The effects of TiO2 nanotubes on bond strength and radiopacity of a self-adhesive resin cement in self-curing mode / Os efeitos de nanotubos de TiO2 na resistência de união e radiopacidade de um cimento resinoso auto-adesivo no modo auto-polimerizável

Objective: The aim of this in vitro study w as t o analyze the influence of the titanium dioxide nanotubes i n a self-cure mode polymerization of a dual resin luting agent through push out bond strength and radiopacity tests. Material and Methods: After mixed with a commercial du al self-adhesive resin cement, three concentrations o f tit anium dioxide nanotubes (0.3, 0.6, and 0.9% by weight) we re analyzed in self-curing mode. T he bond strength to bovine root dentin and fi berglass posts was assessed with the push out bond str ength t est and was evaluated in three thirds (cervical, middle and apical) (n=10), followed by failure mode analysis (SEM), and the ISO standard 9917-2 was followed for radiopacity test (n=10). Data were statistically analyzed by one-way ANOVA test, followed by Tukey's test (α=0.05). Results: Reinforced self-adhesive resin cement with 0.6% titanium dioxide nanotubes showed significant difference compared to the control gr oup for push out test (p=0.00158). The modified groups did not s how significant difference among thirds (p=0.782). Radiopacity sh owed higher value for group w ith 0.9% titanium dioxide nanotubes in comparison w ith control group (p<0.001). Conclusion: The addition of titanium dioxide nanotubes to a self-adhesive resin cement increased the bond strength to dentin and radiopacity values in the self-cure polymerization mode (AU)

Objetivo: O objetivo deste estudo in vitro foi analisar a influência de nanotubos de dióxido de titânio na polimerização química de um agente cimentante resinoso dual através de testes de resistência à união e radiopacidade. Material e Métodos: Após misturado com um cimento resinoso auto-adesivo comercial, três concentrações de nanotubos de dióxido de titânio (0,3, 0,6 e 0,9% em peso) foram analisadas. A resistência da união para a dentina da raiz bovina e os pinos de fibra de vidro foi avaliada pelo teste de push-out e avaliada em três terços (cervical, médio e apical) (n = 10), seguido pelo análise de modo de falha (MEV) e a norma ISO 9917-2 foi seguido para teste de radiopacidade (n = 10). Os dados foram analisados estatisticamente pelo teste ANOVA um fator seguido do teste de Tukey (α = 0,05). Resultados: O cimento resinoso auto-adesivo reforçado com nanotubos de dióxido de titânio a 0,6% mostrou diferença significativa em comparação com o grupo controle para teste de push-out (p=0,00158). Os grupos modificados não mostraram diferença significativa entre os terços (p=0,782). A radiopacidade mostrou maior valor para o grupo com nanotubos de dióxido de titânio 0,9% em comparação com o grupo controle (p<0,001). Conclusão: A adição de nanotubos de dióxido de titânio a um cimento resinoso auto-adesivo aumentou a os valores de resistência de união à dentina e radiopacidade no modo de polimerização química do agente cimentante (AU)

TiO2 nanotube-containing glass ionomer cements display reduced aluminum release rates.

Titanium dioxide nanotubes (TiO2-nts) were incorporated into a glass ionomer cement (GIC) with improved mechanical properties and antibacterial activity. The aims of the present in vitro study were to define the elemental characterization, aluminum (Al) release rate, and initial working time for GIC reinforced with TiO2-nts, in an experimental caries model. TiO2-nts were incorporated into GIC powder components at 5% by weight, and compared with unblended GIC. Experimental approaches used energy-dispersive spectrometry (EDS), atomic absorption spectrophotometry (AAS), and brightness loss to define surface element properties, Al release rates, and initial working time, respectively. Statistical analysis was performed by 2-way ANOVA, Tukey's test, generalized linear models, and Student's t test (a = 0.05). EDS data analysis revealed that TiO2-nts incorporated into GIC had no significant impact on the typical elemental composition of GICs in an in vitro caries model. Regarding the demineralizing solution, GIC with TiO2-nt significantly decreased the Al release rate, compared with the control group (p < 0.0001). Moreover, TiO2-nt incorporated into GIC did not alter the initial working time of the material (p > 0.05). These findings add information to our scientific body of knowledge concerning the potential impact of TiO2-nt on the performance of conventional GICs.

