Immersion In Phosphate-buffered Saline Research Articles

Durable and Robust Antibacterial Polypropylene Hernia Mesh for Abdominal Wall Defect Repair.

Polypropylene (PP) mesh is commonly used in repairing abdominal wall hernia (AWH). However, the use of synthetic prosthesis comes with the risk of developing a prosthetic infection, resulting in delayed healing, secondary surgery, and potentially increased mortality. To address these issues, a facile surface functionalization strategy for PP mesh based on phytic acid (PA) and polyhexamethylene guanidine (PHMG) was constructed through a one-step co-deposition process, referred to as the PA/PHMG coating. The development of PA/PHMG coating is mainly attributed to the surface affinity of PA and the electrostatic interactions between PA and PHMG. The PA/PHMG coating could be completed within 4 h under mild conditions. The prepared PA/PHMG coatings on PP mesh surfaces exhibited desirable biocompatibility toward mammalian cells and excellent antibacterial properties against the notorious "superbug" methicillin-resistant Staphylococcus aureus (MRSA) and tetracycline-resistant Escherichia coli (TRE). The PA/PHMG-coated PP meshes showed killing ratios of over 99% against MRSA in an infected abdominal wall hernia repair model. Furthermore, histological and immunohistochemical analysis revealed a significantly attenuated degree of neutrophil infiltration in the PA/PHMG coating group, attributed to the decreased bacterial numbers alleviating the inflammatory response at the implant sites. Meanwhile, the pristine PP and PA/PHMG-coated meshes showed effective tissue repair, with the PA/PHMG coating group exhibiting enhanced angiogenesis compared with pristine PP meshes, suggesting superior tissue restoration. Additionally, PP meshes with the highest PHMG weight ratio (PA/PHMG(3)) exhibited excellent long-term robustness under phosphate-buffered saline (PBS) immersion with a killing ratio against MRSA still exceeding 95% after 60 days of PBS immersion. The present work provides a facile and promising approach for developing antibacterial implants.

Design and evaluation of an MMP-9-responsive hydrogel for vital pulp therapy

ObjectiveTo design and evaluate a matrix metalloproteinase 9 (MMP-9)-responsive hydrogel for vital pulp therapy. MethodsA peptide linker with optimized sensitivity toward MMP-9 was crosslinked with 4-arm poly (ethylene glycol)-norbornene (PEG-NB) by thiol-norbornene photo-polymerization. This resulted in the formation of a hydrogel network in which the peptide IDR-1002 was incorporated. Hydrogel characterization and gelation kinetics were examined with Fourier-transform infrared spectroscopy, scanning electron microscopy, rheological testing, and swelling evaluation. Hydrogel degradation was examined through multiple exposure to pre-activated MMP-9, to simulate flare-ups of dental pulp inflammation. The IDR-1002 released from degraded hydrogels was measured with high-performance liquid chromatography. Effect of IDR-1002 released from hydrogels on one-week-old multispecies oral biofilms was evaluated using confocal laser scanning microscopy. ResultsMMP-9-responsive, injectable, and photo-crosslinkable hydrogels were successfully synthesized. When hydrogel degradation and release of IDR-1002 were examined with exposure to pre-activated MMP-9, IDR-1002 release was significantly correlated with elevated levels of MMP-9 (p < 0.05). The effectiveness of IDR-1002 in killing bacteria in multispecies oral biofilms was significantly enhanced when the hydrogels were immersed in 10 nM or 20 nM pre-activated MMP-9, compared to immersion in phosphate-buffered saline (p < 0.05). ConclusionsThe MMP-9-responsive hydrogel is a promising candidate for on-demand delivery of bioactive agent in vital pulp therapy. Clinical significanceMMP-9 is one of the most important diagnostic and prognostic biomarkers for pulpitis. An MMP-9-responsive hydrogel has potential to be used as an in-situ on-demand release system for the diagnosis and treatment of dental pulp inflammation.

