Effect of graphene-oxide-modified osteon-like concentric microgrooved surface on the osteoclastic differentiation of macrophages / 华西口腔医学杂志

OBJECTIVES@#This study aimed to investigate the effect of new biomimetic micro/nano surfaces on the osteoclastic differentiation of RAW264.7 macrophages by simulating natural osteons for the design of concentric circular structures and modifying graphene oxide (GO).@*METHODS@#The groups were divided into smooth titanium surface group (SS), concentric microgrooved titanium surface group (CMS), and microgroove modified with GO group (GO-CMS). The physicochemical properties of the material surfaces were studied using scanning electron microscopy (SEM), contact-angle measurement, atomic force microscopy, X-ray photoelectron spectroscopy analysis, and Raman spectroscopy. The effect of the modified material surface on the cell biological behavior of RAW264.7 was investigated by cell-activity assay, SEM, and laser confocal microscopy. The effect on the osteoclastic differentiation of macrophages was investiga-ted by tartrate-resistant acid phosphatase (TRAP) immunofluorescence staining and quantitative real-time polymerase chain reaction (qRT-PCR) experiments.@*RESULTS@#Macrophages were arranged in concentric circles along the microgrooves, and after modification with GO, the oxygen-containing groups on the surface of the material increased and hydrophilicity increased. Osteoclasts in the GO-CMS group were small in size and number and had the lowest TRAP expression. Although it promoted the proliferation of macrophages in the GO-CMS group, the expression of osteoclastic differentiation-related genes was lower than that in the SS group, and the difference was statistically significant (P<0.05).@*CONCLUSIONS@#Concentric circular microgrooves restricted the fusion of osteoclasts and the formation of sealing zones. Osteomimetic concentric microgrooves modified with GO inhibited the osteoclastic differentiation of RAW 264.7 macrophages.

Effects of nano titanium dioxide on gut microbiota based on human digestive tract microecology simulation system in vitro / 北京大学学报(医学版)

OBJECTIVE@#To explore the effects of oral exposure to titanium dioxide nanoparticles (TiO2 NPs) on the composition and structure of human gut microbiota.@*METHODS@#The particle size, shape, crystal shape and degree of agglomeration in ultrapure water of TiO2 NPs were characterized. The in vitro human digestive tract microecological simulation system was established by simulating the fluid environment and physical conditions of stomach, small intestine and colon, and the stability of the simulation system was evaluated. The bacterial communities were extracted from human feces and cultured stably in the simulated system. They were exposed to 0, 20, 100 and 500 mg/L TiO2 NPs, respectively, and the bacterial fluids were collected after 24 h of exposure. The effect of TiO2 NPs on the composition and structure of human gut microbiota was analyzed by 16S rRNA sequencing technology. Linear discriminant analysis effect size (LEfSe) was used to screen differential bacteria, and the Kyoto encyclopedia of genes and genomes (KEGG) database for functional prediction.@*RESULTS@#The spherical and anatase TiO2 NPs were (25.12±5.64) nm in particle size, while in ultra-pure water hydrated particle size was (609.43±60.35) nm and Zeta potential was (-8.33±0.22) mV. The in vitro digestive tract microecology simulation system reached a relatively stable state after 24 hours, and the counts of Enterococci, Enterobacte-rium, and Lactobacillus reached (1.6±0.85)×107, (5.6±0.82)×107 and (2.7±1.32)×107, respectively. 16S rRNA sequencing results showed that compared with the control group, the number and evenness of gut microbiota were not significantly affected at phylum, class, order, family and genus levels in TiO2 NPs groups (20, 100 and 500 mg/L). The relative abundance of some species was significantly changed, and a total of 42 different bacteria were screened between the TiO2 NPs groups (20, 100 and 500 mg/L) and the control group [linear discriminant analysis(LDA) score>3], represented by Enterobacter, Bacteroidaceae, Lactobacillaceae, Bifidobacteriaceae and Clostridium. Further predictive analysis of gut microbiota function showed that TiO2 NPs might affect oxidative phosphorylation, energy meta-bolism, phosphonate and phosphonate metabolism, and methane metabolism (P < 0.05).@*CONCLUSION@#In human digestive tract microecological simulation system, TiO2 NPs could significantly change the composition and structure of human gut microbiota, represented by Enterobacter and probiotics, and may further affect a variety of metabolism and function of the body.

Effect of titanium dioxide nanoparticles on the stereological parameters of the dentate gyrus and the morphology of granular hippocampal neurons in mice / Efecto de las nanopartículas de dióxido de titanio sobre los parámetros estereológicos del giro dentado y morfología de las neuronas granulares del hipocampo en ratones

SUMMARY: This study aims to investigate the Effects of Titanium dioxide nanoparticles (TiO2 NPs) on the stereological parameters in the dentate gyrus and the morphology of granular hippocampal neurons in adult mice. Adult male mice (n=20, weight average: 45 g) were randomly divided into four groups including: group receiving saline (controls), low-dose (LD) 2.5 mg/kg TiO TiO2 NPs, medium-dose (MD) 5 mg/kg TiO2 NPs and high-dose (HD) 10 mg/kg TiO2 NPs, daily using gavage for 35 days. To estimate the volume of the hippocampus, dentate gyrus, and sub-layers of dentate gyrus the Cavalieri principle was used. The physical dissector was used to determine the numerical density of dentate gyrus granular cells. For analyzing the morphology of dentate gyrus granular cells the qualitative Golgi staining was used. Our data showed that the total volume of the hippocampus, dentate gyrus and its sublayers including molecular, granular and polymorph in TiO2 treated mice decreased significantly compared to the control group. Moreover, the total number and numerical density of dentate gyrus granular sub layer cells showed a significant reduction in all three experimental groups compared to the control group. The granular cells of the dentate gyrus had shorter dendritic length and decreased dendritic branches in the TiO2-treated in comparison with the control mice. These data can justify the disorders related to memory, learning and hippocampus neurons damages due to using of TiO2 NPs.

RESUMEN: En este estudio se analizaron los efectos de las nanopartículas de dióxido de titanio (TiO2 NP) sobre los parámetros estereológicos en el giro dentado y la morfología de las neuronas granulares del hipocampo en ratones adultos. Se dividieron aleatoriamente ratones machos adultos (n = 20, promedio de peso: 45 g) en cuatro grupos: grupo que recibió solución salina (controles), dosis baja (LD) 2,5 mg/kg NP de TiO2, dosis media (MD) 5 mg/kg de NP de TiO2 y dosis altas (HD) de 10 mg/kg de NP de TiO2, por vía utilizando sonda durante 35 días. Para estimar el volumen del hipocampo, el giro dentado y las subcapas del giro dentado se utilizó el principio de Cavalieri. Se utilizó el disector físico para determinar la densidad numérica de las células granulares del giro dentado. Para analizar la morfología de las células granulares del giro dentado se usó la tinción cualitativa de Golgi. Nuestros datos mostraron que el volumen total del hipocampo, el giro dentado y sus subcapas, incluyendo la molecular, granular y polimorfos, en ratones tratados con TiO2, disminuyó significativamente en comparación con el grupo de control. Además, el número total y la densidad numérica de las células de la subcapa granular del giro dentado mostró una reducción significativa en los tres grupos experimentales en comparación con el grupo control. Las células granulares del giro dentado tenían una longitud dendrítica menor y ramas dendríticas disminuidas en los ratones tratados con TiO2 en comparación con los ratones del grupo control. Estos datos pueden justificar los trastornos relacionados con la memoria, el aprendizaje y los daños en las neuronas del hipocampo debido al uso de NP de TiO2.

