Análise das propriedades mecânicas do cimento de ionômero de vidro de alta viscosidade após diferentes protocolos de proteção superficial: um estudo in vitro

Abstract

The presence of moisture during initial setting is a factor that influences the quality and longevity of restorations, especially ionomeric cements due to their mechanical fragility. The aim of this study was to evaluate the pH of different surface protection materials (SPM) and to analyze the sorption, solubility, hardness and surface characterization of high-viscosity glass ionomer cement (GIChv). Disks of GIChv were made as test specimens. The SPM were distributed according to the experimental groups: liquid petroleum jelly; solid petroleum jelly; liquid glycerin; adhesive; nail base and; without application. Indicator strips were used to analyze the pH of the SPM. After being made, the specimens were weighed and subjected to the protocol for applying the protective materials, stored in microtubes with distilled water in a bacteriological oven at 37°C. For the sorption test, the specimens were weighed immediately, at 24 hours, 7 days and 14 days. For the solubility test, the specimens were submitted to 14 days in a desiccator and weighed after this period. For the knoop hardness test, the specimens were analyzed using a microdurometer after the sorption and solubility challenges and rehydrated for 24 hours in a new microtube with distilled water. Microphotographs were taken using the lenses attached to the microdurometer. The values were tabulated and a descriptive analysis was carried out using the one-way ANOVA test supplemented by Tukey at 5% significance. The pH test showed that the SPM were acidic. In the sorption test, the liquid petroleum jelly group differed from the other groups (p<0.05). In the solubility test, the group without application showed no statistical difference from the other groups (p>0.05). In the microhardness test, the adhesive group showed a statistical difference when compared to the other experimental groups (p<0.05). In the microphotographs, the nail base group shows an irregular surface pattern compared to the other groups, while the others are similar to the group without application. The SPM have acidity. There was no difference in sorption and solubility after application of the SPM with the group without application, and the application of the adhesive reduced the hardness of the GIChv.