Niobium oxyhydroxide as a bioactive agent and reinforcement to a high-viscosity bulk-fill resin composite

Abstract Objective The present in vitro study incorporated niobium oxyhydroxide fillers into an experimental high-viscosity bulk-fill resin composite to improve its mechanical performance and provide it a bioactive potential. Methodology Scanning electron microscopy synthesized and characterized 0.5% niobium oxyhydroxide fillers, demonstrating a homogeneous morphology that represented a reinforcement for the feature. Fillers were weighed, gradually added to the experimental resin composite, and homogenized for one minute, forming three groups: BF (experimental high-viscosity bulk-fill resin composite; control), BF0.5 (experimental high-viscosity bulk-fill resin composite modified with 0.5% niobium oxyhydroxide fillers), and BFC (commercial bulk-fill resin composite Beautifil Bulk U, Shofu; positive control). In total, 10 specimens/groups (8 × 2 × 2 mm) underwent flexural strength (FS) tests in a universal testing machine (Instron) (500N). Resin composites were also assessed for Knoop hardness (KH), depth of cure (DoC), degree of conversion (DC), elastic modulus (E), and degree of color change (ΔE). The bioactive potential of the developed resin composite was evaluated after immersing the specimens into a simulated body fluid in vitro solution and assessing them using a Fourier-transformed infrared spectroscope with an attenuated total reflectance accessory. One-way ANOVA, followed by the Tukey's test (p<0.05), determined FS, DC, KH, and ΔE. For DoC, ANOVA was performed, which demonstrated no significant difference between groups (p<0.05). Conclusions The high-viscosity bulk-fill resin composite with 0.5% niobium oxyhydroxide fillers showed promising outcomes as reinforcement agents and performed well for bioactive potential, although less predictable than the commercial resin composite with Giomer technology.

Preparation and antibacterial properties of a copper-niobium coating on a titanium surface by a microarc oxidation-microwave hydrothermal method / 口腔疾病防治

Objective@#To prepare a copper-nobium antibacterial coating on a titanium surface by a microarc oxidation-microwave hydrothermal two-step method and to study its surface structure and antibacterial properties.@*Methods@#Using titanium coated with a microarc oxidation coating (MAO group) as the substrate, copper and niobium were introduced by a microwave hydrothermal method in low (MHL-Cu group), medium (MHM-Cu group) and high (MHH-Cu group) copper chloride solutions and niobium oxalate (MH-Nb group) solutions, respectively. The component with the highest copper content was determined by energy spectrum analysis, and the copper-niobium composite coating (MH-Cu/Nb group) was prepared by microwave hydrothermal mixing with niobium oxalate. The microstructure, element distribution and phase composition of the specimens were characterized by scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction, and the bacteriostatic effect of the coating onEscherichia coliand Staphylococcus aureus was determined by the film method. @* Results@#Energy dispersive spectrometry showed that Cu was introduced onto the surface of the MHL-Cu, MHM-Cu, and MHH-Cu groups, and the atomic ratios of copper in each group were （0.68 ± 0.04）%,（1.17 ± 0.06）%, and （1.64 ± 0.03）%. The difference between groups was statistically significant (P< 0.01). Scanning electron microscopy showed a crater-like porous structure on the surface of the MAO group, and the MHL-Cu, MHM-Cu, MHH-Cu, MH-Nb, MH-Cu/Nb groups maintained micropore morphology. The roughness increased with increasing Cu2+ concentration, in which the MH-Nb and MH-Cu/Nb groups showed gully like structures simultaneously. X-ray diffraction showed that the coating of the MAO group was mainly composed of titanium and anatase phase TiO2, and the coatings of the MHL-Cu, MHM-Cu, MHH-Cu, MH-Nb, MH-Cu/Nb groups were mainly composed of anatase and rutile phase TiO2. Compared with the MAO group, Escherichia coli and Staphylococcus aureus in the MHH-Cu, MH-Nb, MH-Cu/Nb groups decreased to varying degrees, with significant differences (P< 0.001); compared with the MH-Cu/Nb group, the colony number difference had statistical significance (P> 0.05)@*Conclusion@#The rough, porous coating containing copper and niobium prepared by the microarc oxidation-microwave hydrothermal two-step method can effectively inhibit the growth ofEscherichia coli and Staphylococcus aureus.

