Preformulation screening of lipids using solubility parameter concept in conjunction with experimental research to develop ceftriaxone loaded nanostructured lipid carriers

Abstract Development of ceftriaxone loaded nanostructured lipid carriers to increase permeability of ceftriaxone across uninflamed meninges after parenteral administration. Lipids were selected by theoretical and experimental techniques and optimization of NLCs done by response surface methodology using Box-Behnken design. The Δδt for glyceryl monostearate and Capryol90 were 4.39 and 2.92 respectively. The drug had maximum solubility of 0.175% (w/w) in glycerol monostearate and 2.56g of Capryol90 dissolved 10mg of drug. The binary mixture consisted of glyceryl monostearate and Capryol90 in a ratio of 70:30. The optimized NLCs particle size was 130.54nm, polydispersity index 0.28, % entrapment efficiency 44.32%, zeta potential -29.05mV, and % drug loading 8.10%. In vitro permeability of ceftriaxone loaded NLCs was 5.06x10-6 cm/s; evidently, the NLCs pervaded through uninflamed meninges, which, was further confirmed from in vivo biodistribution studies. The ratio of drug concentration between brain and plasma for ceftriaxone loaded NLCs was 0.29 and that for ceftriaxone solution was 0.02. With 44.32% entrapment of the drug in NLCs the biodistribution of ceftriaxone was enhanced 7.9 times compared with that of ceftriaxone solution. DSC and XRD studies revealed formation of imperfect crystalline NLCs. NLCs improved permeability of ceftriaxone through uninflamed meninges resulting in better management of CNS infections.

Encapsulation of benznidazole in nanostructured lipid carriers and increased trypanocidal activity in a resistant Trypanosoma cruzi strain

Abstract Chagas disease is a neglected parasitic disease caused by Trypanosoma cruzi, whose treatment has remained unsatisfactory for over 50 years, given that it is limited to two drugs. Benznidazole (BZN) is an efficient antichagasic drug used as the first choice, although its poor water-solubility, irregular oral absorption, low efficacy in the chronic phase, and various associated adverse effects are limiting factors for treatment. Incorporating drugs with such characteristics into nanostructured lipid carriers (NLC) is a promising alternative to overcome these limiting obstacles, enhancing drug efficacy and bioavailability while reducing toxicity. Therefore, this study proposed NLC-BZN formulations in different compositions prepared by hot-melt homogenization followed by ultrasound, and the optimized formulation was characterized by FTIR, DRX, DSC, and thermogravimetry. Biological activities included in vitro membrane toxicity (red blood cells), fibroblast cell cytotoxicity, and trypanocidal activity against epimastigotes of the Colombian strain of T. cruzi. The optimized NLC-BZN had a small size (110 nm), negative zeta potential (-18.0 mV), and high encapsulation (1.64% of drug loading), as shown by infrared spectroscopy, X-ray diffraction, and thermal analysis. The NLC-BZN also promoted lower in vitro membrane toxicity (<3% hemolysis), and 50% cytotoxic concentration (CC50) for NLC-BZN in L929 fibroblast cells (110.7 µg/mL) was twice the value as the free BZN (51.3 µg/mL). Our findings showed that the NLC-BZN had higher trypanocidal activity than free BZN against the epimastigotes of the resistant Colombian strain, and this novel NLC-BZN formulation proved to be a promising tool in treating Chagas disease and considered suitable for oral and parenteral administration

The relationships among Flory-Huggins specific interaction parameters, maximum amorphous capacity, and solid-state interactions of spray dried amorphous drug dispersions with conventional and novel pharmaceutical polymers / Las relaciones entre los parámetros de interacción específicos de Flry-Huggins, la capacidad amorfa máxima y las interacciones en estado sólido de las dispersiones de fármacos amorfos secados por aspersión con polímeros farmacéuticos convencionales y nuevos

This study evaluated the specific interactions between drug and polymers in amorphous spray dried dispersions (SDDs). Four Biopharmaceutics Classification System (BCS) II class drugs were evaluated. Binary and ternary SDDs were manufactured with conventional polymers and arabinogalactan. Specific interaction parameters between drug and polymer were determined using theoretical calculations and DSC data. Analytical methods were used to evaluate solid and solution state interactions. Maximum amorphous content for each formulation was calculated using DSC. Flory-Huggins Specific Interaction Parameters were calculated. Negative specific parameters were associated with solid-state interactions and improved capacity of drug in the amorphous state. Ternary SDDs containing drug, polymer, and arabinogalactan displayed similar hydrogen bonding as was observed with binary SDDs. Solution-state interactions observed in binary systems may be used in tertiary systems to improve the amorphous drug capacity and improved dissolution compared to the binary. The resultant tertiary systems are an improvement over binary drug polymer systems.

