Surface Wettability of a Natural Rubber Composite under Stretching: A Model to Predict Cell Survival.

We report the stress-strain effect of a stretchable natural rubber (NR)-calcium phosphate composite on the surface wettability (SW) using an innovative approach coupling a uniaxial tensile micromachine, goniometer, and microscope. In situ contact angle measurements in real time were performed during mechanical tension. Our results show that SW is guided by the stress-strain relationship with two different characteristics, depending on the static or dynamic experiments. The results evidenced the limits of the classical theory of wetting. Furthermore, based on the mechanically tunable SW of the system associated with the cytocompatibility of the NR composite, we have modeled such a system for application as a cell support. From the experimental surface energy value, our proposed 3D modeling numerical simulation predicted a window of opportunities for cell-NR survival under mechanical stimuli. The presented data and the thermodynamics-based theoretical approach enable not only accurate correlation of SW with mechanical properties of the NR composite but also provide huge potential for future cell supportability in view of tissue engineering.

Effects of negatively and positively charged Ti metal surfaces on ceramic coating adhesion and cell response.

This manuscript reports an evaluation of the effects of simple chemical-heat treatments on the deposition of different ceramic coatings, i.e., TiO2, CaTiO3 and CaP, on commercially pure titanium (cp-Ti) and Ti6Al4V and the influence of the coatings on cells interaction with the surfaces. The ceramic materials were prepared by the sol-gel method and the coating adhesion was analyzed by pull-off bending tests. The wettability of positively or negatively charged surfaces was characterized by contact angle measurements, which also enabled the calculation of the surface free energy through the polar-apolar liquids approach. Both acid and alkaline treatments activated the cp-Ti, whereas Ti6Al4V was only activated by the alkaline treatment. Such treatment led to increased hydrophilicity with inhibition of the fibroblastic response on Ti6Al4V. On the other hand, osteoblastic cells adhered to and proliferated on the positively and negatively charged surfaces. The maximum adhesion strength (~ 3400 N) was obtained with a negative Ti6Al4V-CaTiO3-CaP multilayer surface.

Surface treatment of dental porcelain: CO2 laser as an alternative to oven glaze.

This work tested continuous CO2 laser as a surface treatment to dental porcelain and compared it to oven glaze (auto-glaze) by means of roughness and color parameters. Three commercial veneering porcelains with different crystalline content were tested: VM7, VM9, and VM13. Porcelain discs (3.5 × 2.0 mm, diameter × height) were sintered and had one side ground by a diamond bur (45 µm) simulating a chairside adjustment in a clinical office. Specimens (n = 7) were divided into the following groups: C--control (no treatment), G--auto-glaze (oven), and L--surface continuous irradiation with CO2 laser (Gem Laser, Coherent; λ = 10.6 µm). Laser was tested in three exposure times (3, 4, or 5 min) and two irradiances (45 and 50 W/cm(2)). Roughness parameters (Ra, Rz, and Rpm/Rz) were measured using a rugosimeter (Surftest 301, Mitutoyo). Color differences (ΔE) between the G and L groups were calculated (VITA Easyshade); ΔE values up to 3.3 were considered as not perceivable. A surface analysis was conducted by stereomicroscopy (Olympus SZ61) and SEM (Stereoscan 440, LEO). Crystalline content of specimens from groups C and L (50 W/cm(2), 5 min) was assessed by X-ray diffraction and then compared. Surface roughness (Ra and Rz) observed for laser-irradiated groups was similar to G for all studied porcelains. Rpm/Rz ratios were near 1.0 for all groups that indicated a sharp ridge profile for all specimens. Only one laser condition studied (50 W/cm(2), 3 min) from VM7 porcelain resulted in color difference (ΔE = 3.5) to G. Specimens irradiated with 50 W/cm(2) for 5 min presented the smoother surface observed by SEM, comparable to G. X-ray diffraction data revealed an increase in leucite crystallite size for VM9 and VM13 porcelains after laser treatment. Regarding roughness, continuous CO2 laser applied on porcelain surface was as effective as conventional oven auto-glaze.

Titanium dioxide and modified titanium dioxide by silver nanoparticles as an anti biofilm filler content for composite resins.

