Differences According to the Type of Exogenous Hyaluronic Acid and its Frequency of Infiltration in the Treatment of Temporomandibular Osteoarthritis / Diferencias Según el Tipo de Ácido Hiaurónico Exógeno y su Frecuencia de Infiltración en el Tratamiento de la Osteoartritis Temporomandibular

SUMMARY: One of the most important minimally invasive treatments today in temporomandibular joint osteoarthritis (TMJ- OA) is the intra-articular exogenous hyaluronic acid (HA) injection, which has yielded good results in pain relief and improves mandibular function with few side effects. However, the effectiveness of HA continues to be controversial, partly due to the heterogeneity in the injection protocols in their molecular weight, viscosity and frequency of infiltration, among other properties. The aim of this review is to identify the differences in the histological and clinical effects of the different types of HA and the frequency of infiltration on TMJ-OA treatment. Materials and methods: A bibliographic search was performed in the PubMed, Web of Science and Scopus databases. The search was limited up to September 2022. Search terms included "osteoarthritis", "hyaluronic acid, "molecular weight", "concentration", "viscosity", "dose" and "temporomandibular", using AND/OR as Boolean terms. Results: Exogenous HA in its different molecular weights offers an improvement in histological and clinical characteristics. Apparently, low and medium molecular weight HA presents better results. No clinical studies related to the degree of HA viscosity were found. Respect to the frequency of infiltration, single injection, weekly injections for 3 weeks, weekly injections for 5 weeks and other protocols are used. However, their comparison is complex. There seems to be differences in the effects of the different HA preparations for the treatment of TMJ-OA, mainly in their molecular weight. However, the evidence remains scant.

Uno de los tratamientos mínimamente invasivos más importantes en la actualidad en la artrosis de la articulación temporomandibular (OATM) es la inyección intraarticular de ácido hialurónico (AH) exógeno, que ha dado buenos resultados en el alivio del dolor y mejora la función mandibular con pocos efectos secundarios. Sin embargo, la efectividad del AH continúa siendo controversial, en parte debido a la heterogeneidad en los protocolos de inyección en cuanto a su peso molecular, viscosidad y frecuencia de infiltración, entre otras propiedades. El objetivo de esta revisión fue identificar las diferencias en los efectos histológicos y clínicos de los diferentes tipos de HA y la frecuencia de infiltración en el tratamiento de TMJ-OA. Se realizó una búsqueda bibliográfica en las bases de datos PubMed, Web of Science y Scopus. La búsqueda se limitó hasta septiembre de 2022. Los términos de búsqueda incluyeron "osteoartritis", "ácido hialurónico", "peso molecular", "concentración", "viscosidad", "dosis" y "temporomandibular", utilizando AND/OR como términos booleanos. El HA exógeno en sus diferentes pesos moleculares ofrece una mejora en las características histológicas y clínicas. Aparentemente, el AH de bajo y medio peso molecular presenta mejores resultados. No se encontraron estudios clínicos relacionados con el grado de viscosidad del HA. Respecto a la frecuencia de infiltración, se utilizan inyecciones únicas, inyecciones semanales durante 3 semanas, inyecciones semanales durante 5 semanas y otros protocolos. Sin embargo, su comparación es compleja. Parece haber diferencias en los efectos de las diferentes preparaciones de HA para el tratamiento de la OA-TMJ, principalmente en su peso molecular. Sin embargo, la evidencia sigue siendo escasa.

Age-Related Features of the Viscosity of Plasma and Mitochondrial Membranes of Hepatocytes in Liver Cirrhosis.

The viscosity of plasma and mitochondrial membranes of hepatocytes was studied in young (3-month-old) and old (9-month-old) male Wistar rats. It was shown that viscosity of hepatocyte plasma and mitochondrial membranes in young rats under optimal vital functions in the area of protein-lipid membrane contacts was significantly lower than in old rats. No age-related differences in the viscosity of lipid-lipid membrane contacts and in the polarity of protein-lipid contacts and lipid layers were found. Liver cirrhosis induced by carbon tetrachloride and ethanol administration was associated with increased fluidity of the plasma and mitochondrial membranes of hepatocytes in rats of both age groups. The decrease in membrane viscosity in young rats occurred due to a decrease of the viscosity in the area of protein-lipid and lipid-lipid contacts, while in old rats in the area of protein-lipid contacts. Carbon tetrachloride and ethanol did not affect the polarity of lipid contacts and lipid layers.