Analysis of osteogenic potential on 3mol% yttria-stabilized tetragonal zirconia polycrystals and two different niobium oxide containing zirconia ceramics

PURPOSE: This study was performed to evaluate the osteogenic potential of 3mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) and niobium oxide containing Y-TZPs with specific ratios, new (Y,Nb)-TZPs, namely YN4533 and YN4533/Al20 discs. MATERIALS AND METHODS: 3Y-TZP, YN4533 and YN4533/Al20 discs (15 mm diameter and 1 mm thickness) were prepared and their average surface roughness (Ra) and surface topography were analyzed using 3-D confocal laser microscope (CLSM) and scanning electron microscope (SEM). Mouse pre-osteoblast MC3T3-E1 cells were seeded onto all zirconia discs and evaluated with regard to cell attachment and morphology by (CLSM), cell proliferation by PicoGreen assay, and cell differentiation by Reverse-Transcription PCR and Quantitative Real-Time PCR, and alkaline phosphatase (Alp) staining. RESULTS: The cellular morphology of MC3T3-E1 pre-osteoblasts was more stretched on a smooth surface than on a rough surface, regardless of the material. Cellular proliferation was higher on smooth surfaces, but there were no significant differences between 3Y-TZP, YN4533, and YN4533/Al20. Osteoblast differentiation patterns on YN4533 and YN4533/Al20 were similar to or slightly higher than seen in 3Y-TZP. Although there were no significant differences in bone marker gene expression (alkaline phosphatase and osteocalcin), Alp staining indicated better osteoblast differentiation on YN4533 and YN4533/Al20 compared to 3Y-TZP. CONCLUSION: Based on these results, niobium oxide containing Y-TZPs have comparable osteogenic potential to 3Y-TZP and are expected to be suitable alternative ceramics dental implant materials to titanium for aesthetically important areas.

Nanopartículas de óxidos de ferro e nióbio com diferentes recobrimentos: síntese, caracterização e avaliação do potencial biológico / Iron oxide nanoparticles with different coatings and niobium oxide nanoparticles: synthesis, characterization and assessment of biological potential

Nanopartículas (NPs) tem ganhado notoriedade crescente em aplicações biomédicas. Podendo ser constituídas de diversos materiais, NPs tem sido empregadas como agentes de contraste, na liberação direcionada e controlada de fármacos, em terapia para tratamento de câncer, em catálise heterogênea, entre outras aplicações. As nanopartículas magnéticas de óxido de ferro (MNP) destacam-se pela multiplicidade de aplicações, apesar de serem pouco caracterizadas quanto à toxicidade celular. Outras nanopartículas com excelente potencial são as constituídas de óxido de nióbio (NbONPs), as quais merecem atenção especial, pois o Brasil é detentor de 98% das reservas comercialmente viáveis deste elemento. Neste trabalho NPs destes dois metais de transição (ferro e nióbio) foram sintetizadas, almejando entender suas interações com materiais, biomoléculas e meios biológicos. Diversas metodologias foram desenvolvidas e testadas com intuito de otimizar a morfologia e o rendimento da preparação, resultando na escolha de decomposição térmica para MNP e, para NbONPs, escolheu-se a impregnação do óxido de nióbio sobre uma matriz de MNPs recobertas com sílica. No caso das MNPs, procedeu-se ao recobrimento das mesmas com lipídeos zwitteriônicos (Dioleilfosfatidilcolina (DOPC)) e carregados positivamente (Brometo de dioctadecildimetilamônio (DODAB)). Foram inicialmente caracterizadas as suas propriedades em diversos ambientes biológicos para posteriormente realizarmos ensaios de citoxicidade em queratinócitos humanos (HaCaT). Avaliamos também a degradação das NPs em diferentes pH, bem como, a interação das mesmas com membranas miméticas de vesículas gigantes unilamelares (GUVs - Giant Unilamellar Vesicles), com visualização microscópica. As MNPs recobertas com DODAB mostraram-se mais tóxicas para os queratinócitos em cultura e também causaram lise das GUVs. No caso das NbONPs, avaliou-se a acidez proveniente do Nb2O5 e o seu potencial em catálise heterogênea, bem como a avaliação da citotoxicidade em HaCaT revelou um potencial uso biomédico

