Progress in Application of Heparin Coating in Blood Contact Medical Devices / 中国医疗器械杂志

Blood compatibility is the main restriction of blood-contacting medical devices in clinical application, especially long-term blood-contacting medical devices will stimulate the immune defense mechanism of the host, resulting in thrombosis. Heparin anticoagulant coating links heparin molecules to the surface of medical device product materials, improves the compatibility between the material surface interface and the body, and reduces the host immune defense reactions. This study reviews the structure and biological properties of heparin, the market application status of heparin-coated medical products, the insufficiency and improvement of heparin coating, which can provide a reference for the application research of blood contact medical devices.

Comparison of deflection forces of esthetic archwires combined with ceramic brackets

Abstract Coated archwires and ceramic brackets have been developed to improve facial esthetics during orthodontic treatment. However, their mechanical behavior has been shown to be different from metallic archwires and brackets. Therefore, the aim of this study was to compare the deflection forces in coated nickel-titanium (NiTi) and esthetic archwires combined with ceramic brackets. Material and Methods Non-coated NiTi (NC), rhodium coated NiTi (RC), teflon coated NiTi (TC), epoxy coated NiTi (EC), fiber-reinforced polymer (FRP), and the three different conventional brackets metal-insert polycrystalline ceramic (MI-PC), polycrystalline ceramic (PC) and monocrystalline ceramic (MC) were used. The specimens were set up on a clinical simulation device and evaluated in a Universal Testing Machine (Instron). An acrylic device, representative of the right maxillary central incisor was buccolingually activated and the unloading forces generated were recorded at 3, 2, 1 and 0.5 mm. The speed of the testing machine was 2 mm/min. ANOVA and Tukey tests were used to compare the different archwires and brackets. Results The brackets presented the following decreasing force ranking: monocrystalline, polycrystalline and polycrystalline metal-insert. The decreasing force ranking of the archwires was: rhodium coated NiTi (RC), non-coated NiTi (NC), teflon coated NiTi (TC), epoxy coated NiTi (EC) and fiber-reinforced polymer (FRP). At 3 mm of unloading the FRP archwire had a plastic deformation and produced an extremely low force in 2; 1 and 0.5 mm of unloading. Conclusion Combinations of the evaluated archwires and brackets will produce a force ranking proportional to the combination of their individual force rankings.

Characterization and coating stability evaluation of nickel-titanium orthodontic esthetic wires: an in vivo study

Abstract The objective of this study was to compare coating dimensions and surface characteristics of two different esthetic covered nickel-titanium orthodontic rectangular archwires, as-received from the manufacturer and after oral exposure. The study was designed for comparative purposes. Both archwires, as-received from the manufacturer, were observed using a stereomicroscope to measure coating thickness and inner metallic dimensions. The wires were also exposed to oral environment in 11 orthodontic active patients for 21 days. After removing the samples, stereomicroscopy images were captured, coating loss was measured and its percentage was calculated. Three segments of each wire (one as-received and two after oral exposure) were observed using scanning electron microscopy for a qualitative analysis of the labial surface of the wires. The Lilliefors test and independent t-test were applied to verify normality of data and statistical differences between wires, respectively. The significance level adopted was 0.05. The results showed that the differences between the wires while comparing inner height and thickness were statistically significant (p < 0.0001). In average, the most recently launched wire presented a coating thickness twice that of the control wire, which was also a statistically significant difference. The coating loss percentage was also statistically different (p = 0.0346) when the latest launched wire (13.27%) was compared to the control (29.63%). In conclusion, the coating of the most recent wire was thicker and more uniform, whereas the control had a thinner coating on the edges. After oral exposure, both tested wires presented coating loss, but the most recently launched wire exhibited better results.

