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Shulyatnikova O.A., Rogozhnikov G.I., Leonova L.E., Lokhov V.A., Shulyatyev A.F., Mozgovaya L.A. BIOMECHANICAL ANALYSIS OF CLAMPING SYSTEM FOR FIXATION OF PROSTHESIS-OBTURATOR Received: 30.09.2017 Received in revised form: 30.09.2017 Accepted: 30.09.2017 Published: 30.09.2017 ![]() Abstract:
The increase of the level of injuries with damage in the maxillofacial region and the number of patients with jaw bone formation leads to the development of persistent esthetic and functional disorders. The severity of these disorders is determined by the volume of the defect. The greatest difficulty in orthopedic treatment is acquired defects of the upper jaw with the presence of oronasal compound. In this case, it is necessary to solve the problems of fixing the prosthesis, substitution of the functional and esthetic integrity of the maxillofacial system, creation of hermeticism at the border of connection of the oral cavity with the nasal cavity. Paper deals with biomechanical analysis of stress-strain state in the human dentofacial system induced by prosthesis-obturator installation. Prosthesis is made from suggested polyamide material Vertex ThermoSens with inclusion of nanostructured titanium dioxide up to one percent of mass. Main attention is paid to influence of clamper occlusion plate on stress distribution in the tooth at the maximal occlusion loads. Computations are conducted in the frame of linear theory of elasticity for isotropic body. The computer-aided design model is constructed based on 3D-scanning of the prosthesis-obturator. As a result of calculations, a substantiation of the clamping system for fixing the prosthesis-obturator with the use of suggested material and a type of supporting-retaining clamp is given. The obtained stresses are less than the maximum permissible stresses in the material. At the border of the tooth–clamper arm, there are also no critical stresses.
Key words: prosthesis-obturator, clamper, finite element method. Authors:
References: Kamaltdinov M.R., Trusov P.V., Zaytseva N.V. MULTI-COMPONENT MIXTURE FLOW IN THE STOMACH AND DUODENUM ALLOWING FOR FUNCTIONAL DISORDERS: RESULTS OF NUMERIC MODELLING FOR DETERMINING ACIDITY Received: 30.09.2017 Received in revised form: 30.09.2017 Accepted: 30.09.2017 Published: 30.09.2017 ![]() Abstract:
This paper covers certain aspects of mathematic model development for describing mixture flow in the antroduodenum. It details data for numeric research on pH level distribution in the antroduodenal section of the gastrointestinal tract. One-phase multi-component mixture contains components which are dissolved at the molecular level: hydrochloric acid, sodium hydrocarbonate, water, and a product of the reaction between acid and alkaline. The model allows for functional disorders in four antroduodenum sections which result in poorer secretory and motor functions performance. Mathematical tasking includes mass and momentum conservation equations for mixture components taking account mass sources due to components secretion and neutralization reaction. Kinematic boundary conditions are set on antroduodenum walls allowing for peristaltic motion (no slip condition). As for other boundaries of the examined area (inlet/outlet sections), here we set values of the 1st phase mass fractions, pressure, and conditions under which tangent components of stress vector are equal to zero. To determine pH level of the mixture via components concentrations, we obtained two algebraic equations, cubic and quatric ones. Model parameters were identified on the basis of data taken from literature and performed ultrasound research. We discuss various calculated scenarios where we examined impacts exerted by initially increased acidity (for example, due to acidic fluid intake) on dynamic acidity spread in the tract depending on fluid volume and pH level, occurence of functional disorders in alkaline secretion and in antrum motility. We showed that drinks with pH = 2.3 can potentially damage mucous coat of the tract walls, especially if alkaline secretion disorders occur. The approaches we suggest in the paper can in future be used for working out individual recommendations on consuming food and drinks with increased acidity.
