Análise laboratorial da rugosidade e estabilidade de cor da resina acrílica imersa em soluções desinfetantes para higiene de prótese totais após diferentes períodos de tempo

Abstract

The objective of this study was to verify the color change and surface roughness of the acrylic resin (with or without polishing) after immersion in different disinfectant solutions. 45 specimens of thermopolymerized acrylic resin (measuring 30mm in length, 10mm in width and 4mm in thickness) were randomly divided into three groups (n = 15). The specimens were immersed (20 minutes) in the following solutions: 0.25% sodium hypochlorite (HS), acetic acid (vinegar) and distilled water (control group). For the readings of the response variables, the surface roughness was performed by a portable digital rugosimeter and for color change, a digital spectrophotometer - Easy Shade, which uses the color system Internationale de L'Eclairage Standard Commission (CIE Lab). The color and surface roughness reading was performed before and after each immersion, the experimental period was 5 years, with readings equivalent to 0, 1, 2, 3, 4 and 5 years, based on the time of 20 minutes of daily immersion in disinfectant solutions and control. The data were analyzed comparing period and solution by the Kruskal Wallis test and in cases of difference the complementary test SNK (Student Newman Keuls) was used. The comparison between polished and unpolished surfaces was used the Mann-Whitney test. The level of significance was 0.05. As a result, the study showed that the vinegar did not change the surface roughness, while the 0.25% sodium hypochlorite changed the polished surface of the specimens in the 2-year period (p <0.001), , after which it appeared similar to the group control. Regarding color change, HS 0.25% and vinegar caused color change in the unpolished surface in the 5-year period (p <0.001), and the HS 0.25% presented the largest change. On the polished surface, the vinegar did not change over time, whereas the HS 0.25% only suffered in the period of 5 years (p <0.01). At the end of the study both solutions proved that they can be used as a hygiene method, maintaining the physical properties of the materials of the total dentures within acceptable values.