Study of novel coating strategy for coronary stents: simutaneous coating of VEGF and anti- CD34 antibody / Estudo da nova estratégia de revestimento para stents coronários: revestimento simultâneo de VEGF e anticorpo anti-CD34

Abstract Introduction: Intravascular coronary stenting has been used in the treatment of coronary artery disease (CAD), with a major limitation of in-stent restenosis (ISR). The 316 stainless steel has been widely used for coronary stents. In this study, we developed a novel coating method to reduce ISR by simultaneously coating vascular endothelial growth factor (VEGF) and anti-CD34 antibody on 316L stainless steel. Methods: Round 316L stainless steel sheets in the D-H group were polymerized with compounds generated from condensation reaction of dopamine and heparin using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS). Sixteen sheets from the D-H group were further immersed into 1ug/ml VEGF165 and 3mg/ml heparin sodium one after another for 10 times, and named as the D-(H-V)10 group. Eight sheets from the D-(H-V)10 group were coated with anti-CD34 antibody and termed as the D-(H-V)10-A group. Immunofluorescence assay and ELISA were used to evaluate whether the 316L stainless steel disks were successfully coated with VEGF and anti-CD34 antibody. Results: The results of immunofluorescence assay and ELISA showed that VEGF could be detected in the D-(H-V)10 and D-(H-V)10-A group, suggesting the steel sheets were successfully covered with VEGF. Anti-CD34 antibody could only be observed in the D-(H-V)10-A group, which was the only group coated with CD34 antibody. Both results suggested that the 316L stainless steel sheets were successfully coated with VEGF and anti-CD34 antibody. Conclusion: Our study developed a method to simultaneously coat VEGF and anti-CD34 antibody to stainless metal steel. This research serves as a fundamental role for a novel coating strategy. .

Resumo Introdução: O stent coronário intravascular tem sido utilizado no tratamento de doença arterial coronária, com uma maior limitação de restenose intra-stent (RIS). O aço inoxidável 316 tem sido amplamente utilizado para stents. Neste estudo, foi desenvolvido um novo método de revestimento para reduzir a RIS para revestir simultaneamente o fator de crescimento endotelial vascular (VEGF) e anti-CD34 em aço inoxidável 316L. Métodos: Placas de aço inoxidável 316L redondas no grupo DH foram polimerizadas com compostos gerados a partir da reacção de condensação de dopamina e heparina utilizando N- (3-dimetilaminopropil) -N'-etilcarbodiimida (EDC) e N-hidroxissuccinimida (NHS). Dezesseis folhas a partir do grupo DH foram ainda imersas em 1 ug/ml de VEGF 165 e 3 mg/ml de heparina sódica, um após outro por 10 vezes, sendo denominado como o grupo D-(HV)10. Oito folhas de D-(HV)10 foram revestidas com anticorpo anti-CD34 e denominado como grupo D-(HV)10-A. Testes de imunofluorescência e ELISA foram usados para avaliar se os discos de aço inoxidável 316L foram revestidos com sucesso com VEGF e anticorpo anti-CD34. Resultados: Os resultados dos testes de imunofluorescência e ELISA mostraram que o VEGF pôde ser detectado nos grupos D-(HV)10 e D-(HV)10-A, evidenciando que as chapas de aço foram cobertas com VEGF com sucesso. O anticorpo anti-CD34 podia apenas ser observado no grupo D-(HV)10-A, o único grupo revestido com anticorpo CD34. Ambos os resultados sugerem que as chapas de aço inoxidável 316L foram revestidas com sucesso com VEGF e anticorpo anti-CD34. Conclusão: Nosso estudo desenvolveu um método para revestir simultaneamente VEGF e anti-CD34 de aço inoxidável. Esta pesquisa tem um papel fundamental para a nova estratégia de revestimento. .

Avaliação da biocompatibilidade e da propriedade bactericida de nanotubos de dióxido de titânio impregnados com lectina e nanopartículas de prata para aplicações biomédicas / Biocompatibility evaluation and bactericidal property of impregnated titanium dioxide nanotubes with lectin and silver nanoparticles for biomedical applications

