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FEM simulation of a novel medical device for TMJ therapy

Kwieciński K., Żmudzki Jarosław, Chladek G., Popielski P., Kowalczyk M., Duraj E., Sołtysiak-Niedziela M.

Archives of Materials Science and Engineering

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2023

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Vol. 122, nr 1

34--41

EN

Purpose: Temporomandibular disorders (TMD) are one of the leading health problems in dentistry. The work aimed to evaluate, using FEM, the influence of the material elastic properties of the flexible obstacle of the tongue trainer on the range of deflection and strength. Design/methodology/approach: In prototyping the trainer tongue, the starting point was real models with different extents of the tongue obstacle. moulded from dental wax on a dental stone model. Then versions were tested intraorally for the perception of the space occupied by the tongue. The models were scanned on a 3D scanner, and then a parametric CAD model (NX Siemens) was made on their basis. Finally, in order to take into account, the anatomical aspects, the two extreme ranges of the tongue obstacle, named "Long " and " Short ", were developed. Simulation deflection and material strength tests were made using FEM in the linear range (NX Siemens). Calculations were made for materials with Young's modulus equal to 8 MPa, 80 MPa and 800 MPa. The interaction of the tongue with the force of 5N was assumed. The support was provided by the retention surface on the teeth, with the support of the posterior edge of the obstacle on the palate (palatal variant) or lack of support, i.e., the obstacle freely bending in this area (free variant), was additionally tested. In order to assess the drop or retention of the trainer on the teeth, the second type of simulation was performed with the assumption of horizontal (anteriorly directed) tongue pressure with the force of 10N for the condition of rigid support in the area of the teeth and the periodontal zone from the lingual side. In this variant, a simulation was adopted for a material with a modulus of elasticity E=80 MPa. Findings: The stress values of the flexible obstacle of the trainer were obtained, allowing for the selection of potentially valuable materials for the trainer's construction. The results obtained in the simulations indicate the possibility of using ethylene vinyl acetate (EVA) and its blends. The accumulation of saliva inside the sealed obstacle was found, which indicated the need to look for an area to perforate without losing the load capacity of the obstacle. The structural feasibility of solving the problem of saliva accumulation without a significant change in the load capacity and stiffness of the obstacle was confirmed by simulation. Research limitations/implications: Simplifying the model to a linear range does not allow buckling analysis. In addition, the assumption of a linear material further limits the possibility of analysing materials with softening and plateau characteristics, where the compliance of the structure leads to elastic buckling. Practical implications: The range of deflections and stresses for different stiffness of the elastic element of the trainer was determined in order to select the appropriate material for the medical device (MD). Polyurethanes or silicones provide the range of deflection and strength, but in the case of manufacturing prefabricated trainers thermoformed in the patient's mouth (maximum temperature 75°C), the material that can be used is ethylene vinyl acetate (EVA). Originality/value: Simulation tests made it possible to determine the range of deflections and stress for different stiffness of the flexible obstacle of the trainer in order to select the appropriate material for the medical device.

2

Dental tribology: a systems approach

Sajewicz Eugeniusz

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 4

15--32

EN

Purpose: This article presents the new system approach for the biotribological description of the stomatognathic system, with particular emphasis on one of its subsystems, the dental organ. Methods: The peculiarity of the dental organ is emphasised, associated with a specific autonomic environment, next to the external environment, resulting from the impact of the organism on the dental organ. The autonomic environment increases the number of relations between elements in the dental organ and hinders its examination. Results: The characteristics of the dental organ are described. Its main elements, their properties, and the relationships between them are identified, and the system’s functions, inputs and outputs are presented. The systems approach addresses these difficulties, enabling the analysis of the dental organ and its tribological characteristics. Conclusions: The dental organ has an “autonomic” environment, which significantly increases the number of tribological relationships and complicates their analysis. Knowledge of the tribological attributes of the dental organ can be useful in studying detailed aspects of the function of the dental organ. The specific features of the analysed system and the uniqueness of its structure necessitate the use of appropriate methodology for testing the tribological properties.

3

Recent advance in appliances and materials enhancing therapy of disorders of the stomatognathic system

Sołtysiak-Niedziela M., Kwieciński K., Żmudzki J.

