biomechanics

Dental implants have become a well-publicised treatment modality in dentistry. Implants are generally placed in the private sector by dentists who have undertaken further learning. Biomaterials are materials intended to be in contact with living tissue and / or biological fluids to assess, treat, modify standards or replace any tissue, organ or function of the body. The purpose of this paper is to compare the differences in von Mises stress between spherical and conical impactor, whatever their mass. In order, to predict the material of the crown and to protect the tissues surrounding the implant. This paper presents the model geometry for the modelling of contact problems between two solid bodies (crown/impactor) without friction and that of bone/implant. Three-dimensional finite element model of dental prosthesis was developed considering the impact of the crown. For the design a contact was simulated between the lateral surface of the crown and the impactor. By use the model, computational simulations were performed varying the impactor’s mass for both shapes of impactor. The results also revealed only relatively low levels of stresses were transferred from the implant to the surrounding cortical and cancellous bone, with the majority of the stresses transferred to the cortical bone. Maximum von Mises stress generated by spherical impactor are lower than those obtained by conical impactor. For big mass of the impactor, the stresses may be critical since the mechanical properties of the implant material and the cortical and cancellous bone could not withstand stress magnitudes recorded in this analy-sis. The stresses distribution and magnitude depend of the impactor’s mass and different shapes of (stress - length of implant thread) curves are similar for different masses of the impactor. Indeed, the equivalent stress increases with increasing the impactor’s mass. The stresses were transferred from the implant to the surrounding cortical and cancellous bone.

A distinctive feature of the enamel surface of molars and premolars is the presence of a certain number of fissures - wedge-shaped (V-shaped) notches, the tops of which are natural stress concentrators in the enamel of the tooth crown. To determine the degree of concentration of mechanical stresses in the vicinity of the fissure tip, the problem of the stress-strain state of enamel in the form of an elastic wedge imitating a fissure is considered. The bite force, acting on the food, wedges the fissure and causes a stress-strain state in the vicinity of its tip. The resulting formulas made it possible to estimate the stress-strain state in the vicinity of the fis-sure tip depending on the fissure opening angle, food diameter, and relative deformation of the lateral surface of the fissure.

Modern approach to rehabilitation of patients with limb girdle muscular dystrophy of type I are discussed in this article. Authors thoroughly investigated the clinical picture of limb-girdle muscular dystrophy, pathogenesis of this disease and the main principles of its treatment. On the example of the concrete patient authors considered the clinical picture of the limb-girdle muscle dystrophy and also the biomechanical and energetic parameters of walking. Authors demonstrated, that essential disturbance of the locomotor function is seen in this patient, what is revealed in remarkable diminution of the mean walking velocity, in severe transformation of the temporal structure of walking, in reduction of amplitude of movements at some joints of the lower extremities and increase of amplitude at the other joints, in displacement of all extreme values to the right along the temporal axis, in remarka-ble weakening of the support and push functions of the lower extremities, in change of the form of the vertical component Rz of ground reaction force from two-peaked to the triangu-lar, in expressed diminution of moments of muscle forces at the joints of the lower extremi-ties. Authors also point out, that it is necessary to carry out regular courses of rehabilitation in such patients with the purpose to improve the locomotor function. Besides, it is very ex-pedient to retrace systematically changes of the biomechanical and innervative structure of walking. On the grounds of investigation of structure of walking of patient with limb girdle muscular dystrophy authors revealed necessity of ortheses and the subsequent application of functional electrical stimulation of muscles during walking. On the basis of realization of the trial sessions authors for the first time determined the main correctional influences, nec-essary for these patients and also peculiarities of the amplitude and, especially, temporal programs of functional electrical stimulation of muscles in such patients. Patient herself notes greater stability during walking, possibility of walking greater distance without fatiga-bility. The received results give foundation for the further planning of the course of rehabili-tation in such patients.

Cardiovascular disease is the main cause of mortality in the World. This issue has seriously alarmed governments of developed and developing countries both. Diseases related to the heart play a role as the highest risk for human health. There are many factors contributing to the development of these diseases including poor diet, sedentary lifestyle, high blood pressure and hypertension. In this paper, we present a study of the influence of different factors by the corre-spondence analysis and log-linear models to deal with prediction of cardiovascular disease development. A survey has been conducted amongst affected people of different age groups, gender, and various education levels. Based on this data, we could determine which group would be at the higher risk leading to the cardiovascular disease. It should be noted that all participants were suffering from cardiovascular disease either slightly or seriously. Our findings show that women are at higher risk than men being affected by cardiovascular disease. Moreo-ver, different factors such as smoking, high cholesterol level, physical inactivity and poor diet contribute significantly to the possibility for this disease. Via our analyses, we also can obtain a better comprehension of the data structure and better interpretation of the results by combining two approaches (correspondence analysis and log-linear models). Also, it is concluded that correspondence analysis allows us to find the strong correlations between involving variables. That could lead to the conception of prognostic and biomechanical models using the inter-correlations between variables and building a good structure of big data in the future

The purpose of this study is neural network modeling and determination of the parameters of statokinesiograms, which are carriers of useful information about the features of postural regulation, which determined the obtained trajectory of movements of the human center of mass. A technique for obtaining informative markers by identifying clustering centroids based on self-organizing Kohonen neural networks with the Euclidean metric has been developed. Ko-honen networks trained without a teacher (that is, without the use of a priori diagnostic infor-mation about the state of the subjects) are a powerful and informative method that allows you to obtain not only graphic, but also mathematical markers of health disorders in subjects, to ex-plore the biomechanics of micromovements of the center of pressure based on a flexible math-ematical apparatus — neural network cluster analysis. On the example of the identification of the post-stroke state, a neural network analysis of stabilometric data was carried out and a method for identifying pathobiomechanical markers of statokinesiograms was shown, which made it possible to standardize the type affiliation of the groups of subjects. With the help of neural networks, it was possible to identify clusters that are amenable to biomedical interpretation with a reliability of up to 95.9%, which determines the theoretical significance of the results obtained. Decision trees and a supervised multilayer neural network were also considered. A multilayer neural network made it possible to identify markers of health disorders with a probability of 71.9%.