Effect of different cleansers on the surface of removable partial denture

Removable partial dentures (RPD) demand specific hygienic cleaning and the combination of brushing with immersion in chemical solutions has been the most recommended method for control of biofilm. However, the effect of the cleansers on metallic components has not been widely investigated. This study evaluated the effect of different cleansers on the surface of RPD. Five disc specimens (12 mm x 3 mm metallic disc centered in a 38 x 18 x 4 mm mould filled with resin) were obtained for each experimental situation: 6 solutions [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), 0.05 percent sodium hypochlorite (NaOCl), and distilled water (DW) control] and 2 Co-Cr alloys [DeguDent (DD) and VeraPDI (VPDI)] were used for each experimental situation. A 180-day immersion was simulated and the measurements of roughness (Ra, µm) of metal and resin were analyzed using 2-way ANOVA and Tukey’s test. The surface changes and tarnishes were examined with a scanning electronic microscopy (SEM). In addition, energy dispersive x-ray spectrometry (EDS) analysis was carried out at representative areas. Visually, NaOCl and MI specimens presented surface tarnishes. The roughness of materials was not affected by the solutions (p>0.05). SEM images showed that NaOCl and MI provided surface changes. EDS analysis revealed the presence of oxygen for specimens in contact with both MI and NaOCl solutions, which might suggest that the two solutions promoted the oxidation of the surfaces, thus leading to spot corrosion. Within the limitations of this study, it may be concluded that the NaOCl and MI may not be suitable for cleaning of RPD.

As próteses parciais removíveis (PPR) exigem higienização específica e a associação da escovação com imersão em soluções químicas tem sido o método mais recomendado para controle do biofilme. Entretanto, os efeitos destas soluções não são amplamente reportados em componentes metálicos. Este estudo avaliou o efeito de diferentes agentes de higienização na superfície dos componentes de uma PPR. Foram confeccionados 5 espécimes (disco metálico de 12 x 3 mm centralizado em uma tira de resina com 38 x 18 x 4 mm) para cada situação experimental: 6 soluções [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), hipoclorito de sódio 0,05 por cento (HS) e água destilada (AD) como controle)] e 2 ligas de cobalto-cromo [DeguDent (DD) e Vera PDI (VPDI)] foram utilizadas para cada situação experimental. Foram simuladas imersões de 180 dias. As aferições de rugosidade (Ra, μm) tanto em porção metálica quanto em resina acrílica termopolimerizável foram submetidos ao ANOVA e ao teste de Tukey. As alterações superficiais e manchas foram examinadas por meio de microscopia eletrônica de varredura (MEV). Áreas de interesse foram submetidas à espectrometria por energia dispersiva por raios X (EDS). Visualmente, puderam ser verificadas manchas nas superfícies metálicas quando utilizados HS e MI. A rugosidade dos materiais não foi afetada pelas soluções (p>0,05). As fotomicrografias evidenciaram que HS e MI ocasionaram alterações superficiais. As análises de EDS revelaram a presença de oxigênio nos grupos HS e MI, o que pode sugerir que estas duas soluções causaram oxidação das superfícies, provocando pontos de corrosão. Dentre as limitações do presente estudo, pode-se concluir que estas soluções não são apropriadas para a higienização das PPR.

Propriedades mecânicas de fios de NiTi e CuNiTi com efeito memória de forma utilizados em tratamentos ortodônticos / Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment

Objetivou-se nessa pesquisa comparar oito tipos de fios de NiTi superelásticos e termoativos, de seis empresas comerciais (GAC, TP, ORMCO, MASEL, MORELLI e UNITEK) àqueles com adição de cobre (CuNiTi 27 e 35OC, ORMCO), observando se as propriedades mecânicas dos dois últimos justificariam sua escolha clínica. Para tal foram realizados ensaios de tração e microscopia eletrônica de varredura. Os ensaios de tração foram realizados em máquina de ensaios mecânicos da marca EMIC, modelo DL10000, de 10 toneladas de capacidade, no Instituto Militar de Engenharia (IME). A composição química e a topografia superficial dos fios foram determinadas através da microscopia eletrônica de varredura em microscópio da marca JEOL, modelo JSM-5800 LV com sistema de microanálise EDS (energy dispersive spectroscopy). Os resultados mostraram que, de forma geral, os fios de NiTi termoativados apresentaram cargas mais suaves de desativação em relação aos superelásticos. Entre os fios que apresentaram as cargas biologicamente mais adequadas de desativação estão os termoativados da GAC e da UNITEK. Entre os fios de NiTi superelásticos, os de CuNiTi 27ºC da ORMCO foram os que apresentaram as cargas mais suaves de desativação, sendo semelhantes, estatisticamente (ANOVA), às apresentadas pelos fios de NiTi termoativados da UNITEK para a deformação de 4%. Quando comparados os fios de CuNiTi a 27 e a 35ºC, observou-se que os primeiros apresentaram forças de desativação de, aproximadamente, 1/3 das apresentadas pelos últimos, para a deformação de 4%. Quando analisada a microscopia eletrônica de varredura de superfície, os fios de NiTi superelásticos que apresentaram melhores acabamentos foram os da MASEL e MORELLI e os que apresentaram os piores acabamentos foram os de NiTi e CuNiTi 27ºC da ORMCO...