Preparation and Characterization of Bovine Small Intestine Submucosa (SIS) ‎Hydrogel

The aim of this study was to prepare and characterize a small intestine submucosa (SIS) hydrogel as ‎a bio-scaffold. In this study, SIS from five calves, aged 8-12 months and weighing 250-300 kg, was ‎obtained from a slaughterhouse immediately after slaughtering. The SIS was then decellularized, ‎powdered, and subsequently transformed into a hydrogel. This transformation was achieved by ‎dissolving the decellularized SIS powder in phosphate-buffered saline (PBS) at a concentration of ‎‎50% w/v, and allowing it to form a hydrogel over a 12-hour period at 37 °C. Characterization of the ‎SIS hydrogel was conducted using various techniques. Fourier Transform Infrared Spectroscopy ‎‎(FTIR) was employed to identify the chemical structure of the hydrogel, revealing three primary peaks ‎at 1639 cm-1, 1571 cm-1, and 1338 cm-1, corresponding to amide I, II, and III bands, respectively. ‎Additionally, a broad signal at 3440 cm-1 was observed, indicative of the hydroxyproline side chain. ‎The hydrogel's swelling capacity was evaluated, showing an expansion of 437% after a 12-hour ‎immersion in PBS at a pH of 7.4. Scanning Electron Microscopy (SEM) analysis of the lyophilized ‎hydrogel revealed a highly porous and interconnected architecture, resembling a honeycomb ‎structure. Moreover, the hydrogel's antibacterial efficacy was assessed against Staphylococcus ‎aureus using an agar diffusion test, which demonstrated a zone of inhibition measuring 16.11 mm. ‎The combined chemical, morphological, and antibacterial properties of the SIS hydrogel developed ‎in this study suggest its potential as a promising bio-scaffold for inducing tissue regeneration and ‎restoring tissue function‎.

In Vitro and In Vivo Hydrolytic Degradation Behaviors of a Drug-Delivery System Based on the Blend of PEG and PLA Copolymers.

This paper presents the in vitro and in vivo degradation of BEPO, a marketed in situ forming depot technology used for the formulation of long-acting injectables. BEPO is composed of a solution of a blend of poly(ethylene glycol)-block-poly(lactic acid) (PEG-PLA) triblock and diblock in an organic solvent, where a therapeutic agent may be dissolved or suspended. Upon contact with an aqueous environment, the solvent diffuses and the polymers precipitate, entrapping the drug and forming a reservoir. Two representative BEPO compositions were subjected to a 3-month degradation study in vitro by immersion in phosphate-buffered saline at 37 °C and in vivo after subcutaneous injection in minipig. The material erosion rate, as a surrogate of the bioresorption, determined via the depot weight loss, changed substantially, depending on the composition and content of polymers within the test item. The swelling properties and internal morphology of depots were shown to be highly dependent on the solvent exchange rate during the precipitation step. Thermal analyses displayed an increase of the depot glass transition temperature over the degradation process, with no crystallinity observed at any stage. The chemical composition of degraded depots was determined by 1H NMR and gel permeation chromatography and demonstrated an enrichment in homopolymers, i.e., free PLA and (m)PEG, to the detriment of (m)PEG-PLA copolymers in both formulations. It was observed that the relative ratio of the degradants within the depot is driven by the initial polymer composition. Interestingly, in vitro and in vivo results showed very good qualitative consistency. Taken together, the outcomes from this study demonstrate that the different hydrolytic degradation behaviors of the BEPO compositions can be tuned by adjusting the polymer composition of the formulation.