Evaluation of zinc-oxide nanocoating on the characteristics and antibacterial behavior of nickel-titanium alloy

ABSTRACT Objective: To investigate the effect of ZnO nanocoating on mechanical properties of NiTi orthodontic wires and antibacterial activity. Methods: 0.016 x 0.022-in NiTi orthodontic wires were coated with ZnO nanoparticles using an electrochemical deposition method with three electrodes system in 0.1M Zn(NO3)2. Mechanical properties and frictional resistance of the coated wires were investigated using an universal testing machine. Antibacterial effect of ZnO coating was also investigated. Results: A stable adhered ZnO nanocoating on NiTi wires was obtained. The coated wires have a significant antibacterial activity against S. aureus, S. pyogens and E. coli, and a reduction of frictional forces by 34%. Conclusion: ZnO nanocoating may improve the antibacterial effects of NiTi wires and reduce the frictional resistance. Coating may be implanted in orthodontic practice for faster and safer treatment.

RESUMO Objetivos: Avaliar o efeito do nanorrevestimento de óxido de zinco (ZnO) sobre as propriedades mecânicas e propriedades antibacterianas de fios ortodônticos de NiTi. Métodos: Fios 0,016" x 0,022" de NiTi foram revestidos com nanopartículas de ZnO por meio de um método de deposição eletroquímica com um sistema de três eletrodos a 0,1M Zn(NO3)2. Uma máquina universal de testes foi utilizada para avaliar as propriedades mecânicas e a resistência friccional dos fios revestidos. Além disso, também foram analisadas as propriedades antibacterianas do revestimento de ZnO. Resultados: Obteve-se uma aderência estável das nanopartículas de ZnO sobre os fios NiTi. Os fios revestidos apresentaram atividade antibacteriana significativa contra S. aureus, S. pyogens e E. coli, e apresentaram uma redução de 34% na força de atrito. Conclusão: O revestimento com nanopartículas de óxido de zinco pode melhorar as propriedades antibacterianas e reduzir a resistência friccional dos fios de NiTi. Assim, o revestimento dos fios pode ser utilizado na Ortodontia visando tratamentos mais rápidos e seguros.

Effect of stem cells combined with a polymer/ceramic membrane on osteoporotic bone repair

Abstract Cell therapy associated with guided bone regeneration (GBR) can be used to treat bone defects under challenging conditions such as osteoporosis. This study aimed to evaluate the effect of mesenchymal stem cells (MSCs) in combination with a poly(vinylidene-trifluoroethylene)/barium titanate (PVDF-TrFE/BT) membrane on bone repair in osteoporotic rats. Osteoporosis was induced in female rats by bilateral removal of the ovaries (OVX) or sham surgery (SHAM), and the osteoporotic condition was characterized after 5 months by microtomographic and morphometric analyses. Calvarial defects were created in osteoporotic rats that immediately received the PVDF-TrFE/BT membrane. After 2 weeks, bone marrow-derived MSCs from healthy rats, characterized by the expression of surface markers using flow cytometry, or phosphate-buffered saline (PBS) (Control) were injected into the defects and bone formation was evaluated 4 weeks post-injection by microtomographic, morphometric, and histological analyses. A reduction in the amount of bone tissue in the femurs of OVX compared with SHAM rats confirmed the osteoporotic condition of the experimental model. More bone formation was observed when the defects were injected with MSCs compared to that with PBS. The modification that we are proposing in this study for the classical GBR approach where cells are locally injected after a membrane implantation may be a promising therapeutic strategy to increase bone formation under osteoporotic condition.

Additive manufacturing of titanium alloy could modify the pathogenic microbial profile: an in vitro study

Abstract Additive manufacturing (AM) is an emerging process for biomaterials and medical devices. Direct Laser Metal Sintering (DLMS) is an AM technique used to fabricate Ti-6Al-4V implant materials with enhanced surface-related properties compared with wrought samples; thus, this technique could influence microbial adsorption and colonization. Therefore, this in vitro study was conducted to evaluate the impact of different implant production processes on microbial adhesion of periodontal pathogens. Titanium discs produced using two different processes—conventional and AM—were divided into three groups: conventional titanium discs with machined surface (G1), AM titanium discs with chemical treatment (G2) and AM titanium discs without chemical treatment (G3). Subgingival biofilm composed of 32 species was formed on the titanium discs, and positioned vertically in 96-well plates, for 7 days. The proportions of microbial complexes and the microbial profiles were analyzed using a DNA-DNA hybridization technique, and data were evaluated using Kruskal-Wallis and Dunnett tests (p < 0.05). Lower proportions of the red complex species were observed in the biofilm formed in G2 compared with that in G1 (p < 0.05). Moreover, the proportions of the microbial complexes were similar between G2 and G3 (p > 0.05). Compared with G1, G2 showed reduced levels of Porphyromonas gingvalis , Actinomyces gerencseriae, and Streptococcus intermedius , and increased levels of Parvimonas micra , Actinomyces odontolyticus, and Eikenella corrodens (p < 0.05). The microbial profile of G3 did not differ from G1 and G2 (p > 0.05). The results of this in vitro study showed that titanium discs produced via AM could alter the microbial profile of the biofilm formed around them. Further clinical studies should be conducted to confirm these findings.

A novel application of nano eggshell/titanium dioxide composite on occluding dentine tubules: an in vitro study

Abstract To synthesize Nano eggshell-titanium-dioxide (EB@TiO2) biocomposite and to evaluate its effectiveness in occluding opened dentine tubules. EB@TiO2 was synthesized and characterized using X-ray diffraction (XRD), and Transmission Electron Microscope (TEM). Sixteen simulated bovine dentine discs were prepared and randomly assigned into four groups according to the following treatment (n = 4): Group 1: No treatment; Group 2: eggshell powder; Group 3: EB@TiO2; Group 4: Sensodyne. These were then agitated in a solution of 1g powder and 40mL water for 3hours. Thereafter, each dentine discs from the respective groups were post-treated for 5 min with 2wt% citric acid to test their acid resistant characteristics. Scanning Electron Microscope (SEM) was used to observe the effectiveness of occluded dentine pre-and post-treatment. The cytotoxicity of the synthesized EB@TiO2 was tested using NIH 3T3 assay. ANOVA was used to evaluate the mean values of the occluded area ratio and the data of MTS assay. This was followed by a multi-comparison test with Bonferroni correction (α = .05). The XRD confirmed that EB@TiO2 was successfully modified through ball-milling. The TEM revealed the presence of both spherical and irregular particle shape powders. The SEM result showed that EB@TiO2 could effectively occlude open dentine tubules. Equally, the result demonstrated that EB@TiO2 exhibited the highest acid resistant stability post-treatment. NIH 3T3 assay identified that EB@TiO2 had little effect on the NIH 3T3 cell line even at the highest concentration of 100µg/ml. This study suggests that the application of EB@TiO2 effectively occluded dentine tubules and the occlusion showed a high acid resistant stability.

