ABSTRACT
With the increase in population life expectancy, the search for products with greater durability increases. This leads to search for more and more resistant materials, including in the dental field. Once inorganic particles play a fundamental role in the properties of a composite resin, we searched to evaluate the influence different particles size in its mechanical properties. In these dental resins, we evaluated flexural strength, compressive strength, microhardness Vickers and contraction stress. To avoid unwanted variations, the consistency of these resins did not differ between samples (Consistency Squeeze = 75 N). Besides consistency, other variables of a composite resin (organic matrix composition, initiators, inhibitors) had their amounts fixed, seeking no other influence on the study. Nine types of resins were used in this study, with an average particle size ranging between 0.4μm and 3.0μm, there are three resins composed of single particles (0.4µm, 1.0µm e 3.0 µm) and six resins composed by mixing particles mentioned above. The results were compiled and the data submitted to statistical analysis (ANOVA – Multiple Comparisons Tukey test with 5% significance). The results showed that the synergistic effect of the mixture of particles reflected better properties in compressive strength and flexural strength test as compared to resins with single-size particles. Is possible to conclude too that there is not a single average size range of particles with results superior to other resins in all properties. However, looking for a balance between these properties, samples with an average particle size of 2.02μm and 2.14μm both composed of mixtures of particles (no single particles) showed the best results. As showed by Tukey's statistical analysis, both resins were placed as belonging to the 2 groups that indicate superior properties in all tests.
Keywords
acrylic resins; mechanical properties; particle size