Archives of Materials Science and Engineering

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2018

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Vol. 90, nr 2

74--84

EN

Purpose: Dysfunctions of the stomatognathic system are treated with a lot of appliances. The aim of the work was to evaluate the current state in the field of diagnostic techniques and technological advance in appliances and materials enhancing therapy of occlusion disorders of the stomatognathic system. Design/methodology/approach: The principles of appliances functioning, manufacturing technology and materials were analysed. The analysis was made on the basis of the literature review and patent databases, conducting searches for a combination of keywords: dental material, occlusion, disorder, bruxism, clenching, grinding, appliance, therapy, tongue, oral, exerciser, trainer, mandible muscle, bite splint, dental plate. In the case of principles of functioning, devices that require insertion into the mouth are included in the tests. In technology and materials, attention has been paid to necessity of involving a dental technician or ability to perform appliance intra-orally ("chairside"), as well as mass production with possibility of custom fit. Findings: The most widespread in the treatment of disorders of the stomatognathic system are thermoformed materials and devices that are introduced between the dental arches to counteract occlusions of all teeth or selected teeth or force the position of the mandible in relation to the maxilla. Devices that function differently are those in which therapeutic effects result from toning of activity of the elevating mandibular muscles by provoking activity of the opposing muscles lowering the mandible or reducing intra-oral space, for example, by sublingual plates or tongue trainers. Appliances are mainly manufactured of: poly (ethylene- vinyl acetate) or polycarbonates, as also mouldable polymers such as: acrylics, polyesters and rubbers. Research limitations/implications: Electronic devices that are not intended to therapy but used only to track mandible mobility or muscle activity during sleep were not taken into account. Practical implications: Solutions activating the action of the opposing muscles to the muscles lifting the mandible are few, and among them one device is retained on teeth without interfering in occlusion. Originality/value: Dental materials for dev/ices for treatment of occlusion disorders are selected with no understanding tines influence of elastic and frictional material properties and structures stiffness on the distribution of occlusion forces between the teeth and reactions in temporo-mandibular joints.

4

Tribological tests of the nanomaterials used to reconstruct molars and premolars with the application of the direct method

Ryniewicz W., Herman M., Ryniewicz A. M., Bojko Ł., Pałka P., Ryniewicz A., Madej T.

Tribologia

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2017

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nr 3

155--164

EN

Physiological abrasion of teeth is a process of gradual loss of the hard tissue of opposite teeth resulting from age-related natural dental wear. In abrasion, the cusps and their slopes in the jaw and the mandible become flattened due to the mechanical load applied. The aim of this paper is to carry out a tribological and microstructural evaluation of modern composite materials used to reconstruct the teeth in the lateral part of the dental arch. Five light-cured composite materials were selected for tests. The tests involved the coefficient of friction and resistance to wear in a sliding contact in the presence of artificial saliva and the microstructure of the external surface of samples before the wear process and in the wear-related damaged area. The test method applied, which combines a biomechanical analysis of resistance to wear and the analysis of the microstructure before the wear process and in the wear-related damaged area, makes it possible to evaluate the tribological properties of composite materials used to reconstruct teeth in the lateral part of the dental arch.

PL

Fizjologiczne starcie zębów jest to proces stopniowej utraty twardych tkanek zębów przeciwstawnych w wyniku naturalnego zużycia postępującego z wiekiem. Starcie to polega na jednoczesnym spłaszczaniu guzków i ich stoków w zębach szczęki i żuchwy w warunkach obciążeń biomechanicznych. Celem pracy jest ocena tribologiczna i mikrostrukturalna nowoczesnych materiałów kompozytowych stosowanych do odbudowy ubytków w bocznym odcinku łuku zębowego. Do badań wybrano 5 materiałów kompozytowych utwardzanych światłem. Przeprowadzono badania współczynnika tarcia i odporności na zużycie w kontakcie ślizgowym, w obecności sztucznej śliny oraz badania mikrostrukturalne warstwy wierzchniej próbek przed procesem zużycia oraz w strefie skazy zużyciowej. Zastosowana metoda badań łącząca biomechaniczną analizę odporności na zużycie z analizą mikrostruktury przed procesem zużycia oraz w skazie zużyciowej pozwala na ocenę właściwości tribologicznych materiałów kompozytowych do odbudowy zębów w bocznym odcinku łuku.

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Ocena zaburzeń stawu skroniowo – żuchwowego w aspekcie aktywności bioelektrycznej

Szymańska D.

Aktualne Problemy Biomechaniki

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2014

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z. 8

151--156

PL

Celem pracy była elektromiograficzna ocena i porównanie aktywności bioelektrycznej wybranych mięśni układu stomatognatycznego dwóch osób dotkniętych dysfunkcją stawu skroniowo – żuchwowego (ang. temporomandibular disorders - TMD) o różnym stopniu nasilenia, oraz osoby zdrowej deklarującej brak objawów TMD.

EN

The aim of the study was an electromyography assessment and comparison of stomatognatic system’s selected muscles bioelectrical activity. The material consisted of two subjects who suffers from differential intensity of temporomandibular disorders (TMD) and the another one who’s healthy and doesn’t declare symptoms of TMD