O titânio e suas ligas são os materiais mais comumente utilizados na substituição de tecidos duros por possuírem resistência mecânica, biocompatibilidade, resistência à corrosão e fácil manipulação. Embora o titânio possua várias vantagens sobre outros biomateriais, seu uso em longo prazo pode ocasionar problemas de rejeição. A modificação da superfície do titânio a fim de criar microrrugosidades é uma estratégia efetiva para melhorar a adesão e proliferação celular sobre implantes. Quando um implante danifica ou invade as barreiras epitelial e das mucosas, pode servir como reservatório para microrganismos e desta forma predispor à infecção. Neste sentido, o objetivo deste trabalho foi modificar a superfície do titânio, utilizando nanopartículas de prata (Ag) e lectina, a fim de melhorar a sua biocompatibilidade e conferir propriedades antimicrobianas a este material. O racional por trás destas mudanças é que a criação de uma topografia em nanoescala pode contribuir para mimetizar o ambiente celular melhorando a osseointegração e diminuindo o risco de infecção. Em nosso estudo, nanotubos de dióxido de titânio (NTs-TiO2) com estrutura bem distribuída e organizada, com diâmetro em torno de 70-80nm, foram sintetizados por anodização eletroquímica e decorados com nanopartículas de Ag usando a técnica de layer-by-layer (LbL), enquanto a lectina do peixe Oreochromis niloticus (OniL) foi incorporada aos NTs-TiO2 por spin coating. Estas amostras foram caracterizadas e avaliadas quanto a sua citotoxidade, adesão celular, potencial osteogênico e atividade bactericida. Nossos resultados mostraram que tanto as nanopartículas de Ag, como a Onil foram incorporadas com sucesso à superfície dos NTs-TiO2. Entretanto nossas preparações de LbL não foram capazes de melhorar a biocompatibilidade ou inibir o crescimento de bactérias nos NTs-TiO2. Por outro lado, a funcionalização dos NTs-TiO2 com a OniL induziu eficientemente a adesão e proliferação dos osteoblastos. Nossos resultados apontam para o uso da lectina OniL para melhorar a qualidade dos implantes de NT-TiO2 existentes.

The use of silane-coated industrial glass fibers in splinting periodontally mobile teeth.

In the past, direct stabilization and splinting of teeth using an adhesive technique required the use of wires, pins, or mesh grids. Problems with the current fiber reinforcement materials are their inherent thickness when embedded within composite resin, their availability in fixed widths and their high cost. This paper discusses the use of silane-coated industrial grade glass fibers, which can be bundled in the form of ribbon according to the required thickness and length. Of the three patients discussed in this paper, none has exhibited debonding or recurrent caries over 1-year period. By reinforcing composite splints with these industrial grade glass fibers, dentists can provide patients with restorations and splints that are economical, fracture resistant, and more durable than most alternative splinting materials of the past.

Status of surface treatment in endosseous implant: A literary overview.

The attachment of cells to titanium surfaces is an important phenomenon in the area of clinical implant dentistry. A major consideration in designing implants has been to produce surfaces that promote desirable responses in the cells and tissues. To achieve these requirements, the titanium implant surface can be modified in various ways. This review mainly focuses on the surface topography of dental implants currently in use, emphasizing the association of reported variables with biological outcome.

Preparation and characterization of hydroxyapatite-coated iron oxide particles by spray-drying technique

Magnetic particles of iron oxide have been increasingly used in medical diagnosis by magnetic resonance imaging and in cancer therapies involving targeted drug delivery and magnetic hyperthermia. In this study we report the preparation and characterization of iron oxide particles coated with bioceramic hydroxyapatite by spray-drying. The iron oxide magnetic particles (IOMP) were coated with hydroxyapatite (HAp) by spray-drying using two IOMP/HAp ratios (0.7 and 3.2). The magnetic particles were characterized by way of scanning electronic microscopy, energy dispersive X-ray, X-ray diffraction, Fourier transformed infrared spectroscopy, flame atomic absorption spectrometry,vibrating sample magnetometry and particle size distribution (laser diffraction). The surface morphology of the coated samples is different from that of the iron oxide due to formation of hydroxyapatite coating. From an EDX analysis, it was verified that the surface of the coated magnetic particles is composed only of HAp, while the interior containsiron oxide and a few layers of HAp as expected. The results showed that spray-drying technique is an efficient and relatively inexpensive method for forming spherical particles with a core/shell structure.