Antibacterial effect of titanium alloys with copper nanoparticles: in vitro study

Objective: To evaluate the in-vitro antimicrobial effect of Titanium alloys with Copper Nanoparticles (CuNP) against Streptococcus mutans and Phorphyromonas gingivalis. Materials and Methods: An in vitro study was carried out. The unit of analysis corresponded to 10 healing abutments. In 5 abutments Copper nanoparticles (CuNP) electrodeposition was applied. The remaining 5 abutments corresponded to control. The healing abutments were then immersed in culture medium for S. mutans and P. gingivalis for 14 days. Results: The agar plates with CuNP-coated abutments showed a lower growth, statistically significant for both bacterial strains. Conclusion: There is a statistically significant lower growth of S. mutans and P. gingivalis in healing abutments with CuNP.

Shear bond strength and adhesive remnant index of orthodontic brackets bonded to enamel using adhesive systems mixed with TiO2 nanoparticles

ABSTRACT Introduction: It is recently suggested that titanium dioxide (TiO2) nanoparticles can be added to bracket luting agents in order to reduce bacterial activity and protect the enamel. However, it is not known if this addition can affect the shear bond strength (SBS) below clinically acceptable levels. Therefore, this study examined this matter within a comprehensive setup. Methods: This in vitro experimental study was conducted on 120 extracted human premolars randomly divided into four groups (n=30): in groups 1 and 2, Transbond XT light-cured composite with or without TiO2 was applied on bracket base; in groups 3 and 4, Resilience light-cured composite with or without TiO2 was used. Brackets were bonded to teeth. Specimens in each group (n=30) were divided into three subgroups of 10 each; then incubated at 37°C for one day, one month, or three months. The SBS and adhesive remnant index (ARI) were calculated and compared statistically within groups. Results: The SBS was not significantly different at one day, one month or three months (p>0.05) but composites without TiO2 had a significantly higher mean SBS than composites containing TiO2 (p<0.001). The SBS of Transbond XT was significantly higher than that of Resilience (p<0.001). No significant differences were noted in ARI scores based on the type of composite or addition of TiO2 (p>0.05). Conclusions: Addition of TiO2 nanoparticles to Transbond XT decreased its SBS to the level of SBS of Resilience without TiO2; thus, TiO2 nanoparticles may be added to Transbond XT composite for use in the clinical setting.

RESUMO Introdução: recentemente, sugeriu-se que nanopartículas de dióxido de titânio (TiO2) poderiam ser adicionadas ao cimento adesivo para reduzir a atividade bacteriana e proteger o esmalte. Entretanto, não se sabe se esse acréscimo pode reduzir a resistência adesiva ao cisalhamento (RAC) a níveis inferiores aos clinicamente aceitáveis. Assim, o presente estudo examinou essa questão dentro de um contexto abrangente. Métodos: esse estudo experimental in vitro foi realizado em 120 pré-molares humanos, aleatoriamente divididos em quatro grupos (n=30). Nos grupos 1 e 2, o adesivo fotopolimerizável Transbond XT com e sem TiO2 foi aplicado na base do braquete. Nos grupos 3 e 4, utilizou-se o adesivo fotopolimerizável Resilience com e sem TiO2. Os braquetes foram colados aos dentes e as amostras de cada grupo (n=30) foram divididas em três subgrupos de dez amostras cada, as quais foram incubadas a 37°C por, respectivamente, um dia, um mês e três meses. A RAC e o índice de adesivo remanescente (IAR) foram calculados e estatisticamente comparados entre os grupos. Resultados: a RAC não apresentou diferença significativa após um dia, um mês ou três meses (p > 0,05), mas os adesivos sem TiO2 apresentaram uma RAC média significativamente mais elevada do que os adesivos que continham TiO2 (p< 0,001). A RAC do Transbond XT foi significativamente mais elevada do que a do Resilience (p< 0,001). Não foram observadas diferenças significativas nos IARs, seja para o tipo de adesivo ou para a adição de TiO2 (p> 0,05). Conclusões: a adição de nanopartículas de TiO2 ao Transbond XT reduziu sua RAC a níveis semelhantes aos da RAC do Resilience TiO2. Assim, as nanopartículas de TiO2 podem ser acrescentadas ao adesivo Transbond XT para a aplicação clínica.

Effect of titanium tetrafluoride varnish on fibroblasts (NIH/3T3): viability assay, morphological analysis and cell signals for apoptotic pathways / Efeito do verniz de tetrafluoreto de titânio sobre fibroblastos (NIH/3T3): ensaios de viabilidade, morfologia e sinalização celular para apoptose

Current knowledge supports the application of TiF4 varnish to protect against tooth caries and erosion; however, it is indispensable to know its cytotoxic potential and the mechanism involved on it before applying in patients. Therefore, this study aimed to evaluate 1) The cytotoxic effect of titanium tetrafluoride (TiF4) varnish compared with sodium fluoride (NaF) varnish on murine fibroblast (NIH/3T3), varying the fluoride concentration and time of treatment and 2) The percentage of apoptosis and its mechanism (both mitochondrial mediated by the Bcl-2 family- and death receptorpathways) in human gingival fibroblasts (HGF) and murine fibroblasts (NIH/3T3) treated with TiF4 varnish compared to NaF varnish for 6 h. Step 1) NIH/3T3 were exposed to NaF or TiF4 varnishes containing 0.95, 1.95 or 2.45% F, for 6, 12 or 24 h. MTT viability (n=6) and Hoescht/PI stain assays (n=3) as well as the cells morphology (HE, only for 24 h, n=3) and stiffness (AFM, only for 2.45% F, 6 or 12 h) were analyzed. Both varnishes, at 1.90 and 2.45% F, reduced cells viability by similar extent (33-86% at 6 h, 35-93% at 12 h, and 87-98% at 24 h) compared to control, regardless of the type of fluoride. TiF4 and NaF (2.45% F) reduced cell stiffness to a similar extent, but only TiF4 differed from control. Step 2) HGF and NIH/3T3 were exposed to NaF or TiF4 (2.45% F) varnishes for 6 h. Cells were examined by the TUNEL method using fluorescence microscope. The caspases-3, -8 and -9 activities were assessed. The cDNA for cytocrome c, Bax, Bad, Bcl-2, VDAC-1 and Fas-L was amplified by quantitative PCR (qPCR). Bax, Bcl-2 and Fas-L were further detected by western blot. Both fluorides similarly increased the percentage of apoptosis, while they failed in activating caspases-3, -8 and -9 for both types of cells. Bax/Bcl-2 ratio, cytochrome C and VDAC-1 gene expressions were not altered by both fluoride treatments. However, NaF varnish increased the amplification of Fas-L gene for NIH/3T3 and HGF, while TiF4 varnish induced lower Bad/Bcl-2 ratio expression compared to control for NIH/3T3, but not for HGF. No effect of the fluorides was detected in the proteins analysis. TiF4 and NaF have similar cytotoxicity on NIH/3T3, which is dependent on the F concentration and the exposure time. Both fluorides, at the studied conditions, similarly induce a low percentage of apoptosis, with consequent modest activation of Bcl-2 and Fas-L-dependent signaling pathways.(AU)