Viscoelastic surface electrode arrays to interface with viscoelastic tissues.

Living tissues are non-linearly elastic materials that exhibit viscoelasticity and plasticity. Man-made, implantable bioelectronic arrays mainly rely on rigid or elastic encapsulation materials and stiff films of ductile metals that can be manipulated with microscopic precision to offer reliable electrical properties. In this study, we have engineered a surface microelectrode array that replaces the traditional encapsulation and conductive components with viscoelastic materials. Our array overcomes previous limitations in matching the stiffness and relaxation behaviour of soft biological tissues by using hydrogels as the outer layers. We have introduced a hydrogel-based conductor made from an ionically conductive alginate matrix enhanced with carbon nanomaterials, which provide electrical percolation even at low loading fractions. Our combination of conducting and insulating viscoelastic materials, with top-down manufacturing, allows for the fabrication of electrode arrays compatible with standard electrophysiology platforms. Our arrays intimately conform to the convoluted surface of the heart or brain cortex and offer promising bioengineering applications for recording and stimulation.

Effect of solvent type on the dispersion quality of spray-and freeze-dried CNCs in PLA through rheological analysis.

Polylactide (PLA) nanocomposites with spray-and freeze-dried cellulose nanocrystals (i.e., SCNC and FCNC) were prepared through solution casting using four different solvents: tetrahydrofuran (THF), chloroform (CHL), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). Small amplitude oscillatory shear rheological analysis was extensively employed to explore the CNC dispersion quality in PLA. Overall, the rheological properties differences of PLA/SCNC and PLA/FCNC nanocomposites were not very significant. Moreover, the use of THF and CHL did not lead to a proper dispersion of CNCs in PLA due to their low dielectric constants. On the other hand, while the use of DMF was effective on the enhancement of CNC dispersion, DMSO could more dramatically lead to such enhancement due to its higher dielectric constant. The percolation threshold in PLA/SCNC nanocomposites prepared with DMF and DMSO was predicted around 1.52 and 0.12 wt% CNC, respectively. The crystallization behavior of PLA/nanocomposites prepared with DMF and DMSO were also explored.

Acceptance of different types of thickeners, with and without flavoring, in hospitalized patients with dysphagia - A pilot study.

INTRODUCTION: Introduction: the goal of this work was to evaluate the acceptance of various types of thickeners, specifically modified starch thickener and gum thickener, both with and without flavoring. Patients and methods: a randomized sample of 40 hospitalized patients with oropharyngeal dysphagia was recruited. The taste, smell, and appearance of each type of thickener were evaluated, as well as the volume of liquid ingested by the patients taking each type of thickener (modified starch thickener vs. gum thickener, both with and without flavoring). Results: the overall acceptance of gum thickener was significantly higher than that of modified starch thickener (7.45 (1.57) vs. 5.10 (2.43), respectively; p = 0.001). When a food flavor was added to the thickened water, the overall rating of the product was higher than when no flavor was added (7.70 (1.53) vs. 4.85 (2.16); p < 0.001). The difference between the daily volume of water consumed by the patients who received gum thickeners (928.33 (331.27) mL) and those who received starch thickeners (670.00 (288.35) mL) was statistically significant (p = 0.012). Patient consumption was also higher when flavoring was added as compared to when it was not (943.33 (302.45) mL) vs. (655.00 (304.60) mL; p = 0.005). Conclusion: the acceptances of the thickener and of water intake by patients with dysphagia were both significantly higher when using gum thickeners compared to starch thickeners, and when adding flavoring.

INTRODUCCIÓN: Introducción: el objetivo de este trabajo fue evaluar la aceptación de varios tipos de espesantes (almidón modificado frente a gomas) con y sin saborizante. Pacientes y métodos: se reclutaron 40 pacientes hospitalizados con disfagia orofaríngea. Se evaluaron el sabor, el olor y la apariencia de cada tipo de espesante, así como el volumen de líquido ingerido por los pacientes que tomaban cada tipo de espesante (espesante de almidón modificado vs. espesante de goma, ambos con o sin saborizante). Resultados: la aceptación general del espesante de goma fue significativamente mayor que la del almidón modificado (7,45 (1,57) vs. 5,10 (2,43); p = 0,001). Cuando se añadió un saborizante al agua espesada, la calificación general fue mejor (7,70 (1,53) frente a 4,85 (2,16); p < 0,001). La diferencia entre el volumen diario de agua consumida por los pacientes que recibieron espesantes de goma (928,33 (331,27) ml) y los que recibieron espesantes de almidón (670,00 (288,35) ml) fue estadísticamente significativa (p = 0,012). El consumo de líquido también fue mayor cuando se agregó el saborizante (943,33 (302,45) ml frente a 655,00 (304,60) ml; p = 0,005). Conclusión: la aceptación del espesante y la ingesta de agua por parte de los pacientes con disfagia fueron significativamente mayores cuando se utilizaron espesantes de goma, en comparación con los espesantes de almidón, y al agregar saborizantes.