As partículas de óxido de ferro têm sido extensivamente usadas em diagnósticos médicos como agente de contraste para imagem por ressonância magnética e na terapia do câncer, dentre estas, liberação de fármacos em sitos alvos e hipertermia magnética. Neste estudo nós reportamos a preparação e caracterização de partículas magnéticas de óxido de ferro revestidas com a biocerâmica hidroxiapatita. As partículas magnéticasde óxido de ferro (PMOF) foram revestidas com hidroxiapatita por spray-drying usando duas razões PMOF/HAp (0,7 e 3,2). As partículas magnéticas foram caracterizadas por microscopia eletrônica de varredura, energia dispersiva de raios X, difração de raios X, espectroscopia de absorção no infra vermelho com transformada de Fourier, espectrometria de absorção atômica com atomização em chama, magnetometria de amostra vibrante e distribuição do tamanho de partícula (difração a laser). A morfologia da superfície das amostras revestidas é diferente das de óxido de ferro devido à formação do revestimento de hidroxiapatita. A partir da análise de energia dispersiva de raios X foi verificado que a superfície das partículas magnéticas é composta somente por hidroxiapatita, enquanto o interior contém óxido de ferro e uma pequena camada de hidroxiapatita, como esperado. Os resultados mostraram que atécnica de spray-drying é um método eficiente e relativamentede baixo custo para formação de partículas esféricas com estrutura núcleo/casca.

Screening and formulation of chemoattractant coatings for artificial reef structures.

This study was carried out to augment the colonization of marine benthic communities on artificial reef structure. Increasing marine pollution along with various natural hazards cause severe damages to marine algae and associated fauna. In recent years, artificial reefs have been deployed in coastal regions of several parts of the world in order to increase the marine productivity. They are mainly built with concrete materials, however their leachates have considerable impacts on algae. Therefore to increase the algal colonization five chemoattractants such as ferrous sulfate, zinc oxide, ammonium nitrate, sodium phosphate and ferrous lactate were screened against spores of a fouling alga, Ulva pertusa. FeSO4 / ZnO (8:2) and ferrous lactate coatings showed the highest spore attachment with 52 +/- 5.2 cm2 and 79.5 +/- 10.2 cm2 spores respectively (p<0.01). Furthermore using these chemoattractants, coating formulations were made and their performances were investigated at East coast (Ayajin harbor) and South coast (Meejo harbor) of Korea. A maximum fouling coverage (with green algae 25%, red algae 11.3% and brown algae 63.7%) was estimated from ferrous lactate coatings (p<0.01). Different composition of coating formulations and their chemoattractive properties were evaluated.

Comparison of the effectiveness of four organic chemoattractants towards zoospores of Ulva pertusa and macrofouling.

Algal spores respond to many environmental variables, especially to chemical "cues". This chemotactic response can be utilized to attract spores, thereby colonization of a new substrata is possible to be influenced. In this attempt, four chemoattractant candidates were screened against spores of Ulva pertusa to reveal their efficiencies. Attachment and subsequent germination of Ulva spores were effectively influenced by these chemoattractant candidates. In particular 100 microg cm2 of D-glucose coating was found to enhance spore attachment by > 150%. Furthermore, field investigations carried out with test panels, clearly indicate the chemoattractive properties of test coatings. In recent years, various anthropogenic activities and natural hazards cause detrimental impacts on the benthic algae and other fishery resources. Artificial reefs have been laid on many coastal regions to increase or restore marine resources. Chemoattractant coatings can be applied on artificial surfaces to increase the colonization of benthic forms. It also can be used in the mariculture devices. Influence of chemoattractants on Ulva spores and fouling biomass estimated on test panels are discussed.

Preload and torque removal evaluation of three different abutment screws for single standing implant restorations

Several authors still consider the mechanical problems of fracture and component loosening as the main causes of failure of implant-supported restorations. The purpose of this in vitro study was to compare the preload of three types of screw for transmucosal abutment attachment used in single implant-supported prosthesis through strain gauge and removal torque measurements. Three external hex fixtures were used, and each received a transmucosal abutment (Cera One®), which was fixed to the implant with its respective screw: Group A- gold screw, Group B- titanium screw and Group C- surface-treated titanium screw (Ti-Tite®). Ten screws of each type were attached applying a 30.07±0.28 Ncm torque force and maintained in position for 5 minutes. After this, the preload values were measured using strain gauges and a measurement cell. Gold screws presented higher preload values (131.72±8.98 N), followed by surface-treated titanium screws (97.78±4.68 N) and titanium screws (37.03±5.69 N). ANOVA (p<0.05) and Tukey's test (p<0.05) were applied. Statistically significant differences were found among the groups for both preload and removal torque values. In conclusion, gold screws may be indicated to achieve superior longevity of the abutment-implant connection and, consequently, prosthetic restoration due to greater preload values yielded.