Synthesis and characterization of mesoporous bioactive glass nanoparticles loaded with peganum harmala for bone tissue engineering

Globally, there is an increase in a number of bone disorders including osteoarthritis (OA), osteomyelitis, bone cancer, and etc., which has led to a demand for bone tissue regeneration. In order to take use of the osteogenic potential of natural herbs, mesoporous bioactive glass nanoparticles (MBGNs) have the ability to deliver therapeutically active chemicals locally. MBGNs influence bioactivity and osteointegration of materials making them suitable for bone tissue engineering (BTE). In the present study, we developed Peganum Harmala (P. harmala) loaded MBGNs (PH-MBGNs) synthesized via modified Stöber process. The MBGNs were analyzed in terms of surface morphology, chemical make-up, amorphous nature, chemical interaction, pore size, and surface area before and after loading with P. harmala. A burst release of drug from PH-MBGNs was observed within 8 h immersion in phosphate buffer saline (PBS). PH-MBGNs effectively prevented Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) from spreading. Furthermore, PH-MBGNs developed a hydroxyapatite (HA) layer in the presence of simulated body fluid (SBF) after 21 days, which confirmed the in-vitro bioactivity of MBGNs. In conclusion, PH-MBGNs synthesized in this work are potential candidate for scaffolding or a constituent in the coatings for BTE applications.

Physical-chemical properties and acellular bioactivity of newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer

ObjectivesTo evaluate the physiochemical properties and apatite-forming ability of a newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer (C3S-BG-P) and compare its results with the Nishika BG canal sealer and BioRoot™ RCS. MethodsThe physicochemical properties (setting time, flow, solubility, film thickness, and radiopacity) of C3S-BG-P, Nishika BG canal sealer, and BioRoot™ RCS were evaluated in accordance with ANSI/ADA 57/2000 (reaffirmed 2012) and ISO 6876:2012 for root canal sealing materials. The in vitro apatite-forming ability was evaluated after 28 days of immersion of disc-shaped specimens in phosphate-buffered saline (PBS) using field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. ResultsThe results of physiochemical tests indicated that all the tested sealers complied with the ADA and ISO standards; however, the solubility of the BioRoot did not meet the two standards. C3S-BG-P revealed significantly superior properties in all physicochemical tests compared to Nishika and BioRoot; however, the solubility of Nishika was significantly lower than that of C3S-BG-P. Furthermore, all tested sealers exhibited apatite precipitation on their surfaces after 28 days of immersion in PBS. ConclusionsC3S-BG-P had superior physicochemical properties, which mitigated the disadvantages of calcium silicate-based sealers. Moreover, it exhibited apatite precipitation after immersion in PBS. Further in vivo studies utilizing animal models or clinical studies are necessary to support the rationale of the newly developed sealer for clinical application.

Intratubular crystal formation in the exposed dentin from nano-sized calcium silicate for dentin hypersensitivity treatment

The aim of this study is to evaluate intratubular crystal formation from the experimental material consisting of dicalcium silicate (C2S) and tricalcium silicate (C3S) with nano-scaled particle size. A total of twenty-four specimens were made by isolating 8 mm of the cervical part centered at the cementoenamel junction of extracted premolars. Twelve specimens were not treated and considered as control. The experimental material was applied to the other twelve specimens by brushing for 10,000 strokes. Each group was randomly divided into four subgroups according to the period of immersion in phosphate buffer saline (PBS) for 1, 30, 60, and 90 days each. The specimens were sectioned longitudinally and examined with scanning electron microscopy and energy dispersion X-ray spectroscopy. The intratubular crystal were formed in PBS and densely filled the dentinal tubules over time. The crystal formation occurred at a depth of more than 50 μm from the dentin surface. The Ca/P ratio of formed intratubular crystals was 1.68 after 3 months. The experimental material consisting of C2S and C3S with a nanoscale particle size can form hydroxyapatite-like crystals in dentinal tubules in PBS, and there is a possibility of reducing dentin hypersensitivity by blocking the dentinal fluid flow.

Analysis of porosity, sealer dissolution and apical extrusion of endodontic sealers: A micro computed tomography study.