New insights into the alleviating role of starch derivatives on dough quality deterioration caused by freeze.

The alleviating role of starch derivatives on the quality deterioration of frozen steamed bread dough was investigated in terms of derivative structure, the bread characteristics and dough properties including freezable water contents, yeast activity as well as dough viscoelasticity. The addition of starch derivatives including short-clustered maltodextrin (SCMD), DE2 maltodextrin (MD) and pregelatinized starch (PGS) significantly increased the specific volume and decreased the hardness of steamed bread compared with Control bread after 8-week frozen storage. Lower freezable water content was found in PGS dough than SCMD dough, which was consistent with the results of water absorption index of starch derivatives. The analysis of dough gassing rate and yeast survival ratio demonstrated SCMD could provide more cryoprotection for yeast cells. Meanwhile, a higher elastic module and a more continuous gluten-network structure of SCMD dough were found after 8-week frozen storage. These results indicated starch derivatives especially SCMD were promising to be used as the alternative improvers in frozen dough production.

Phosphorylated xanthan gum-Ag(I) complex as antibacterial viscosity enhancer for eye drops formulation.

Topical instillation of eye drops represents the treatment of choice for many ocular diseases. Ophthalmic formulations must meet general requirements, i.e. pH, osmolality, transparency and viscosity to ensure adequate retention without inducing irritation and the development of eye infections. We developed a phosphorylated xanthan gum-Ag(I) complex (XGP-Ag) showing pH (pH = 7.1 ± 0.3) and osmolality values (311 ± 2 mOsm/kg) close to that of human tears (pH = 6.5-7.6 and 304 ± 23 mOsm/kg) thanks to the presence of phosphate moieties along the chain. The presence of phosphate groups covalently bound to the XG chains avoids their dispersion in fluid, thus reducing the risk of corneal calcification. 0.02% w/v XGP-Ag solution showed high transparency (higher than 95% along the entire visible range), adequate refractive index (1.334 ± 0.001) and viscosity in the range: γ 1 s-1-10,000 s- 1 (26.4 ± 0.8-2.1 ± 0.4 mPa·s). Its cytotoxicity and capability to hinder bacterial proliferation was also verified.

Unraveling the binding mechanism of an Oxovanadium(IV) - Curcumin complex on albumin, DNA and DNA gyrase by in vitro and in silico studies and evaluation of its hemocompatibility.

An oxovanadium(IV) - curcumin based complex, viz. [VO(cur)(2,2´-bipy)(H2O)] where cur is curcumin and bipy is bipyridine, previously synthesized, has been studied for interaction with albumin and DNA. Fluorescence emission spectroscopy was used to evaluate the interaction of the complex with bovine serum albumin (BSA) and the BSA-binding constant (Kb) was calculated to be 2.56 x 105 M-1, whereas a single great-affinity binding site was revealed. Moreover, the hemocompatibility test demonstrated that the complex presented low hemolytic fraction (mostly below 1%), in all concentrations tested (0-250 µΜ of complex, 5% DMSO) assuring a safe application in interaction with blood. The binding of the complex to DNA was also investigated using absorption, fluorescence, and viscometry methods indicating a binding through a minor groove mode. From competitive studies with ethidium bromide the apparent binding constant value to DNA was estimated to be 4.82 x 106 M-1. Stern-Volmer quenching phenomenon gave a ΚSV constant [1.92 (± 0.05) x 104 M-1] and kq constant [8.33 (± 0.2) x 1011 M-1s-1]. Molecular docking simulations on the crystal structure of BSA, calf thymus DNA, and DNA gyrase, as well as pharmacophore analysis for BSA target, were also employed to study in silico the ability of [VO(cur)(2,2´-bipy)(H2O)] to bind to these target bio-macromolecules and explain the observed in vitro activity.