Nanoparticles (NPs) have received increasing attention in biomedical applications. NPs can be constituted by different materials and have been used as contrast agents, in drug delivery, in cancer therapy, in heterogeneous catalysis, among other applications. Magnetic iron oxide nanoparticles (MNP) are notable for their multiplicity of applications, although they are poorly characterized for cellular toxicity. Other nanoparticles with excellent potential are made of niobium oxide (NbONPs), which deserve special attention, since Brazil holds 98% of the commercially viable reserves of this element. In this Thesis, NPs of these two transition metals (iron and niobium) were synthesized, aiming to understand their interactions with materials, biomolecules and media biological. Several methodologies were developed and tested to optimize the morphology and yield of the preparation, resulting in the choice of thermal decomposition for MNPs and, for NbONPs, the impregnation of niobium oxide on a matrix of silica-coated MNPs. In the case of MNPs, they were also coated with lipid zwitterionics (Dioleoyl phosphocholine (DOPC)) and positively charged (Dimethyldioctadecylammonium bromide (DODAB)) lipids. Its properties were initially characterized in several biological environments for later cytotoxicity assays in human keratinocytes (HaCaT). It evaluated the degradation of the NPs in different pH, as well as their interaction with giant unilamellar vesicle (GUVs) mimetic membranes, with microscopic visualization. MNPs coated with DODAB were more toxic to keratinocytes in culture and caused lysis of GUVs. In the case of NbONPs, acidity from Nb2O5 was evaluated in heterogeneous catalysis, as well as the evaluation of HaCaT cytotoxicity revealed a potential biomedical use

Cytotoxicity and Bioactivity of Calcium Silicate Cements Combined with Niobium Oxide in Different Cell Lines

Abstract The aim of this study was to evaluate the cytotoxicity and bioactivity of calcium silicate-based cements combined with niobium oxide (Nb2O5) micro and nanoparticles, comparing the response in different cell lines. This evaluation used four cell lines: two primary cultures (human dental pulp cells - hDPCs and human dental follicle cells - hDFCs) and two immortalized cultures (human osteoblast-like cells - Saos-2 and mouse periodontal ligament cells - mPDL). The tested materials were: White Portland Cement (PC), mineral trioxide aggregate (MTA), white Portland cement combined with microparticles (PC/Nb2O5µ) or nanoparticles (PC/Nb2O5n) of niobium oxide (Nb2O5). Cytotoxicity was evaluated by the methylthiazolyldiphenyl-tetrazolium bromide (MTT) and trypan blue exclusion assays and bioactivity by alkaline phosphatase (ALP) enzyme activity. Results were analyzed by ANOVA and Tukey test (a=0.05). PC/Nb2O5n presented similar or higher cell viability than PC/Nb2O5µ in all cell lines. Moreover, the materials presented similar or higher cell viability than MTA. Saos-2 exhibited high ALP activity, highlighting PC/Nb2O5µ material at 7 days of exposure. In conclusion, calcium silicate cements combined with micro and nanoparticles of Nb2O5 presented cytocompatibility and bioactivity, demonstrating the potential of Nb2O5 as an alternative radiopacifier agent for these cements. The different cell lines had similar response to cytotoxicity evaluation of calcium silicate cements. However, bioactivity was more accurately detected in human osteoblast-like cell line, Saos-2.

Resumo O objetivo deste estudo foi avaliar a citotoxicidade e bioatividade de cimentos à base de silicato de cálcio associados com óxido de nióbio (Nb2O5) micro e nanoparticulados, e comparar a resposta em diferentes linhagens celulares. Foram utilizadas quatro linhagens celulares: duas culturas primárias (células da polpa dentária humana - hDPCs e células do folículo dentário humano - hDFCs) e duas culturas imortalizadas (células osteoblásticas humanas - Saos-2 e células do ligamento periodontal de ratos - mPDL). Os materiais analisados foram: Cimento Portland branco (PC); Agregado trióxido mineral (MTA); PC associado com micropartículas (PC/Nb2O5µ) ou nanopartículas (PC/Nb2O5n) de óxido de nióbio (Nb2O5). A citotoxicidade foi avaliada pelos ensaios de brometo de metil-tiazolil-difeniltetrazólio (MTT) e azul de tripan, e a bioatividade pela atividade da enzima fosfatase alcalina (ALP). Os resultados foram analisados por ANOVA e teste de Tukey (a=0,05). O grupo do PC/Nb2O5n apresentou viabilidade celular semelhante ou maior do que o grupo do PC/Nb2O5μ em todas as linhagens celulares. Além disso, ambos os grupos apresentaram viabilidade celular semelhante ou maior do que o MTA. Saos-2 apresentaram maior atividade de ALP, com destaque para o material PC/Nb2O5μ aos 7 dias de exposição. Concluiu-se que cimentos de silicato de cálcio associados com Nb2O5 micro ou nanoparticulado apresentaram citocompatibilidade e bioatividade, demonstrando potencial do Nb2O5 como agente radiopacificador alternativo para estes cimentos. As linhagens celulares estudadas apresentaram resposta semelhante na avaliação da citotoxicidade de cimentos de silicato de cálcio. No entanto, a bioatividade é melhor detectada na linhagem de células osteoblásticas humanas, Saos-2.