The aim of the study was to determine the porosity, dissolution and apical extrusion of AH Plus, MTA Fillapex and EndoSequence BC sealer after immersion in phosphate buffered saline (PBS) using microcomputed tomography (micro-CT). Forty-eight single-rooted teeth were selected. Gutta percha and one of the aforementioned root canal sealers was used for obturation using continuous wave technique. The specimens were scanned after obturation and after seven days of immersion in PBS, by using micro-computed tomography. Porosity, sealer dissolution and apical extrusion were calculated. Statistical analysis was done by using paired t-test, post hoc tukey test and Fischer exact test. Significantly higher percentage of porosity and dissolution of sealer in the apical 4mm was found for MTA Fillapex and EndoSequence BC sealer than for AH Plus. The incidence of apical extrusion was significantly more in MTA Fillapex (56.25%), followed by EndoSequence BC (31.25%) and AH Plus (0%). None of the three root canal sealers exhibited perfect three-dimensional obturation. The sealers manifested porosity, dissolution and apical extrusion to varying degrees both after obturation and after storage in PBS for 7 days.

Synthesis of Tetraethoxysilane-Reacted Hydroxyapatite Nanoparticles and Their Stabilization in Phosphate-Buffered Saline.

Hydroxyapatite (HA) particle, which is an inorganic component of biological hard tissues, is being applied as a bioceramic for biotechnology and medicine fields. However, early bone formation is difficult in the implantation of well-known stoichiometric HA into our body. To solve this problem, it is important to control the shapes and chemical compositions of the physicochemical properties of HA to be functionalized as the state similar to the biogenic bone. In this study, the physicochemical properties of the HA particles synthesized in the presence of tetraethoxysilane (TEOS) (SiHA particles) were evaluated and investigated. In particular, the surface layers of the SiHA particles were successfully controlled by adding silicate and carbonate ions in the synthetic, which would be involved in the bone formation process, and their elusive reaction behavior with phosphate-buffered saline (PBS) was also evaluated. The results showed that the ions in the SiHA particles increased with the increase in the added TEOS concentration, and the silica oligomer was also formed on the surfaces. The ions were present not only in the HA structures but also on the surface layers, indicating the formation of the non-apatitic layer containing the hydrated phosphate and calcium ions. The change in state of the particles with the immersion in PBS was evaluated, the carbonate ions eluted from the surface layer into PBS, and the free water component in the hydration layer increased with the immersion time in PBS. Therefore, we successfully synthesized the HA particles containing silicate and carbonate ions, suggesting the important state of the surface layer consisting of the characteristic non-apatitic layers. It was found that the ions in the surface layers can react with PBS and leach out, weakening the interaction of hydrated water molecules on the particle surfaces to increase the free water component in the surface layer.

Full factorial design of experiment-based and response surface methodology approach for evaluating variation in uniaxial compressive mechanical properties, and biocompatibility of photocurable PEGDMA-based scaffolds

The goal of this study is to fabricate biocompatible and minimally invasive bone tissue engineering scaffolds that allow in situ photocuring and further investigate the effect on the mechanical properties of the scaffold due to the prevailing conditions around defect sites, such as the shift in pH from the physiological environment and swelling due to accumulation of fluids during inflammation. A novel approach of incorporating a general full factorial design of experiment (DOE) model to study the effect of the local environment of the tissue defect on the mechanical properties of these injectable and photocurable scaffolds has been formulated. Moreover, the cross-interaction between factors, such as pH and immersion time, was studied as an effect on the response variable. This study encompasses the fabrication and uniaxial mechanical testing of polyethylene glycol dimethacrylate (PEGDMA) scaffolds for injectable tissue engineering applications, along with the loss in weight of the scaffolds over 72 h in a varying pH environment that mimics in vivo conditions around a defect. The DOE model was constructed with three factors: the combination of PEGDMA and nano-hydroxyapatite referred to as biopolymer blend, the pH of the buffer solution used for immersing the scaffolds, and the immersion time of the scaffolds in the buffer solution. The response variables recorded were compressive modulus, compressive strength, and the weight loss of the scaffolds over 72 h of immersion in phosphate-buffered saline at respective pH. The statistical model analysis provided adequate information in explaining a strong interaction of the factors on the response variables. Further, it revealed a significant cross-interaction between the factors. The factors such as the biopolymer blend and pH of the buffer solution significantly affected the response variables, compressive modulus and strength. At the same time, the immersion time had a strong effect on the loss in weight from the scaffolds over 72 h of soaking in the buffer solution. The biocompatibility study done using a set of fluorescent dyes for these tissue scaffolds highlighted an enhancement in the pre-osteoblasts (OB-6) cell attachment over time up to day 14. The representative fluorescent images revealed an increase in cell attachment activity over time. This study has opened a new horizon in optimizing the factors represented in the DOE model for tunable PEGDMA-based injectable scaffold systems with enhanced bioactivity.