OBJECTIVE: The aim of this study was to evaluate the antibacterial activity of a composite resin modified by TiO2 and TiO2/Ag nanoparticles and their influence over different properties. METHODS: TiO2 and TiO2/Ag NPs were synthesized by polymeric precursor and microwave-assisted hydrothermal methods and then, characterized by different techniques. Direct contact test was performed using Filtek™ Z350XT blended with 0.5; 1 and 2% (wt.) of NPs against Streptococcus mutans to determine the best concentration to the other tests. After that, the modified composite resin was tested against S. mutans 7-day biofilm (CFU/mL). Also, compressive and diametral tensile strength (n=40), degree of conversion (n=25) and surface roughness (n=50) was performed. The data were analyzed by ANOVA and Tukey's test for multiple comparison at 5% significance level. RESULTS: The direct contact test demonstrates that by increasing the nanoparticle content, the bacterial growth is significantly reduceed (p<0.05). The inclusion of 2% of TiO2/Ag NPs significantly decreased (p<0.05) the biofilm accumulation of S. mutans on the composite resin surface compared to the control Group. The TiO2 NPs treated with an organosilane increased compressive strength of composite resin (p<0.05). Degree of conversion remained unchanged (p>0.05) and the surface roughness increased with the NPs (p<0.05), except for the TiO2 by polymeric precursor Group (p>0.05). SIGNIFICANCE: The development of an antibacterial dental restorative material that hinder S. mutans biofilm without sacrificing the mechanical and physical properties is desirable in dental material science.

Synthesis, characterization and application of Ag doped ZnO nanoparticles in a composite resin.

The biofilm accumulation over the composite resin restorations can contribute to the formation of secondary caries. In this way, antibacterial restorative composite resins are highly desired. Then, the purpose of this study was to modify a composite resins using Ag doped ZnO nanoparticles (NPs), evaluate the antibacterial and mechanical properties of the modified composite resin. The ZnO/AgNPs were synthesized by two different routes, polymeric precursor and coprecipitation methods, and characterized by thermal decomposition, X-ray diffraction, specific surface area by N2 desorption/desorption and scanning electron microscopy (SEM). Antibacterial activity of composite resin specimens (4 mm in height and 2 mm in diameter; n = 15) modified by ZnO/Ag nanoparticles was performed against 7-days Streptococcus mutans biofilm. Colony forming units (CFU/mL) were used to evaluate the bacterial activity. Additionally, the morphology and the bacteria adherence area were analyzed by SEM images. Cylindrical specimens (6 mm in height and 4 mm in diameter; n = 20) of the composite resin containing ZnO/Ag NPs were prepared to perform compressive strength in a universal mechanical test machine, and the surface of fractured specimens was analyzed by EDX element mapping to verify NPs homogeneity. The normal distribution was confirmed and the two-way analysis of variance (ANOVA) and Tukey's test for pair comparison were performed. The nanospheres of ZnO/Ag lead to a better biofilm inhibition, than nanoplates. No difference on compressive strength was found for the composite resin modified by ZnO/Ag nanoplates. Based on these results, this material could be a good option as a new restorative material.

Towards the production of natural rubber-calcium phosphate hybrid for applications as bioactive coatings.

This paper assesses the morphological, structural and bio-physicochemical stability of natural rubber (NR) Hevea brasiliensis coatings incorporated with microparticles of calcium phosphate-based (CaP) bioactive ceramics. Optical and electronic spectroscopic imaging techniques were employed to successfully evaluate the NR encapsulation capability and the stability of the coating in a biologically relevant media for bio-related application, i.e., simulated body fluid (SBF). The chemical structure of the natural polymer, the microchemical environment at the NR-CaP interface and the morphology of the CaP clusters were fully characterized. Further, the response of the hybrid coating to SBF was evaluated by incubating the samples for 30 days. The hybrid coating formed on Si surface (inert substrate) exhibited both stability and biodegradability in different levels (time dependence), thus opening horizons for applications as coatings for both biomaterials and drug delivery systems.

Wettability Study on Natural Rubber Surfaces for Applications as Biomembranes.