Conhecimento atual suporta a aplicação de verniz de TiF4 para proteção contra cárie e erosão dentárias; entretanto, é indispensável conhecer o seu potencial citotóxico e o mecanismo envolvido antes de aplicá-lo em pacientes. Portanto, o objetivo deste estudo foi avaliar 1) o efeito citotóxico do verniz de tetrafluoreto de Titânio (TiF4) comparado ao fluoreto de sódio (NaF), em fibroblastos NIH/3T3, variando a concentração de fluoreto e o tempo de tratamento 2) a porcentagem de apoptose e seus mecanismos (ambos mitocondrial mediado pela família Bcl-2 e pelo receptor de morte celular) em fibroblastos gengivais humanos (FGH) e fibroblastos murinos (NIH/3T3) tratados com verniz de TiF4 comparado com verniz de NaF por 6 h. Etapa 1) NIH/3T3 foram expostos a vernizes de NaF e TiF4 contendo 0,95, 1,95 ou 2,45% F, por 6, 12 ou 24 h. Ensaios de viabilidade por MTT (n=6) e Hoechst 33342/iodeto de propídeo (n=3) bem como a morfologia (HE, apenas para 24 h, n = 3) e a rigidez celular (MFA, apenas para 2,45% F, 6 ou 12 h) foram realizados. Ambos os vernizes com 1,90 e 2,45% F reduziram a viabilidade das células de forma semelhante (33-86% em 6 h, 35-93% em 12 h e 87-98% em 24 h) em comparação com o controle, independentemente do tipo de fluoreto. TiF4 e NaF (2,45%) reduziram de forma similar a rigidez celular, mas somente TiF4 diferiu do controle no período de 6 h. Etapa 2) FGH e NIH/3T3 foram tratadas com verniz de NaF ou TiF4 por 6h. As células foram examinadas pelo método de TUNEL, usando microscopia de fluorescência. A atividade das caspases -3, -8 e -9 foram avaliadas. O cDNA para citocromo C, Bax, Bad, Bcl-2, VDAC-1 e Fas-L foi amplificado e quantificado por PCR em tempo real (qPCR). A expressão das proteínas Bax, Bcl-2 e Fas-L foi quantificada por western blot. Ambos os fluoretos aumentaram de forma semelhante a porcentagem de apoptose, enquanto falharam na ativação de caspases-3, -8 e -9 para ambos tipos celulares. A expressão gênica da relação Bax/Bcl-2, do citocromo C e do VDAC-1 não foram alteradas por ambos fluoretos. No entanto, o verniz NaF aumentou a amplificação do gene Fas-L para ambas as células, enquanto que o verniz TiF4 induziu menor expressão da razão Bad/Bcl-2 em comparação com o controle para NIH/3T3, mas não para FGH. Nenhum efeito foi detectado na análise de proteínas. TiF4 e NaF apresentam citotoxicidade similar em NIH/3T3, a qual é dependente da concentração de F e do tempo de exposição. Ambos os fluoretos, nas condições estudadas, induzem uma baixa porcentagem de apoptose, com consequente modesta ativação das vias de sinalização dependentes de Bcl-2 e Fas-L.(AU)

Analysis of the antimicrobial and anti-caries effects of TiF4 varnish under microcosm biofilm formed on enamel

Abstract Titanium tetrafluoride (TiF4) is known for interacting with enamel reducing demineralization. However, no information is available about its potential antimicrobial effect. Objectives This study evaluated the antimicrobial and anti-caries potential of TiF4 varnish compared to NaF varnish, chlorhexidine gel (positive control), placebo varnish and untreated (negative controls) using a dental microcosm biofilm model. Material and Methods A microcosm biofilm was produced on bovine enamel previously treated with the varnishes, using inoculum from human saliva mixed with McBain saliva, under 0.2% sucrose exposure, for 14 days. All experiments were performed in biological triplicate (n=4/group in each experiment). Factors evaluated were: bacterial viability (% dead and live bacteria); CFU counting (log10 CFU/mL); and enamel demineralization (transverse microradiography - TMR). Data were analysed using ANOVA/Tukey's test or Kruskal-Wallis/Dunn's test (p<0.05). Results Only chlorhexidine significantly increased the number of dead bacteria (68.8±13.1% dead bacteria) compared to untreated control (48.9±16.1% dead bacteria). No treatment reduced the CFU counting (total microorganism and total streptococci) compared to the negative controls. Only TiF4 was able to reduce enamel demineralization (ΔZ 1110.7±803.2 vol% μm) compared to both negative controls (untreated: ΔZ 4455.3±1176.4 vol% μm). Conclusions TiF4 varnish has no relevant antimicrobial effect. Nevertheless, TiF4 varnish was effective in reducing enamel demineralization under this model.

Effects of titanium dioxide nanoparticles and lipopolysaccharide on antioxidant function of liver tissues in mice / 北京大学学报(医学版)

OBJECTIVE@#To compare the effects of different sized titanium dioxide (titanium dioxide, TiO2) on the antioxidant function of liver tissues in mice, and study the effect of TiO2 nanoparticles on the susceptibility of lipopolysaccharide (LPS) on liver tissues.@*METHODS@#Ninety 4-week-old clean-grade male ICR mice were divided into 18 groups, in which the mice were fed for different feed involving ordinary feed, nanometer TiO2 feed which meant the feed including 1% (mass fraction) TiO2 nanoparticles, and submicron TiO2 feed which meant the feed including 1% (mass fraction) TiO2 submicron particles. Respectively, they were fed for 1 month, 3 months and 6 months. On the second day after the feeding, respectively, 0 and 10 mg/kg LPS were given by gavage. The mice were harvested after 4 h and the body weight and liver weight for calculating the liver coefficient were recorded. Then the liver tissue homogenates were prepared for determining the antioxidant indexes including the total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA).@*RESULTS@#The change of body weight in mice was only discovered in group fed for 1 month, which showed significant decrease of body weight in treatment groups compared with control group. And there was no significant change of the liver coefficient in each group. Compared with control groups, nanometer TiO2 groups and submicron TiO2 group, the activity of T-AOC, T-SOD and MDA of nanometer TiO2+LPS group and submicron TiO2+LPS group in which the mice were fed for 1 month and 6 months increased in different degree. And another result was also existing. The MDA activity of liver in different sized treatment groups fed for 3 months decreased. Neither significant difference between the results of different sized TiO2 treatment groups, nor significant difference among different sized TiO2 groups and the control groups were observed.@*CONCLUSION@#Longterm peroral TiO2 nanoparticles and TiO2 submicron particles are more likely to cause damage to the liver in the growing mice, and the damage may be either reductive or oxidative. In addition, small sized TiO2 can increase the susceptibility of mice liver to LPS and the susceptibility will increase with the increase of exposure time.

