Wyniki wyszukiwania - Biblioteka Nauki

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Właściwości mechaniczne wybranych kompozytów stomatologicznych stosowanych do stabilizacji zębów

100%

Grądzka-Dahlke M. , Tokajuk G. , Wilczko M. , Pawińska M. , Stokowska W.

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tom R. 4, nr 11

326-330

PL

Przedstawiono wyniki wstępnych badań właściwości wytrzymałościowych kompozytów stomatologicznych. Zazwyczaj przy wyborze konkretnych materiałów spośród szerokiej oferty handlowej właściwości mechaniczne nie są brane pod uwagę. Decydują tutaj cechy estetyczne, łatwość aplikacji itp. Przedmiot prezentowanych badań stanowiły wybrane zestawienia osnowy i zbrojenia kompozytów stosowanych do szynowania zębów. Oceniano wartości modułu sprężystości, naprężenia niszczącego oraz odkształcenie materiałów podczas statycznego trójpunktowego zginania. Uzyskane wyniki badań porównawczych wskazują na możliwość optymalnego doboru osnowy i zbrojenia kompozytu do poszczególnych zastosowań klinicznych w celu zapewnienia najbardziej korzystnych warunków zrostu tkanki kostnej.

EN

Dental practice today utilizes a large number of different materials. Specific advantages of using materials in various applications are considereded. New developments of polymeric composites for restorative filling materials are mainly focused on the reduction of polimerization shrinkage and improvement of biocompatibility, aesthetics, wear resistance and processing properties. The mechanical properties, especially the elastic modulus are very important parameters for evaluating and ranking composites used to stabilizing mobile teeth during periodontal therapy. The preliminary results of mechanical properties estimation of selected dental composite materials have been presented in this paper. Fifteen different composites were examinated in this study. Materials were chosen from among present commercially available components. Three light-curing resin materials were used as a matrix reinforced with five various fillers (Tab. 1). Samples were prepared according to ISO standard. The fracture strength, flexural modulus and deformation were determined for each material in static three-point bending test in an universal testing machine (Fig. 1). The results of comparative tests suggested, that fracture properties of the dental composites are highly influenced by the matrix material (Fig. 2). Higher values of flexural modulus were recorded for composites based on LCR matrix. These materials may be used during periodontal therapy, where teeth should be rigidly fixed. However composites with Flow-It matrics revealed a significantly higher flexibility. The elastic modulus was lower, while the values of fracture deformation strain were highest in this group of specimens. These properties allow the use of those materials for teeth stabilization in posttraumatic therapy. SEM analysis of the fractured surfaces suggested two kinds of failure mechanism of tested materials (Fig. 3). In this study no significant differences were found between the flexural modulus and specimen deformation of the composites with various fillers. It indicated that the filler type has lower influence on fracture parametrs of dental materials than the matrix. This effect is assumed to be related to inherent flaws, especially inadequate adhesion of polymer matrix to the filler and air porosities included in the composite material (Fig. 4). The performed study showed it possible to choose the optimum composite components for specific clinical application on the ground of mechanical properties tests.

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Mieszalnik z przekładnią planetarną dla kompozytów światłoutwardzalnych

84%

Boryga M. , Graboś A. , Fidut W. , Kalbarczyk G. , Stasiek A. , Dzwonkowski J.

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tom T. 91, nr 8

1518-1522

PL

Przedstawiono wyniki badań symulacyjnych i fizykochemicznych oraz realizację techniczną stanowiska do wytwarzania kompozytów światłoutwardzalnych. Badania symulacyjne przeprowadzono dla klasycznego i zmodyfikowanego napędu mieszadła z przekładnią planetarną. Na zaprojektowanym i zbudowanym stanowisku z napędem zmodyfikowanym przeprowadzono proces mieszania kompozytu zgodnie z opracowaną procedurą. Badania właściwości fizykochemicznych uzyskanego kompozytu przeprowadzono zgodnie z normą PN-EN ISO 4049:2000. Zbudowane stanowisko z mieszalnikiem planetarnym oraz przedstawiona procedura mieszania wykorzystane zostały do wytwarzania kompozytów światłoutwardzalnych na skalę przemysłową.

EN

A process for mixing resins and fillers was simulated, 3D-modelled and implemented in an industrial scale mixer for production of light-cured resin-matrix composites for dentistry. The composites showed good mech. properties as well as low soly. and water absorption.

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Tribological characteristics of enamel–dental material contacts investigated in vitro

84%

Wojda S. , Szoka B. , Sajewicz E.

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tom Vol. 17, no. 1

21--29

EN

Purpose: The aim of this study was to investigate wear and friction behaviour of tooth enamel against selected dental restorative materials. Methods: The experimental material was obtained under simulated mastication, during which human tooth enamel was subjected to friction and wear in contact with composite dental materials: Estelite Sigma and FulFil Extra. Results: The results have shown that the enamel’s resistance to tribological wear is significantly higher than the resistance of the dental materials tested. The microscopic observations of the sample surfaces subsequent to the tribological research as well as the analysis of the chemical composition of the surface layer confirm the existence of diverse tribological wear mechanisms dependent on the type of dental materials used. Conclusions: Composite materials such as Estellite Sigma and FulFil Extra are characterized by greater resistance to wear and are less destructive to enamel than the material investigated by the authors earlier. It has also been stated that the spherical shape of the filler particles (Estellite Sigma) has a beneficial effect in reducing enamel wear.

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

67%

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

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tom 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.