The purpose of this study was to evaluate the early tensile bond strengths of three different resin cements; Super Bond C&B (conventional and quick type) and ResiCem to a CAD/CAM composite block. A ...CAD/CAM composite block (Shofu Block HC) was ground and silanized according to the manufacturers’ instructions before cementation. A conventional tensile bond strength test (Ø: 4 mm) was performed 10 min, 1 h and 24 h after bonding. Super Bond C&B (quick type) showed the highest bond strength at 24 h. However, results of a three-point bend test showed the mechanical properties were weaker for the Super Bond C&B cements compared with composite cement, Resicem. The 4-META/MMA-TBB resin is a suitable resin cement to bond to a CAD/CAM composite block.
We studied the phase stability of Ce-substituted magnetoplumbite-type Sr ferrite under various oxygen pressures. We have successfully obtained Ce-substituted samples as revealed from X-ray ...diffraction and wavelength dispersion X-ray analyses. The solubility limit of Ce in Sr1-xCexFe12O19 was estimated to be x = 0.24 at ambient pressure, which is reduced to 0.05-0.10 under higher oxygen pressures. The variation of the c -axis against x and the reduction of the solubility by increasing oxygen pressure suggests that the valence of Ce is not 4+ but 3+. The solubility limit of Ce is dominated not only by the ionic radius but also by the valence instability of Ce.
The aim of this study was to investigate the effects of potassium fluoride (KF) and sodium fluoride (NaF) in different concentrations on micro-shear bond strength (µSBS) and their protective effects ...against acid. The enamel blocks were treated with several concentrations of KF and NaF. For µSBS, Clearfil SE Bond 2 was applied to the treated surface and resin composite was light-cured, then examined using a universal testing machine. For acid resistance test, the specimens were immersed in acidic solution (pH 4.5), then examined under 3D confocal laser scanning microscope (CLSM). In µSBS, KF at 1,000, 9,000, and 10,000 ppm did not show differences compared with the control, while other concentrations of KF and NaF led to decreased µSBS. Higher concentrations of NaF and KF showed higher resistance to the acid challenge. So, we concluded that various concentrations of KF and NaF solutions had specific effects on µSBS and acid resistance.
This study evaluated the bonding performance of coronal dentin disks, designed for biological restoration, and CAD/CAM resin composite disks when bonded to flat dentin surfaces using dual-cure resin ...cements, with and without a resin-coating (RC) technique. Three distinct groups were established within the non-RC group, each using one of the two types of resin cements in a self-adhesive mode: one-step self-etch adhesive (1-SEA) without light-cure, 1-SEA with light-cure, and a separate group using an alternate cement. Within the RC group, a subgroup was established for each cement. The microtensile bond strength (μTBS) of the disk-dentin beam was tested after 0 and 10,000 thermocycles in a 5°C/55°C. No significant μTBS difference was observed among the non-RC groups. However, when using RC, the μTBSs of coronal dentin disks significantly exceeded those of CAD/CAM resin composite disks. Thermocycle aging did not affect μTBS in any of the bonding methods, except in self-adhesive mode.
The objective was to evaluate the effect of application of silver diamine fluoride (SDF) on discoloration of demineralized dentin over time. Dentin specimens were divided into four groups according ...to time of dentin demineralization. A 38% SDF solution was then applied to the dentin surfaces. Half of the specimens were placed in light-proof boxes while the remainder were exposed to light. Both groups were maintained at 37˚C. Color change was determined using a spectrophotometer at different time intervals. SEM/EDS analysis were also undertaken. The 13 h EDTA demineralized group showed the highest values for color change among different time intervals, with the control being the lowest. The light exposed groups showed more color change compared to the unexposed groups. We concluded that the degree of dentin demineralization leads to a significant increase of the rate of dentin color change after application of SDF.
Abstract
Acidic biotrickling filters (BTF) can be used for simultaneous removal of hydrogen sulfide (H2S) and siloxane from biogas. In this study, the performance of a BTF under different acidic pH ...conditions was investigated. The removal profile of H2S showed that 90% of H2S removal was achieved during the first 0.4 m of BTF height with down-flow biogas. Decamethylcyclopentasiloxane (D5) removal decreased from 34.5% to 15.6% when the pH increased from 0.88 to 3.98. Furthermore, the high partition coefficient of D5 obtained in under higher pH condition was attributed to the higher total ionic strength resulting from the addition of sodium hydroxide solution and mineral medium. The linear increase in D5 removal with the mass transfer coefficient (kL) indicated that the acidic recycling liquid accelerated the mass transfer of D5 in the BTF. Therefore, the lower partition coefficient and higher kL under acidic pH conditions lead to the efficient removal of D5. However, the highly acidic pH 0.9 blocked mass transfer of H2S and O2 gases to the recycling liquid. Low sulfur oxidation activity and low Acidithiobacillus sp. content also deteriorated the biodegradation of H2S. Operating the BTF at pH 1.2 was optimal for simultaneously removing H2S and siloxane.