Effect of TiO2 nanoparticles incorporation on antibacterial properties and shear bond strength of dental composite used in Orthodontics

ABSTRACT Introduction: Plaque accumulation and bond failure are drawbacks of orthodontic treatment, which requires composite for bonding of brackets. As the antimicrobial properties of TiO2 nanoparticles (NPs) have been proven, the aim of this study was to evaluate the antimicrobial and mechanical properties of composite resins modified by the addition of TiO2 NPs. Methods: Orthodontics composite containing 0%, 1%, 5% and 10% NPs were prepared. 180 composite disks were prepared for elution test, disk agar diffusion test and biofilm inhibition test to collect the counts of microorganisms on three days, measure the inhibition diameter and quantify the viable counts of colonies consequently. For shear bond strength (SBS) test, 48 intact bovine incisors were divided into four groups. Composites containing 0%, 1%, 5% and 10% NPs were used for bonding of bracket. The bracket/tooth SBS was measured by using an universal testing machine. Results: All concentration of TiO2 NPs had a significant effect on creation and extension of inhibition zone. For S. mutans and S. sanguinis, all concentration of TiO2 NPs caused reduction of the colony counts. Composite containing 10% TiO2 NPs had significant effect on reduction of colony counts for S. mutans and S. sanguinis in all three days. The highest mean shear bond strength belonged to the control group, while the lowest value was seen in 10% NPs composite. Conclusions: Incorporating TiO2 nanoparticles into composite resins confer antibacterial properties to adhesives, while the mean shear bond of composite containing 1% and 5% NPs still in an acceptable range.

RESUMO Introdução: o acúmulo de placa e as descolagens de braquetes são algumas desvantagens presentes no tratamento ortodôntico, no qual se requer o uso de materiais compósitos para a colagem dos braquetes. Objetivo: tendo em vista que as propriedades antimicrobianas das nanopartículas (NPs) de TiO2 já foram confirmadas, o objetivo do presente estudo foi avaliar as propriedades antimicrobianas e mecânicas de resinas compostas modificadas pela adição de NPs de TiO2. Métodos: compósitos ortodônticos contendo 0%, 1%, 5% e 10% de NPs foram preparados. Cento e oitenta discos de compósito foram preparados para o teste de eluição, o ensaio de difusão em ágar por disco, e o ensaio de inibição da formação de biofilme, para se calcular as contagens de microrganismos ao longo de três dias, medir o diâmetro da inibição e, consequentemente, quantificar as contagens de colônias viáveis. Para o teste de resistência da colagem ao cisalhamento (SBS), 48 incisivos bovinos intactos foram divididos em quatro grupos, nos quais os compósitos contendo 0%, 1%, 5% e 10% de NPs foram utilizados para colagem dos braquetes. A SBS da interface braquete/dente foi medida em uma máquina universal de ensaios. Resultados: todas as concentrações de NPs de TiO2 apresentaram efeito significativo na formação e na extensão da zona de inibição. Para o S. mutans e o S. sanguinis, todas as concentrações de NPs de TiO2 causaram redução na contagem das colônias. O compósito contendo 10% de NPs de TiO2 apresentou uma diminuição significativa na contagem de colônias de S. mutans e S. sanguinis durante os três dias. A média mais alta da SBS foi observada no grupo controle, enquanto o valor mais baixo foi observado para o compósito com 10% de NPs. Conclusões: a incorporação de nanopartículas de TiO2 nas resinas compostas lhes conferiu propriedades antibacterianas, e o valor médio da SBS das resinas contendo 1% e 5% de NPs apresentou-se dentro de uma faixa aceitável.

Efecto de las nanopartículas industriales TiO 2 , SiO 2 y ZnO sobre la viabilidad celular y expresión génica en médula ósea roja de mus musculus / Effect of the Industrial Nanoparticles TiO 2 , SiO 2 and ZnO on Cell Viability and Gene Expression in Red Bone Marrow of Mus Musculus

RESUMEN Objetivos Evaluar el efecto de las nanopartículas de ZnO, TiO2 y SiO2 sobre la viabilidad celular y la expresión génica de las interleuquinas 7 y 3 y del factor estimulante de colonias de granulocito - macrófago (GM-CSF) en Mus musculus. Materiales y métodos Se extrajo médula ósea roja de cinco roedores (Balb/c) para el estudio de viabilidad celular mediante la prueba de MTT. Por otro lado, grupos cinco roedores fueron inoculados vía intraperitoneal con dosis de 0,5; 1; 2,5; 5 y 10 mg/kg de nanopartículas de ZnO y SiO2 y de 5; 10; 15; 20 y 25 mg/kg de nanopartículas de TiO2, 30 h después, se obtuvo el ARN a partir de la médula ósea roja para los análisis de expresión génica empleando las técnicas de PCR y RT-PCR cuantitativa. Resultados Las nanopartículas de ZnO y SiO2 redujeron la viabilidad celular de una manera dosis-dependiente en un 37 y 26%, respectivamente, a partir de una dosis de 1 mg/kg. En cuanto al efecto sobre la expresión génica, a las dosis 5 y 10 mg/kg, las nanopartículas de TiO2 redujeron en mayor porcentaje la expresión de las interleuquinas 7 y 3 (55,3 y 70,2% respectivamente), con respecto a la expresión del GM-CSF, el mayor porcentaje de reducción lo produjo las nanopartículas de SiO2 (91%). Las nanopartículas de ZnO redujeron a partir de las dosis de 20 y 25 mg/kg. Conclusiones Las nanopartículas de ZnO, SiO2 y TiO2 alteran la viabilidad celular y la expresión génica en la médula ósea de ratón.

ABSTRACT Objectives To evaluate the effect of ZnO, TiO2 and SiO2 nanoparticles on cell viability and expression of the interleukin 7, interleukin 3, and granulocyte-macrophage colony stimulating factor (GM-CSF) genes in Mus musculus. Material and methods Red bone marrow was extracted from five Balb/c mice for the analysis of cell viability using the MTT test. The mice were divided into two groups of five each: one group was inoculated intraperitoneally with 0.5, 1.0, 2.5, 5.0, and 10 mg/kg of ZnO and SiO2 nanoparticles, respectively, and the other group was inoculated with 5.0, 10.0, 15.0, 20.0, and 25 mg/kg of TiO2 nanoparticles, respectively. Thirty hours later, RNA was extracted from the red bone marrow of the mice in both groups for gene expression analysis using quantitative PCR and RT-PCR. Results ZnO and SiO2 nanoparticles reduced cell viability in a dose-dependent manner by 37% and 26%, respectively, starting at a dose of 1 mg/kg. TiO2 nanoparticles at 5 mg/kg and 10 mg/kg reduced the gene expression of interleukins 7 and 3 by 55.3% and 70.2%, respectively, and SiO2 nanoparticles caused the greatest decrease (91%) in the expression of GM-CSF. ZnO nanoparticles reduced the expression of GM-CSF starting at doses of 20 mg/kg and 25 mg/kg. Conclusions ZnO, SiO2 and TiO2 nanoparticles affect cell viability and gene expression in the mouse bone marrow.