Solubilizing temperature of crystalline drug in polymer carrier: A rheological investigation on a posaconazole-copovidone system with low drug load.

Measuring the solubility of a crystalline active pharmaceutical ingredient (API) in a polymer-rich system is challenging due to the high viscosity of the polymer which kinetically impedes reaching the solubility equilibrium. In this study, a rheological approach of determining the solubilizing temperature of a crystalline API in a polymeric carrier has been developed. To validate the method, a model physical mixture of crystalline posaconazole and copovidone with a relatively low API load (25 wt%) was utilized. First, a comparison between conventional differential scanning calorimetry (DSC) and a rheological temperature ramp was conducted to illustrate that the rheological method could capture the melting point depression behavior similarly to the more well-known DSC technique. Second, to further understand the dissolution process of the crystalline posaconazole into the copovidone carrier and precisely measure the solubilizing temperature, a series of isothermal rheological time sweeps were carried out at various temperatures selected based on the rheological temperature sweep. Because the dissolved API molecule imparted a plasticizing effect to the polymeric carrier, the complex viscosity of the API-polymer system decreased gradually over time and correlated well to an exponential decay function. Moreover, dependent on the applied temperature, the API-polymer system eventually accomplished distinct equilibrium states (complex viscosities) within different time frames. The obtained time constants at different temperatures were fitted to the Arrhenius equation, allowing the determination of the activation energy of the mixing process. The results indicated that once the processing temperature exceeded a critical point below the melting point of the crystalline API, the API-polymer solubilization process switched from a surface dominated dispersive mechanism to a molecular-level solubilization mode, manifested by the significantly increased activation energy. To the best of our knowledge, the currently developed rheological approach was the first successful measurement of the solubilizing temperature of a crystalline drug in a polymer-rich system.

Preliminary Evaluation of 3D Printed Chitosan/Pectin Constructs for Biomedical Applications.

In the present study, chitosan (CS) and pectin (PEC) were utilized for the preparation of 3D printable inks through pneumatic extrusion for biomedical applications. CS is a polysaccharide with beneficial properties; however, its printing behavior is not satisfying, rendering the addition of a thickening agent necessary, i.e., PEC. The influence of PEC in the prepared inks was assessed through rheological measurements, altering the viscosity of the inks to be suitable for 3D printing. 3D printing conditions were optimized and the effect of different drying procedures, along with the presence or absence of a gelating agent on the CS-PEC printed scaffolds were assessed. The mean pore size along with the average filament diameter were measured through SEM micrographs. Interactions among the characteristic groups of the two polymers were evident through FTIR spectra. Swelling and hydrolysis measurements confirmed the influence of gelation and drying procedure on the subsequent behavior of the scaffolds. Ascribed to the beneficial pore size and swelling behavior, fibroblasts were able to survive upon exposure to the ungelated scaffolds.

The Modified Volume-Viscosity Swallow Test as a Predictor of Aspiration Pneumonia after Acute Ischemic Stroke.

OBJECTIVES: Dysphagia is common in patients with acute ischemic stroke patients (AIS) and it increases the risk of aspiration pneumonia after AIS. The volume-viscosity swallow test (V-VST) is a useful dysphagia screening tool. Therefore, we aim to explore the association between dysphagia (using the modified V-VST) and aspiration pneumonia in acute ischemic stroke patients. PATIENTS AND METHODS: All patients with acute ischemic stroke (AIS) admitted during 1 January 2018 and 31 December 2018 were screened in this study by completing the modified V-VST within 24 hours after admission. The information of aspiration pneumonia was obtained from electronic medical system (EMS) and discharge notes. RESULTS: Among 624 AIS patient, there were 152(24.36%) patients who suffered from aspiration pneumonia (95% CI, 20.65% - 27.35%) during hospitalization. Among all of them, patients with both impaired safety and impaired efficacy (HR, 7.53, 95%CI, 3.42-16.58, P < 0.001)) had a higher risk of aspiration pneumonia than those with only safety impaired (HR, 2.38, 95%CI, 1.40-4.04, P < 0.001) or only efficacy impaired (HR, 2.47, 95%CI, 1.33-4.57, P = 0.004). The risk of aspiration pneumonia was also associated with their completed volume at each viscosity. The patients with all impairment of three viscosities were also found to be related to the higher risk of developing aspiration pneumonia (P = 0.029). CONCLUSIONS: The Modified V-VST is an easy-hand on, reliable screening tool for dysphagia among patients with AIS. Patient subgroup analyses based on the modified V-VST might be able to predict the risk of aspiration pneumonia during hospitalization.

