Análise de propriedades químicas e mecânicas de diferentes resinas compostas quando mantidas em temperatura de refrigerador e ambiente

Abstract

Resin composites are widely used in dental practice to restore contour, function, and esthetics. They can be handled at different temperatures and must support the conditions of the oral cavity. This in vitro study evaluated the degree of conversion (FTIR/ATR), sorption and solubility (ISO 4049: 2000) and surface hardness (Koop) of seven composite resins (Filtek Z100, Z250, 350, One Bulk Fill, Bulk Fill Flow, Universal and P60) polymerized under two different conditions: 1 – temperature: ambient (25°C) or refrigerated (5°C); and 2 – storage: 7 days and 30 days. The samples were obtained using a cylindrical silicone mold with internal dimensions of 6mm in diameter and 1mm in depth and were polymerized for 20s using a LED device (VALO Cordless LED). The degree of conversion was analyzed by ANOVA on ranks and Student-Newman-Keuls test. The other results were analyzed by two-way ANOVA for repeated measures and Tukey's test. The association between the characteristics of resin composites and the beneficial potential of using the materials at 25°C or 5°C was performed using the Chisquare test. The results were correlated using the Pearson correlation test. The level of significance for all analyses was 5%. All materials showed higher degree of conversion at 25°C. Greater sorption and solubility were observed at 25°C and after 30 days. Greater hardness results were observed at 25°C and after 7 days. Considering the clinical indication, the materials indicated for the posterior region had greater potential to increase hardness when stored at room temperature (p=0.047), while materials for universal use preented greater potential to reduce sorption and solubility at room temperature (p=0.047) Microhybrid materials showed greater potential for reducing solubility when compared to nanoparticulate materials (p=0.047). Resins with greater amount of particles showed higher ability to reduce solubility (p=0.008). Finally, it was observed that the greater the degree of conversion achieved by the material, a higher hardness should be expected.