Este estudio evaluó las interacciones específicas entre el fármaco y los polímeros en dispersiones amorfas secadas por pulverización (SDD). Se evaluaron cuatro fármacos de clase II del Sistema de Clasificación Biofarmacéutica (BCS). Los SDD binarios y ternarios se fabricaron con polímeros convencionales y arabinogalactano. Los parámetros de interacción específicos entre el fármaco y el polímero se determinaron utilizando cálculos teóricos y datos de DSC. Se utilizaron métodos analíticos para evaluar las interacciones del estado sólido y de la solución. El contenido amorfo máximo para cada formulación se calculó usando DSC. Se calcularon los parámetros de interacción específicos de Flory-Huggins. Los parámetros específicos negativos se asociaron con interacciones en estado sólido y una capacidad mejorada del fármaco en el estado amorfo. Los SDD ternarios que contienen fármaco, polímero y arabinogalactano mostraron enlaces de hidrógeno similares a los observados con los SDD binarios. Las interacciones de estado de solución observadas en sistemas binarios pueden usarse en sistemas terciarios para mejorar la capacidad del fármaco amorfo y mejorar la disolución en comparación con el binario. Los sistemas terciarios resultantes son una mejora con respecto a los sistemas de polímeros de fármacos binarios.

Synthesis and characterization of Sophora alopecuroides L. green synthesized of Ag nanoparticles for the antioxidant, antimicrobial and DNA damage prevention activity

Abstract In this study, it was aimed to investigate the amount of antioxidant, protective properties against DNA damage and antibacterial properties against various pathogens after the interaction of Ag metal (Ag NPs/Sa) of Sophora alopecuroides L. (S. alopecuroides L) plant seed, which is grown in Igdir and used in the treatment of many diseases. The DPPH radical quenching activity of Ag NPs/Sa was performed by using Blois method, DNA damage prevention activity by gel electrophoresis and antibacterial property by disk diffusion method. With the green synthesis method, AgNPs obtained as a result of the reaction of the plant and Ag metal are UV visible spectrophotometer (UV-vis), fourier-transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). DPPH radical quenching activity of Ag NPs/Sa was investigated in the concentration range of 25-250 µg/ml. The radical quenching activity at a concentration of 250 µg/ml was 85,215 ± 0,101%, while this value was 93,018% for the positive control BHA. It has been observed that the protective property of pBR322 plasmid DNA damage against OH radicals originating from H2O2 increases with concentration. It has been observed that Ag NPs/Sa has significant antimicrobial properties against some pathogens (B. subtilis ATCC 6633 E. coli ATCC 25952, B. cereus ATCC 10876, P. aeruginosa ATCC 27853, E. faecalis ATCC 29212, S. aureus ATTC 29213 and C. albicans ATTC 90028) that cause disease and even some pathogens are more effective than antibiotics

Development and optimization of metoclopramide containing polymeric patches: impact of permeation enhancers

Abstract The study is aimed to develop a monolithic controlled matrix transdermal patches containing Metoclopramide as a model drug by solvent casting method. Eudragit L100, Polyvinylpyrrolidone K-30, and Methylcellulose were used in different ratios and Polyethylene glycol 400 added as a plasticizer. Resulting patches were evaluated for their physicochemical characters like organoleptic characters, weight variation, folding endurance, thickness, swelling index, flatness, drug content, swelling index, percentage erosion, moisture content, water vapor transmission rate and moisture uptake. Formed patches were also evaluated through Fourier transform spectroscopy (FT-IR), X-ray diffraction (XRD), Differential Scanning calorimetry (DSC) and Scanning Electron Microscopy (SEM). Results of SEM unveiled smooth surface of drug-loaded patches. In-vitro dissolution studies were conducted by using dissolution medium phosphate buffer saline pH 7.4. Effect of natural permeation enhancers was elucidated on two optimized formulations (Z4 and Z9). Different concentrations (5%-10 %) of permeation enhancers i.e. Olive oil, Castor oil and Eucalyptus oil were evaluated on Franz diffusion cell using excised abdominal rat skin. Z4-O2 (Olive oil 10%) had enhanced sustain effect and flux value (310.72) close to the desired flux value. Z4-O2 followed Higuchi release model (R2= 0.9833) with non-fickian diffusion release mechanism (n=0.612)

Co-amorphous technology to improve dissolution and physical stability of silybin / 中国中药杂志

The present study explored the effect of co-amorphous technology in improving the dissolution rate and stability of silybin based on the puerarin-silybin co-amorphous system prepared by the spray-drying method. Solid-state characterization was carried out by powder X-ray diffraction(PXRD), polarizing microscopy(PLM), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC), etc. Saturated powder dissolution, intrinsic dissolution rate, moisture absorption, and stability were further investigated. The results showed that puerarin and silybin formed a co-amorphous system at a single glass transition temperature which was higher than that of any crude drug. The intrinsic dissolution rate and supersaturated powder dissolution of silybin in the co-amorphous system were higher than those of the crude drug and amorphous system. The co-amorphous system kept stable for as long as three months under the condition of 40 ℃, 75% relative humidity, which was longer than that of the single amorphous silybin. Therefore, the co-amorphous technology could significantly improve the dissolution and stability of silybin.

