Addition of silver nanoparticles reduces the wettability of methacrylate and silorane-based composites

Incorporation of silver nanoparticles into composite resins is recommended for their reported antibacterial properties, but this incorporation can affect the wettability of such materials. Therefore, this study evaluated the effect of nano-silver addition to silorane-based and methacrylate-based composites on their contact angle. Nano-silver particles were added to Z250 (methacrylate-based) and P90 (silorane-based) composites at 0.5% and 1% by weight. The control group had no additions. SEM-EDX analysis was performed to confirm the homogeneity of the nano-silver distribution. Seventy-two composite discs were prepared and standardized to the identical surface roughness values, and then distributed randomly into 6 groups containing 12 samples each (N = 12). Two random samples from each group were observed by atomic force microscopy. Distilled water contact angle measurements were performed for the wettability measurement. Two-way ANOVA, followed by the Tukey-HSD test, with a significance level of 5%, were used for data analysis. It was observed that wettability was significantly different between the composites (p = 0.0001), and that the addition of nano-silver caused a significant reduction in the contact angle (p = 0.0001). Wettability varied depending on the concentration of the nano silver (p = 0.008). Silorane-based composites have a higher contact angle than methacrylate-based composites. Within the limitations of this study, it can be concluded that the addition of 0.5% nano-silver particles to the composites caused a decrease in the contact angle of water.

Microtensile bond strength of quartz fiber posts to different composite cores

The aim of this in vitro study was to assess the microtensile bond strength of quartz fiber posts to different composites, and to composite combinations used as core materials. Thirty fiber posts were treated with a 24 percent hydrogen peroxide solution and silanized. The posts were divided into 5 groups according to the resin composite used as follows (n = 6): G1 - Ælite Flow (Bisco, Inc), G2 - Filtek Z250 (3M ESPE), G3 - Biscore (Bisco, Inc), G4 - Ælite Flow + Filtek Z250, G5 - Ælite Flow + Biscore. The resin composites were placed around the posts to produce cylindrical specimens. Two 1-mm² thick sticks containing the post in the center and composite cores on both ends were provided from each cylinder and tested for microtensile strength with a crosshead speed of 0.5 mm/min. One-way ANOVA and Tukey HSD tests were used for statistical analysis. Fractured surfaces were observed using a stereomicroscope with 20× magnification. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured sticks. The results showed that G2 had the highest bond strength values, and the lowest values were seen with G3. There were significant differences between groups 1, 2, 4 and groups 3, 5 (p < 0.05). Under the stereomicroscope, most of the failures were adhesive between the post and core material. Under SEM, Ælite and Z250 had smoother surfaces than Biscore, containing less porosities and voids.