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1.
Adv Healthc Mater ; 8(24): e1901301, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31763779

RESUMO

Due to their excellent size, designability, and outstanding targeted antibacterial effects, nanoparticles have become a potential option for controlling oral biofilm-related infections. However, the formation of an oral biofilm is a dynamic process, and factors affecting the performance of antibiofilm treatments are complex. As such, when examining the existing literature on the antibiofilm effects of nanoparticles, attention should be paid to the specific mechanisms of action at different stages of oral biofilm formation, as well as relevant influencing factors, in order to achieve an objective and comprehensive evaluation. This review is intended to detail the antibacterial mechanisms of nanoparticles during the four stages of the formation of oral biofilms: 1) acquired film formation; 2) bacterial adhesion; 3) early biofilm development; and 4) biofilm maturation. In addition, factors influencing the antibiofilm properties of nanoparticles are summarized from the aspects of nanoparticles themselves, biofilm models, and host factors. The limitations of current research and possible trends for future research are also discussed. In summary, nanoparticles are a promising antioral biofilm strategy. It is hoped that this review can serve as a reference and inspire ideas for further research on the application of nanoparticles for effectively targeting and treating oral biofilms.

2.
Nanoscale Res Lett ; 11(1): 484, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27813025

RESUMO

The widespread application of metallic nanoparticles (NPs) or NP-based products has increased the risk of exposure to NPs in humans. The brain is an important organ that is more susceptible to exogenous stimuli. Moreover, any impairment to the brain is irreversible. Recently, several in vivo studies have found that metallic NPs can be absorbed into the animal body and then translocated into the brain, mainly through the blood-brain barrier and olfactory pathway after systemic administration. Furthermore, metallic NPs can cross the placental barrier to accumulate in the fetal brain, causing developmental neurotoxicity on exposure during pregnancy. Therefore, metallic NPs become a big threat to the brain. However, the mechanisms underlying the neurotoxicity of metallic NPs remain unclear. Programmed cell death (PCD), which is different from necrosis, is defined as active cell death and is regulated by certain genes. PCD can be mainly classified into apoptosis, autophagy, necroptosis, and pyroptosis. It is involved in brain development, neurodegenerative disorders, psychiatric disorders, and brain injury. Given the pivotal role of PCD in neurological functions, we reviewed relevant articles and tried to summarize the recent advances and future perspectives of PCD involvement in the neurotoxicity of metallic NPs, with the purpose of comprehensively understanding the neurotoxic mechanisms of NPs.

3.
Environ Toxicol Pharmacol ; 48: 130-140, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27771506

RESUMO

With the rapid development of nanotechnology, titanium dioxide nanoparticles (TNPs) are widely used in many fields. People in such workplaces or researchers in laboratories are at a higher risk of being exposed to TNPs, so are the consumers. Moreover, increasing evidence revealed that the concentrations of TNPs are elevated in animal organs after systematic exposure and such accumulated TNPs could induce organ dysfunction. Although cellular responses such as oxidative stress, inflammatory response, apoptosis, autophagy, signaling pathways, and genotoxic effects contribute to the toxicity of TNPs, the interrelationship among them remains obscure. Given the pivotal role of oxidative stress, we summarized relevant articles covering the involvement of oxidative stress in TNPs' toxicity and found that TNP-induced oxidative stress might play a central role in toxic mechanisms. However, available data are far from being conclusive and more investigations should be performed to further confirm whether the toxicity of TNPs might be attributed in part to the cascades of oxidative stress. Tackling this uncertain issue may help us to comprehensively understand the interrelationship among toxic cellular responses induced by TNPs and might shed some light on methods to alleviate toxicity of TNPs.