The role of alkali in sweet potato starch-Mesona chinensis Benth polysaccharide gels: Gelation, rheological and structural properties.

According to the Chinese traditional black jelly production process, a critical step to ensure the quality of jelly is to add alkali to it. In this study, the effects of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) on the pasting, rheological, textural, and structural properties of sweet potato starch (SPS)-Mesona chinensis Benth polysaccharide (MCP) gels were evaluated. Adding Na2CO3 at low concentration reduced the final viscosity (FV) of SPS-MCP gels, whereas adding it at a high concentration increased the FV. Adding NaHCO3 can increase the FV of SPS-MCP gels in a concentration-dependent manner. Rheological results indicated that adding NaHCO3 at a low concentration decreased the storage modulus of SPS-MCP gels, whereas adding it at a high concentration increased the storage modulus. The storage modulus of SPS-MCP gels increased with increasing concentration of NaHCO3. The addition of Na2CO3 and NaHCO3 improved the textural properties of SPS-MCP gels and decreased the water mobility. Infrared results indicated that adding alkali can enhance the hydrogen bonding between SPS and MCP. Scanning electron microscopy results suggested that alkali can reduce the size of gels, and make the structure more compact.

Novel High-Throughput Strategy for the Aqueous Solubility Assessment of Peptides and Proteins Exhibiting a Propensity for Gelation: Application to the Discovery of Novel Antibacterial Teixobactin Analogues.

A novel high-throughput aqueous solubility assay was developed for peptides and proteins exhibiting a high gelling propensity (in this case, antibacterial teixobactin analogues). By integrating the assessment of gel formation, as indicated by an increase in the solution viscosity, into the peptide equilibrium solubility screening assay, we were able to estimate the "free-flowing solubility", which is defined as the concentration at which the peptide solution not only is fully dissolved but also is a liquid exhibiting ideal flowing characteristics. In this workflow, peptide solutions passing the turbidity assessment were further screened by viscosity measurements based on nanobead-assisted dynamic light scattering analysis in a 96-well plate. The method is able to effectively detect the initiation of peptide gelation and facilitate compound ranking based on their aqueous solubility. The application of such an approach helped confirm that the substitution of Ser3 in teixobactin led to desired physicochemical improvements and provided a focal point for further chemistry structure-activity relationship exploration.

Lipidico Injection Protocol for Serial Crystallography Measurements at the Australian Synchrotron.

A facility for performing serial crystallography measurements has been developed at the Australian synchrotron. This facility incorporates a purpose built high viscous injector, Lipidico, as part of the macromolecular crystallography (MX2) beamline to measure large numbers of small crystals at room temperature. The goal of this technique is to enable crystals to be grown/transferred to glass syringes to be used directly in the injector for serial crystallography data collection. The advantages of this injector include the ability to respond rapidly to changes in the flow rate without interruption of the stream. Several limitations for this high viscosity injector (HVI) exist which include a restriction on the allowed sample viscosities to >10 Pa.s. Stream stability can also potentially be an issue depending on the specific properties of the sample. A detailed protocol for how to set up samples and operate the injector for serial crystallography measurements at the Australian synchrotron is presented here. The method demonstrates preparation of the sample, including the transfer of lysozyme crystals into a high viscous media (silicone grease), and the operation of the injector for data collection at MX2.

Effect of biochar on rice starch properties and starch-related gene expression and enzyme activities.

We determined the effects of biochar on starch properties and the activities of enzymes and expression levels of genes related to starch in two Japonica rice cultivars. The two rice varieties were subjected to five biochar treatments (0, control; and 5, 10, 20, and 40 t/hm2). In both rice varieties, the content of apparent amylose and resistant starch were lower in biochar treatments than in the control. The proportion of fa chains was higher and that of fb3 chain was lower in the biochar treatments than in the control. Starch viscosity and cooking taste quality were improved by the biochar treatments. In both rice varieties, the activity of granule-bound starch synthase was significantly decreased by biochar treatments, and the activities of soluble starch synthase, starch branching enzyme, and starch debranching enzyme were significantly increased. The transcript levels of genes encoding starch synthases and starch branching enzymes were significantly increased by biochar treatments. We conclude that biochar at a dose of 5-10 t/hm2 can regulate the activity of starch-related enzymes, and this affects the type, content, and fine structure of starch. Therefore, the addition of biochar to soil can improve the viscosity and taste quality of rice starch.

