Wyniki wyszukiwania - BazTech

1

Influence of dental materials on hardness and Young’s modulus of the surface layers of tooth enamel formed as a result of friction

Wojda Sylwia, Sajewicz Eugeniusz

Acta of Bioengineering and Biomechanics

|

2019

|

Vol. 21, no. 1

129--139

EN

The purpose of this work was to determine the influence of dental materials used as permanent fillings on the mechanical properties of the tooth enamel surface layer subjected to friction with these materials. Methods: Dental composite materials (five types) were differentiated in terms of size and shape of the filler particles and matrix type over the course of tests on the chewing simulator under two different loads set during friction. Next, it was measured values of wear and nanoindentation for the resulting friction rates on the enamel (3 different load ranges). Results: It was found that the enamel’s resistance to tribological wear is significantly higher than that of the tested dental materials. It is also important to note that, depending on the penetration depth of the indenter (depends on the indenter pressure), different hardness values and Young’s modulus of enamel were obtained after friction with different dental materials. This demonstrates the formation of a surface layer with different properties than the native material. Conclusions: Analysis of the obtained results suggests the existence of different tribological wear mechanisms, as evidenced by significant differences in the wear values of dental materials and enamel. The data show that the enamel surface layer modified by the contacting dental material is shaped to a certain depth, and different thickness ranges of the changed layer have different properties.

2

Tribological characteristics of enamel–dental material contacts investigated in vitro

Wojda S., Szoka B., Sajewicz E.

Acta of Bioengineering and Biomechanics

|

2015

|

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.

3

Influence of photopolymerization parameters on the mechanical properties of polymer : ceramic composites applied in the conservative dentistry

Pieniak D., Niewczas A. M., Walczak M., Zamościńska J.

Acta of Bioengineering and Biomechanics

|

2014

|

Vol. 16, no. 3

29--35

EN

In this paper the results of study of mechanical properties for four commercial polymer-ceramic composites applied in the conservative dentistry are presented, including one new silorane based composite and three standard composites based on methacrylate compounds. Influence of the type of light of diode and halogen polymerization lamps on the microhardness, flexural strength and elasticity were studied. Both exposed and unexposed specimens were taken into account. An exposure time was also differentiated (40 sec and 60 sec). Basic statistics of the analysed material parameters were determined. A post hoc test (Newman-Keuls) was performed in order to evaluate differences between microhardness of the studied materials, as well as Kruskal-Wallis test to evaluate differences in flexural strength and elasticity modulus of the material. It has been indicated that there is an impact of the type of lamp on the microhardness and flexural strength of composites with methacrylate matrix and lack of such impact in case of composites containing siloranes. Additionally, it has been found that an increase of photopolymerization time has a significantly different impact on the mechanical properties depending on the type of irradiated material.

4

Mieszalnik z przekładnią planetarną dla kompozytów światłoutwardzalnych

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

Przemysł Chemiczny

|

2012

|

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.

5

Właściwości mechaniczne wybranych kompozytów stomatologicznych stosowanych do stabilizacji zębów

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

Kompozyty

|

2004

|

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.