Modern adhesive systems have been developed for enhanced mechanical and antibacterial properties; however, no such systems contain a calcium source to enhance bond strength. Therefore, we evaluated ...the effect of an experimental calcium-containing primer (10 wt% CaCl2) in two-step self-etching adhesive systems on micro-tensile bond strength (μ-TBS) and acid resistance in dentin adhesive interface observations after acid-challenge using scanning electron microscopy. Using two types of primers and bonding agents (Clearfil SE Bond primer (SEP), experimental calcium-containing primer (CaP), Clearfil SE Bond (SEB), and Clearfil Protect Bond), we prepared four experimental groups. The μ-TBS of CaP-SEB did not differ from that of SEP-SEB. Meanwhile, the CaP groups showed a thicker acid-base resistance zone. Thus, two-step self-etching adhesive system composed of experimental calciumcontaining primer can be used as an adhesive system with high acid resistance and acceptable bond strength.
Conventionally, the delivery of biomolecules into bacteria for the generation of characterized or functional mutants has relied greatly on horizontal gene transfer techniques. However, the low ...compatibility of these techniques with novel or hard-to-transform bacteria currently serves as a challenge to the bioengineering field. Here, we explored the use of cell penetrating peptides (CPPs) as an alternative biomolecule delivery approach by investigating the effects of the abiotic factors during CPP permeation. Using the (KFF)
K-FAM conjugate and
as models, we evaluated four abiotic factors where two of these factors, temperature and solution tonicity, promoted (KFF)
K-FAM permeation efficiency. Our data show that optimal (KFF)
K-FAM permeation efficiency was achieved for
at approximately 98.1% under conditions of 37°C (growth optimal temperature) and 50% PBS concentration. Based on these conditions, we subsequently tested the applicability of CPP permeation in various bacterial strains by treating 10 bacterial strains from the Enterobacteriaceae family among which seven strains have no CPP permeation records with (KFF)
K-FAM. Interestingly, when compared with non-optimized conditions, all 10 strains showed a marked increase in CPP permeation ranging between 20 and 90% efficiency. Although using strains within Enterobacteriaceae that are phylogenetically close, our results hinted on the possibility that with proper optimization of the abiotic factors, CPPs could be compatible with a broad range of bacterial strains. Our efforts suggest that CPP could serve as an effective alternative approach for mutant generation and for biomolecule delivery into novel or hard-to-transform bacteria.
In the current study, we sought to evaluate the effects of phosphoryl-oligosaccharides of calcium (POs-Ca) and/or fluoride-containing toothpaste on enamel. Six groups of experimental toothpaste were ...prepared by adding various concentrations of POs-Ca and/or fluoride. A 5 × 10-mm window on the enamel of the bovine incisor was immersed in resin and divided into three areas for “sound”, “demineralized (DEM)”, and “after pH cycle (aft. pH cycle)”. All specimens were subjected to pH cycling, including soaking in a slurry with toothpaste diluted threefold for 5 min. Transverse microradiography was employed to evaluate the mineral recovery, and the pH values of each demineralization solution were measured. The high fluoride concentration group showed a significantly better mineral recovery rate than the others, with no statistical differences between before and after pH cycling among the POs-Ca with low fluoride, POs-Ca only, low fluoride only, and control groups. In the low-concentration fluoride groups, the group containing POs-Ca tended to have a higher remineralization effect than the non-POs-Ca group. After pH cycling, the demineralization solution showed no pH changes in any group. The addition of POs-Ca and fluoride to toothpaste may recover the mineral density in enamel subsurface lesions at low-fluoride concentrations, but the high-fluoride concentrations did not show a meaningful difference in the two groups with and without POs-Ca.
Purpose: The purpose of this study was to investigate the reaction products formed by application of three tooth etchants to hydroxyapatite.Methods: Tooth etchants with three different compositions, ...designed for application to teeth before dental adhesive – “ K-etchant GEL” (containing phosphoric acid), “Enamel Conditioner” (containing organic acids), and “Multi Etchant” (containing acidic monomer) – were applied to hydroxyapatite plates.Results: Atomic force microscopy measurements revealed that Multi Etchant formed nano-sized particles on the hydroxyapatite. X-ray diffraction and Fourier transform infrared spectrometer analyses of the powdered hydroxyapatite indicated that Enamel Conditioner produced calcium tartrate whereas K-etchant GEL generated monetite. These results indicated that each etchant reacted with hydroxyapatite in a different way.Conclusion: Not only differences among the etching ability of etchants, but also differences in the reaction compounds they produce may influence bonding performance in clinical practice.
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