Effect of rewetting solutions on micropush-out dentin bond strength of new bioceramic endodontic material

Abstract To evaluate the influence of rewetting solutions on bond strength to root dentin of conventional gutta-percha (GP) or niobium phosphate glass-based gutta-percha (GNb) associated with a bioceramic sealer. The root canals of 80 human mandibular premolars were prepared using nickel-titanium instruments and irrigation with sodium hypochlorite and EDTA. The teeth were randomly divided into four groups according to the gutta-percha used: GNb or GP associated with EndoSequence BC Sealer (BC) and the solution for rewetting dentin before filling (distilled water; phosphate buffer saline solution - PBS; simulated body fluid - SBF; or no solution). The root canals were filled with a single cone using warm vertical condensation. Micropush-out bond strengths associated with the filling materials in slices from middle root thirds was determined 30 days after root filling. The failure mode was analyzed with stereoscopic lens. The data were statistically analyzed by two-way ANOVA and Holm-Sidak test (p < 0.05). There was significant difference in the types of gutta-percha (p < 0.001) and in the different rewetting solutions (p = 0.003). The interaction between gutta-percha and rewetting solutions was not significant (p = 0.53). The SBF solution provided an increase in bond strength for both gutta-percha solutions. The GNb+BC (3.42 MPa) association increased bond strength when compared with GP+BC (2.0 MPa). The use of SBF as a dentin rewetting solution increased bond strength in the groups studied. Association of GNb with bioceramic sealer was beneficial, increasing the bond strength to dentin when compared with the association with GP.

Evaluation of pulmonary function and respiratory symptoms in pyrochlore mine workers / Avaliação da função pulmonar e sintomas respiratórios em trabalhadores da mineração de pirocloro

ABSTRACT Objective: To identify respiratory symptoms and evaluate lung function in mine workers. Methods: This was a cross-sectional observational study involving production sector workers of a pyrochlore mining company. The subjects completed the British Medical Research Council questionnaire, which is designed to evaluate respiratory symptoms, occupational exposure factors, and smoking status. In addition, they underwent pulmonary function tests with a portable spirometer. Results: The study involved 147 workers (all male). The mean age was 41.37 ± 8.71 years, and the mean duration of occupational exposure was 12.26 ± 7.09 years. We found that 33 (22.44%) of the workers had respiratory symptoms and that 26 (17.69%) showed abnormalities in the spirometry results. However, we found that the spirometry results did not correlate significantly with the presence of respiratory symptoms or with the duration of occupational exposure. Conclusions: The frequencies of respiratory symptoms and spirometric changes were low when compared with those reported in other studies involving occupational exposure to dust. No significant associations were observed between respiratory symptoms and spirometry results.

RESUMO Objetivo: Determinar a presença de sintomas respiratórios e avaliar a função pulmonar de trabalhadores da mineração. Métodos: Estudo observacional de caráter transversal realizado com trabalhadores do setor de produção de uma mineradora de pirocloro. Para avaliar os sintomas respiratórios, fatores de exposição ocupacional e tabagismo, foi aplicado o questionário de sintomas respiratórios British Medical Research Council, e a função pulmonar foi avaliada utilizando-se um espirômetro portátil. Resultados: Participaram do estudo 147 trabalhadores, todos do sexo masculino, com média de idade de 41,37 ± 8,71 anos e com tempo de exposição ocupacional de 12,26 ± 7,09 anos. Foi observado que 33 (22,44%) dos trabalhadores apresentaram sintomas respiratórios e que 26 (17,69%) dos trabalhadores apresentaram alguma alteração nos resultados espirométricos. Entretanto, os resultados espirométricos não se correlacionaram significativamente com sintomas respiratórios e tempo de exposição. Conclusões: As frequências de sintomas respiratórios e de alterações espirométricas apresentaram-se baixas quando comparadas às de estudos que envolviam exposição à poeira ocupacional. Não foram observadas associações significativas dos sintomas respiratórios com os valores espirométricos.