Key words: numeric modelling, multi-component mixture, increased acidity, pH level, antroduodenum, functional disorders. Authors:
References: Filatova O.E., Eskov V.V., Filatov M.A., Ilyashenko L.K. STATISTICAL INSTABILITY PHENOMENON AND EVALUATION OF VOLUNTARY AND INVOLUNTARY MOVEMENTS Received: 23.10.2017 Received in revised form: 23.10.2017 Accepted: 23.10.2017 Published: 23.10.2017 ![]() Abstract:
In 2016, it will be 120 years since the birth of N.A. Bernstein. His critical article was addressed to the conditioned-reflex theory of I.P. Pavlov and was published almost 60 years ago, but to the present time Bernstein hypotheses of "repetition without repetition" has not been studied. Quantitative description of these experimental results is now performed on the basis of construction of samples pairwise comparisons matrices under conditions of multiple repetitions of movements. The quantitative results show differences between voluntary (tapping) and involuntary (postural tremor) movements. It is proved that from the standpoint of chaotic assessment there aren’t significant differences between these movements. New methods were presented for calculating the psychophysiological parameters of man. The new concept of Eskov-Zinchenko effect was presented, which demonstrates the chaotic kaleidoscope of statistical distribution functions f(x) of the obtained samples, the spectral densities of signals and their autocorrelation A(t). The role of consciousness is being discussed in organizing various types of movement. It is proved that the alleged involuntary movements (tremor) and voluntary movements (tapping) differ insignificantly from each other. From the standpoint of the stochastics, these two types of motion are chaotic in fact, because statistical distribution function f(x) changes randomly. The new theory of chaos-self-organization suggests methods of calculation of matrices of pairwise comparisons of samples that provide a clear distinction between tremor and tapping, i.e. between involuntary and voluntary movements. Voluntariness itself, i.e. increasing the role of consciousness in movements, is performed by increase in percentage of stochastics if we compare consecutive samples of tremorogramms and tappingramms. It represents quantitatively the Eskov-Zinchenko effect in evaluation not only the movement, but also in implementation of regulation of various functional systems that provide homeostasis.
Key words: tremor, tapping, chaos, unique systems. Authors:
References: Burykin Y.G., Braginskii M.Y., Korchin V.I., Tretyakov S.A.. METHOD OF QUANTITATIVE EVALUATION THE RANDOMNESS OF ARM MOVEMENTS Received: 23.10.2017 Received in revised form: 23.10.2017 Accepted: 23.10.2017 Published: 23.10.2017 ![]() Abstract:
The article presents a method for quantifying the randomness of arm movements. Habitual human voluntary actions contain an involuntary component. Even simple actions, for example the finger movement can not be performed with movement parameters – such as the amplitude or the frequency, fully controlled. When the experiment is repeated many times, the motor pattern is always different. N. Bernstein described this effect and called it "repetition without repetition". However, the observation of this effect does not give answers to the main questions: what is the cause in each case of this variation? How do we quantify the rates of voluntary and involuntary components in the movement? Human identity means the idea of the cause of actions, as pointed out by I. Sechenov, it is an illusion: the original cause of every action is always the external sensory excitation, because without it no thought is possible. Often extramental sensory stimuli can influence the person’s behavior. This is important in situations related to the problem of choice in the political, social and domestic spheres. Actively developing neuroeconomics is applied orientation, based on the results of neurobiological research, obtained by modern research methods. We proposed a method consisting of statistical comparison of all possible pairs of the received samples and counting the number of matches (i.e. lack of statistically significant differences when comparing this pair of samples – k) for the quantification of randomness of arm movements. The results indicate the variability of output indexes of motor functions, depending on the degree and the type of afferent influences (modality). The largest number of pairs of matching samples observed for voluntary arm movements – 11.6% of the total number, and the lowest at rest 3.2%, while afferentation under static load – 7.1%.
Key words: neuroeconomics, proprioceptors, arbitrariness, involuntary movements of the regulation, coordination, determinism, chaos. Authors:
References: Vinogradova O.B., Elovikova A.N., Nyashin Yu.I., Dubinin A.L. THE STUDY OF THE INFLUENCE OF REMOVING COMPLETE TEETH ON THE FACE AESTHETICS IN THE PROCESS OF ORTHODONTIC TREATMENT OF DISTAL OCCLUSION Received: 23.10.2017 Received in revised form: 23.10.2017 Accepted: 23.10.2017 Published: 23.10.2017 ![]() Abstract:
In the special literature, there are little data on the biomechanics of the dentoalveolar region. Orthodontists meet difficulties in controlling the formation of the occlusion during deformation of the jaws, due to the structural features of their structure. It is also difficult to control the change in the ratio of the jaws and occlusion in three directions in the process of orthodontic treatment, since an increase in the occlusion at rotation of the jaws can negatively affect the aesthetics of the face. The paper presents the direct results of treatment of distal occlusion of teeth with the use of fixed orthodontic technique in 53 patients aged 11-20.5 years, changes in the jaws, bone and soft tissue parameters in order to identify the negative consequences of removing complete teeth on the aesthetics of the face. It is established that the dental arches, apical bases and jaws in the younger and older age change the shape in the process of orthodontic treatment according to the principle of deformation of the elastic body: the dental arches in the premolar and apical bases are widened, their frontal areas are shortened more in patients after tooth removing. In growing patients, the length of the base of the mandible increases. The length of the base of the maxilla, the dimensions of the distances of the jaws, especially after removing of the teeth decrease. The frontal part of the maxilla is displaced posteriorly. Conditions are created to reduce the occlusion height in patients without removing of teeth and to increase occlusion in patients after removing of the two upper premolars. After the extraction of the teeth, there is a tendency to aggravation of facial features due to an increase in nasolabial and nasal convexity. External changes are almost not noticeable at elimination of the main symptom. In addition, quantitative changes in angles occur within the physiological range. The tendency to increase the occlusion with the removing of teeth positively affects the aesthetics of the face: the lips are closed freely, due to the increase of the chin and inter-lip angles, the sub-chin groove becomes less deep. When comparing parameters after treatment with the removing of teeth, more pronounced changes occurred in the mandible parameters: all sizes of the maxilla are statistically significantly less. The majority of bone and soft tissue parameters in the end of treatment became similar in size, irrespective of tooth extraction and did not have a statistically significant difference. The lack of growth of the base of the mandible in patients with a permanent occlusion is a contraindication to the removing of teeth in the distal occlusion caused by underdevelopment of the mandible. The listed questions need of biomechanical research.
