Mechanical properties of selected dental composites used in teeth stabilization
Małgorzata Grądzka-Dahlke*, Grażyna Tokajuk**, Marcin Wilczko**, Małgorzata Pawińska**, Wanda Stokowska** *Politechnika Białostocka, Wydział Mechaniczny, ul. Wiejska 45c, 15-351 Białystok **Akademia Medyczna w Białymstoku, Wydział Lekarski z Oddziałem Stomatologii, ul. Curie-Skłodowskiej 7a, 15-089 Białystok
Annals 4 No. 11, 2004 pages 326-330
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abstract 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. Key words: dental materials, light-cured composites, mechanical properties