Ions Release and pH of Calcium Hydroxide-, Chlorhexidine- and Bioactive Glass-Based Endodontic Medicaments

Abstract This study evaluated pH and release of calcium, sodium and phosphate ions from different medications in human dentin. Fifty premolars were prepared and randomly divided into groups: (CHX) - 2% chlorhexidine gel; (CHX + CH) - CHX + calcium hydroxide PA; (CH) - CH + propylene glycol 600; (NPBG) - experimental niobium phosphate bioactive glass + distilled water; (BG) - bioactive glass (Bio-Gran) + distilled water. The specimens were immersed in deionized water and the pH variations were measured. The quantification of ions in the solutions was made by inductively coupled plasma - atomic emission spectroscopy (ICP/AES) at 10 min, 24 h, 7, 14, 21 and 30 days. The results were analyzed by ANOVA and Tukey`s test, with a significance level of 5%. CH had the highest level of calcium ions release at 30 days, while CHX and BG released more sodium ions. BG, NPBG and CHX released a higher amount of phosphate ions. The pH of CH was significantly higher compared with the other groups. CH favored the greatest increase of pH and calcium ions release. The bioactive glasses released more sodium and phosphate ions and presented an alkaline pH immediately and after 30 days.

Resumo Este estudo avaliou o pH e a liberação de íons cálcio, sódio e fosfato de diferentes medicamentos em dentina humana. Cinquenta pré-molares foram preparados e divididos aleatoriamente em grupos: (CHX) - clorexidina gel 2%; (CHX + CH) - CHX + hidróxido de cálcio PA; (CH) - CH + propilenoglicol 600; (NPBG) - vidro experimental nióbio fosfato bioativo + água destilada; (BG) - vidro bioativo (Bio-Gran) + água destilada. Os espécimes foram submersos em água deionizada e as variações de pH foram mensuradas. A quantificação dos íons nas soluções foi feita por espectrometria de emissão atômica com plasma indutivamente acoplado (ICP - AES) nos tempos de 10 min, 24 h, 7, 14, 21 e 30 dias. Os resultados foram analisados por ANOVA e teste Tukey, com um nível de significância de 5%. Verificou-se que CH a teve a maior liberação íons de cálcio ao final de 30 dias, enquanto CHX e BG liberaram mais íons de sódio. BG, NPBG e CHX apresentaram a maior liberação de íons fosfato. O pH de CH foi significativamente maior em comparação com os outros grupos testados. O grupo CH aumentou o pH e a liberação de íons cálcio. Os vidros bioativos obtiveram uma maior liberação de íons sódio e fosfato e apresentaram pH alcalino imediato e ao final de 30 dias.

Radiopacity and cytotoxicity of Portland cement associated with niobium oxide micro and nanoparticles

Objective Mineral Trioxide Aggregate (MTA) is composed of Portland Cement (PC) and bismuth oxide (BO). Replacing BO for niobium oxide (NbO) microparticles (Nbµ) or nanoparticles (Nbη) may improve radiopacity and bioactivity. The aim of this study was to evaluate the radiopacity and cytotoxicity of the materials: 1) PC; 2) White MTA; 3) PC+30% Nbµ; 4) PC+30% Nbη. Material and Methods For the radiopacity test, specimens of the different materials were radiographed along an aluminum step-wedge. For cell culture assays, Saos-2 osteoblastic-cells (ATCC HTB-85) were used. Cell viability was evaluated through MTT assay, and bioactivity was assessed by alkaline phosphatase activity assay. Results The results demonstrated higher radiopacity for MTA, followed by Nbµ and Nbη, which had similar values. Cell culture analysis showed that PC and PC+NbO associations promoted greater cell viability than MTA. Conclusions It was concluded that the combination of PC+NbO is a potential alternative for composition of MTA. .

Estudo das células primárias dentais, viabilidade celular e bioatividade de materiais á base de silicato de cálcio / Cell viability and bioactivity of Portland cement-based materials in human dental follicle and pulp stem cells, fibroblasts and osteoblasts

Os objetivos deste estudo foram o isolamento e diferenciação de células da polpa (hDPCs) e do folículo (hDFCs) dentário de terceiros molares humanos e utilização para avaliação da citotoxicidade e bioatividade de novos cimentos endodônticos. (Capítulo 1) - Após a obtenção das culturas primárias foram realizados os ensaios vermelho de Alizarina, atividade da enzima fosfatase alcalina (ALP). A expressão gênica de proteína morfogenética óssea (bmp7), sialofosfoproteína dentinária (dspp) e alp foi avaliada. Os ensaios de bioatividade demonstraram maior atividade para hDPCs, além de maior expressão de dspp e alp; a expressão de bmp7 foi semelhante nas duas linhagens. Conclui-se que hDPCs demonstram maior capacidade de diferenciação em células com potencial de mineralização, quando comparadas com hDFCs. (Capítulo 2) – Foram utilizadas linhagens primárias (hDPCs e hDFCs), em comparação com linhagens imortalizadas (células osteoblásticas humanas Saos-2, e do ligamento periodontal de ratos mPDL) para análise dos materiais: 1) Cimento Portland branco (CP); 2) MTA; 3) CP/ óxido de nióbio microparticulado (Nb2O5?); 4) CP/ óxido de nióbio nanoparticulado (Nb2O5n). A citotoxicidade foi avaliada pelos ensaios MTT e Azul de Trypan e a bioatividade pela atividade da ALP. Viabilidade celular foi observada em todas as linhagens; e a atividade de ALP apresentou maior resposta na linhagem Saos-2. Conclui-se que as diferentes linhagens celulares são similares para avaliação da citotoxicidade; entretanto, para avaliação da bioatividade o uso de uma linhagem celular osteoblástica é mais indicado. Além disso, observa-se que materiais à base de Nb2O5? e Nb2O5n mostram potencial como radiopacificador alternativo no MTA

