ABSTRACT
La estética es el paradigma de la odontología restauradora. En la actualidad, se utilizan procedimientos combinados, por la exigencia sostenida de los pacientes por tener piezas dentarias blancas y brillantes. Es así que, para cumplir con esas expectativas, clínicas, en algunos casos se utilizan técnicas de blanqueamiento dentario, mientras que en otros se necesitan procedimientos como los de microabrasión o micro-macro abrasión, para remover manchas oscuras o blancas del esmalte dentario, buscando de esta manera, la satisfacción en lo que a estética se refiere. La microabrasión es un procedimiento muy utilizado en la actualidad por los profesionales odontólogos, por lo anteriormente expuesto o como técnica previa al uso de sistemas adhesivos. Por ello, se pretende con este documento, presentar una revisión sobre conceptos actuales, como así también los condicionantes al momento de seleccionar materiales o realizar el procedimiento de microabrasión.
Subject(s)
Humans , Tooth Discoloration/therapy , Esthetics, Dental , Enamel Microabrasion/methods , Hydrochloric Acid/chemistry , Phosphoric Acids/chemistry , Dental Enamel , Fluorosis, Dental/therapy , Enamel Microabrasion/instrumentation , Dental Restoration, Permanent/methods , Silicon/chemistryABSTRACT
This study evaluated the bond strength (push-out method) and Knoop hardness of Z250 composite resin, photoactivated with XL 2500 curing unit, using different protocols: continuous mode (700mW/cm² for 20s) (CO); soft-start (50 mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS1); soft-start (100 mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS2); soft-start (150 mW/cm² for 5 s, followed by 700mW/cm² for 15s) (SS3); soft-start (200mW/cm² for 5s, followed by 700mW/cm² for 15s) (SS4); soft-start (250mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS5); soft-start (300 mW/cm² for 5 s, followed by 700 mW/cm² for 15 s) (SS6). For the push-out test, the specimens were tested in a universal testing machine at a crosshead speed of 0.5 mm/min. For the hardness test, the specimens were polished for the hardness measurements, using a 50 g load for 15 s. Data were submitted to ANOVA and Tukey's test (alpha=5 percent). The results of bond strength showed that the SS3 group obtained the highest bond strength when compared to the CO group. There were no significant differences among the other modes in relation to the other groups. Regarding the other results in hardness, there were no significant differences among the groups in the surface region and up to 4 mm depth.
Este estudo avaliou a resistência de união (push-out) e a dureza Knoop do compósito Z250, fotoativado por luz de lâmpada halógena XL2500, com diferentes modos: Contínuo (700 mW/cm²/20 s) (CO); Soft-start (50 mW/cm²/5 s + 700 mW/cm²/15 s) (SS1), (100 mW/cm²/5 s + 700 mW/cm²/15 s) (SS2), (150 mW/cm²/5 s + 700 mW/cm²/15 s) (SS3), (200 mW/cm²/5 s + 700 mW/cm²/15 s) (SS4), (250 mW/cm²/5 s + 700 mW/cm²/15 s) (SS5), (300 mW/cm²/5 s + 700 mW/cm²/15 s) (SS6). Para o ensaio de resistência de união, os espécimes foram testados em máquina de ensaio universal com velocidade de 0,5 mm/min. Para o teste de dureza, os espécimes foram polidos para a realização das leituras de dureza, realizadas com carga de 50 g por 15 s. Os dados foram submetidos a ANOVA e ao teste de Tukey (alfa=5 por cento). Os resultados de resistência da união mostraram que o grupo SS3 apresentou maior resistência da união quando comparado ao grupo CO. Não houve diferença entre os demais grupos testados. O teste de dureza Knoop mostrou que não houve diferença entre os grupos até 4 mm de profundidade.
Subject(s)
Humans , Composite Resins/chemistry , Light-Curing of Dental Adhesives/methods , Dental Materials/chemistry , Carbon Compounds, Inorganic/chemistry , Composite Resins/radiation effects , Dental Polishing , Dental Materials/radiation effects , Hardness , Light , Materials Testing , Stress, Mechanical , Surface Properties , Silicon/chemistry , Temperature , Time FactorsABSTRACT
The present study was carried out to observe the cytotoxicity of yellow sand in comparison with silica and titanium dioxide in a rat alveolar type II cell line (RLE-6TN). Yellow sand (China Loess) was obtained from the loess layer in the Gunsu Province of China. The mean particle diameter of yellow sand was about 0.003 +/- 0.001 mm. Major elements of yellow sand were Si(27.7 +/- 0.6%), Al(6.01 +/- 0.17%), and Ca(5.83 +/- 0.23%) in that order. Silica and yellow sand significantly decreased cell viability and increased [Ca2+]i. All three particles increased the generation of H2O2. TiO2 did not change Fenton activity, while silica induced a slight increase of Fenton activity. In contrast, yellow sand induced a significant increase of Fenton activity. Silica, yellow sand and TiO2 induced significant nitrite formations in RLE-6TN cells. Silica showed the highest increase in nitrite formation, while yellow sand induced the least formation of nitrite. Silica and yellow sand increased the release of TNF-a. Based on these results, we suggest that yellow sand can induce cytotoxicity in RLE-6TN cells and reactive oxygen species, Fenton activity and reactive nitrogen species might be involved in this toxicity.
Subject(s)
Aluminum/chemistry , Animals , Calcium/analysis , Cell Line , Cell Survival/drug effects , Culture Media, Conditioned/chemistry , Epithelial Cells/drug effects , Hydrogen Peroxide/analysis , Lung/cytology , Macrophages, Alveolar/drug effects , Nitrites/analysis , Particle Size , Rats , Silicon/chemistry , Silicon Dioxide/chemistry , Titanium/adverse effects , Tumor Necrosis Factor-alpha/drug effectsABSTRACT
The formation and characterization of self-assembled films of zirconium phosphonate / N,N'-di(2-phosphonoethyl)-1,4,5,8-naphthalenediimide (DPN) is presented. The films were produced on glass substrates by deposition of alternating layers of Zr+4 and DPN. Films containing up to 16 layers on each side of the substrate were obtained and monitored by absorption spectroscopy and ellipsometry. When irradiated, the initially colorless films turned to a persistent pinky color reminiscent of that of DPN anion radical. These films are a promising material to the development of photovoltaic devices.
Subject(s)
Biocompatible Materials/chemistry , NAD/chemistry , Zirconium/chemistry , Glass/chemistry , Mass Spectrometry , Silicon/chemistryABSTRACT
The different types of bottles manufactured at El-Nasr Glass and Crystal Co., Mostorod Factory, were tested to determine their class according to the USP. The corrosion resistance of such bottles towards the attack of water, HCl, NaOH and methyl and ethyl alcohols at different temperatures and times was also studied. The results obtained showed that amber glass bottles belong to class III, whereas, green and colorless bottles belong to the NP class according to the USP. The difference in their corrosion resistance was related to the lower alkali content of amber bottles compared to colorless and green bottles. The results of the effects of the different aqueous solutions, as well as temperature and time of attack, were similar to that published on glasses of similar chemical composition