Leveling and aligning orthodontic wires must be able to generate light and continuous forces. Thus need to have high springback and flexibility. For this purpose it was suggested a variety of supereslatic and termoactivated Nickel-Titanium (NiTi) wires that may offer a load-deformation curve, in a constant plataform. Copper NiTi wires are presented as exhibiting better thermoactivating properties for optimum-forces system with better dental movement control. The aim of this study was to compare 8 NiTi superelastic and thermoactivated wires of six different brands (GAC, TP, ORMCO, MASEL, MORELLI and UNITEK) to Copper addicted wires (CuNiTi 270C and 350C, ORMCO) to verify if the mechanical properties of Copper NiTi would support it’s clinical use. Stress-strain tests were done in Engeneering Military Institute (IME-Brazil), through test machine (EMIC- DL 10000 model). Scanning electronic microscope with energy dispersive spectroscopy (JOEL, JSM-5800 LV model) was used to determine chemical composition and superficial topography of the wires. Results showed that, in general, thermoactivated NiTi wires exhibited lower deactivation loads when compared to NiTi superelastics. Among the thermoactivated, the GAC and UNITEK ones are the lighter ones. Among the superelastics, the Copper NiTi 270C (ORMCO) were the lighter ones, statistically similar (ANOVA) to thermoactivated NiTi from UNITEK, for 4% strain. Once Copper NiTi 270C showed deactivated loads 62% lower than Copper NiTi 350C , under 4% strain. As regard to Scanning Electronic Microscopy results for superelastic NiTi wires, better superficial burnishing were found for MASEL and MORELLI ones...

Scanning electronic microscope observation of bone marrow stem cells transfected by IGF-1 gene and cultured onto ostrich true bone ceramic / 实用口腔医学杂志

Objective:To evaluate the biocompatibility of insulin-like growth factor I (IGF-1) gene transfected bone marrow stem cells (MSCs) with ostrich true bone ceramic (OTBC). Methods:Rat MSCs were transfected with IGF-1 gene, and positive clones were selected by G418. The expression of IGF-1 protein in the MSCs was detected by immunocytochemical technique. The IGF-1 transfected MSCs were cultured with OTBC and the morphology of the cells was observed by scanning electronic microscope(SEM) at different time point. Results:Immunohistochemical staining suggested that the IGF-1 protein was expressed in the IGF-1 transfected MSCs. The cells adhered to OTBC and stretched well after 24 h of culture. The IGF-1 transfected MSCs proliferated on the surface of OTBC with culture time.Conclusion:The OTBC has a good biocompatibility with IGF-1 transfected MSCs.

Study on Enzymology and Morphology Effects of Extractions of Cyanobacteria on Primary Cultured Hepatocyte / 环境与健康杂志

Objective To make a further study on the character and mechanism of hepatotoxic effect of microcystin(MC),which stands for the extractions of cyanobacteria Methods The enzymology and morphology effects of different concentrations of 0.1,1,10 ?g/ml extractions of cyanobacteria on primary cultured hepatocyte were observed Results It was shown that the concentrations of LDH and AST increased in the culture medium after exposure to MC at concentrations of 0.1 ,1 and 10 ?g/ml No significant changes of concentrations of AKP, GGT, ALT and GSH were observed in the culture media of tested groups.An active proliferation of cultured hepatocytes with apopotosis or necrosis were observed in the center of the proliferation foci in the treated groups.Characterisitic morphological alterations such as irregular shape,cytoplasmic cavity,plasma membrane blebs and protrusions were viewed in scanning electronic microscope as well as in cultured cell. Conclusion The extractions of cyanobacteria could promote the proliferation of hepatocyte and might influence the physiological and biochemical function and the integrity of hepatocyte

EFFECTS OF SCHWANN CELLS ON SURVIVAL AND DIFFERENTIATION OF NEURAL STEM CELLS in vitro / 解剖学报

Objective Whether Schwann cells could promote the survival and differentiation of neural stem cells was explored in vitro. Methods Neural stem cells were dissociated and cloned from the hippocampal tissue of newborn rats.Schwann cells were also dissociated and purified simultaneously from the sciatic nerves and brachial plexus nerves of newborn rats.Then Schwann cells and neural stem cells were Co cultured.The expression of nestin of the neural stem cells and the expression of neurofilament(NF) or glial fibrillary acidic protein(GFAP)of the differentiated cells were detected by immunohistochemistry.The morphological changes of neural stem cells were examined with scanning electronic microscope. Results Compared with control group,the number of surviving neural stem cells and differentiated neuron like cells was significantly increased in Co cultured (Schwann cells add neural stem cells)groups.The primary processes of neuron like cells in Co cultured groups were obviously longer than that in control groups.The irregular convex or concave of the body of neural stem cells became plain and smooth in Co cultured group.Co cultured Schwann cells and neural stem cells have grown to touch together in following manner:1.Body touch body;2.Body touch process;3.Process touch process.Conclusion\ Schwann cells can promote the survival and differentiation of co cultured neural stem cells in vitro.