Resin-based pit-and-fissure sealants are often used to form a barrier on the occlusal surface of molars to treat caries lesions; however, bacteria can remain in the pit and fissures without detection, increasing the risk of secondary caries. Sealants with antimicrobial properties or microbial repellent actions might be advantageous. The aim of this study was to assess the inhibitory effect of a 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB)-incorporated sealant against Streptococcus mutans. MAE-DB (4% wt) was incorporated into a commercially available sealant, Eco-S resin-based pit-and-fissure sealant (Vericom Co., Ltd., Korea); a sealant without MAE-DB served as a negative control, and Clinpro™ Sealant (3M™ ESPE™), a fluoride-releasing resin, was used as a commercial control. The effects of the cured sealants and their eluents on the growth of S. mutans were determined according to colony-forming unit counts and metabolic tests. The effects of the cured sealants on the adherence and membrane integrity of S. mutans were investigated using confocal laser-scanning microscopy (CLSM) in conjunction with fluorescent indicators. Compared with the negative control and commercial control, the cured MAE-DB-incorporated pit-and-fissure sealant exhibited a significant inhibitory effect on the growth of S. mutans (P < 0.05), whereas the eluents did not show any detectable antibacterial activity. The commercial control also showed no detectable bactericidal activity. Moreover, the aged experimental material retained its property of contact inhibition of biofilm formation. The fluorescence analysis of CLSM images demonstrated that the cured MAE-DB-incorporated sealant could hamper the adherence of S. mutans and exert a detrimental effect on bacterial membrane integrity. The incorporation of MAE-DB can render a pit-and-fissure sealant with contact antibacterial activity after polymerization via influencing the growth, adherence, and membrane integrity of S. mutans. Therefore, MAE-DB-containing pit-and-fissure sealant shows promise for preventing or controlling dental caries on occlusal pit and fissures of molars.
The purpose of this study was to investigate the effect of zircon-based tricolor pigments (praseodymium zircon yellow, ferrum zircon red, and vanadium zircon blue) on the color, thermal property, crystalline phase composition, microstructure, flexural strength, and translucency of a novel dental lithium disilicate glass-ceramic. The pigments were added to the glass frit, milled, pressed, and sintered. Ninety monochrome samples were prepared and the colors were analyzed. The effect of the pigments on thermal property, crystalline phase composition, and microstructure were determined by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. Addition of the pigments resulted in the acquisition of subtractive primary colors as well as tooth-like colors, and did not demonstrate significant effects on the thermal property, crystalline phase composition, microstructure, and flexural strength of the experimental glass-ceramic. Although significant differences (p < 0.01) were observed between the translucencies of the uncolored and 1.0 wt % zircon-based pigment colored ceramics, the translucencies of the latter were sufficient to fabricate dental restorations. These results indicate that the zircon-based tricolor pigments can be used with dental lithium disilicate glass-ceramic to produce abundant and predictable tooth-like colors without significant adverse effects, if mixed in the right proportions.
AIM:To observe the influence of different abutment teeth on the esthetic results of veneer restorations for tetracycline stained teeth by mimicking clinical situations.METHODS:Ceramic veneers were bonded to different artificially stained background with Choice resin cements.The L* a* b* values of different restorations were recorded and compared afterwards.RESULTS:The L* a* b* values were significantly different(P 0.005) among different simulated background(abutment teeth).With the decrease of the brightness value of the background,the L* value decreased greatly and the color difference(△E) increased obviously.It showed that the color of the abutment teeth influenced the color of the restoration significantly,and the influence was the least when the abutment teeth color was yellow.CONCLUSION:Yellowish abutment teeth shows the least color influence on venner restorations.Dark grey color shows the most significant effect on the color of veneers,therefore masking cements should be used to bond the veneer when abutment teeth color is dark grey.
Alumina ceramics is densely sintered at 1450℃ by using CaO-MgO-SiO2 glass(CMS-G) and TiO2 as sintering assistant.The effect that the weight content of CMS-G and TiO2 to sintering character,and fine texture and sintering kinetics of alumina ceramics is studied.The results show that CMS-G and TiO2 can accelerate density of alumina ceramics effectively,the relative density of alumina ceramics is up to 98.25%,when content of CMS-G is 3% and TiO2 is 1%.Sintering process is controlled by diffusion,and activation energy of liquid phase sintering is 113.4kJ/mol.
In drone-assisted mobile networks, Drone-mounted Base Stations (DBSs) are responsively and flexibly deployed over any Places of Interest (PoI), such as sporadic hotspots and disaster-struck areas, where the existing mobile network infrastructure is unable to provide wireless coverage. In this paper, a DBS is an aerial base station to relay traffic between a nearby Macro Base Station (MBS) and the users. In addition, Free Space Optics (FSO) is applied as the backhauling solution to significantly increase the capacity of the backhaul link between an MBS and a DBS. Most of the existing DBS placement solutions assume the FSO-based backhaul link provides sufficient link capacity, which may not be true, especially when a DBS is placed far away from an MBS (e.g., > 10 km in disaster-struck areas) or in a bad weather condition. In this paper, we formulate a problem to jointly optimize bandwidth allocation and DBS placement by considering the FSO-based backhaul link capacity constraint. A Backhaul awaRe bandwidth allOcAtion and DBS placement (BROAD) algorithm is designed to efficiently solve the problem, and the performance of the algorithm is demonstrated via extensive simulations.
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