Bone response to a Ca- and P-enriched titanium surface obtained by anodization

This study evaluated bone response to a Ca- and P- enriched titanium (Ti) surface treated by a multiphase anodic spark deposition coating (BSP-AK). Two mongrel dogs received bilateral implantation of 3 Ti cylinders (4.1 x 12 mm) in the humerus, being either BSP-AK treated or untreated (machined - control). At 8 weeks postimplantation, bone fragments containing the implants were harvested and processed for histologic and histomorphometric analyses. Bone formation was observed in cortical area and towards the medullary canal associated to approximately 1/3 of implant extension. In most cases, in the medullary area, collagen fiber bundles were detected adjacent and oriented parallel to Ti surfaces. Such connective tissue formation exhibited focal areas of mineralized matrix lined by active osteoblasts. The mean percentages of bone-to-implant contact were 2.3 (0.0-7.2 range) for BSP-AK and 0.4 (0.0-1.3 range) for control. Although the Mann-Whitney test did not detect statistically significant differences between groups, these results indicate a trend of BSP-AK treated surfaces to support contact osteogenesis in an experimental model that produces low bone-to-implant contact values.

O objetivo desse estudo foi avaliar a resposta do tecido ósseo à superfície de titânio (Ti) enriquecida com Ca e P obtida por anodização (BSP-AK). Três cilindros de Ti (4,1 x 12 mm) BSP-AK ou usinado (controle) foram implantados bilateralmente nos úmeros de dois cães de raça indefinida. Oito semanas após a implantação, os fragmentos ósseos contendo os implantes foram removidos e processados para análises histológica e histomorfométrica. A formação óssea foi observada na região cortical e no canal medular até aproximadamente um terço da extensão do implante. Na maioria dos casos, feixes de fibras colágenas dispostos paralelamente à superfície do implante foram observados na região medular. Nessa região observaram-se também áreas focais de formação de matriz mineralizada e osteoblastos ativos. Os implantes do grupo BSP-AK apresentaram média de contato osso-implante 2,3 por cento, com medidas variando de 0,0 a 7,2 por cento e os do grupo controle tiveram média 0,4 por cento, com medidas variando de 0,0 a 1,3 por cento. Apesar do teste de Mann-Whitney não mostrar diferença estatisticamente significante entre os grupos, nossos resultados indicaram uma tendência para a ocorrência de osteogênese de contato na superfície BSP-AK em um modelo experimental que resulta em baixos valores de contato osso-implante.

Microtensile bond strength of a repair composite to leucite-reinforced feldspathic ceramic

The purpose of this study was to evaluate the microtensile bond strength of a repair composite resin to a leucite-reinforced feldspathic ceramic (Omega 900, VITA) submitted to two surface conditionings methods: 1) etching with hydrofluoric acid + silane application or 2) tribochemical silica coating. The null hypothesis is that both surface treatments can generate similar bond strengths. Ten ceramic blocks (6x6x6 mm) were fabricated and randomly assigned to 2 groups (n=5), according to the conditioning method: G1- 10 percent hydrofluoric acid application for 2 min plus rinsing and drying, followed by silane application for 30 s; G2- airborne particle abrasion with 30 µm silica oxide particles (CoJet-Sand) for 20 s using a chairside air-abrasion device (CoJet System), followed by silane application for 5 min. Single Bond adhesive system was applied to the surfaces and light cured (40 s). Z-250 composite resin was placed incrementally on the treated ceramic surface to build a 6x6x6 mm block. Bar specimens with an adhesive area of approximately 1 ± 0.1 mm² were obtained from the composite-ceramic blocks (6 per block and 30 per group) for microtensile testing. No statistically significant difference was observed between G1 (10.19 ± 3.1 MPa) and G2 (10.17 ± 3.1 MPa) (p=0.982) (Student's t test; á = 0.05). The null hypothesis was, therefore, accepted. In conclusion, both surface conditioning methods provided similar microtensile bond strengths between the repair composite resin and the ceramic. Further studies using long-term aging procedures should be conducted.