TiO2 nanotube-containing glass ionomer cements display reduced aluminum release rates

Abstract Titanium dioxide nanotubes (TiO2-nts) were incorporated into a glass ionomer cement (GIC) with improved mechanical properties and antibacterial activity. The aims of the present in vitro study were to define the elemental characterization, aluminum (Al) release rate, and initial working time for GIC reinforced with TiO2-nts, in an experimental caries model. TiO2-nts were incorporated into GIC powder components at 5% by weight, and compared with unblended GIC. Experimental approaches used energy-dispersive spectrometry (EDS), atomic absorption spectrophotometry (AAS), and brightness loss to define surface element properties, Al release rates, and initial working time, respectively. Statistical analysis was performed by 2-way ANOVA, Tukey's test, generalized linear models, and Student's t test (a = 0.05). EDS data analysis revealed that TiO2-nts incorporated into GIC had no significant impact on the typical elemental composition of GICs in an in vitro caries model. Regarding the demineralizing solution, GIC with TiO2-nt significantly decreased the Al release rate, compared with the control group (p < 0.0001). Moreover, TiO2-nt incorporated into GIC did not alter the initial working time of the material (p > 0.05). These findings add information to our scientific body of knowledge concerning the potential impact of TiO2-nt on the performance of conventional GICs.

Titanium dioxide nanotubes added to glass ionomer cements affect S. mutans viability and mechanisms of virulence.

This in vitro study evaluated the impact of TiO2 nanotubes (n-TiO2) incorporated into glass ionomer cement (GIC) on Streptococcus mutans (S. mutans) characteristics at cellular and molecular levels. n-TiO2, synthesized by the alkaline method (20 nm in size), was added to Ketac Molar EasyMix® at 0%, 3%, 5%, and 7% by weight. S. mutans strains were cultured on GIC disks with addition or not of n-TiO2 for 1, 3, and 7 days and the following parameters were assessed: inhibition halo (mm) (n=3/group); cell viability (live/dead) (n=5/group); cell morphology (SEM) (n=3/group); and gene expression by real-time PCR (vicR, covR, gtfB, gtfC, and gtfD) (n=6/group). The data were analyzed by the Kruskal-Wallis test, repeated-measures ANOVA or two-way ANOVA, and Tukey's and Dunn's post-hoc tests (α=0.05). The agar diffusion test showed a higher antibacterial property for 5% n-TiO2 compared with 3% and 7% (p<0.05) with no effect of time (1, 3, and 7 days). The cell number was significantly affected by all n-TiO2 groups, while viability was mostly affected by 3% and 5% n-TiO2, which also affected cell morphology and organization. Real-time PCR demonstrated that n-TiO2 reduced the expression of covR when compared with GIC with no n-TiO2 (p<0.05), with no effect of time, except for 3% n-TiO2 on vicR expression. Within-group and between-group analyses revealed n-TiO2 did not affect mRNA levels of gtfB, gtfC, and gtfD (p>0.05). Incorporation of n-TiO2 at 3% and 5% potentially affected S. mutans viability and the expression of key genes for bacterial survival and growth, improving the anticariogenic properties of GIC.

Polythiophene derivatives as chemical sensors: a DFT study on the influence of side groups.

Conjugated polymers have been considered promising candidates for applications in chemical sensors, mainly due to their high versatility of synthesis, low cost, light weight, and suitable optoelectronic properties. In this context, polythiophene (PT) derivatives have been successfully employed. However, at the same time that the versatility of the synthesis allows the production of varied derivatives, the complexity of interactions with analytes hinders an efficient design of compounds with improved sensing properties. In the present report, electronic structure calculations were employed to identify promising PT derivatives for chemical sensor applications. Structural, optoelectronic, and reactivity properties of a set of branched PT derivatives were evaluated. Adsorption studies considering different gaseous compounds were conducted for selected systems. The results suggest that an appropriate choice of the side groups can lead to derivatives with improved sensorial properties. In particular, PT-CN derivative was identified as the most promising compound for high sensitive chemical sensors towards SO2 and NH3 analytes.

Titanium dioxide nanotubes added to glass ionomer cements affect S. mutans viability and mechanisms of virulence

Abstract This in vitro study evaluated the impact of TiO2 nanotubes (n-TiO2) incorporated into glass ionomer cement (GIC) on Streptococcus mutans (S. mutans) characteristics at cellular and molecular levels. n-TiO2, synthesized by the alkaline method (20 nm in size), was added to Ketac Molar EasyMix® at 0%, 3%, 5%, and 7% by weight. S. mutans strains were cultured on GIC disks with addition or not of n-TiO2 for 1, 3, and 7 days and the following parameters were assessed: inhibition halo (mm) (n=3/group); cell viability (live/dead) (n=5/group); cell morphology (SEM) (n=3/group); and gene expression by real-time PCR (vicR, covR, gtfB, gtfC, and gtfD) (n=6/group). The data were analyzed by the Kruskal-Wallis test, repeated-measures ANOVA or two-way ANOVA, and Tukey's and Dunn's post-hoc tests (α=0.05). The agar diffusion test showed a higher antibacterial property for 5% n-TiO2 compared with 3% and 7% (p<0.05) with no effect of time (1, 3, and 7 days). The cell number was significantly affected by all n-TiO2 groups, while viability was mostly affected by 3% and 5% n-TiO2, which also affected cell morphology and organization. Real-time PCR demonstrated that n-TiO2 reduced the expression of covR when compared with GIC with no n-TiO2 (p<0.05), with no effect of time, except for 3% n-TiO2 on vicR expression. Within-group and between-group analyses revealed n-TiO2 did not affect mRNA levels of gtfB, gtfC, and gtfD (p>0.05). Incorporation of n-TiO2 at 3% and 5% potentially affected S. mutans viability and the expression of key genes for bacterial survival and growth, improving the anticariogenic properties of GIC.