Potential Alendronate Sodium drug carrier by preparation and characterization of sodium alginate cross-linked Montmorillonite

Abstract In drug therapy, it is important to provide therapeutic levels of drug to the site of action and maintain them during the treatment. This work describes the in vitro release of alendronate from sodium alginate cross-linked Montmorillonite (MMT) composite beads. Effect of crosslinking cation, concentration of montmorillonite and media on encapsulation efficiencies, and release profiles of alendronate were studied. Beads were characterized using equilibrium swelling ability study, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Energy-dispersive x-ray spectroscopy (EDX) and scanning electron microscopy (SEM). Results indicate that addition of montmorillonite increases the encapsulation efficiencies and slows down the release rates significantly.

Ganoderma applanatum extract mediated synthesis of silver nanoparticles

Abstract Nanotechnology has been used in the field of medicine and pharmacology for its greater efficacy of drug delivery than crude molecules of drugs. In the present study medicinal mushroom Ganoderma applanatum extract mediated silver nanoparticles (AgNPs) were synthesized, characterized by Ultraviolet-visible (UV-Vis.) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction, Dynamic light scattering (DLS) and Furior transform-infrared (FTIR) spectroscopy. Maximum absorbance was recorded at 435nm by UV-Vis. The synthesized nanoparticles of 13.54nm-255nm in size with an average particle size of 58.77nm were analyzed by DLS. FTIR-Spectroscopy provided high transmission at 3606cm-1 corresponds for phenolic capping biochemical. Thus G. applanatum extract can be used for synthesis of silver nanoparticles and the synthesized nanoparticles may be used for development of future therapeutic agent for treatment of diseases.

Cristalogénesis biológica y cristalografía en la elucidación de la estructura tridimensional de las proteínas. Revisión narrativa / Protein tridimensional structure by biological crystallogenesis and crystallography. Narrative review

La obtención de información estructural tridimensional de una proteína es de suma importancia en campos tan variados como la bioquímica funcional, las ciencias de materiales o biomédicas. Siendo actualmente la difracción de rayos X de monocristal el estándar de oro para la consecución de este objetivo, la obtención de dicho monocristal sigue siendo un cuello de botella desde el punto de vista práctico, y poco entendido desde el punto de vista teórico. En este artículo se revisa desde la perspectiva estructural de la proteína la forma en que los rayos X permiten obtener la información estructural y las condiciones fisicoquímicas que permiten la formación de un cristal adecuado para estos experimentos.

Obtaining three-dimensional structural information of a protein is of utmost importance in various fields such as functional biochemistry, materials science, or biomedical sciences. Even though single crystal X-ray diffraction is currently the gold standard for this purpose, growing said single crystal is still a bottleneck from a practical viewpoint, and not fully understood from a theoretical point of view. In this article, we review, from a protein structure perspective, the way X-rays provide structural information, and the physicochemical conditions that promote the formation of an adequate crystal for these experiments.

Curcumin solid dispersion based on three model acrylic polymers: formulation and release properties

Abstract To investigate structure-property relationship of polymer-based curcumin solid dispersion (SD), three acrylic polymers were used to formulate curcumin SD by solvent evaporation method. Curcumin Eudragit EPO SD (cur@EPO), curcumin Eudragit RS PO SD (cur@RSPO) and curcumin Eudragit RL PO SD (cur@RLPO) showed deep red, golden orange and reddish orange color, respectively. Cur@RSPO entrapped 15.42 wt% of curcumin followed by cur@RL PO and cur@EPO. FTIR spectra indicated that in cur@EPO, curcumin may transfer hydrogen to the dimethylaminoethyl methacrylate group and thus change its color to red. In contrast, curcumin may form hydrogen bonding with Eudragit RS PO and Eudragit RL. Curcumin exists in amorphous state in three SDs as proved by differential scanning calorimetry and X-Ray diffraction measurement. In vitro digestion presented that lower pH value in simulated gastric fluid (SGF) stimulates the curcumin release from cur@EPO while permeability influences the release profile in other two SDs. When in simulated intestinal fluid (SIF), first order release model governs the release behaviors of all three SDs which showed sustained release pattern. Our results are helpful to elucidate how structure of polymer may impact on the major properties of curcumin contained SD and will be promising to broaden its therapeutic applications.