A proposta desse estudo foi avaliar a resistência à microtração entre uma resina composta e uma cerâmica feldspática submetida a diferentes tratamentos de superfície. A hipótese foi que os tratamentos de superfície (deposição de sílica + silanização e o ácido fluorídrico + silanização) promovessem resistências adesivas semelhantes. Dez blocos cerâmicos (Omega 900) de 6x6x6mm foram confeccionados e divididos em dois grupos: G1 - ácido fluorídrico 10 por cento/2 min + silanização; G2 Sistema CoJet: jateamento com partículas de sílica de 30 µm (CoJet-Sand) + ESPE-Sil. Em seguida, o adesivo Single Bond foi aplicado na superfície e fotopolimerizado (40 s); a resina composta Z-250 foi condensada, obtendo-se um bloco de 6 mm. Depois da armazenagem (água destilada/37ºC/7 dias), espécimes retangulares foram seccionados com disco diamantado (6 corpos-de-prova por bloco e 30 corpos-de-prova por grupo), com 1 ± 0,1 mm² de área adesiva. Cada corpo-de-prova foi fixado a um dispositivo adaptado com cianoacrilato e o teste de tração foi realizado. Os dados foram submetidos ao Teste t de Student (p>0,05). A hipótese nula foi aceita (p=0.982): G1 (10,19 ± 3,1 MPa) e G2 (10,17 ± 3,1 MPa) foram similares estatisticamente. Concluiu-se que os métodos de condicionamento da superfície cerâmica geram resistência adesiva similar à da cerâmica. Estudos posteriores empregando envelhecimento a longo prazo devem ser realizados.

An in vitro comparison of implant materials cell attachment, cytokine and osteocalcin production

Bone deposition, for any implant system, is the deciding factor for the success. The biochemical signals at the cellular level will help elucidate the direction of host response. In this report, intercellular messenger, cytokines, that are regulatory for osteoblast and osteoclast function, were measured. Production of osteocalcin, a marker for osteoblast maturation was also estimated. Human osteoblast-like cells from osteosarcoma cell line MG 63 were grown in wells in the presence of titanium (Ti), titanium alloy (Ti6A14V) and stainless steel implant materials incubated at 37 degrees C. Interleukin-1alpha (IL-1alpha), IL-6, IL-8, IL-11 and osteocalcin were quantitated using standard enzyme linked immunosorbant assay (ELISA) kits from the growth media extracted at specific intervals over the critical ten day period. In all dishes, cells were seen adhering to the base after 24 hours and to confluence at 96 hours. Both IL-1alpha and IL-11 were not produced in sufficient quantities to be measured in the assay (< pg/ml). Interleukin-6 production was significantly higher for stainless steel than for titanium and the alloy. There was a progressive rise in osteocalcin production for titanium contrasted to a basal rate for stainless steel and alloy. Interleukin-8 levels for all metals and controls increased markedly after two days implicating inherent cellular characteristics. A relatively high constant range for macrophage colony stimulating factor from the first day was seen for all metals, including the controls. In conclusion, it appears that titanium implants activate osteocalcin production while stainless steel activates IL-6.

Fluoride release from restorative materials coated with an adhesive

A retenção aos tecidos dentais, tanto de resinas fluoretadas, quanto de cimentos de iônomero de vidro modificados por resina, pode ser melhorada pela associação de um sistema adesivo, promovendo a formação de camada híbrida. Esta técnica traria vantagens desde que a presença do adesivo, sendo parte da camada híbrida, não funcionasse como uma barreira contra a passagem de íons flúor até a superfície dental próxima às restaurações. O objeitvo do presente estudo foi avaliar a liberação de flúor dos materiais restauradores Vitremer (3M) e Heliomolar (Vivadent), tendo como controle a resina composta Z100 (3M), através de uma aplicação de um adesivo (Scotch Bond Multi Purpose Plus - 3M). Dez discos de cada material foram preparados: 5 foram cobertos com adesivo, enquanto os demais não. Os discos foram imersos em frascos separados contendo saliva artificial, sendo esta trocada diariamente. As medidas de liberação de flúor foram feitas nos dias 1, 5, 10, 15, e 20 por um eletrodo combinado de flúor (9609 BN-Orion) coplado a um analisador de íons (A-720 Procyon). Testes ANOVA de uma via e SNK foram aplicados aos resultados para comparar os perfis de cada material. Os resultados mostraram que, com a metodologia empregada, o uso de um adesivo dental foi capaz de reduzir significantemente a liberação de flúor do material Vitremer e reduzir a níveis não detectßveis o flúor liberado pela resina fluoretada.