Esterification modified starch by phosphates and urea via alcohol solvothermal route for its potential utilization for urea slow-releasing.

The natural starch (NS) is modified by an esterification process which is accomplished by reacting the NS and phosphate together with urea via a facile alcohol solvothermal method. After modification, a series of obvious variations can be easily confirmed for the resulted starch phosphate carbamides (denoted as SPC) compared with that of NS, such as the introduction of new groups of CO, PO, P-O-C and P-O-H together with new elements of N and P in starch molecular structure unit confirmed in FT-IR and XPS analyses and the decreased crystallinity along with formed surface defect demonstrated in XRD and SEM measurements. Furthermore, the formed SPC has a higher viscosity of 480 mPa.s-1 and lower gelatinization temperature of under 10 °C than that of the NS. More importantly, when the SPC is utilized as outer coating material together with ethylcellulose (EC) as inner coating material for preparing double-layer slow-release urea (denoted as EC/SPC based SRU), the EC/SPC based SRU has a desirable slow-release behavior with release percentages of 40.9% for 12 h in water and merely 59.6% for 20 day together with even exceeding 30 days in soil. Conclusively, this work provides a facile preparation approach for the SPC and its creative application for the preparation of SRU.

Effect of bleaching protocols on surface roughness and color change of high- and low-viscosity bulk-fill composite resins.

The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson & Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p<0.05). Ra increased significantly (p<0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p<0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p<0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change.

Este estudo in vitro teve objetivo de avaliar o efeito de protocolos clareadores sobre a rugosidade de superfície (Ra), alteração de cor e micromorfologia de resina bulk-fill de baixa viscosidade (Filtek Bulk Fill Flow, 3M ESPE), alta viscosidade (Filtek Bulk Fill, 3M ESPE) e de uma resina composta nanoparticulada (controle) (Filtek Z350 XT, 3M ESPE). Quarenta amostras de cada resin composta (discos de 5 mm de diâmetro e 2 mm de espessura) foram aleatoriamente divididas em quatro grupos , de acordo com protocolo clareador (n=10): a) Gel de peróxido de carbamida (Opalescence, Ultradent Products) (2 horas/dia, por 14 dias); b) Gel de peróxido de hidrogênio (Opalescence Boost, Ultradent Products) (3 sessões de clareamento, uma por semana, 45 min/sessão); enxaguatório clareador (Listerine Whitening Extreme, Johnson & Johnson) (2 min/dia, por 14 dias); d) água destilada (controle). As amostras foram submetidas a leituras, em triplicata (Ra e cor (parâmetros CIELab) antes e depois do contato com os protocolos clareadores. A micromorfologia de superfície foi conduzida em microscópio eletrônico de varredura (MEV). Ra e parâmetros de cor (ΔL, Δa, Δb e ΔE) foram analisados por modelos lineares generalizados (α=0.05). A Ra da resina bulk-fill de alta viscosidade foi significantemente superior do que para os outros compósitos (p<0.05). A Ra aumentou significantemente (p<0.05) e a superfície ficou mais irregular (MEV) para todos os compósitos, independente do protocolo clareador (p<0,05). A resina bulk-fill de alta viscosidade obteve menor ΔE (p<0.05) do que a resina composta nanoparticulada, imersa em água destilada. Pode-se concluir que as características de cada resina composta influenciaram de forma mais significativa a Ra do que o protocolo clareador. A resina bulk fill de alta viscosidade apresentou menor alteração de cor.

Temporary/Permanent Dual Cross-Link Gels Formed of a Bioactive Lactose-Modified Chitosan.

Mounting evidences have recognized that dual cross-link and double-network gels can promisingly recapitulate the complex living tissue architecture and overcome mechanical limitations of conventional scaffolds used hitherto in regenerative medicine. Here, dual cross-link gels formed of a bioactive lactose-modified chitosan reticulated via both temporary (boric acid-based) and permanent (genipin-based) cross-linkers are reported. While boric acid rapidly binds to lactitol flanking diols increasing the overall viscosity, a slow temperature-driven genipin binding process takes place allowing for network strengthening. Combination of frequency and stress sweep experiments in the linear stress-strain region shows that ultimate gel strength, toughness, and viscoelasticity depend on polymer-to-genipin molar ratio. Notably, herewith it is demonstrated that linear stretching correlates with strain energy dissipation through boric acid binding/unbinding dynamics. Strain-hardening effect in the nonlinear regime, along with good biocompatibility in vitro, points at an interesting role of present system as biological extracellular matrix substitute.