This manuscript reports an experimental study on surfaces of natural rubber membranes modified by incorporation of calcium phosphate particles. In particular, we focused on the wettability, a subject for biological aspects. Five surfaces of natural rubber (NR) membranes (pure, polymer-bioceramic composite (NR-CaP), and three modified surfaces subjected to a simulated body fluid (NR-SBF)) were produced and characterized by confocal Raman-spectroscopy, AFM, SEM, and XPS, and the results were correlated with the wetting properties. Seven liquids (water, formamide, di-iodomethane, ethylene glycol, hexadecane, simulated body fluid, and human blood droplets) were used in different experimental sections. Static and dynamic contact angle measurements were conducted to obtain the solid-liquid tensions, work of adhesion, and depinning forces. The incorporation of CaP particles in the polymer decreases the roughness and increases the interfacial adhesion, and there was no dependence between the morphology and equilibrium contact line. The hydrophobic state of the NR surfaces is preserved. After exposure to a biological environment, the NR surfaces were chemically modified increasing blood wettability and decreasing the negative surface charges and the contact angle to values close to those associated with protein adsorption and cell adhesion, therefore opening possibilities for applications of these materials as biomembranes. On the other hand, the concepts applied, regarding different wettability aspects, should enable the evaluation of biomaterial surfaces and provide new insights allowing a better understanding of body fluid-material interfaces.

Zinc oxide 3D microstructures as an antimicrobial filler content for composite resins.

The aim of this study was to evaluate the antibacterial activity of a composite resin modified by 3D zinc oxide (ZnO) microstructures and to verify possible alterations on its mechanical properties. ZnO was synthesized by hydrothermal approach and characterized by X-ray diffraction (XRD), surface area by Brunauer, Emmett and Teller (BET), Fourier transform infrared spectroscopy (FTIR) and Field emission scanning electron microscopy (FESEM). The minimum inhibitory concentrations of ZnO against Streptococcus mutans, Escherichia coli, Staphylococcus aureus, and Candida albicans were determinated. The composite resin FiltekTM Z350XT (3M of Brazil) was blended with 0.2%, 0.5%, and 1% in weight of ZnO and submitted to antibacterial assay by direct contact test against S. mutans, the leading cause of dental caries and the most cariogenic oral streptococci. Additionally, it was performed compressive and diametral tensile strength tests of the modified composite resin. Microrods and hollow microrods of ZnO were obtained and its MIC values were found to be 125 µg/mL for S. mutans, 500 µg/mL for C. albicans and 62.5 µg/mL for S. aureus. For the tested concentrations, it was not found MIC against E. coli. The direct contact test showed a significant antibacterial capacity of modified composite resin (p > 0.05 for all concentrations). The compressive and diametral tensile strength remains no changed after inclusion of microparticles (p > 0.05 for all concentrations). The modification of the composite resin with small amounts of ZnO microparticles significantly inhibited the S. mutans growth on resin surface without significant alterations of its mechanical strength.

Experimental and Monte Carlo evaluation of the neutron flux of an assembly with two AmBe sources.

This work aimed to determine the irradiator thermal (under-cadmium) and fast (over-cadmium) neutron fluxes, of the Nuclear Experimental Laboratory of the Nuclear Engineering Center (CNEN-IPEN, São Paulo, Brazil), and the possibility of this irradiator use for Neutron Activation Analysis (NAA), by the absolute method. To establish the facility specifications, the neutron flux values along the irradiator axis were determined experimentally and calculated by Monte Carlo method. The irradiator presents the advantage of supplying a stable neutron flux for a long period, eliminating the need to use standard material (comparative method), so that the process becomes agile, practical and economical.

Porcelain monolayers and porcelain/alumina bilayers reinforced by Al2O3/GdAlO3 fibers.

AIM: This work tested the effect of the addition of Al(2)O(3)/GdAlO(3) longitudinal fibers in different contents to veneering porcelain of two dental all ceramic systems. METHODS: Fibers (0.5 mm diameter) obtained by the Laser Heated Pedestal Growth (LHPG) method were added to bar-shaped specimens made by veneer porcelain (monolayers) or both the veneer and the core ceramic (bilayers) of two all-ceramic systems: In-Ceram Alumina-glass infiltrated alumina composite (GIA) and In-Ceram 2000 AL Cubes-alumina polycrystal (AP) (VITA Zahnfabrik). The longitudinal fibers were added to veneering porcelain (VM7) in two different proportions: 10 or 17 vol%. The bars were divided into nine experimental conditions (n=10) according to material used: VM7 porcelain monolayers, VM7/GIA, VM7/AP; and according to the amount of fibers within the porcelain layer: no fibers, 10 vol% or 17 vol%. After grinding and polishing the specimens were submitted to a three point bending test (crosshead speed = 0.5 mm/min) with porcelain positioned at tensile side. Data were analyzed by means of one-way ANOVA and a Tukey's test (α=5%). Scanning electronic microscopy (SEM) was conducted for fractographic analysis. RESULTS: Regarding the groups without fiber addition, VM7/AP showed the highest flexural strength (MPa), followed by VM7/GIA and VM7 monolayers. The addition of fibers led to a numerical increase in flexural strength for all groups. For VM7/GIA bilayers the addition of 17 vol% of fibers resulted in a significant 48% increase in the flexural strength compared to the control group. Fractographic analysis revealed that the crack initiation site was in porcelain at the tensile surface. Cracks also propagated between fibers before heading for the alumina core. CONCLUSIONS: The addition of 17 vol% of Al(2)O(3)/GdAlO(3) longitudinal fibers to porcelain/glass infiltrated alumina bilayers significantly improved its flexural strength. 10 vol% or 17 vol% of fibers inclusion increased the flexural strength for all groups.