The aims of this study were to isolate and differentiate pulp (hDPCs) and follicle (hDFCs) cells obtained from human third molars and to use them in cytotoxicity and bioactivity assays of new dental materials. (Chapter 1) - After obtaining the stem cultures, Alizarin Red, alkaline phosphatase (ALP) activity and gene expression by Real Time PCR of bone morphogenetic protein (BMP7), dentin sialophosphoprotein (DSPP) and ALP were performed. The bioactivity asssays showed greater activity for hDPCs, and increased expression of dspp and alp; the expression of bmp7 was similar in both cell lines. We conclude that hDPCs demonstrate greater ability to differentiate into cells with mineralization potential when compared with hDFCs. (Chapter 2) - stem lineages (hDPCs and hDFCs) were used, compared to immortalized lineages (human osteoblastic cells Saos-2, and periodontal ligament of mice cells mPDL) for analysis of the following materials: 1) white Portland cement (PC); 2) MTA; 3) C/ microparticulated of niobium oxide (Nb2O5µ); 4) CP/nanoparticulated niobium oxide (Nb2O5n). Cytotoxicity was performed by MTT and Trypan Blue assays and bioactivity by ALP activity assay. Cell viability was observed in all cell lines, and ALP activity showed greater response in Saos-2. We conclude that the different cell lines are similar in cytotoxicity, however, to evaluate the bioactivity, using an osteoblastic cell line is more appropriate. Moreover, it is observed that materials based on Nb2O5µ and Nb2O5n show potential for alternative use to MTA

Pentóxido de nióbio como carga para materiais de base polimérica para uso odontológico / Niobium pentoxide as filler for polymer-based materials for dental use

O objetivo desta tese foi caracterizar o pentóxido de nióbio (Nb2O5), produzir materiais compósitos de matriz polimérica de uso odontológico e avalia-los. As partículas de Nb2O5 foram caracterizadas com difração de raios-X, microscopia eletrônica de varredura, granulometria a laser, método de Brunauer–Emmett–Teller e espectroscopia micro-Raman. Um adesivo experimental foi desenvolvido com a incorporação de diferentes concentrações de Nb2O5 (0, 5, 10 e 20 %, em peso). Este adesivo foi avaliado quanto à radiopacidade, grau e cinética de conversão, microdureza e a sua interface com a dentina. Um cimento endodôntico experimental de cura dual também foi desenvolvido com a incorporação de diferentes concentrações de Nb2O5 (0, 80, 100 e 120 %, em peso). Este cimento foi avaliado quanto à radiopacidade, escoamento, espessura de película, microdureza e grau de conversão (imediatamente, 7 dias e 14 dias após a fotoativação). A avaliação do Nb2O5 mostrou que as partículas utilizadas apresentavam estrutura monoclínica, com formato irregular, com tamanho médio de 38,16 μm, área de superfície de 3,86 m2/g e estrutura química compatível com pentóxido de nióbio. A radiopacidade e dureza do adesivo aumentaram com a incorporação do Nb2O5 e ele pode ser detectado no interior da interface dentina/adesivo. No cimento endodôntico a incorporação do Nb2O5 também aumentou a radiopacidade e a dureza e reduziu o escoamento apenas no grupo com 120 %. O grau de conversão aumentou até 14 dias após a fotoativação, com exceção do grupo com 80%. Após a caracterização do Nb2O5 e da produção dos materiais experimentais, foi feito o depósito de pedido de patente de invenção. Conclui-se que o pentóxido de nióbio é uma nova e promissora partícula para uso em Odontologia como agente e carga...

