Kuritsyn A. V. Kutsevlyak V. I. Kondratyev A. V.

DENTISTRY

Scentific article

To date, relatively new, but incomparably fast developing area of dentistry is a dental implantology. Successful dental implant surgery must be preceded by careful assessment of a patient, the analysis of the clinical situation, and hygiene indicators, and also an opportunity of forecasting of interaction implant particular configuration with the bone tissue of the jaw segment. The impact evaluation of basic geometrical parameters of various implants on the behavior of biomechanical systems devoted to a sufficiently large number of works, in which the only acknowledgement of the key role the configuration of the basic part of the implant on the stress state of the bone tissue of the jaw segment. Earlier for different configurations of the implant were obtained view of the stress-strain condition on the boundary of “the basic part of the implant and bone”, which have allowed to estimate influence of his basic geometrical parameters on the behavior of biomechanical systems in General. The purpose of this study was to identify the functional relationship between the main geometrical parameters (diameter, length and angle of the crown abutment) screw various configuration and stressed state of the bone tissue of the jaw segment that defines the behavior of biomechanical systems “screw implant – jaw segment. ” As object of research was adopted synthesized by us earlier virtual model of biomechanical systems “screw implant – jaw segment”, determination of the stress-deformed state of elements which under the action of maximum chewing load is equal to 300 H performed using a software complex finite element analysis. Similarly, this paper of the geometric parameters of the implant correspond to the manufacturer “Anthogyr”. As a base case for the study was chosen configuration implant diameter of the threaded part = 4 mm, h = 10 mm and inclination angle of esthetic abutment = 15. For a quantitative estimation of stressed state of biomechanical systems were used earlier received in work picture of distribution of equivalent von Mises stress. It is very convenient for the analysis of the stress state is the use of the factor of safety (FOS – factor of safety), calculated as the ratio of maximum permissible voltage to current – Mises equivalent. It is obvious that at FOS > 1 for bone tissue of the jaw segment provides such a field operating voltages on all areas of its contact with the anchor screw part of the implant that they do not exceed the value of traumatic stress. If FOS < 1, this condition is not satisfied, and bone predicted the emergence of structural changes, which can develop in its resorption. Figure 3 shows the received picture of the distribution of factor FOS for compact and spongy bone tissue of the jaw segment for the basic version of the implant. Analysis of the obtained results have allowed to draw a conclusion that the most loaded element biomechanical system is porous bone, a minimum safety factor of FOS is much less margin compact bone. On this basis for qualitative estimation of the influence of geometrical parameters of implant – diameter (d), of the length (l), the angle of the abutment (Phi) on the stress state of biomechanical systems “screw implant – jaw segment” was used the minimum value of the coefficient for FOS spongy bone. In order to be able to analytically calculate its values with arbitrary values of these parameters need to know the function of three variables. Given the specificity and complexity of simulation of this biomechanical systems, this functional dependence can be obtained absolutely-only table way in the series of finite element calculations under discrete change of parameters of the implant. Taking this into account, the identification of the required dependencies can be carried out by a method of multiple regression 6. So, for example, when using a regression model of the second order can obtain the detailed function, connecting the value of safety factor FOS spongy bone with geometric parameters of the implant. Conclusions. Analysis of the obtained results allows to make the following conclusions. To estimate the influence of geometrical parameters of biomechanical systems “screw implant – jaw segment” on the stress state of the spongy tissue of a series of finite element calculations, which made it possible to reveal the basic tendencies of change of its factor FOS in relation to the magnitude of traumatic stress, depending on the diameter of implant length and angle of the abutment. Regression analysis of the results of a series of finite element calculations biomechanical system that allowed to install the analytical relationship between its geometrical parameters and factor FOS spongy bone. Due unsustainable growth complexity of finite element calculations of the time was used only linear model, which is reflected in a low coefficient of determination (R2 = 0,8617) analytical dependences. For minimum configurations implant necessary for the approximation of the functional dependence between stock FOS spongy bone and diameter, the implant length and angle of abutment, implemented an efficient algorithm of its linearization. Analytic dependence has a high coefficient of determination (R2 = 0,9662) in the considered range of configurations implant that allows to recommend it for practical application.

method of final elements (MFE), intense the deformed state (IDS), dental implant, abatment

«Bulletin of problems biology and medicine» Issue 3 part 3 (112), 2014 year, 302-309 pages, index UDK 616. 314-089. 843-035