Titanium dioxide nanotubes incorporated into bleaching agents: physicochemical characterization and enamel color change.

OBJECTIVE: Titanium dioxide nanotubes are nanostructures that can accelerate the oxidation reaction of bleaching procedures and promote a more effective whitening effect. This study evaluated physicochemical properties of bleaching agents incorporated with titanium dioxide (TiO2) nanotubes, and the effects on tooth color change at different periods. METHODOLOGY: 40 premolars were treated according to the following groups (n=10): CP - 10% carbamide peroxide (1 hour daily/21 days); CPN - CP incorporated into TiO2; HP - 40% hydrogen peroxide (three 40-minute sessions/7 days apart); HPN - HP incorporated into TiO2. Color shade was evaluated at five different periods (baseline, after 7, 14 and 21 days of bleaching, and 7 days after end of treatment) according to Vita Classical, CIELab and CIEDE2000 scales. Mean particle size (P), polydispersity (PO) and zeta potential (ZP) were evaluated using dynamic light scattering. Data on the different variables were analyzed by mixed model tests for measures repeated in time (ZP e L*), generalized linear models for measures repeated in time (P, PO, Vita Classical and b*), and Friedman and Mann-Whitney tests (a* and color change/ΔE and ΔE00). RESULTS: CP and CPN presented higher P, higher PO and lower ZP than HP and HPN (p≤0.05). All groups showed a significant decrease in Vita Classical color scores after 7 days of bleaching (p<0.05), and HPN presented a greater significant reduction than the other groups. L* increased in TiO2 presence, in all groups, without any differences (p>0.05) in bleaching time. A significant reduction occurred in the a* and b* values for all the groups, and HPN presented lower a* and b* values (p<0.05) than CPN. ΔE was clinically noticeable after 7 days, in all groups, and all groups resulted in a perceptible color change according to ΔE00. CONCLUSION: TiO2 did not influence physicochemical properties of the bleaching agents. HPN presented more effective tooth bleaching than CPN.

TiO2 nanotubes improve physico-mechanical properties of glass ionomer cement.

OBJECTIVES: The aim of this study was to determine the physico-mechanical properties of a high viscosity glass ionomer cement (GIC) reinforced with TiO2 nanotubes (TiO2-nt). METHODS: TiO2-nt was incorporated into the GIC powder components (Ketac Molar EasyMix™) in concentrations of 0% (control group), 3%, 5%, 7% by weight. Compressive strength (n = 10/group), three point bending for flexural strength (n = 18/group), microshear bond strength to dentin and failure mode (n = 20/group), and surface roughness and weight loss before and after brushing simulation (30,000 cycles) (n = 8/group) were evaluated. Data were submitted to Shapiro-Wilk, ANOVA, Tukey and Chi-square tests (α ≤ 0.05). RESULTS: Addition of 5% of TiO2-nt into GIC presented the highest values for compressive strength and differed from the control, 3% and 7% groups (p = 0.023). There were no significant differences in flexural strength (p = 0.107) and surface roughness before and after the dental brushing (p = 0.287) among the groups. GIC added with 5% TiO2-nt showed the lowest weight loss values (p = 0.01), whereas the control, 3% or 5% TiO2-nt groups presented similar microshear bond strength values (p ≥ 0.05). The 5% TiO2-nt group featured higher microshear bond strength than the 7% TiO2-nt group (p = 0.034). Cohesive in material was the most representative failure mode for all groups. SIGNIFICANCE: The incorporation of TiO2-nt did not affect GIC's adhesiveness to dentin, but improved its compressive strength at 5%. Furthermore, TiO2-nt decreased the percentage of weight loss after GIC's surface wear.

Yttria-stabilized tetragonal zirconia polycrystal/resin luting agent bond strength: Influence of Titanium dioxide nanotubes addition in both materials.

