1,720,994 research outputs found
Physically augmented coating of macrorough titanium surface with human SAOS-2 osteoblasts and bone matrix
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SiO2-P2O5-CaO glasses and glass-ceramics with and without ZnO: relationships among composition, microstructure, and bioactivity
No full textBioactive glasses and glass-ceramics of the system SiO2-P2O5-CaO with and without zinc were synthesized by sol-gel with the aim to address the influence of both the chemical composition and the microstructure on the growth of hydroxycarbonate apatite (HCA) following soaking in simulated body fluid (SBF). In the standard compositions 58S, 70S, and 80S the silica precursor was also partially replaced with a nanoscale silica powder (HiSil) in order to separate the contributions of porosity and composition. The combined use of XRPD, N2 absorption measurements, and SEM allowed us to establish quantitative correlations among the above-mentioned quantities. We found that the HCA formation rate increases with the silica content and that an important role is played by the specific surface area of the samples. Notably, the addition of even small quantities (0.4 wt%) of ZnO at the expenses of both CaO and P2O5 in the 58S glass leads to the increase, with respect to the 58S sample, of both the HCA formation rate and the HCA content after 8 days of treatment in SBF. A preliminary result revealed that sample with 0.4 wt % ZnO displayed good in vitro biocompatibility as shown by LDH assay
Antibacterial effects of six endodontic sealers
No full textPurpose: The objective of this study was to perform an in vitro evaluation of the antibacterial properties of 6 endodontic sealers (Endomethasone C, Argoseal, Bioseal Normal, Acroseal, AH Plus, Sicura Seal). Methods: The agar diffusion test (well and paper disc methods) with Enterococcus faecalis, Staphylococcus aureus and Streptococcus mutans was used. For the well method, Petri dishes were inoculated with bacterial suspensions. Each well was completely filled with freshly mixed endodontic sealer. For the paper disc method, sterile paper discs were immersed in freshly mixed sealers and put on agar plates. Diameters of halos formed around the sealers were measured after 24 h and 48 h. Statistical analysis: The effects of well method and of paper disc method were analyzed by 1-way ANOVA. Results: Endomethasone C, Argoseal and Bioseal showed the largest inhibition halos for all the tested microorganisms, while Sicura Seal and AH Plus showed low antibacterial effects. Moreover, the comparison of well method and paper disc methods showed significant statistical differences (P<0,01) for all sealers and indicated a dose-dependent antimicrobial effect
Effect of electrospun fiber diameter and alignment on macrophage activation and secretion of proinflammatory cytokines and chemokines
Full text linkMacrophage activation can be modulated by biomaterial topography according to the biological scale (micrometric and nanometric range). In this study, we investigated the effect of fiber diameter and fiber alignment of electrospun poly(L-lactic) (PLLA) scaffolds on macrophage RAW 264.7 activation and secretion of proinflammatory cytokines and chemokines at 24 h and 7 days. Macrophages were cultured on four different types of fibrous PLLA scaffold (aligned microfibers, aligned nanofibers, random microfibers, and random nanofibers) and on PLLA film (used as a reference). Substrate topography was found to influence the immune response activated by macrophages, especially in the early inflammation stage. Secretion of proinflammatory molecules by macrophage cells was chiefly dependent on fiber diameter. In particular, nanofibrous PLLA scaffolds minimized the inflammatory response when compared with films and microfibrous scaffolds. The histological evaluation demonstrated a higher number of foreign body giant cells on the PLLA film than on the micro- and nanofibrous scaffolds. In summary, our results indicate that the diameter of electrospun PLLA fibers, rather than fiber alignment, plays a relevant role in influencing in vitro macrophage activation and secretion of proinflammatory molecules
Photodynamic effect of tetra-substituted N-methyl-pyridyl-porphine combined with the action of vancomycin or host defense mechanisms disrupts Staphylococcus epidermidis biofilms
No full textThe skin commensal and opportunistic pathogen Staphylococcus epidermidis is an important cause of nosocomial infections. Virulence is attributable to formation of biofilm, which provides a microenvironment that protects the bacterium from attack by the host immune system and by chemotherapy. In this study we extended to S. epidermidis strategies previously aimed at treatment of S. aureus biofilms using photodynamic treatment (PDT) combined with chemotherapy or phagocytosis. A significant reduction in bacterial survival was observed when structurally distinct biofilms were exposed to the cationic porphyrin, tetra-substituted N-methyl-pyridyl-porphine (TMP), and simultaneously to visible light. Of note, the extent of biofilm clearance depended on its maturation stage: developing, young biofilms, were more sensitive towards PDT than mature biofilms. Furthermore, PDT-treated biofilms exposed to vancomycin or subjected to phagocytic action of whole blood were almost completely eradicated. The data we obtained establish that PDT combined with antibiotics or host defenses may also be a useful approach for the inactivation of S. epidermidis biofilms