The aim of this thesis was to characterize the niobium pentoxide (Nb2O5), to produce resin-based composite for dental applications and evaluate them. Niobium pentoxide was characterised by X-ray diffraction, surface area, particle size, micro-Raman and scanning electron microscopy. An experimental adhesive resin was formulated with 0, 5, 10 and 20 wt% Nb2O5. The formulated adhesive resins were evaluated based on microhardness, degree of conversion, radiopacity and interface (resin/dentin) characterisation by micro-Raman. An experimental dual-cured root canal sealer was produced with a methacrylate-based comonomer blend. Nb2O5 was added at four different concentrations: 0, 80, 100 and 120wt%. Radio-opacity, flow, film thickness, microhardness and degree of conversion (after 1, 7 and 14 days) were evaluated. The particles used in this study presented a monoclinic crystalline phase with typical chemical groups, mean size of 38.16 μm and 3.86 m2/g of surface area. Microhardness and radiopacity increased with higher amounts of Nb2O5, and the particles were able to penetrate into the hybrid layers. Microhardness and radiopacity increased with higher amounts of Nb2O5 in the adhesive resin, and the particles were able to penetrate into the hybrid layers. For the endodontic cement, the radiopacity and microhardness increased with the Nb2O5 addition. The flow was significantly smaller for the 120% group. All groups except those with 80wt% had higher values for degree of conversion after 14 days than immediately after photocuring. After the Nb2O5 characterization and the production of experimental materials, an application for patent was done. Niobium pentoxide is a new and promising filler for dental materials production...

A comparative evaluation of metallurgical properties of stainless steel and TMA archwires with timolium and titanium niobium archwires - An in vitro study.

Objectives: This study aims to evaluate and compare the mechanical and metallurgical properties of stainless steel and titanium molybdenum alloy (TMA) archwires, with recently introduced timolium and titanium niobium arch wires. Materials and Methods: Archwires were categorized into four groups (group I to IV) with 10 samples in each group. They were evaluated for tensile strength, yield strength, modulus of elasticity, load deflection, frictional properties and weld characteristics. Results: The results were statistically analyzed using ANOVA test and it indicated that stainless steel has high strength, high stiffness and low friction compared to other arch wires, thereby proving that it is the best choice for both sliding as well as frictionless retraction mechanics. TMA with its high formability, low stiffness and low load deflection property is suited to apply consistent force in malaligned teeth but, high friction limits its use in retraction only with loop mechanics. Conclusion: Timolium possesses comparatively low stiffness, better strength and behaves as an intermediate between stainless steel and TMA and hence can be tried for almost all clinical situations. Low springback and high formability of titanium-niobium archwire allows creation of finishing bends and thus it can be used as finishing archwire.

In vivo biocompatibility of beta titanium alloys for internal fixation instruments / 中国矫形外科杂志

[Objective]To develop new beta titanium alloys made of titanium, niobium and zirconium (Ti-Nb-Zr) which have higher strength, lower moduli of elasticity. Its biocompatibility in vivo is evaluated in this paper. [Method](1) 24 SD rats were used in the modified air pouch model experiments. Air was injected subcutaneously on the back of rats to form the pouches and the Ti-Nb-Zr particles were introduced into them. The liquid in the pouches was harvested 48 hours later for IL-6 and TNF-?ELISA procedure and the capsules for histology examination. All the results were compared with Ti-6Al-4V. (2) Ti-Nb-Zr bone plates were fixed onto tibias of rabbits. The capsules around the plates and the bone under them were observed at 4, 8, 12, 24 and 36 weeks respectively. Ti-Nb-Zr-bone interfaces were emphasized in this procedure. This time the control material was stainless steel. [Result](1)Ti-Nb-Zr and Ti-6Al-4V particles made the air pouches secret more TNF-? than that of the control (P

An in vitro study of the biocompatibility of Ti-Nb-Zr Bate titanium alloy / 中国矫形外科杂志

[Objective]To evaluate the biocompatibility of a new bate titanium alloys made of titanium, niobium and zirconium (Ti-Nb-Zr) which have higher strength and lower elastic modulus by in vitro study.[Method](1)the cell toxicity of Ti-Nb-Zr was evaluated using L-929 cell line's relative growth rate (RGR) which was transformed into 6 toxicity ranks in according with the national standard;(2)the J774A.1macrophages cultured with Ti-Nb-Zr particles whose diameter was about 1 ?m for 24-48 hours were observed using inverted phase contrast microscopy and transmission electron microscopy. Expression of IL-6 and TNF-? mRNA in these cells were measured using RT-PCR technique. The TNF-? in the supernatant was also measured using ELISA method. All the results were compared with the traditional orthopedic implants metal materials such as Ti-6Al-4V and Co-Gr-Mo.[Result]The cell toxicity of Ti-Nb-Zr was ranked zero degree. The particles could be seen in the macrophages under the light microscopy. Ti-Nb-Zr particles made the J774.A1 macrophages less configurative changes than Ti-6Al-4V and Co-Gr-Mo did.Expressions of IL-6 and TNF-? mRNA in J774.A1 cell were increased after stimulation for 48 hours by all kinds of metallic materials. The TNF-? in the supernatants of Ti-Nb-Zr group were less than that of the Ti-6Al-4V and Co-Gr-Mo groups (P