PURPOSE: To evaluate the shear bond strength (SBS) between Y-TZP and a resin luting agent, after 1 of 2 enhancing strategies with TiO2--nts was applied, either to the resin luting agent or the Y-TZP mass, in different concentrations. METHODS: In the Strategy TiO2-nts on ceramic, the resin luting agent Panavia F2.0™ (Kuraray) and an experimental Y-TZP with added concentrations of TiO2--nts (0%, 1%, 2%, and 5% vol/vol) and a commercial Y-TZP, comprised 5 different groups (n = 10). In the Strategy TiO2-nts on cement, the resin luting agent RelyX U200™ (3 M ESPE) was added with different concentrations of TiO2--nts (0%, 0.3%, 0.6%, 0.9% wt/wt) luted to a commercial Y-TZP, comprising 4 different groups (n = 10). The Y-TZP discs were included in acrylic bases, and a cylinder (3 × 3 mm) of the correspondent luting agent for each respective group was applied over them. After 24 h, specimens were subjected to SBS assessments in a universal testing machine. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy analyses were also performed on Y-TZP surfaces. Data were analyzed via analysis of variance and Tukey tests (α = 0.05). RESULTS: TiO2-nts on ceramic influenced the bond strength significantly, but not linearly; TiO2-nts on cement did not influence bond strength when analyzed separately, nor in comparison with the first. CONCLUSION: Y-TZP enhancements with TiO2-nts led to a higher SBS with Panavia F2.0, a 5% TiO2--nt concentration presented the highest bond strength. Modified Rely X U200 did not improve SBS.

Titanium dioxide nanotubes incorporated into bleaching agents: physicochemical characterization and enamel color change

Abstract Titanium dioxide nanotubes are nanostructures that can accelerate the oxidation reaction of bleaching procedures and promote a more effective whitening effect. Objective This study evaluated physicochemical properties of bleaching agents incorporated with titanium dioxide (TiO2) nanotubes, and the effects on tooth color change at different periods. Methodology 40 premolars were treated according to the following groups (n=10): CP - 10% carbamide peroxide (1 hour daily/21 days); CPN - CP incorporated into TiO2; HP - 40% hydrogen peroxide (three 40-minute sessions/7 days apart); HPN - HP incorporated into TiO2. Color shade was evaluated at five different periods (baseline, after 7, 14 and 21 days of bleaching, and 7 days after end of treatment) according to Vita Classical, CIELab and CIEDE2000 scales. Mean particle size (P), polydispersity (PO) and zeta potential (ZP) were evaluated using dynamic light scattering. Data on the different variables were analyzed by mixed model tests for measures repeated in time (ZP e L*), generalized linear models for measures repeated in time (P, PO, Vita Classical and b*), and Friedman and Mann-Whitney tests (a* and color change/ΔE and ΔE00). Results CP and CPN presented higher P, higher PO and lower ZP than HP and HPN (p≤0.05). All groups showed a significant decrease in Vita Classical color scores after 7 days of bleaching (p<0.05), and HPN presented a greater significant reduction than the other groups. L* increased in TiO2 presence, in all groups, without any differences (p>0.05) in bleaching time. A significant reduction occurred in the a* and b* values for all the groups, and HPN presented lower a* and b* values (p<0.05) than CPN. ΔE was clinically noticeable after 7 days, in all groups, and all groups resulted in a perceptible color change according to ΔE00. Conclusion TiO2 did not influence physicochemical properties of the bleaching agents. HPN presented more effective tooth bleaching than CPN.

Novel Nanotechnology of TiO2 Improves Physical-Chemical and Biological Properties of Glass Ionomer Cement.

The aim of this study was to assess the performance of glass ionomer cement (GIC) added with TiO2 nanotubes. TiO2 nanotubes [3%, 5%, and 7% (w/w)] were incorporated into GIC's (Ketac Molar EasyMix™) powder component, whereas unblended powder was used as control. Physical-chemical-biological analysis included energy dispersive spectroscopy (EDS), surface roughness (SR), Knoop hardness (SH), fluoride-releasing analysis, cytotoxicity, cell morphology, and extracellular matrix (ECM) composition. Parametric or nonparametric ANOVA were used for statistical comparisons (α ≤ 0.05). Data analysis revealed that EDS only detected Ti at the 5% and 7% groups and that GIC's physical-chemical properties were significantly improved by the addition of 5% TiO2 as compared to 3% and GIC alone. Furthermore, regardless of TiO2 concentration, no significant effect was found on SR, whereas GIC-containing 7% TiO2 presented decreased SH values. Fluoride release lasted longer for the 5% and 7% TiO2 groups, and cell morphology/spreading and ECM composition were found to be positively affected by TiO2 at 5%. In conclusion, in the current study, nanotechnology incorporated in GIC affected ECM composition and was important for the superior microhardness and fluoride release, suggesting its potential for higher stress-bearing site restorations.