Electrophoretic deposition, microstructure and selected properties of zein/cloves coatings on 316L stainless steel

In the present study, we develop zein coatings containing cloves (flower buds of the Syzygium aromaticum tree, a well-known aromatic natural herb) on stainless steel substrates via electrophoretic deposition. The antibacterial activity, drug release, surface (morphology, roughness, and wettability), corrosion, and adhesion properties of the produced zein/cloves coatings were elucidated in detail. The coatings deposited an applied electric field of 20 V/cm with a deposition time of 5 min yielded uniform zein/cloves coatings with a thickness of ~9 μm, which was confirmed by scanning electron microscopy. Fourier transformation infrared spectroscopy analysis confirmed the presence of zein and cloves functional groups in the zein/cloves coatings. The results of tape tests exhibited that the adhesion between the coatings and the substrate was rated as ‘5B’ (Excellent) according to the ASTM-D3359 standard. The zein/cloves coatings exhibited an average roughness of 0.8 ± 0.05 and a contact angle of 60° ± 2°, making them appropriate for orthopedic applications. The antibacterial studies exhibited that the zein/cloves coatings developed zone of inhibition against Staphylococcus aureus and Escherichia coli, confirming the strong antibacterial potential of the coatings. UV–Vis Spectroscopy elucidated that after one week of immersion in phosphate buffer saline, ~65 % of eugenol was released from the zein/cloves coatings. Furthermore, the zein/cloves coatings improved the corrosion resistance by ~3 orders of magnitude compared to bare 316L stainless steel. Antimicrobial and drug release studies confirmed that the zein/cloves coatings can provide a targeted drug delivery system with a potent antimicrobial effect.

Microstructured Optical Fiber Made From Biodegradable and Biocompatible Poly(D,L-Lactic Acid) (PDLLA)

We have fabricated and characterized microstructured biodegradable and biocompatible polymer optical fibers using commercially available poly(D,L-lactic acid) (PDLLA). We first report on the preparation of the preforms by means of a novel technique based on transfer molding and on the fiber manufacturing using a regular heat-drawing process. We address the influence of the polymer processing on the decrease of the molar mass of PDLLA following the preform fabrication and the fiber optic drawing process. We investigate the in vitro degradation of the fabricated fibers in phosphate buffered saline (PBS) that reveals 21, 25 and 43% molar mass loss over a period of 105 days for fibers with diameters of 400, 200 and 100 μm, respectively. Cutback measurements return an attenuation coefficient as low as 0.065 dB/cm at 898 nm for a microstructured fiber with a diameter of 219 ± 27 μm. Due to immersion in PBS at 37 °C, the optical loss increases by 0.4 dB/cm at 950 nm after 6 h and by 0.8 dB/cm after 17 h.