Assuntos
Exposição Ambiental/efeitos adversos , Nanopartículas/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Titânio/toxicidade , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Dano ao DNA , Metilação de DNA/efeitos dos fármacos , Humanos , Nanopartículas/química , Estresse Oxidativo/genética , Estresse Oxidativo/imunologia , Distribuição Tecidual , Titânio/química , Titânio/farmacocinética
4.
Nanoscale Res Lett ; 11(1): 291, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27295259

RESUMO

With the rapid development of nanotechnology, metallic (metal or metal oxide) nanoparticles (NPs) are widely used in many fields such as cosmetics, the food and building industries, and bio-medical instruments. Widespread applications of metallic NP-based products increase the health risk associated with human exposures. Studies revealed that the brain, a critical organ that consumes substantial amounts of oxygen, is a primary target of metallic NPs once they are absorbed into the body. Oxidative stress (OS), apoptosis, and the inflammatory response are believed to be the main mechanisms underlying the neurotoxicity of metallic NPs. Other studies have disclosed that antioxidant pretreatment or co-treatment can reverse the neurotoxicity of metallic NPs by decreasing the level of reactive oxygen species, up-regulating the activities of antioxidant enzymes, decreasing the proportion of apoptotic cells, and suppressing the inflammatory response. These findings suggest that the neurotoxicity of metallic NPs might involve a cascade of events following NP-induced OS. However, additional research is needed to determine whether NP-induced OS plays a central role in the neurotoxicity of metallic NPs, to develop a comprehensive understanding of the correlations among neurotoxic mechanisms and to improve the bio-safety of metallic NP-based products.

5.
Shanghai Kou Qiang Yi Xue ; 20(1): 1-5, 2011 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-21451889

RESUMO

PURPOSE: To determine the optimum pigments concentration on the physical and mechanical properties. METHODS: In this study, control samples were prepared from MDX-4-4210 silicone base and tested along with the pigmented samples for comparison in accordance with the national standards. The pigments concentration to base elastomer was set at 0.1, 0.15, 0.2, 0.25, 0.3wt%,respectively; while other conditions were kept same, then the major physical properties of the elastomer were studied with a tensile tester. The data was processed with SPSS10.0 software package. RESULTS: When comparing the pigmented samples with the control, the tensile strength, the ultimate elongation, the tear resistance and the Shore A hardness of the MDX-4-4210 silicone elastomer was affected by the addition of the pigments. A decrease was found,while, the incorporation of pigments had no effect on the permanent deformation rate of the resulting elastomer by the addition of the pigments. CONCLUSIONS: The results obtained from physical and mechanical testing of pigmented silicone samples suggest that incorporation of 0.2wt% by weight of pigments can alter the initial physical and mechanical behavior of the base elastomer. Supported by National Natural Science Foundation of China (30630066).


Assuntos
Teste de Materiais , Prótese Maxilofacial , Dimetilpolisiloxanos , Dureza , Humanos , Elastômeros de Silicone , Resistência à Tração
6.
Nan Fang Yi Ke Da Xue Xue Bao ; 31(2): 259-61, 2011 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-21354906

RESUMO

OBJECTIVE: To determine the infinite optical thickness of dentine porcelain of IPS E.max A color series. METHODS: Cylindrical dentine porcelain specimens of the IPS E.max A color series were prepared with a diameter of 13 mm and thickness of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 mm. The chromatic value of all the specimens was determined with CM-5 spectrometer against standard black and white background. The chromatic aberration (deltaE) was calculated by regression equation. RESULTS: The infinite optical thickness of dentine porcelain of the IPS E.max A color series ranged from 2.341 to 3.333 mm for a deltaE of 1.0, and from 2.064 to 2.904 mm for a deltaE of 1.5. As the chromaticity or thickness increased, the influence by the background color decreased, and the color of specimens became gradually close to the intrinsic color. CONCLUSION: The thickness of the background dentine porcelain specimens must exceed its infinite optical thickness to represent the intrinsic color and avoid the influence by the extrinsic color.


