Composites based on graphene oxide (GO), reduced graphene oxide (RGO) and zinc oxide (ZnO) with different mass ratios (8, 100 and 600) were synthesized through the hydrothermal method at 100 °C and used as reinforcement materials to commercial glass-ionomers cements (GIC). X-ray diffraction (XRD) characterization confirmed the graphite oxidation and ZnO formation as a wurtzite phase. Infrared spectroscopy analyses showed bands of oxygen-containing groups on the GO surface, which reduced after thermal treatment and RGO formation. D and G bands were observed in all samples synthesized, which presented morphology similar to flowers with a crystallite size of 18 nm. The effect on the mechanical properties of GIC after reinforcement with 0.1 wt% of RGO and 3 wt% of the composites was evaluated using a one-way analysis of variance (ANOVA). It was verified slight improvements in the hardness of GIC.

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RESUMOEste estudo avaliou a capacidade de molhamento e adaptação compósitos resinosos de três diferentes viscosidades às paredes cavitárias de preparos padronizados realizados em dentes bovinos simulando cavidades tipo Classe I de Black. Um molde realizado com silicone de adição foi feito de cada cavidade previamente à restauração para título de controle da capacidade de molhamento e adaptação. Com as restaurações finalizadas, os dentes foram submetidos à desmineralização de sua estrutura permitindo que a restauração fosse facilmente destacada para a sua avaliação. Os corpos de prova foram avaliados com o auxílio de um perfilômetro 3D. Dentre os grupos estudados o melhor desempenho foi da resina bulk fill flow. Os resultados sugerem que a viscosidade dos compósitos resinosos restauradores interfere diretamente na capacidade de molhamento e adaptação deles às paredes cavitarias e que devem ser considerados pelo menos como uma camada de aplicação inicial.

Context (Background): Resin composites are the most widely used material for restoring cervical defects. However, the high failure rate of these restorations is still a concern. Aims: The aim of this in vitro study was to evaluate, using microtomography (μCT), the interfacial gap and voids formation in Class V cavities in premolars restored with materials with lower polymerization shrinkage combined with different restorative techniques. Settings and Design: Cervical defects were created in 30 intact premolar and were randomly distributed to be restored by one of the following techniques (n = 6): Composite resin with two increments (CR), organic modified polymer (ORMOCER) with single (OR1) or two increments (OR2, or low viscosity bulk-fill composite resin with single (BF1) or two increments (BF2). Methods and Material: Each tooth was scanned before filling to determine the volume of interest (VOI) to be applied in the second μCT after restoration and to control the cavity volume among the groups. In the μCT after filling, the volume of interfacial gaps and voids was calculated for each group. Statistical Analysis: The groups were compared using one-way and Tukey HSD post hoc test (α = 0.05). Results: It was possible to identify higher gap formation in the OR1 group and higher void formation in CR group (P < 0.05). OR2 group showed better results than the group with one increment. BF2 showed the best filling capacity. Conclusions: It was possible to conclude that the material and the number of increments directly influenced the internal adaptation and voids formation of Class V restorations.