Nova proposta para avaliação da solubilidade de materiais biocerâmicos em tubos de dentina após imersão em PBS: um estudo laboratorial

Abstract Introduction Repair materials must have low solubility. Phosphate buffered saline (PBS) allows simulating clinical condition and interaction with dentin may be important for the correct evaluate of mass loss of bioceramic cements. Objective To evaluate the effect of distilled water (DW), or PBS immersion on the solubility of Bio-C Repair (BCR, Angelus) or MTA Repair HP (MTAHP, Angelus) using a dentin tube model. Material and method Bovine dentin tubes with a length of 4 mm, an internal diameter of 1.5 mm and walls thickness of approximately 1 mm were made. The specimens were immersed in DW for 24h, then filled with BCR or MTAHP (n = 14) and stored in an oven at 37°C and 95% humidity for 24h. After being weighed on a precision balance to determine the initial mass, the specimens were immersed in DW (pH 6.5) or PBS (pH 7.0) (n = 7) for 28 days. Empty tubes also were used for calculating the mass loss of the dentin (n=4). After this period, the specimens were weighed until stabilization of the final mass occurred (0.001g). The solubility of each material was evaluated. ANOVA and Tukey statistical tests were performed (α=0.05). Result BCR and MTAHP showing gain of mass in DW and mass loss in PBS (p&lt;0.05). Conclusion The immersion solution influenced the solubility of BCR and MTAHP using dentin tube model. The new methodological proposal could be an alternative to ISO standards for testing the solubility of bioceramic cements.

Characterization and In Vitro Biocompatibility of Two New Bioglasses for Application in Dental Medicine-A Preliminary Study.

Bioactive glasses (BGs), also known as bioglasses, are very attractive and versatile materials that are increasingly being used in dentistry. For this study, two new bioglasses-one with boron (BG1) and another with boron and vanadium (BG2)-were synthesized, characterized, and tested on human dysplastic keratinocytes. The in vitro biological properties were evaluated through pH and zeta potential measurement, weight loss, Ca2+ ions released after immersion in phosphate-buffered saline (PBS), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) analysis. Furthermore, biocompatibility was evaluated through quantification of lactate dehydrogenase activity, oxidative stress, transcription factors, and DNA lesions. The results indicate that both BGs presented the same behavior in simulated fluids, characterized by high degradation, fast release of calcium and boron in the environment (especially from BG1), and increased pH and zeta potential. Both BGs reacted with the fluid, particularly BG2, with irregular deposits covering the glass surface. In vitro studies demonstrated that normal doses of the BGs were not cytotoxic to DOK, while high doses reduced cell viability. Both BGs induced oxidative stress and cell membrane damage and enhanced NFkB activation, especially BG1. The BGs down-regulated the expression of NFkB and diminished the DNA damage, suggesting the protective effects of the BGs on cell death and efficacy of DNA repair mechanisms.

Determination of Optimum Zn Content for Mg–xZn–0.5Mn–0.5Sr Alloy in Terms of Mechanical Properties and In Vitro Corrosion Resistance

This study investigated the microstructure, compressive properties and in vitro corrosion behavior of biodegradable Mg–xZn–0.5Mn–0.5Sr (ZMJ) alloy with Zn content of 0 to 5 wt% in the as-cast state. Increasing the Zn content in ZMJ alloy refined the grains from 215 to 95 µm and changed the secondary particles from Mg17Sr2 to Mg6Zn2Sr and MgZn phases. As the Zn content increased, the compressive yield strength increased from 44 to 67 MPa due to grain boundary strengthening. At immersion in phosphate-buffered saline for 7 days, the addition of Zn from 0 to 0.1 wt% reduced the corrosion rate from 0.71 to 0.48 mm/y, and 0.85 wt% Zn was alloyed to obtain the lowest corrosion rate of 0.45 mm/y. However, adding more Zn significantly increased the corrosion rate up to 3.31 mm/y. Thus, the best anti-corrosion performance can be obtained at 0.85 wt% Zn, which was attributed to its lowest Volta potential difference between the main secondary particles and the α-Mg matrix among ZMJ alloy. Based on this, the optimal Zn content for ZMJ alloy can be determined to be about 1 wt% by comprehensively considering the mechanical properties and in vitro corrosion behavior for biomedical applications. Graphical abstractMicrographs of (a,c) the specimen as-built in vertical direction (Type I) and (b,d) the specimen as-built in horizontal direction (Type II) to the building platform.