Experimental nano calcium aluminate/tri calcium silicate root repair: Synthesis, physical and mechanical properties compared to mineral trioxide aggregate and Biodentine / Reparo radicular experimental de nano aluminato de cálcio/silicato de tri cálcio: Síntese, propriedades físicas e mecânicas em comparação com agregado de trióxido mineral e Biodentine

Objective: Endodontic perforation is a challenging mishap that should be repaired with a biocompatible material, Mineral trioxide aggregate (MTA) and Biodentine are the most commonly used repair materials. However, these materials are expensive, (MTA) has prolonged setting time and difficult manipulation. The purpose of this study is to prepare the experimental nano calcium-aluminate/tri-calcium-silicate (CA/C3S) material and comparing its physical properties with biodentine and MTA, to evaluate the experimental material eligibility to compete the commercial repair materials. And to perform part two (animal study) that will evaluate the cytotoxicity, the biocompatibility and the efficacy of (CA/C3S) in furcal perforation repair compared to diode laser. Material and Methods: A mixture of calcium carbonate and aluminum oxide was used to formulate calcium aluminate phase (CA), tri-calcium-Silicate phase (C3S) was formulated by firing of calcium carbonate and quartz. The produced powders were investigated by X-ray diffraction, then (CA) and (C3S) mixed with water.(CA/ C3S) compared with MTA and biodentine for setting-time, micro-hardness, dimensional-stability and solubility. Results: Mean setting time of (CA/C3S) was (32.70±0.75min) which is significantly higher than MTA and Biodentine. The Mean microhardness of (CA/C3S) was (56.50±7.41VHN) which has no statical difference with MTA and Biodentine. Solubility results showed weight increase for (CA/C3S) as following (6.29±3.05)and loss of weight for MTA and Biodentine. The percentage of change in dimensions for(CA/C3S) increased as following (0.64±0.78) while decreased for MTA and Biodentine. Conclusion: The experimental (CA/C3S) material showed good microhardness, dimensional stability and acceptable setting time that could be improved in further work (AU)

Objetivo: A perfuração endodôntica é um percalço desafiador que deve ser reparado com um material biocompatível, Agregado de trióxido mineral (MTA) e Biodentina são os materiais de reparo mais comumente usados. No entanto, esses materiais são caros, (MTA) tem tempo de presa prolongado e difícil manipulação. O objetivo deste estudo é preparar o material experimental de nano aluminato de cálcio/silicato tricálcico (CA/C3S) e comparar suas propriedades físicas com biodentina e MTA, para avaliar a elegibilidade do material experimental para competir com os materiais de reparo comerciais. E realizar a segunda parte (estudo animal) que avaliará a citotoxicidade, a biocompatibilidade e a eficácia do (CA/C3S) no reparo de perfuração de furca em comparação ao laser de diodo.Material e Métodos: Uma mistura de carbonato de cálcio e óxido de alumínio foi usada para formular a fase de aluminato de cálcio (CA), a fase tri-cálcio-silicato (C3S) foi formulada por queima de carbonato de cálcio e quartzo. Os pós produzidos foram investigados por difração de raios X, em seguida (CA) e (C3S) misturados com água. (CA/ C3S) comparados com MTA e biodentina para tempo de presa, microdureza, estabilidade dimensional e solubilidade. Resultados: O tempo médio de presa de (CA/C3S) foi (32,70±0,75min) que é significativamente maior que MTA e Biodentine. A microdureza média de (CA/C3S) foi (56,50±7,41VHN) que não tem diferença estática com MTA e Biodentine. Os resultados de solubilidade mostraram aumento de peso para (CA/C3S) conforme a seguir (6,29±3,05) e perda de peso para MTA e Biodentine. A porcentagem de mudança nas dimensões para (CA/C3S) aumentou como segue (0,64±0,78), enquanto diminuiu para MTA e Biodentine. Conclusão: O material experimental (CA/C3S) apresentou boa microdureza, estabilidade dimensional e aceitável tempo de presa, que pode ser melhorado em trabalhos futuros (AU)

Calendula officinalis L. flower extract-mediated green synthesis of silver nanoparticles under LED light

Abstract Silver nanoparticles (AgNPs) are among the most known nanomaterials being used for several purposes, including medical applications. In this study, Calendula officinalis L. flower extract and silver nitrate were used for green synthesis of silver nanoparticles under red, green and blue light-emitting diodes. AgNPs were characterized by Ultraviolet-Visible Spectrophotometry, Field Emission Scanning Electron Microscopy, Dynamic Light Scattering, Electrophoretic Mobility, Fourier Transform Infrared Spectroscopy and X-ray Diffraction. Isotropic and anisotropic silver nanoparticles were obtained, presenting hydrodinamic diameters ranging 90 - 180 nm, polydispersity (PdI > 0.2) and moderate stability (zeta potential values around - 20 mV)