Effect of bleaching protocols on surface roughness and color change of high- and low-viscosity bulk-fill composite resins / Efeito de protocolos clareadores na rugosidade de superfície e alteração de cor de resinas compostas bulk-fill de alta e baixa viscosidade

ABSTRACT The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson & Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p<0.05). Ra increased significantly (p<0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p<0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p<0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change.

RESUMO Este estudo in vitro teve objetivo de avaliar o efeito de protocolos clareadores sobre a rugosidade de superfície (Ra), alteração de cor e micromorfologia de resina bulk-fill de baixa viscosidade (Filtek Bulk Fill Flow, 3M ESPE), alta viscosidade (Filtek Bulk Fill, 3M ESPE) e de uma resina composta nanoparticulada (controle) (Filtek Z350 XT, 3M ESPE). Quarenta amostras de cada resin composta (discos de 5 mm de diâmetro e 2 mm de espessura) foram aleatoriamente divididas em quatro grupos , de acordo com protocolo clareador (n=10): a) Gel de peróxido de carbamida (Opalescence, Ultradent Products) (2 horas/dia, por 14 dias); b) Gel de peróxido de hidrogênio (Opalescence Boost, Ultradent Products) (3 sessões de clareamento, uma por semana, 45 min/sessão); enxaguatório clareador (Listerine Whitening Extreme, Johnson & Johnson) (2 min/dia, por 14 dias); d) água destilada (controle). As amostras foram submetidas a leituras, em triplicata (Ra e cor (parâmetros CIELab) antes e depois do contato com os protocolos clareadores. A micromorfologia de superfície foi conduzida em microscópio eletrônico de varredura (MEV). Ra e parâmetros de cor (ΔL, Δa, Δb e ΔE) foram analisados por modelos lineares generalizados (α=0.05). A Ra da resina bulk-fill de alta viscosidade foi significantemente superior do que para os outros compósitos (pp<0.05). A Ra aumentou significantemente (p<0.05) e a superfície ficou mais irregular (MEV) para todos os compósitos, independente do protocolo clareador (pp<0,05). A resina bulk-fill de alta viscosidade obteve menor ΔE (pp<0.05) do que a resina composta nanoparticulada, imersa em água destilada. Pode-se concluir que as características de cada resina composta influenciaram de forma mais significativa a Ra do que o protocolo clareador. A resina bulk fill de alta viscosidade apresentou menor alteração de cor.

Surface Geometry of Four Conventional Nanohybrid Resin-Based Composites and Four Regular Viscosity Bulk Fill Resin-Based Composites after Two-Step Polishing Procedure.

OBJECTIVES: The aim of the study was to determine the quantitative and qualitative surface structure of contemporary RBCs in posterior teeth reconstructions: regular viscosity bulk fill and conventional composites, obtained after two-stage polishing procedure. MATERIALS AND METHODS: Four conventional nanohybrid composites (Tetric EvoCeram, GrandioSO, Filtek Z550, and Ceram·X Mono) and four regular viscosity bulk fill composites (Tetric EvoCeram Bulk Fill, X-tra fil, Filtek Bulk Fill Posterior, and QuixFil) were tested. Samples of each RBC were prepared using PMMA cylindrical mold. After two-step polishing procedure, a surface geometry was evaluated under profilometry (Turbowave v. 7.36, Hommel-Etamic) and SEM (VEGA 3, Tescan Analytics). To evaluate differences between values, the following nonparametric tests were used: Friedman's ANOVA, Wilcoxon's matched-pair test, ANOVA Kruskal-Wallis, and Mann-Whitney U. RESULTS: All conventional RBCs showed Ra values in the range of 0.20-0.26 µm. Bulk fill showed higher values in range of 0.49-1.36 µm except for Filtek Bulk Fill Posterior, which achieved 0.23 µm Ra value. SEM images of conventional RBCs were described as smooth surfaces with slight damage except for TEC, which presented smooth surface with no damage. Bulk fill composites showed rough surface, except for TBF, which presented smooth surface with slight damage. CONCLUSIONS: Regular viscosity bulk fill composites do not constitute a homogeneous group regarding surface roughness after polishing. They obtain, for the most part, poorer smoothness values after polishing than conventional RBCs.