Influence of the argon ratio on the structure and properties of thin films prepared using PECVD in TMSAc/Ar mixtures

Capacitively coupled RF glow discharge was used to form novel coatings of SiOxCyHz using varying proportions of trimethylsilyl acetate (TMSAc) monomer and the carrier gas argon. The properties of the TMSAc-based plasma polymers produced depend significantly on the proportion of argon in TMSAc/Ar gaseous mixture, which ranged from 0 % to 75 %. Reaction mixtures containing less than 50 % Ar produced hydrophobic polymers, for which the indentation hardness values were less than 1.5 GPa. Seventy-five percent argon in the reaction mixture yielded a crosslinked carbon-rich organosilicon structure with a hardness of 6 GPa. As many applications require good stability in a liquid environment, the TMSAc-based coatings were immersed in phosphate buffered saline (PBS) for 14 days. Because any material used in a medical application must be resistant to the techniques used for sterilization, the prepared coatings were subjected to a standard sterilization procedure using UVC radiation. A degree of the structural changes induced by both environments corresponded to the argon ratio used for production of thin films. Possible degradation mechanisms were examined and discussed. Using 7.7–21.4 % Ar during the deposition process led to the TMSAc-based plasma polymers exhibiting good resistance to the prolonged immersion in PBS and UVC sterilization.

Physicochemical and Biological Properties of AH Plus Bioceramic

IntroductionThe purpose of this study was to evaluate the physicochemical and biological properties of AH Plus Bioceramic (AHPB; Dentsply Sirona, Charlotte, NC) in comparison to AH Plus (AHP, Dentsply Sirona) and EndoSequence BC Sealer (BC; Brasseler, Savannah, GA). MethodsThe setting time, radiopacity, flow, solubility, calcium ion release, and pH were evaluated following ISO guidelines. Surface characterization and chemical constitution were evaluated by scanning electron microscopy/energy-dispersive X-ray spectroscopy. The antibacterial effect was tested against Enterococcus faecalis. Sealer cytotoxicity was tested using the XTT cell viability assay. Analysis of variance, Tukey, and unpaired t tests were used with a significance level of 5%. ResultsThe initial setting time of AHPB was shorter than AHP and BC (P ≤ .0001), whereas AHP showed a shorter final setting time (P ≤ .0001). AHPB was more radiopaque than BC (P = .0012) but less radiopaque than AHP (P = .0001). AHPB was more soluble than AHP (P ≤ .0001), whereas no difference was observed between AHPB and BC (P > .05). Immersion in phosphate-buffered saline decreased the solubility of AHPB and BC (P ≤ .005). AHPB calcium ion release was higher than AHP (P ≤ .05) but less than BC (P ≤ .0001). AHPB had the highest flow followed by AHP and BC (P > .05). All sealers were alkaline and able to eradicate E. faecalis. Surface morphology and chemical composition of all sealers changed after immersion in water and phosphate-buffered saline. Cell viability for AHPB and BC was higher than AHP (P ≤ .0001). ConclusionsAHPB presented adequate properties to be considered a good sealer, however, the high solubility may negatively impact the quality of the obturation.

The effect of polyethylene glycol on printability, physical and mechanical properties and osteogenic potential of 3D-printed poly (l-lactic acid)/polyethylene glycol scaffold for bone tissue engineering

