Efeito da incorporação de nanopartículas de zinco e cobre em dois sistemas adesivos univer- sais, nas propriedades biológicas, mecânicas e adesivas à dentina hígida e artificialmente afetada por cárie

Abstract

Objectives: This study evaluated the effect of addition of zinc oxide and copper nanoparticles (ZnO/CuNp) in different concentrations into two universal adhesives systems, on biological, mechanical and adhesive properties on sound and artificially caries-affected dentin. Materials and methods: ZnO/CuNp (0% [control]; 5/0.1 and 5/0.2 wt%) were added in Prime&Bond Active [PBA; Dentsply-Sirona] and Ambar Universal [AMB; FGM]. The antimicrobial activity (AMA) was evaluated against Streptococcus mutans. For cytotoxicity (CTX), Saos-2 cell-line was used, and the anti-MMP -2, -8 and -9 activity of the ZnO/CuNp was evaluated. For ultimate tensile strength (UTS) and microhardness (MH), specimens were tested after 24h and 28d. For in vitro degree of conversion (DC), specimens were evaluated after 24h by Fourier Transformed Infrared (FTIR) and micro-Raman spectroscopy. For water sorption (WS) and solubility (So), specimens were tested for 28d. For zinc oxide/copper release (ZnO-CuR), the samples were stored in 2% nitric acid solution and the properties measured for 28d. The occlusal enamel of two hundred and sixteen teeth was removed and the adhesives were applied to the surface of sound and artificially caries-affected dentin, in etch-and-rinse and self-etch strategy. After, composite resin build-ups, specimens were sectioned to obtain resin–dentine sticks. It was evaluated in resin-dentine microtensile bond strength (μTBS), nanoleakage (NL), microleakage evaluation by confocal laser scanning microscopy (ML) and in situ DC after 24h of water storage. ANOVA and Tukey’s test were applied (α = 0.05). Results: The addition of ZnO/CuNp increase AMA when compared to control (p<0.05) without increasing cytotoxicity (p>0.05) or negatively influencing UTS, MH, in vitro DC and in situ DC (p>0.05). The effect of the addition of ZnO/CuNp on the WS and SO was adhesive system dependent. High ZnO-CuR was observed in adhesives with highest concentration of ZnO/CuNp (p <0.05). μTBS values were maintaining with ZnO/CuNp addition. However, lower NL (p<0.05) and ML was observed for ZnO/CuNp groups. In addition, ZnO/CuNp present anti-MMP-2, -8 and -9 activity. Conclusions: The addition of ZnO/CuNp in the tested concentrations in universal adhesive systems may be an alternative to provide antimicrobial activity and improves the integrity of the hybrid layer, without jeopardizing biological, adhesives and mechanical properties.