Inhibition of α-glucosidase, pancreatic lipase, and antioxidant property of Myrcia hatschbachii D. Legrand containing gallic and ellagic acids / Inhibición de la α-glucosidasa, la lipasa pancreática y la propiedad antioxidante de Myrcia hatschbachii D. Legrand que contiene ácidos gálico y elágico

Several species of the Myrcia genus have been used in folk medicine to treat diabetes. Therefore, the aim of this work was to investigate the inhibitory activity of α-glucosidase and pancreatic lipase in the crude extract (EBF) and in the ethyl acetate fraction (FFA) of Myrcia hatschbachii, as well as to identify isolated phenolic compounds and to evaluate the antioxidant property and preliminary in vitro toxicity against Artemia salina. EBF (IC50: 3.21 µg/mL) and FFA (IC50: 1.14 µg/mL) showed inhibitory activity superior to acarbose (IC50: 193.65 µg/mL). In addition, they showed inhibitory effects of pancreatic lipase (IC50: 556.58 µg/mL for EBF and 532.68 µg/mL for FFA), antioxidant potential, absence of preliminary toxicity and presence of gallic andellagic acids in FFA. The relevant results in the inhibition of α-glucosidase and pancreatic lipase motivate new studies for the development of herbal medicines that assist in the treatment of diabetic patients.

Varias especies del género Myrcia se han utilizado en la medicina popular para tratar la diabetes. Por lo tanto, el objetivo de este trabajo fue investigar la actividad inhibitoria de la α-glucosidasa y la lipasa pancreática en el extracto crudo (EBF) y en la fracción de acetato de etilo (FFA) de Myrcia hatschbachii, así como identificar compuestos fenólicos aislados y evaluar la propiedad antioxidante y toxicidad in vitro preliminar contra Artemia salina. EBF (IC50: 3.21 µg/mL) y FFA (IC50: 1.14 µg/mL) mostraron una actividad inhibitoria superior a la acarbosa (IC50: 193.65 µg/mL). Además, mostraron efectos inhibitorios de la lipasa pancreática (IC50: 556.58 µg/mL para EBF y 532.68 µg/mL para FFA), potencial antioxidante, ausencia de toxicidad preliminar y presencia de ácidos gálico y elágico en FFA. Los resultados relevantes en la inhibición de la α-glucosidasa y la lipasa pancreática motivan nuevos estudios para el desarrollo de medicamentos a base de hierbas que ayudan en el tratamiento de pacientes diabéticos.

The Effect of Different Surface Treatment Protocols on the Shear Bond Strength to Repressed Lithium Disilicate Glass Ceramics / Efeito de diferentes protocolos de tratamento de superfície na resistência ao cisalhamento de vitrocerâmica de dissilicato de lítio reprensado

Objective: The present study aimed to evaluate the effect of repressing and different surface treatment protocols on the shear bond strength of lithium disilicate glass-ceramics. Material and Methods: A total of 52 lithium disilicate glass-ceramic discs (IPS emax Press, Ivoclar Vivadent) were fabricated using the heat-press technique. The discs were divided into two groups; group (P): discs fabricated from new e.max ingots (n=26), group (R): discs fabricated from reused e.max buttons (n=26). Each group was subdivided into subgroup (E): discs were etched with hydrofluoric acid (9.5%) (n=13), subgroup (S): discs were air-abraded with 110 µm alumina particles. All specimens were subjected to X-ray Diffraction analysis, Scanning Electron Microscope, Energy Dispersive X-Ray, Thermo-Cycling, and Shear Bond Strength Testing. Results: Repressed Etched subgroup (RE) recorded the statistically highest shear bond strength value, followed by the Pressed Etched subgroup (PE), while the statistically lowest shear bond strength value was recorded for the Pressed Air-Abraded subgroup (PS) and Repressed Air-Abraded subgroup (RS). Conclusion: Repressing the leftover buttons for the construction of new lithium disilicate glass-ceramic restorations has no adverse effect on the bond strength of the resin cement to the ceramic. Hydrofluoric acid surface treatment improves the shear bond strength and durability of resin cement bond to both pressed and repressed lithium disilicate glass-ceramic. Air-abrasion cannot be considered as a reliable surface treatment when bonding to lithium disilicate glass-ceramics. (AU)