Assuntos
Coroas , Porcelana Dentária/química , Pigmentação em Prótese , Preparo Prostodôntico do Dente/métodos , Materiais Revestidos Biocompatíveis/química , Planejamento de Prótese Dentária , Humanos
7.
Nan Fang Yi Ke Da Xue Xue Bao ; 30(10): 2281-3, 2287, 2010 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-20965825

RESUMO

OBJECTIVE: To investigate the effect of three types of veneering porcelain on the bending strength of KAVO Y-TZP/porcelain layered structure. METHODS: KAVO zirconia ceramics were used as the substructure. To form Y-TZP/porcelain bilayered structure, a leucite-based veneering porcelain was fired on the zirconia substructures by slip-casting technique with dentin washbake, and two nano-fluorapatite-based veneering porcelains were fired on the zirconia substructures by either slip-casting or pressed-on technique with or without liner coverage. The bending strength was tested according to ISO 6872 standard, and the veneered surfaces of the fracture samples were analyzed by scanning electron microscopy (SEM). RESULTS: For covering KAVO zirconia core material, the conventional veneering slurry-porcelain combined with liner or wash firing had significant higher bending strength than pressed-on porcelain. SEM showed that the main failure type at the interface was adhesive failure. CONCLUSION: Thin layer sintering using washbake program or liner on KAVO zirconia surface increases the surface wettability, and this procedure may be indispensable when veneering on the surface of dental zirconia.


Assuntos
Porcelana Dentária , Resistência ao Cisalhamento , Zircônio , Análise do Estresse Dentário
8.
Nan Fang Yi Ke Da Xue Xue Bao ; 30(5): 945-8, 2010 May.
Artigo em Chinês | MEDLINE | ID: mdl-20501363

RESUMO

OBJECTIVE: To investigate the effect of two methods of pigmentation on the flexural strength of dental Y-TZP/porcelain layered structure. METHODS: KaVo zirconia substructures were pigmented by dipping presintered blocks in the coloring solution VITA LL1 and LL5, and colored TZ-3YS zirconia substructures were fabricated by adding pigments before isostatic pressing. The colors No.1 and No.5 were used for the test. The specimens were made in monolithic or bilayered forms, and the flexural strength was tested. XRD and SEM with EDX were used to analyze the characteristics of the surface structure. RESULTS: In KaVo group, no significant differences were found in the flexural strength between white and LL1 and LL5 colored monoclinic materials, nor in bilayered structures. While in TZ-3YS group, significant differences were noted in the flexural strength between color No.5 white and color No.1 monoclinic materials, but not between the latter two subgroups. The flexural strength was significantly lowered by veneering with porcelain in both zirconia groups, and similar findings were observed with the monoclinic materials. Only the tetragonal phase was detected in both of the zirconia groups. CONCLUSION: Pigmentation has no apparent effects on the bonding strength between the veneering porcelain and zirconia. Both coloring methods are appropriate when the concentration of the pigments is under deliberate control.


Assuntos
Colagem Dentária , Porcelana Dentária/química , Análise do Estresse Dentário , Pigmentação , Ítrio/química , Zircônio/química , Materiais Dentários , Facetas Dentárias , Teste de Materiais , Resistência à Tração
9.
Nan Fang Yi Ke Da Xue Xue Bao ; 29(5): 906-8, 2009 May.
Artigo em Chinês | MEDLINE | ID: mdl-19460705

RESUMO

OBJECTIVE: To determine the chroma value of sintered IL1-IL5 zirconia materials in comparison with the Vita In-Ceram YZ color shade. METHODS: Five types of shading dental zirconia ceramics with color gradient were prepared by adding Fe2O3, CeO2, and Bi2O3 to the zirconia powder, and their chroma values were determined using a spectrophotometer and the color difference was calculated. RESULTS: The chroma value ranges were L: 67.76-77.78, a: -2.19-3.80, and b: 12.13-25.01. Slight deltaE was found between IL1 and LL1, IL2 and LL2, and IL3 and LL3. The deltaE between IL4 and LL4 could be compensated by veneering porcelain, whereas deltaL between IL5 and LL5 could not be compensated in this manner. CONCLUSION: Shading dental zirconia ceramics can be prepared by addition of metal oxides with color similar to the Vita In-Ceram YZ color shades to match that of the veneering porcelain in clinical practice.


Assuntos
Porcelana Dentária , Ligas Metalo-Cerâmicas , Pigmentação em Prótese , Zircônio , Cor , Facetas Dentárias , Pigmentação em Prótese/métodos , Espectrofotometria
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