Adhesión al metal de porcelana opaca, según su tratamiento / Bonding of opaque porcelain to metal, according to its treatment

Dentro de la odontología restauradora, la cerámica dental es un material utilizado por su eficacia funcional y cosmética. Dada su naturaleza cristalina, resulta frágil al impacto. Es por ello que se ha difundido su uso en combinación con metales. Esta combinación confiere resistencia mecánica para soportar las distintas condiciones mecánicas y funcionales a que es sometida en la boca. Sin embargo, pueden observarse desprendimientos de la cerámica del casquete metálico, debido a fallas en la unión entre las dos partes. Aunque las causas pueden ser varias, en este trabajo especialmente se ha tratado la adhesión de la cerámica al metal, otorgando un rol fundamental al tratamiento previo de la superficie de este último (mecánico-rotatorio, y físico-térmico). Para este estudio se confeccionaron un número preestablecido de muestras coladas a partir de dos aleaciones a base de níquel-cromo, las que fueron tratadas por medios mecánicos-rotatorios y abrasión, a través de partículas de óxido de aluminio a presión. A su vez, los metales así tratados fueron divididos en dos grupos: oxidado y no oxidado. Se seleccionaron tres porcelanas de baja fusión y fueron realizadas las cocciones sobre cada una de las muestras. De las distintas propuestas para probar la adhesión existente en la literatura, en este trabajo se utilizó la prueba por desprendimiento por flexión controlada. Los resultados muestran diferencias significativas en la unión, según sea el tratamiento previo de la aleación

Superfície de titânio modificada por jateamento mecânico e/ou tratamento ácido / Titanium surface modified by mechanical blasting and/or acid treatment

Foram preparadas amostras de chapas de titânio com nove condiçöes de superfície, sendo três lixadas até lixa 600 e seis jateadas com óxido de alumínio (alumina com granulometria 65mm e 250mm). Seis condiçöes foram entäo submetidas a tratamento ácido com soluçäo de ácido sulfúrico/clorídico ou soluçäo contendo ácido fluorídrico. Essas superfícies foram caracterizadas por meio de técnicas, como microscopia eletrônica de varredura (MEV/EDS), espectroscopia de fotoelétrons por raio X (XPS) e medidas de rugosidade média. A soluçäo contendo ácido fluorídrico foi eletiva na remoçäo das partículas de alunina, provenientes do jateamento mecânico, e na criaçäo de uma microscopia homogeneamente rugorosa

Oseointegración: una cascade de eventos / Osseointegration: a cascade of events

Por medio de esta revisión bibliográfica se pretende mostrar lo que existe en la actualidad sobre la biocompatibilidad, las características del titanio y su uso para implantes dentales y los eventos celulares y moleculares que se desencadenan con la colocación de un implante intraóseo en los maxilares. Se discute la terminología de: biotolerante, bioinerte, bioactivo, biointegración, bioaceptabilidad. Se establecen las características que hacen del titanio el material de eleción para su uso en los implantes dentales y los factores que permiten que se logre con ellos la oseointegración. En cuanto a los fenómenos celulares, se destaca el papel del osteoblasto como el blanco perfecto que permite desencadenar el proceso biológico que lleva a la oseointegración. A la vez se discute a nivel molecular todo el proceso de fenomenologías que ocurre desde el momento de la colocación del implante para permitir por parte del organismo una cicatrización normal alrededor de un cuerpo extraño. Esta información nos lleva a pensar que el entendimiento y manejo de todos estos eventos celulares y moleculares serían de gran utilidad para mejorar el éxito de los implantes dentales y extender su uso a sitios anatómicos que presentan dificultad a la terapéutica actual