Objetivo: O presente estudo teve como objetivo avaliar o efeito da reprensagem e de diferentes protocolos de tratamento de superfície na resistência ao cisalhamento de vitrocerâmica de dissilicato de lítio. Materiais e Métodos: Um total de 52 discos de vitrocerâmica de dissilicato de lítio (IPS emax Press, Ivoclar Vivadent) foram fabricadas usando a técnica de prensagem quente. Os discos foram divididos em dois grupos: grupo (P): discos fabricados a partir de novo lingotes de e-max (n=26), grupo (R): discos fabricados a partir de botões de emax reutilizados (n=26). Cada grupo foi subdividido em subgrupo (E): discos condicionados com ácido fluorídrico (9,5%) (n=13), subgrupo (S) discos foram abrasivos com partícula 110 µm de alumínio. Todos os espécimes foram submetidos a analise de difração de raio-x, microscópio eletrônico de varredura, raio-x de energia dispersiva, termociclagem e teste de resistência de cisalhamento. Resultados: O subgrupo Reprensado-condicionado (RE) registrou o valor estatisticamente mais alta em relação a resistência ao cisalhamento, seguido pelo subgrupo Prensado-condicionado (PE), enquanto o valor estatisticamente mais baixo de resistência ao cisalhamento foi o subgrupo Prensado-Jateado (OS) e o subgrupo Reprensado-Jateado (RS). Conclusão: A reprensagem dos botões restantes para a construção de novas restaurações vitrocarâmicas de dissilicato de lítio não apresentou efeitos adversos na resistência de unicãp do cimento resinoso à cerâmica. O tratamento de superfície com ácido fluorídrico melhora a resistência ao cisalhamento e a durabilidade do cimento resinoso para vitrocerâmica de dissilicato de lítio prensada e reprimida. A abrasão por ar não pode ser considerada um tratamento de superfície confiável quanto a colagem da vitrocerâmica de dissilicato de lítio (AU)

Efeito do envelhecimento hidrotérmico e mecânico na performance à fadiga de zircônias de alta translucidez / Effect of hydrothermal and mechanical aging on the fatigue performance of high-translucency zirconias

O objetivo deste trabalho foi avaliar a resistência à fadiga e ciclos até a falha de 3 zircônias odontológicas após envelhecimento hidrotérmico isolado e um novo protocolo alternado. Discos de zircônia "Y"Z T (VITA), INCORIS "T"ZI (Dentsply Sirona) e "K"ATANA UTML (Noritake Kuraray) (N=135) ­ 1ª, 2ª e 3ª gerações, respectivamente ­, foram divididos em 9 grupos (n=15), com 3 tratamentos para cada zircônia: CF ­ Controle, somente com fadiga mecânica; EF ­ Envelhecido em reator hidrotérmico a 134 ºC por 20 h + Fadiga; EFA: 4 passos de envelhecimentos de 5h alternados com fadiga. O teste de fadiga em flexão biaxial foi realizado com configuração de pistão sob 3 esferas, utilizando o método step-stress (carga inicial: 100 Mpa, step: 50 MPa/10.000 ciclos, frequência: 20 Hz). Os dados foram analisados através de teste Kaplan-Meir e Mantel-Cox com α=0,05, além da análise de Weibull. Discos fraturados foram analisados em estereomicroscópio, Microscopia Eletrônica de Varredura (MEV) e Difratômetro de Raios-X (DRX). O envelhecimento isolado com fadiga aumentou a resistência do grupo TEF (810 ± 76 MPa), enquanto diminuiu a do YEF (516 ± 38 MPa), o protocolo alternado aumentou a resistência apenas para a YZ T (730 ± 59 MPa). A KATANA UMTL não apresentou diferenças para ambos os tratamentos. Igualmente, foi a única a não sofrer transformação de fase T-M. O grupo TEF apresentou maior taxa sobrevivência à fadiga (147,000.00 ciclos). A origem de fratura para todos os espécimes deu-se no lado de tração em defeitos pré-existentes. Zircônias de 2ª geração possuem melhor comportamento mecânico e longevidade pós-envelhecimento e fadiga. Embora seja menos resistente, a KATANA UTML não sofreu degradação