One of the challenges in critical size bone defect repairing is the use of a porous degradable scaffold with appropriate properties to the host tissue. Nowadays, the three-dimensional (3D) printing method can produce custom and personalized scaffolds and overcome the problems of traditional methods by controlling the porosity and dimensions of biomaterial scaffolds. In this study, polylactic acid/polyethylene glycol (PLA/PEG) scaffolds were prepared with different PEG percentages (0, 5, 10, 15 and 20 wt%) by fused deposition modeling (FDM) to optimize printability and achieve suitable physico-mechanical properties and also enhance cellular behavior for bone tissue engineering and actually, this study complements previous studies. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were employed for chemical, morphological and thermal evaluations, respectively. It was shown that the adding of 20 wt% PEG to PLA 3D printed scaffolds reduced water contact angle (from 78.16 ± 3.27 to 60.00 ± 2.16), and increased surface wettability. The results also showed that the mechanical properties of the printed scaffolds were not significantly reduced by adding 5 and 10 wt% of PEG. The addition of PEG increased the degradability of scaffolds during immersion in phosphate buffer saline (PBS) solution for 8 weeks and PLA/PEG20 scaffold with 50.96 % had the highest rate of degradation. MTT assay showed that none of the studied scaffolds had cytotoxicity against MG-63 cells and increasing the PEG levels to 20 wt%, increased cell viability and adhesion and osteogenic differentiation. According to the obtained physical, mechanical and biological results, PLA/PEG scaffold printed by the FDM method can be an appropriate candidate for use in bone repair applications.

Acid neutralizing and remineralizing orthodontic adhesive containing hydrated calcium silicate

ObjectivesThe objective of this study was to evaluate an orthodontic adhesive containing hydrated calcium silicate (hCS) in terms of its bond strength with the enamel surface and its acid-neutralization and apatite-forming abilities. MethodsThe experimental orthodontic adhesives were composed of 30 wt.% resin matrix and 70 wt.% filler, which itself was a mixture of silanized glass filler and hCS in weight ratios of 100% glass filler (hCS 0), 17.5% hCS (hCS 17.5), 35% hCS (hCS 35.0), and 52.5% hCS (hCS 52.5). The degree of conversion (DC) and shear bond strength (SBS) of bovine enamel surfaces were tested. pH measurements were performed immediately upon submersion of the specimens in a lactic acid solution. The surface precipitates that formed on specimens immersed in phosphate-buffered saline (PBS) were analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and Raman spectroscopy after 15, 30, and 90 days. ResultsThe experimental groups exhibited no significant differences in DC and had clinically acceptable SBS values. The hCS-containing groups showed increasing pH values as more hCS was added. hCS 52.5 produced Ca- and P-containing surface precipitates after PBS immersion, and hydroxyapatite deposition was detected after 15, 30, and 90 days. ConclusionsThese results suggest that orthodontic adhesives containing hCS are effective for acid neutralization. Furthermore, hCS has an apatite-forming ability for enamel remineralization. Clinical significanceThe novel orthodontic adhesive containing hCS exhibits a potential clinical benefit against demineralization and enhanced remineralization of the enamel surface around or beneath the orthodontic brackets.

Development of an electrospun poly(\u03b5-caprolactone)/collagen-based human amniotic membrane powder scaffold for culturing retinal pigment epithelial cells

The common retinal diseases are age-related macular degeneration (AMD) and retinitis pigmentosa (RP). They are usually associated with the dysfunction of retinal pigment epithelial (RPE) cells and degeneration of underlying Bruch’s membrane. The RPE cell transplantation is the most promising therapeutic option to restore lost vision. This study aimed to construct an ultrathin porous fibrous film with properties similar to that of native Bruch’s membrane as carriers for the RPE cells. Human amniotic membrane powder (HAMP)/Polycaprolactone (PCL) scaffolds containing different concentrations of HAMP were fabricated by electrospinning technique. The results showed that with increasing the concentration of HAMP, the diameter of fibers increased. Moreover, hydrophilicity and degradation rate were improved from 119° to 92° and 14 to 56% after 28 days immersion in phosphate-buffered saline (PBS) solution, respectively. All scaffolds had a porosity above 85%. Proper cell adhesion was obtained one day after culture and no toxicity was observed. However, after seven days, the rate of growth and proliferation of ARPE-19 cells, a culture model of RPE, on the PCL-30HAMP scaffold (HAMP concentration in PCL 7.2% by weight) was higher compared to other scaffolds. These results indicated that PCL-30HAMP fibrous scaffold has a great potential to be used in retinal tissue engineering applications.