Efeito da incorporação de cobre nas propriedades mecânicas e adesivas à dentinas de um sistema adesivo universal

Abstract

The purpose of this in vitro study was to evaluate the effect of addition of copper nanoparticles on a universal adhesive system in microtensile bond strength (μTBS) and nanoleakage (NL) of sound, eroded and carious resin-dentin interface, using both self-etch [SE] and total-etch [TE] adhesive strategies. As well as degree of conversion (DC), interface micromorphology (IM), ultimate tensile strength (UTS), cumulative water sorption (WS) and solubility (So) of the adhesive system and copper radiopacity (CR). The experimental adhesive system was formulated with the addition of 0,1% copper nanoparticles on Ambar Universal. For μTBS and NL, 120 human third molars were randomly distributed in 12 experimental conditions (n=10) based on the combination of the variables: concentration of copper [0 and 0,1%] vs. dentin surface (sound, eroded and carious) vs. adhesive strategies (TE and SE). After bonding procedures and restored with composite resin, teeth were stored for 24h and then longitudinally sectioned to obtain specimens – dentin-resin sticks (0,8mm2), tested in a tension of 0,5mm/min for μTBS. For NL, 3 specimens per tooth were prepared and analyzed by scanning electron microscopy (SEM). For DC, 3 sticks of resin-dentin of each experimental condition were analyzed by Raman spectroscopy. For IM, 3 sticks of resin-dentin were prepared and analyzed by FEG. For UTS, 5 samples of each condition were tested after 24 hours and 28 days of storage (n = 10). For WS and So, 10 samples of each experimental condition (n = 10) were tested during 56 days. For radiopacity, 5 CPAs of each experimental condition (n = 5) were submitted to 5 digital radiographs, for comparison in gray scale in Adobe Photoshop Software. The data of μTBS, NL and DC (Raman) were analyzed by three-way ANOVA, submitted to Tukey's post hoc test for multiple comparisons. For UTS, data were analyzed by two-way ANOVA. For CR, data were analyzed by one-way ANOVA. The data of WS and So were evaluated by Student’s T-test. Statistical significance was set at α = 0.05. The inclusion of 0,1% of copper nanoparticles on the universal adhesive system improved μTBS values on sound and eroded substrates. The copper adhesive improved NL on sound dentin, for both strategies. For UTS, radiopacity, WS and So, the addition of copper showed no statistical difference in the results. DC was most affected by eroded dentin associated with ER strategy and adhesive containing copper, which resulted in smaller tags, in reduced quantity.