Pro-inflammatory Analysis of Macrophages in Contact with Titanium Particles and Porphyromonas gingivalis

Abstract During insertion of titanium dental implants, particles may shear from the implant to the periimplant region causing osteolysis, and their association with bacteria can exacerbate the inflammatory reaction. However, the association of a high invasive bacterium from the oral cavity, Porphyromonas gingivalis (Pg), and titanium particles remains unknown. This study evaluated pro-inflammatory reaction of human macrophages in contact with micro and nanoparticles of titanium associated with Porphyromonas gingivalis lipopolysaccharide (PgLPS). THP-1 cell were used and treated for 12, 24 and 48 h following 6 groups: Control(C), PgLPS (L); Microparticles (M); Nanoparticles (N); PgLPS and microparticles (LM); PgLPS and nanoparticles (LN). The following assays were carried out: i) cell viability using MTS, ii) cell morphology by SEM and iii) expression of tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) by qRT-PCR and ELISA. For statistics two-way ANOVA followed by Tukey's test was used (p<0.05). After treatment, cells presented similar viability and morphology demonstrating that the treatments were not able to induce cell death. Gene expression was significantly higher for TNF-α and IL1-β after 12 h, and for IL-6 after 24 h in the N and LN groups. Cytokine production over time was an ascending curve for TNF-α with the peak at 48 h and IL1-β and IL-6 had a straight line among the time points, although cells from N group presented a significant production of IL-6 at 48 h. In conclusion, these results suggest that titanium nanoparticles stimulate stronger pro-inflammatory response in macrophages, independent of their association with LPS from P.gingivalis.

Resumo Durante a inserção de implantes dentários partículas de titânio podem ser liberadas na região peri-implantar levando ao processo de osteólise e a associação com a bactéria pode exacerbar ainda mais a reação inflamatória. Entretanto, a associação de uma bactéria altamente invasiva da cavidade oral, Porphyromonas gingivalis (Pg) e partículas de titânio ainda não foi investigada. Este estudo avaliou a reação pró-inflamatória de macrófagos humanos em contato com micro e nanopartículas de titânio associada a lipopolissacarídeo P. gingivalis (PgLPS). As células THP-1 foram utilizadas e tratadas durante 12, 24 e 48 h nos 6 seguintes grupos: Controle (C), PgLPS (L); micropartículas (M); nanopartículas (N); PgLPS e micropartículas (LM); PgLPS e nanopartículas (LN). Em seguida foram realizados os seguintes ensaios: i) a viabilidade celular utilizando MTS, ii) a morfologia celular por MEV e iii) expressão do fator de necrose tumoral alfa (TNF-α), interleucina-1 beta (IL-1β) e interleucina 6 (IL-6) por qRT-PCR e ELISA. Como estatística foi realizado o teste ANOVA two-way seguido pelo teste de Tukey (p<0,05). Após o tratamento, as células apresentaram viabilidade e morfologia semelhantes, demonstrando que os tratamentos não foram capazes de induzir a morte celular. A expressão de genes foi significativamente mais elevada para o TNF-α e IL1-β após 12h, e para a IL-6 após 24 horas em N e grupos de LN. A produção de citocinas em relação ao tempo representou uma curva ascendente para o TNF-α com o pico em 48 h, enquanto que para IL1-β e IL-6 se apresentou como uma linha reta com relação ao tempo, exceto pelo grupo N que foi significativo para IL-6 em 48 h . Conclui-se, a partir destes resultados, que as nanopartículas de titânio produziram o maior estímulo na resposta pró-inflamatória nos macrófagos, independente da sua associação com LPS de P. gingivalis.

The In Situ Effect of Titanium Tetrafluoride Gel on Erosion/Abrasion Progression in Human Dentin

Abstract Erosion incidence is increasing and its control is still a challenge in clinical practice. This study evaluated 4% TiF4-gel effects on eroded human dentin subjected to in situ erosive/abrasive episodes. Seventy-two previously eroded dentin slabs (0.05 M citric acid, pH 2.3, 20 min) were allocated to 6 groups (n=12) according to the treatment to be performed during the in situ phase and number of erosive/abrasive cycles, as follows: 4% TiF4-gel applied once (TiF41), twice (TiF42) or three times (TiF43) followed by 1, 2 and 3 erosive/abrasive cycles, respectively. Gel was applied before the beginning of the next cycle. Control groups were subjected to 1 (C1), 2 (C2) and 3 (C3) erosive/abrasive cycles only. A seventh group (n=12) comprised in vitro uneroded samples (UN) subjected to 3 erosive/abrasive cycles. Each cycle corresponded to 2 days of erosive (citric acid 0.5%, pH 2.6, 6x/day) and abrasive (electric toothbrush, 10 s/sample, 1 x/day) challenges. Samples were evaluated under profilometry and environmental scanning electron microscopy (ESEM). Atomic force microscopy images (AFM) were also made (n=3). Repeated measures 2-way ANOVA and Tukey test (p<0.001) showed that TiF42, which did not differ from TiF41 and TiF43, revealed a significant reduction in surface loss compared to all control groups. TiF41 and TiF43 showed no significant difference from C1, but both groups demonstrated significantly smaller surface loss than C2 and C3. ESEM and AFM micrographs suggested alterations on treated surfaces compared to samples from control groups, showing reduced diameters of dentinal tubules lumens. Therefore, TiF4 was able to reduce the progression of erosive/abrasive lesions.

Resumo A incidência da erosão tem aumentado e o seu controle ainda é um desafio na prática clínica. Este estudo avaliou os efeitos do gel de TiF4 a 4% sobre a dentina humana erodida submetida a episódios erosivos/abrasivos in situ. Setenta e dois fragmentos de dentina previamente erodida (ácido cítrico 0,05 M, pH 2,3, 20 min) foram distribuídas em 6 grupos (n=12) de acordo com o tratamento a ser realizado durante a fase in situ e o número de ciclos erosivos/abrasivos, como descrito a seguir: gel de TiF4 a 4% aplicado uma (TiF41), duas (TiF42) ou três vezes (TiF43) seguido de 1, 2 e 3 ciclos erosivos/abrasivos, respectivamente. As aplicações dos géis foram realizadas antes do início do ciclo erosivo seguinte. Grupos controle foram submetidos a 1 (C1), 2 (C2) e 3 (C3) ciclos erosivos/abrasivos apenas. Um sétimo grupo (n=12) compreendia amostras sem erosão in vitro (UN) submetidas a 3 ciclos erosivos/abrasivos. Cada ciclo correspondia a 2 dias de desafios erosivos (ácido cítrico a 0,5%, pH 2,6, 6x/dia) e abrasivos (escova de dentes elétrica, 10 s/amostra, 1x/dia). As amostras foram avaliadas em perfilômetro e Microscopia Eletrônica de Varredura Ambiental (MEV). Imagens de microscopia de força atômica (AFM) também foram capturadas (n=3). ANOVA a 2-fatores para medidas repetidas e o teste de Tukey (p<0,001) demonstraram que TiF42, que não diferiu do TiF41 e TiF43, revelou redução significativa na perda de superfície quando comparado a todos os grupos controle. TiF41 e TiF43 não apresentaram diferença estatisticamente significativa em relação ao C1, mas ambos os grupos demonstraram perda de superfície significativamente menor que C2 e C3. Micrografias de MEV e AFM sugeriram alterações nas superfícies tratadas quando comparadas a amostras dos grupos controle, apresentando redução no diâmetro das luzes dos túbulos dentinários. Portanto, o TiF4 foi capaz de reduzir a progressão das lesões erosivas/abrasivas.

