Aim: The purpose of this in vitro study was to assess the shear bond strength (SBS) and bond failure types of a resin-composite to six pulp-capping materials used in primary teeth. Study design: Eight-disc specimens from each pulp-capping material (6 groups) to bond to Filtek™ Z350 XT Flowable using a standard PVC tube (2×2mm). All groups were prepared according to the instruction of the manufacturer. The SBS was measured with a crosshead speed of 0.5 mm/min using a universal testing machine. Failure mode evaluation was completed using Digital Microscope by two independent examiners. Results: Urbical LC® showed the highest SBS (Mean±SD) followed by ProRoot® MTA and TheraCal LC® (35.422±2.910, 22.114±2.515, and 21.175±1.983) respectively. ANOVA showed significant differences between all groups (P=0.0001). Urbical LC® and Photac™ Fil QuickAplicap™ were statistically significant different from all other pulp-capping materials groups. ProRoot® MTA was statistically significant different than Biodentine® (P=0.0001) and Photac™ Fil (P=0.0001). The total number of bond failure was recorded for cohesive B failure/cohesive in the pulp-capping material (14) and adhesive failure (14). Conclusion: Most of the tested pulp-capping materials bonded to Filtek™ Z350 XT demonstrated clinically acceptable and high SBS. Urbical LC showed the highest SBS while Biodentine® showed the lowest SBS.
Background: The purpose of this in vitro study was to investigate the effects of water-jet flossing on the color stability and surface roughness of five resin-based composites. Material and Methods: Five commercially available composite resins were studied. Nine disc-shaped specimens (6x2mm) were fabricated from each composite. The specimens were randomly allocated into three groups and three different treatments were performed on each group: storage in water (control group), water-jet flossing using 50 Psi water pressure, and water-jet flossing using 100 Psi water pressure. The water-jet flossing was performed in a standardized manner using a Waterpik® Aquarius® water flosser. Color and roughness were measured at baseline and at the end of 30 minutes of treatment, which is approximately equivalent to 5 years of simulated water-jet flossing for 1 minute once a day. The data were statistically analyzed using two-way analysis of variance (ANOVA) with Bonferroni and Tukey's post-hoc tests. Results: No significant color change was found after 5 simulated years of water-jet flossing, irrespective of composite type and water-flossing pressure setting (p > 0.05). Furthermore, none of composite specimens showed any significant surface roughness changes except for the two composites with spherical filler specimens in the 100 Psi treatment group. These composites exhibited a significant increase in surface roughness compared with the nano-filled composite (p = 0.001 and p = 0.006). However, the differences were clinically acceptable (≈0.2 µm). Conclusions: In terms of surface roughness and color, water-jet flossing is safe to be used on composite restorations within the settings of this study.
Woven fabrics were bestowed with antibacterial property by the simple adsorption of rare-earth metal ions, and the underlying mechanism was investigated using electron spin resonance (ESR) spectroscopy. The adsorption of Ce 3+ ions on wool, silk, and cotton fabrics resulted in significant inhibition of Staphylococcus aureus (a gram-positive bacterium), with maximum antibacterial activities (viable bacterial count compared to the reference) of 4.7, 5.8, and 5.2, respectively. Even after 50 wash cycles, the values remained at 3.9, 2.9, and 4.8, respectively. The adsorption of La 3+ and Gd 3+ ions on wool fabrics also resulted in antibacterial activities of 5.8 and 5.9, respectively. In addition, wool adsorbed with Ce 3+ exhibits a satisfactory antibacterial activity of 6.2 against Escherichia coli (a gram-negative bacterium). Such bacterial inhibition is attributed to Fenton reactions between the adsorbed rare-earth ions and hydrogen peroxide (H 2 O 2 ) produced during bacterial metabolism, as determined from the ESR spectra collected using the spin trap method in the presence of H 2 O 2 . The safety of cerium nitrate was also investigated, and no significant issues arose, indicating that it was a safe antibacterial agent. This facile method of imparting antibacterial properties to natural fabrics may be useful for preventing infections in humans.
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