Effectiveness of intraoral suction systems and aspirating tips for evacuation of aluminum oxide particles during use of air-abrasion

Aim: The purpose of this study was to compare the effectiveness of a high-volume evacuation and a conventional intraoral suction system and aspirating tips for capturing aluminum oxide particles during use of an air-abrasion device. Methods: A phantom head was fixed at the dental chair head with secured a metallic device with 5 horizontal shafts, corresponding to operator’s clock related working positions, and one vertical shaft to simulate the operator’s nasal cavity. Petri plates were fixed to the shafts at distances of 20, 40 and 60 cm from the center of the oral cavity of the phantom head to collect the aluminum oxide particles spread over during air abrasion. The dust was aspirated with two types of suction tips used with both suction systems: a conventional saliva ejector and a saliva ejector customized by the adaptation of a 55-mm-diameter funnel. Results: The amount of particles showed that the greatest abrasive particle deposition occurred at a distance of 20 cm from the center of the oral cavity of the phantom head at 9 o’clock operatory position with the conventional saliva ejector attached to high-volume evacuation system. Conclusions: The greatest deposition of aluminum oxide particles occurred at the shortest distance between the operator and the center of the oral cavity, while using the high-volume evacuation system associated to the conventional suction tip.

Controle da deposição de partículas de óxido de alumínio emitidas pelo sistema de abrasão a ar em consultório odontológico / Deposition control of aluminum oxide particles emitted by air-abrasion system indental office

Nesse estudo, avaliou-se a deposição de partículas de óxido de alumínio no campo operatório do cirurgião-dentista durante o emprego de um aparelho de abrasão a ar e sucção odontológica convencional parasucção do pó gerado. Um dispositivo metálico, simulando as posições de trabalho do cirurgião-dentista,possibilitou a captação das partículas durante o abrasionamento de dentes artificiais. Sugadores de salivaconvencional e modificado por funil foram empregados no sistema de sucção convencional da equipe odontológicacom a finalidade de captar o pó de óxido de alumínio. Os resultados foram expressos por meio deanálise estatística gráfica em função da quantidade em massa de partículas de óxido de alumínio obtida emfunção da distância e posição de trabalho do operador ao centro da boca de um manequim. A maior deposiçãode partículas ocorreu a 20 cm de distância do operador em relação ao centro da boca e na posição detrabalho 9h, quando se empregou o sugador de saliva convencional.

In this study the aluminum oxide particle deposition was evaluated in the operatory position of the dentistduring an air abrasion system application with conventional dental suction (CDS) for the aspiration of thedust. A metallic device, simulating the operatory position of the dentist was used to particles deposition duringthe abrasion of an artificial tooth. A conventional saliva ejector and a modified ejector by funnel-shapedattachment were used in conventional dental suction (CDS) to dust suction. The results were expressed inaluminum oxide particles mass in relation to the operatory position and distance from operator to the centerof the mouth. Statistical graphical analysis showed that the greatest particle deposition occurred at 20cm ofdistance from the operator to the center of the mouth, in the 9 o'clock operator position when the conventionalsaliva ejector was used.

Uma proposta de coleta de informaçöes para contas pacientes / Proposed of information colect to patient bills

Registrar e contabilizar procedimentos, materiais e medicamentos em grandes hospitais, é uma tarefa complexa que é composta das diferentes funções e modelos de dados. As informações necessárias às tarefas de gerência de faturamento, envolvem inúmeras unidades administrativas, técnicas e operacionais. Para introduzir uma solução automatizada desta gerência, propôs-se para o Incor, um modelo baseado na utilização de banco de dados relacional com ferramenta de 4GL.