This study aimed to evaluate the fatigue strength and cycles for failure of 3 dental zirconias after isolated and a novel hydrothermal and mechanical fatigue cycling aging protocol. "Y"Z T (VITA), INCORIS "T"ZI (Dentsply Sirona) and "K"ATANA UTML (Noritake Kuraray) zirconia discs (N=135), were divided into 9 groups (n=15), according to 3 proposed treatments for each zirconia: CF (control ­ only mechanical fatigue cycling); AF (aging in hydrothermal reactor at 134°C for 20 h + mechanical fatigue cycling ); AFA (Alternating protocol: 4 steps of 5 h of hydrothermal aging intercalated with mechanical fatigue cycling). Mechanical fatigue aging was performed according to the step stress approach through biaxial flexural setup (piston-on-3-balls, initial strength: 100 MPa, step: 50 MPa/ci000, frequency: 20 Hz) until failure. Data were analyzed using KaplanMeier and Mantel-Cox test (α=0.05), in addition to Weibull analysis. Fractured discs were analyzed in stereomicroscope, Scanning Electron Microscopy and XRay Diffraction. Continuous hydrothermal and mechanical fatigue cycling decreased the fatigue strength of YAF group (516 ± 38 MPa), while the alternating protocol increased it (730 ± 59 MPa). KATANA UTML showed no differences for both treatments and did not undergo T-M phase transformation. The TAF group showed the highest fatigue strength (810 ± 76 MPa) and cycles for failure (147,000.00 cycles). The fracture origin for all specimens was on the tensile side in pre-existing defects. INCORIS TZI zirconia have higher fatigue strength after hydrothermal and mechanical fatigue aging. Although less resistant, KATANA UTML did not suffer chemical degradation

Ação antimicrobiana, citotoxicidade, composição química e radiopacidade de cimentos biocerâmicos reparadores / Antimicrobial action, cytotoxicity, chemical composition and radiopacity of repair bioceramic cement

Os cimentos biocerâmicos possuem diversas aplicações clinicas na área de endodontia. Este estudo teve como objetivo avaliar a ação antimicrobiana do cimento de cinco óxidos minerais "5MO", do agregado trióxido mineral "MTA" que já é um material consagrado, como também do agregado trióxido mineral reparador de alta plasticidade "MTA HP", e comparar a capacidade dos mesmos na eliminação de microrganismos anaeróbios, comumente encontrados em infecções endodônticas primárias por meio de teste de MTT; avaliar e comparar também a biocompatibilidade dos mesmos através testes de citotoxicidade de MTT sobre cultura de macrófagos de camundongos (RAW 264.7) e osteoblastos (MG-63); avaliar a composição química dos mesmos através da microscopia eletrônica de varredura "MEV" acoplada a espectroscopia de raios X por dispersão em energia "EDS ou EDAX" e avaliar a fase por difração de raios-X "DRX"; além de avaliar a sua radiopacidade. Neste estudo, foi observada a atividade antibiofilme efetiva dos grupos experimentais sobre alguns microrganismos anaeróbios incluindo Porphyromonas gingivalis, Porphyromonas endodontalis, Parvimonas micra, Fusobacterium nucleatum e Prevotella intermedia, por outro lado, os mesmos foram biocompatíveis sobre os macrófagos e osteoblastos após 5 min de contato. Além disso, foram encontrados principais componentes químicos em que a presença de titânio, enxofre e potássio e a ausência de tungstênio no 5MO o torna diferente do MTA e do MTA HP, e a presença de estrôncio no MTA HP o torna diferente do 5MO e do MTA. Todos os biocerâmicos avaliados apresentaram uma radiopacidade adequada para serem utilizados clínicamente de acordo com o protocolo para radiopacidade de materiais dentários, publicado pela International Standards Organization (ISO). Sendo assim, os cimentos biocerâmicos 5MO, MTA HP, e MTA possuem ação antimicrobiana efetiva contra todos os microrganismos anaeróbios analisados, são biocompatíveis, possuem componentes químicos em comum, e possuem radiopacidade adequada para o uso clínico de material dentário.

Bioceramic cements have several clinical applications in endodontics. This study aimed to evaluate the antimicrobial action of the cement of five mineral oxides "5MO", mineral trioxide aggregate "MTA" which is already an established material, as well as the mineral trioxide aggregate repair high plasticity "MTA HP", and to compare their ability to eliminate anaerobic microorganisms, commonly found in primary endodontic infections by means of MTT test; to evaluate and compare their biocompatibility through MTT cytotoxicity tests on mouse macrophage cultures (RAW 264.7) and osteoblasts (MG-63); evaluate their chemical composition through scanning electron microscopy "SEM" coupled with energy dispersion X-ray spectroscopy "EDS or EDAX" and evaluate the phase by X-ray diffraction "XRD"; in addition to evaluating its radiopacity. In this study, all tested bioceramic cements were effective over some anaerobic microorganisms including Porphyromonas gingivalis, Porphyromonas endodontalis, Parvimonas micra, Fusobacterium nucleatum and Prevotella intermedia, on the other hand, they were biocompatible on macrophages and osteoblasts after 5 minutes of contact. In addition, main chemical components were found in which the presence of titanium, sulfur and potassium and the absence of tungsten in 5MO makes it different from MTA and MTA HP, and the presence of strontium in MTA HP makes it different from 5MO and MTA. All evaluated bioceramic cements presented adequate radiopacity to be used clinically according to the protocol for radiopacity of dental materials, published by the International Standards Organization (ISO). Thus, 5MO, MTA HP, and MTA bioceramic cements have effective antimicrobial action against all tested anaerobic microorganisms, are biocompatible, have chemical components in common, and have adequate radiopacity for the clinical use of dental material.