Atividade antibacteriana de tubos endotraqueais revestidos com dióxido de titânio padrão e dopados com nitrogênio: um estudo in vitro / Antibacterial activity of standard and N-doped titanium dioxide-coated endotracheal tubes: an in vitro study

RESUMO Objetivo: Avaliar a atividade antibacteriana contra Staphylococcus aureus e Pseudomonas aeruginosa de dois revestimentos endotraqueais com nanopartículas e fotocatálise sob luz visível. Métodos: Testaram-se dois tipos de nanopartículas de titânio: anatase padrão (TiO2) e TiO2 nano-dopada (N-TiO2). As nanopartículas foram colocadas em superfície interna de segmentos de tubos endotraqueais comerciais, aplicadas sobre um filtro de acetato de celulose; os tubos endotraqueais controle foram deixados sem revestimento de nanopartículas. Em cada tubo endotraqueal foi inoculado um total de 150 unidades formadoras de colônia e, a seguir, estes foram expostos a uma fonte de luz fluorescente (3700 lux, comprimento de onda de 300 - 700nm) por 5, 10, 20, 40, 60 e 80 minutos. Contaram-se as Unidades Formadoras de Colônia após 24 horas de incubação a 37ºC. A inativação bacteriana foi calculada como a redução porcentual do crescimento bacteriano em comparação a tubos não expostos à luz. Resultados: Na ausência de luz, não se observou qualquer atividade antibacteriana relevante contra qualquer das cepas estudadas. Para P. aeruginosa, ambos os revestimentos tiveram inativação bacteriana mais elevada do que o controle em qualquer dos momentos de avaliação (p < 0,001), sendo que não se observaram diferenças entre o revestimento padrão e nano-dopado. Para S. aureus, a inativação foi maior que os controles, começando a partir de 5 minutos para nano-dopado (p = 0,018) e 10 minutos para o revestimento padrão (p = 0,014); a inativação com a forma nano-dopada foi maior do que com a forma padrão aos 20 minutos (p < 0,001), 40 minutos (p < 0,001) e 60 minutos (p < 0,001). Conclusões: O revestimento com nanopartículas de titânio comercial padrão e nano-dopado inibiu o crescimento bacteriano sob a luz fluorescente visível. o revestimento nano-dopado teve maior atividade antibacteriana contra S. aureus em comparação à atividade observada com o revestimento com anatase padrão.

ABSTRACT Objective: The aim of this study was to assess the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa of two nanoparticle endotracheal tube coatings with visible light-induced photocatalysis. Methods: Two types of titanium dioxide nanoparticles were tested: standard anatase (TiO2) and N-doped TiO2 (N-TiO2). Nanoparticles were placed on the internal surface of a segment of commercial endotracheal tubes, which were loaded on a cellulose acetate filter; control endotracheal tubes were left without a nanoparticle coating. A bacterial inoculum of 150 colony forming units was placed in the endotracheal tubes and then exposed to a fluorescent light source (3700 lux, 300-700 nm wavelength) for 5, 10, 20, 40, 60 and 80 minutes. Colony forming units were counted after 24 hours of incubation at 37°C. Bacterial inactivation was calculated as the percentage reduction of bacterial growth compared to endotracheal tubes not exposed to light. Results: In the absence of light, no relevant antibacterial activity was shown against neither strain. For P. aeruginosa, both coatings had a higher bacterial inactivation than controls at any time point (p < 0.001), and no difference was observed between TiO2 and N-TiO2. For S. aureus, inactivation was higher than for controls starting at 5 minutes for N-TiO2 (p = 0.018) and 10 minutes for TiO2 (p = 0.014); inactivation with N-TiO2 was higher than that with TiO2 at 20 minutes (p < 0.001), 40 minutes (p < 0.001) and 60 minutes (p < 0.001). Conclusions: Nanosized commercial and N-doped TiO2 inhibit bacterial growth under visible fluorescent light. N-TiO2 has higher antibacterial activity against S. aureus compared to TiO2.

In situ effect of titanium tetrafluoride varnish on enamel demineralization

Abstract The effect of a 4% titanium tetrafluoride (TiF 4 ) varnish on enamel demineralization was evaluated. Twelve volunteers participated in this double-blind, randomized crossover study. Six enamel specimens were positioned in intraoral appliances throughout four treatment stages: 4% TiF 4 varnish (experimental varnish), 5% sodium fluoride (NaF) varnish (Duraphat ® ), placebo varnish, and negative control (deionized water). After 24 h, the varnishes were removed and plaques were allowed to accumulate. A 20% sucrose solution was dripped onto enamel blocks (10x/day). Enamel alterations were analyzed by surface microhardness (SMH), percentage of surface loss (%SML), cross-sectional microhardness (CSMH), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS). Student's paired t-test was used for SMH analysis and repeated-measures analysis of variance (ANOVA) for %SML and CSMH (∆Z) analyses (p-value=0.05). The TiF 4 varnish group had lower %SML than the placebo and control groups (p=0.044 and p=0.003, respectively), thus showing its capacity to inhibit surface demineralization. TiF 4 and NaF varnishes demonstrated a protective effect against mineral loss on the enamel subsurface. Both were statistically different from the control group when CSMH was analyzed (p=0.000). A titanium dioxide film was observed on enamel surfaces of the TiF 4 group SEM images. EDS confirmed the presence of titanium in all TiF 4 samples. The 4% TiF 4 varnish is a promising compound capable of reacting with enamel to protect it against surface and subsurface demineralization.

Caracterização físico-química, mecânica e biológica de cimento autoadesivo aditivado com nanotubos de dióxido de titânio / Physical-chemical, mechanical and biological characterization of reinforcement self-adhesive resin cement titanium dioxide nanotubes