Human adipose-derived stem cells (hASCs) proliferate and differentiate in osteoblast-like cells on trabecular titanium scaffolds
Full text linkAbstract
The use of stem cells in regenerative medicine is an appealing area of research that has received a great deal of interest in recent years. The population called human adipose tissue-derived stem cells (hASCs) share many of the characteristic of its counterpart of marrow including extensive proliferative potential and the ability to undergo multilineage differentiation along classical mesenchymal lineages: adipogenesis, chondrogenesis, osteogenesis, and myogenesis. The aim of this study was to evaluate with biochemical and morphological methods the adhesion and differentiation of hASCs grown on trabecular titanium scaffolds. The hASCs isolated from subcutaneous adipose tissue after digestion with collagenase were seeded on monolayer and on trabecular titanium scaffolds and incubated at 37 degrees C in 5% CO(2) with osteogenic medium or control medium.The results showed that hASCs were able to adhere to titanium scaffolds, to proliferate, to acquire an osteoblastic-like phenotype, and to produce a calcified extracellular matrix with protein, such as, decorin, fibronectin, osteocalcin, osteonectin, osteopontin, and type I collagen. These data suggest that this kind of scaffold/cells construct is effective to regenerate damaged tissue and to restore the function of bone tissue
Surface modification of titanium fiber-mesh through a culture of human SAOS-2 osteoblasts inside an electromagnetic bioreactor
No full textAdhesion of Streptococcus mutans to different restorative materials
No full textABSTRACT: Adherence of oral bacteria to the surface of dental restorative materials is considered
an important step in the development of secondary caries and periodontal disease. The aim of this
study was to investigate and compare the adherence of different restorative materials to Streptococcus
mutans strain (CCUG35176) in order to ascertain possible differences. The materials tested
ranged across different classes including: flowable composites (Gradia Direct LoFlo; Filtek Supreme
XT Flowable), anterior composites (Gradia Direct Anterior), universal composites (Filtek Supreme
XT), packable composites (Filtek Silorane; Filtek P60), glass-ionomers (Fuji IX Gp Extra; Equia) and
a control reference material (Thermanox plastic coverlips). Bacterial suspension was deposited onto
each material and the adhesion was evaluated trough the colony forming units (CFUs) determination.
Packable silorane-based composite was found to be less adhesive than posterior packable composite
P60, flowable composites and glass ionomers. The fluoride of glass ionomers did not prevent the attachment
of S. mutans; furthermore, after roughness analysis and SEM investigations, the hypothesis
that the difference in bacterial adhesion can be determined by the particular surface chemistry of the
material itself as well as by different electrostatic forces between bacteria and restorative surfaces
must be given serious consideration
Improved cell growth by Bio-Oss/PLA scaffolds for use as a bone substitute
Full text linkThe objective of this study was to investigate the surface modification of a natural bone substitute, Bio-Oss, coated with a synthetic polymer poly-D,L-lactide (PLA), in order to improve cell growth. Bio-Oss is a natural bone substitute made of the mineralized portion of bovine bone. The material is used mainly to fill bone defects in periodontal and maxillofacial surgery and permit reossification. Poly-a-hydroxyacids such as polylactic acid are receiving an increasing attention due to their ability to retain a great quantity of water, good biocompatibility, low interfacial tension, and minimal mechanical and frictional irritation. All of these features are appealing from the perspective of bioenvironmental mimicking. The human osteosarcoma cell line SAOS-2 was added to the top of scaffolds uncoated or coated with PLA and incubated at 37° in 5% CO_{2} for 15 days. PLA-coated scaffolds improved cell growth. Polymer degradation behaviour, extraction and measurement of the extracellular matrix proteins of the cultured scaffolds (such as decorin, fibronectin osteocalcin, osteonectin, osteopontin and type-I and type-III collagen), immunolocalization of bone proteins and morphological analysis of the scaffolds confirmed the bioactive properties of Bio-Oss/PLA4M suggesting that it could be a valuable grafting materia
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