Study of crystallization, microstructure and mechanical properties of lithium disilicate glass-ceramics as a function of the sintering temperature / Estudo da cristalização, microestrutura e propriedades mecânicas de uma vitrocerâmica de dissilicato de lítio em função da temperatura de sinterização

Objective: The purpose of the present study was to synthesize and characterize lithium disilicate glass-ceramics through the Li2O-SiO2system for determining the most satisfactory sintering parameter by evaluating the crystalline composition, microstructure and mechanical properties. Material and methods: The glass-ceramics were prepared from a glass precursor by means of the melting/cooling technique with a composition of 33.33 Li2O and 66.67 SiO2 (mol.%). The specimens were compressed by the uniaxial pressing technique and three different thermal treatments were used for sintering: 850 °C (Group 1), 900 °C (Group 2), and 950 °C (Group 3), which were determined based on the differential scanning calorimetry (DSC) result. The glass-ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Archimedes method, microhardness and biaxial flexural strength analyses. Results: The results regarding XRD predominantly showed lithium disilicate phase for all the heat treatments performed. Moreover, grains with a needle form were more predominantly observed in the SEM images for Group 3, as well as a higher densification and consequently higher mechanical properties. In contrast, Group 1 presented the lowest mechanical properties and densification, as well as the highest porosity. Conclusion: The present study demonstrated how extremely important it is to follow the heat treatment recommended by the manufacturers of ceramics, including time and temperature, which possess direct effects in the crystalline phase formation, as well as in the material's microstructure and mechanical properties (AU)

Objetivo: O presente estudo teve como objetivo sintetizar e caracterizar uma vitrocerâmica de dissilicato de lítio através do sistema Li2O-SiO2para determinar o parâmetro de sinterização mais satisfatório através da avaliação da composição cristalina, microestrutura e propriedades mecânicas. Material e Métodos: As vitrocerâmicas foram preparadas a partir de um vidro precursor pelo método fusão/resfriamento utilizando a composição de 33.33 Li2O e 66.67 SiO2 (mol.%). As amostras foram prensadas utilizando uma técnica de prensagem uniaxial e três tratamentos térmicos diferentes foram utilizadas para sinterização: 850 °C (Grupo 1), 900 °C (Grupo 2), e 950 °C (Grupo 3), que foram determinados através do resultado da análise diferencial de calorimetria. As vitrocerâmicas foram caracterizadas através das análises de difração de raios X (DRX), microscopia eletrônica de varredura (MEV), métodos de Arquimedes, microdureza e ensaio de flexão biaxial. Resultados: Os resultados de DRX mostraram predominantemente a fase de dissilicato de lítio para todos os tratamentos realizados. Além disso, grãos com forma agulhada foram mais predominantemente observados por MEV no grupo 3, assim como uma densificação maior e consequentemente valores maiores das propriedades mecânicas. Em contraste, o grupo 1 apresentou os menores valores de propriedades mecânicas e densificação, e também a maior porosidade. Conclusão: O presente estudo demonstrou como é extremamente importante seguir o tratamento térmico recomendado pelos fabricantes de cerâmica, incluindo tempo e temperatura, que possuem efeitos diretos na formação da fase cristalina, assim como na microestrutura do material e propriedades mecânicas. (AU)

Microstructural and mechanical analysis of two CAD-CAM lithium disilicate glass-reinforced ceramics

Abstract The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.

Influence of alumina air-abrasion for highly translucent partially stabilized zirconia on flexural strength, surface properties, and bond strength of resin cement

Abstract Objective This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ. Methodology Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests. Results The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging. Conclusion Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.

The effects of repetitive firing processes on the optical, thermal, and phase formation changes of zirconia

PURPOSE: The aim of this study was to investigate the effect of different numbers of heat treatments applied to superstructure porcelain on optical, thermal, and phase formation properties of zirconia.MATERIALS AND METHODS: Forty zirconia specimens were prepared in the form of rectangular prism. Specimens were divided into four groups (n = 10) according to the number of firing at heating values of porcelain. Color differences and translucency parameter were measured, and X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were performed. Data were analyzed with analysis of variance (ANOVA).RESULTS: There were no statistically significant differences in ΔE, TP, L, a, and b value changes of the zirconia specimens as a result of repetitive firing processes (P>.05).CONCLUSION: Although additional firing processes up to 4 increase peak density in thermal analysis, additional firing processes up to 4 times can be applied safely as they do not result in a change in color and phase character of zircon frameworks.