O objetivo desse estudo foi realizar a caracterização do cimento resinoso autoadesivo RelyX U200 aditivado de nanotubos de dióxido de titânio (nt-TiO2) em diferentes concentrações (0,3, 0,6, e 0,9% em peso) quanto às suas propriedades físico-químicas, mecânicas e biológica. Duas condições de polimerização foram analisadas: autopolimerizável (grupos: AC, A03, A06 e A09) e dual (grupos: DC, D03, D06 e D09). Para análise do grau de conversão foi utilizada a espectroscopia de infravermelho com transformada de Fourier com registro do espectro nos tempos de 3, 6, 9, 12 e 15 minutos. Os picos das bandas de comprimento de onda de 1638 cm-1 e de 1608 cm-1 foram identificados para cálculo do grau de conversão. Os dados foram submetidos à ANOVA de medidas repetidas seguido de comparações múltiplas de Tukey (=0,05). A análise de sorção e solubilidade foi realizada por meio da confecção de discos de cimento resinoso (10 mm ø × 2 mm) (n=8) monitorados quanto à sua massa depois de ciclos de hidratação/desidratação. A resistência à flexão em 3 pontos e módulo de elasticidade foram mensurados por meio de barras (2 × 2 × 25 mm) de cimento resinoso (n=10) levadas à máquina universal de ensaios. Para análise de Dureza Knoop utilizou-se microdurômetro com carga de 50g /10 segundos. Nos discos de cimento resinoso de 10 mm ø × 2 mm foram realizadas 5 endentações equidistantes 0,5mm e medidas em aumento de 50×. Para resistência de união ao cisalhamento, sobre discos de zircônia sinterizados foi aplicado o cimento resinoso (n=10) nas dimensões de 3 mm ø × 2 mm. Por meio de dispositivo foram levados à máquina universal de ensaios. Os dados encontrados de sorção e solubilidade e de cada propriedade mecânica foram submetidos aos testes ANOVA a dois critérios e de comparações múltiplas de Tukey (=0,05). Exceto para resistência ao cisalhamento que se utilizou o teste de comparação de Fischer (=0,05). Para viabilidade celular (n=8) foi realizado teste de MTT apenas na condição dual. Os grupos estudados foram: DC, D03, D06, D09, CP (controle positivo), CN (controle negativo). Após 24, 48 e 72 horas os níveis de absorbâncias foram analisados por meio de espectrofotometria no leitor de ELISA. Os dados foram submetidos aos testes ANOVA a dois critérios e de comparações múltiplas de Tukey (=0,05). Os resultados mostraram que a adição de nt-TiO2, independente da concentração, aumentou os valores de grau de conversão do cimento resinoso para a condição autopolimerizável e dual em todos os tempos estudados. Já para sorção e solubilidade não houve influência nos resultados da concentração de nanotubos inseridos e da condição de polimerização. Para resistência flexural, a adição de nt-TiO2 nas concentrações de 0,3% (A03) e 0,9% (A09) resultou em dados similares ao controle na condição dual (DC). O valor médio de módulo de elasticidade aumentou com a adição de 0,9% (A09), similar a todos os grupos da condição dual, em que adição de nt-TiO2 não influenciou os resultados. A adição de 0,6% (A06 e D06) e 0,9% (A09 e D09) de nt-TiO2 ao cimento aumentou os valores de dureza quando comparado aos grupos controle (AC e DC). Para resistência de união ao cisalhamento, a concentração de 0,3% de nt-TiO2 (A03 e D03) aumentou os valores quando comparado aos grupos A06, D06, A09 e D09 porém sem diferença para os grupos controle (AC e DC). Para viabilidade celular no período de 24h, os grupos D03, D06 e D09 obtiveram resultado similar ao grupo CP, já o grupo DC apresentou valores de absorbância inferiores ao CP, usado como parâmetro de comparação. Em 48 e 72h, todos os grupos experimentais não demonstraram diferença significativa em comparação ao grupo CP. O grupo CN apresentou diferença para os demais em todos dos tempos estudados. A adição de nt-TiO2 ao cimento resinoso autoadesivo representa uma estratégia promissora para potencializar suas propriedades físico-químicas e mecânicas sem prejuízo das propriedades biológicas.(AU)

The aim of this study was to characterize the self-adhesive resin cement RelyX U200 additive, titanium dioxide nanotubes (nt-TiO2), at different concentrations (0.3%, 0.6%, and 0.9% by weight) and to determine their physicochemical, mechanical and biological properties. Two polymerization conditions were analyzed: self-curing (groups AC, A03, A06 and A09) and dual-curing (groups DC, D03, D06 and D09). To analyze the conversion degree, Fourier transform infrared spectroscopy was used, and the spectrum was recorded at 3, 6, 9, 12 and 15 minutes. The peaks of the wavelength bands, 1638 cm-1 and 1608 cm-1, were identified to calculate the degree of conversion. The data were subjected to a repeated-measures ANOVA followed by a Tukey multiple-comparison test (=0.05). The sorption and solubility analysis was performed by making resin-cement discs (10 mm ø × 2 mm) (n=8) and monitoring their masses after the hydration/dehydration cycles. The 3-point flexural strength and the modulus of elasticity of resin-cement bars (2 × 2 × 25 mm) (n=10) were measured using a universal testing machine. The Knoop microhardness was analyzed with a load of 50 g and a time of 10 seconds. On each resin cement disc, 5 equidistant indentations of 0.5 mm were made, and the measures were increased by 50×. To test bonding shear strength, resin cement was applied to sintered zirconia discs (3 mm ø × 2 mm) (n=10). The bonded discs were then taken to the universal testing machine. Their sorption, solubility and each mechanical property were submitted to a two-way ANOVA and a Tukey multiple-comparison test (=0.05). The shear strength was submitted to a Fischer comparison test (=0.05). To test cell viability (n=8), a MTT assay was performed using only the dual-curing condition. The studied groups were: DC, D03, D06, D09, CP (positive control) and CN (negative control). After 24, 48 and 72 hours, the absorbance levels were analyzed using an ELISA spectrophotometry reader. The data were submitted to a two-way ANOVA and a Tukey multiple-comparison test (=0.05). The results showed that the addition of nt-TiO2, regardless of concentration, increased the conversion degree values for the self-curing resin cement and for the dual-curing at all times studied. The sorption and solubility were not influenced by the concentration of the nanotubes or the polymerization condition. Regarding flexural strength, the addition of the nt-TiO2 in concentrations of either 0.3% (A03) or 0.9% (A09) resulted in data similar to those in the dual-curing control (DC) condition. The average modulus of elasticity increased with the addition of 0.9% nt-TiO2 (A09), and as with all the groups in the dual-curing condition, the addition of nt-TiO2 did not affect the results. The addition of either 0.6% (A06 and D06) or 0.9% (A09 and D09) of nt-TiO2 cement increased hardness values relative to the control groups (AC and DC). The group with a 0.3% concentration of nt-TiO2 (A03 and D03) showed higher bonding shear strength values than several of the groups with higher concentrations (A06, D06 and D09), but the A09 group had no difference relative to either control group (AC or DC). For cell viability in the 24-h period, the D03 D06 and D09 groups achieved a result similar to that of the CP group with significant difference to the DC group that had lower absorbance values. At the benchmarks of 48 and 72 h, and only the CN group showed a significant difference compared to others. The addition of nt-TiO2 is a promising strategy for improving the physical-chemical and mechanical properties without prejudice the biological properties.(AU)

Los desafíos médicos, sociales e institucionales que dejó la poliomielitis: la rehabilitación integral en la Argentina de mediados del siglo XX / The medical, social and institutional challenges resulting from poliomyelitis: comprehensive rehabilitation in Argentina in the mid-twentieth century

La poliomielitis en forma epidémica despertó diversos desafíos, uno de los cuales fue la rehabilitación de las secuelas que había dejado esta dolencia en muchas de las personas que la padecieron. La parálisis y las formas en cómo se fue transformando, el concepto de rehabilitación física (donde el objetivo era solo restituir la movilidad de los músculos afectados), la rehabilitación integral que incluía los planos sociales, educativos y profesionales, en la Argentina de mediados del siglo XX, son los temas tratados en este artículo. Usa la metodología de historia institucional que dialoga de manera permanente con la historia de la salud y de la enfermedad.

Poliomyelitis on an epidemic scale gave rise to several challenges, one of which was the rehabilitation from the after-effects on many of the people who suffered from the disease. Paralysis and the ways it transformed the concept of physical rehabilitation (where the objective was only to restore the mobility of the affected muscles) and comprehensive rehabilitation that included social, educational and professional aspects in Argentina in the mid-twentieth century are the themes addressed in this article. It uses the methodology of institutional history that interacts in an ongoing manner with the history of health and disease.