Bate titanium alloys for orthopedic implants:fabrication,X-ray diffraction analysis,and biomechanics / 中国矫形外科杂志

[Objective] To develop new bate titanium alloys made of titanium,niobium and zirconium(Ti-Nb-Zr)which have higher strength,lower moduli of elasticity and better biocompatibility for orthopedic implants.[Methods]Alloy elements including titanium,niobium and zirconium were melted together and forged into forging Ti-Nb-Zr.Four kinds of alloys were developed because of the different proportion of alloy elements.All alloys were studied using X-ray diffraction analysis,biomechanical measurements,and scanning and transmission electron microscopy.[Results]X-ray diffraction analyses showed that all the candidates were beta alloys.The as-cast alloys had the strength values in 584~718 Mpa,elastic modulus values in 59~68 Gpa.The peak-aged alloys had the strength values in 706~874 Mpa,elastic modulus values in 59~66 Gpa,elongation rates in 5.4%~20%.The forging procedure could increase the strength significantly but almost have no influence in elastic modulus of Ti-Nb-Zr.[Conclusion]The Ti-Nb-Zr beta titanium alloys developed in our lab have lower modulus and high strength both.It is a promising material for orthopedic implants.

Influence on Ni seperation from TiNi alloy by coating its surface with Ti or TiNb alloy / 中国矫形外科杂志

[Objective]To investigate the influence of Nitinol modified on its surfaces by the coating of titanium or titanium-niobium alloy on separat ion of Ni~(2+).[Method]The specimens from 1 to 7 days after the experiments were collected and the concentration of Ni~(2+) were cletermined by physiologic saline immersing test,low temperature ashing furnace,Mg(NO_3)_2 as matrix modifier and graphite furnace atomic absorption spectrometry(GFAAS).[Result]Specimens of Nitinol were devided into 3 groups:alloy coated with Ti(Ti group);alloy with Titanium-Niobium(TiNi group);only Nitanol without coating group.Obvious separation of Ni~(2+) was detected in the groups of Nitinol that were not modified and were put in baking oven(37℃),the separating procedure was mainly within 4 days,the separation rate(10~(-7)??g? cm~(-2)?s~(-1)) from the first to the forth days was 18.2,3.45,1.75 and 0.45 respectively,the Ni~(2+)was no more separated from the fifth day.Whereas,Ni~(2+) was not separated in the groups of Nitinol that were modified by the coating of metallic Ti and TiNb alloy.The recovery rate of the experiments was between 94.6%～108.6%.[Conclusion]The coating of Ti or TiNb on the surfaces of Nitinol stopped Nitinol from separating Ni~(2+).

A tissue response to the titanium alloy (Ti-13Zr-6Nb) in vivo / 대한치과보철학회지

STATEMENT OF PROBLEM: Mechanisms of tissue-implant interaction and the effect of the implant surface on the behavior of cells has not yet been clarified. PURPOSE: This study was performed to investigate the tissue reaction to the titanium alloy submerged into rat peritoneum in vivo. MATERIALS AND METHODS: Titanium alloys (titanium-13Zirconium-6Niobium) were inserted inside the peritoneal cavity of Sprague Dawley rats. After 3 months, the tissue formed around the inserted titanium alloys were examined with a light-microscope. Tissue reaction around the material was analyzed by confocal microscopy to evaluate their biocompatibility in a living body. RESULTS: In in vivo study, foreign body type multinucleated giant cells were found in the fibrous tissue formed as a reaction to the foreign material (4 in 20 cases), but the inflammatory reaction was very weak. After experiment, the contaminants of biomaterials was removed from living tissue. In confocal microscopy, we observed that the staining of vinculin and actin showed mixed appearance. In a few cases, we found that the staining of vinculin and beta-catenin showed the prominent appearance. CONCLUSION: We found that titanium-13Zirconium-6Niobium alloy was an excellent biomaterial.