Key words: orthodontic treatment, dentoalveolar biomechanics, distal occlusion, premolar removing, face profile change. Authors:
References: Khamidulina O.N., Pogosian I.A., Tkachenko T.Ya., Marchuk Yu.V. BIOMECHANICAL FEATURES OF THE STATOKINEMATICAL CHANGES IN THE MUSCULOSKELETAL SYSTEM IN CHILDREN CRANIOVERTEBRAL ZONE PATHOLOGY Received: 23.10.2017 Received in revised form: 23.10.2017 Accepted: 23.10.2017 Published: 23.10.2017 ![]() Abstract:
The functional stability of the musculoskeletal system in children with the pathology of the craniovertebral region was determined. The paper presents a comparative analysis of the results of stabilo and statokinesiometric methods of examinations of 120 children of the main group with different pathologies of the craniovertebral area of posttraumatic and dysplastic genesis and 18 children of the comparison group without this pathology. The possibility of using stabilometry to evaluate statokinematic functions of the musculoskeletal system in children with the pathology of the craniovertebral region was studied. It is shown that biomechanical indices of patients with pathology of the craniovertebral region have distinct differences from the parameters of the comparison group. At the same time, there was no clear separation between the indices of the main groups, which is explained by the predominance of nonspecific static-coordinating disorders over specific ones. The biomechanical criteria of functional disorders of the musculoskeletal system in this category of patients are shown in the form of a displacement of the common center of mass of the body in the frontal and sagittal planes (forward and to the left), as well as an increase in the length of the statokinesiogram by 3-4 times and an increase in the vibration rate of the general center of mass of the body in 1.5 times compared with the control group.
Key words: statokinesiometry, ñraniovertebral zone pathology, children, discriminant analysis. Authors:
References: Kudyashev A.L., Hominets V.V., Teremshonok A.V., Korostelev K.E., Nagorny E.B., Dol A.V., Ivanov D.V., Kirillova I.V., Kossovich L.Yu. BIOMECHANICAL BACKGROUND FOR THE FORMATION OF PROXIMAL TRANSITION KYPHOSIS AFTER THE TRANSPEDICULAR FIXATION OF THE LUM Received: 30.10.2017 Received in revised form: 30.10.2017 Accepted: 30.10.2017 Published: 30.10.2017 ![]() Abstract:
Modern surgical vertebrology considers transpedicular fixation to be the most effective and widespread method of treating patients with diseases and spinal trauma, in which stabilization and correction are necessary. Nevertheless, this method of treatment can be accompanied by a rapid progression of degenerative-dystrophic changes in vertebral segments that are located above the fixed vertebrae. This entails the formation of a proximal transition kyphosis, occurring in 26–39% of cases with posterior rigid fixation of vertebrae. It is believed that such postoperative complications can be avoided if, during the operation, normal sagittal spine-pelvic relationships are normalized. Preoperative planning conducted on the basis of biomechanical modelling will prove the need to perform correction and fixation of the spine in accordance with the individual parameters of the sagittal spine-pelvic balance. In this work, a biomechanical finite element simulation of surgical correction and fixation of spine for two models was performed: with spine-pelvic relationships unbalanced in sagittal plane and for a balanced spine-pelvic complex. As the initial data, a computerized tomogram and an X-ray of a specific patient who underwent surgery on the spine were used. The results of finite element modelling revealed significant differences in the stress-strain state of the examined models and allowed us to formulate the prerequisites for the formation and rapid progression of degenerative-dystrophic changes in the spinal segments located above the fixed vertebrae and to substantiate, in terms of biomechanics, the need for correcting the sagittal profile patient when performing operations on the spine and pelvic complex.
Key words: spine, spine -pelvic complex, modelling, finite element method, stress-strain state, sagittal balance. Authors:
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