Comparison via Digital Radiography of Radiopacity Levels of Composite Materials with Various Shades and Viscosities

Aim of the present in vitro study is to evaluate the radiopacity levels of composite resins with various shades and viscosity.10 mm×2 mm discs were prepared from 7 condensable and 4 flowable composites(n=10).An aluminum step wedge ranging from 2.0 to 10.0 mm in thickness was placed on the occlusal film.Digital radiographs were taken using a dental X-ray device and radiographic densities of each step of the aluminum wedge and the samples were recorded to the computer.Five readings were taken and means were calculated.One-Way Anova and Tamhane post hoc tests were performed.While G-eanial Posterior has the highest radiopacity value followed by Filtek Z550,Aelite Flo has the lowest radiopacity value.Posterior composites show higher radiopacity and flowable composites with higher filler loadings have superior radiopacity levels to condensable composites.Enamel and body shades of the composite brands have also statistically significant differences in radiopacity scores.Eventually,radiopacity level of a composite resin material is not affected by the size of fillers;however,the composition,shape and loading of the fillers can specify the radiodensity.

Injectable and thermosensitive hydrogels mediating a universal macromolecular contrast agent with radiopacity for noninvasive imaging of deep tissues

It is very challenging to visualize implantable medical devices made of biodegradable polymers in deep tissues.Herein,we designed a novel macromolecular contrast agent with ultrahigh radiopacity(iodinate content>50%)via polymerizing an iodinated trimethylene carbonate monomer into the two ends of poly(ethylene glycol)(PEG).A set of thermosensitive and biodegradable polyester-PEG-polyester triblock copolymers with varied polyester compositions synthesized by us,which were soluble in water at room temperature and could spontaneously form hydrogels at body temperature,were selected as the demonstration materials.The addition of macromolecular contrast agent did not obviously compromise the injectability and thermogelation properties of polymeric hydrogels,but conferred them with excellent X-ray opacity,enabling visualization of the hydrogels at clinically relevant depths through X-ray fluoroscopy or Micro-CT.In a mouse model,the 3D morphology of the radiopaque hydrogels after injection into different target sites was visible using Micro-CT imaging,and their injection volume could be accurately obtained.Furthermore,the subcutaneous degradation process of a radiopaque hydrogel could be non-invasively monitored in a real-time and quantitative manner.In particular,the corrected degradation curve based on Micro-CT imaging well matched with the degradation profile of virgin polymer hydrogel determined by the gravimetric method.These findings indicate that the macromolecular contrast agent has good universality for the construction of various radiopaque polymer hydrogels,and can nondestructively trace and quantify their degradation in vivo.Meanwhile,the present methodology developed by us affords a platform technology for deep tissue imaging of polymeric materials.

Improving the radiopacity of Fe-Mn biodegradable metals by magnetron-sputtered W-Fe-Mn-C coatings:Application for thinner stents

In this exploratory work,micrometric radiopaque W-Fe-Mn-C coatings were produced by magnetron sputtering plasma deposition,for the first time,with the aim to make very thin Fe-Mn stents trackable by fluoroscopy.The power of Fe-13Mn-1.2C target was kept constant at 400 W while that of W target varied from 100 to 400 W producing three different coatings referred to as P100,P200,P400.The effect of the increased W power on coatings thickness,roughness,structure,corrosion behavior and radiopacity was investigated.The coatings showed a power-dependent thickness and W concentration,different roughness values while a similar and uniform columnar structure.An amorphous phase was detected for both P100 and P200 coatings while γ-Fe,bcc-W and W_(3)C phases found for P400.Moreover,P200 and P400 showed a significantly higher corrosion rate(CR)compared to P100.The presence of W,W_(3)C as well as the Fe amount variation determined two different micro-galvanic corrosion mechanisms significantly changing the CR of coatings,0.26±0.02,59.68±1.21 and 59.06±1.16μm/year for P100,P200 and P400,respectively.Sample P200 with its most uniform morphology,lowest roughness(RMS=3.9±0.4 nm)and good radiopacity(~6%)appeared the most suitable radiopaque biodegradable coating investigated in this study.

Production and characterisation of new bioresorbable radiopaque Mg–Zn–Y alloy to improve X-ray visibility of polymeric scaffolds

For the medical diagnosis,radiopaque materials(RM)made from high specific gravity elements like Pt,Au,Ta,Iodine,Bromine are either attached or blended or coated on an implant to makes it detectable under X-ray/Fluoroscopy/CT-Scan.RM facilitate the surgeon in an operation theatre to position an implant during the surgery.Mainly,RM are non-degradable,thus in case of biodegradable implants,it may detach from the body and accumulate in vital organ cause serious health issue.Therefore,a new bioresorbable radiopaque material(BRM)was produced by alloying the high specific gravity elements Zn(35%w/w)and Y(4%w/w)with Mg metal.In this alloy,three main phases were identified,alpha Mg,Mg_(7)Zn_(3)and icosahedral quasicrystalline I-phase Mg3Zn6Y,which reinforce the Mg matrix.Hereafter,BRM was powdered to a size of less than 25 microns and blended in different ratios with bioresorbable poly-L-lactic acid(PLLA)for fabricating PLLA/BRM bio-composite.BRM microparticles were uniformly distributed and interfacial bonded with the matrix.The X-ray was passed through bio-composite to captureμCT radiograph for evaluating linear attenuation co-efficient(μ)and optical density(OD).Thermal analysis reveals that BRM particles act as a nucleating site and enhance the crystallinity of the polymeric chain.During the In Vitro accelerated degradation study,the alkaline nature of BRM neutralise the acidity of PLLA and balance the pH of the body fluid to reduce the inflammatory reactions,but this compromises the stability of the polymer as it increases the decomposition rate.

A General Strategy for Efficiently Constructing Multifunctional Cluster Fillers Using a Three-Fluid Nozzle Spray Drying Technique for Dental Restoration

Multifunctional fillers are greatly required for dental resin composites(DRCs).In this work,a spray dryer with a three-fluid nozzle was applied for the first time to construct high-performance complex nanoparticle clusters(CNCs)consisting of different functional nanofillers for dental restoration.The application of a three-fluid nozzle can effectively avoid the aggregation of different nanoparticles with opposite zeta potentials before the spray drying process in order to construct regularly shaped CNCs.For a SiO_(2)–ZrO_(2) binary system,the SiO_(2)–ZrO_(2) CNCs constructed using a three-fluid nozzle maintained their excellent mechanical properties((133.3±4.7)MPa,(8.8±0.5)GPa,(371.1±13.3)MPa,and(64.5±0.7)HV for flexural strength,flexural modulus,compressive strength,and hardness of DRCs,respectively),despite the introduction of ZrO_(2) nanoparticles,whereas their counterparts constructed using a two-fluid nozzle showed significantly decreased mechanical properties.Furthermore,heat treatment of the SiO_(2)-ZrO_(2) CNCs significantly improved the mechanical properties and radiopacity of the DRCs.The DRCs containing over 10%mass fraction ZrO_(2) nanoparticles can meet the requirement for radiopaque fillers.More importantly,this method can be expanded to ternary or quaternary systems.DRCs filled with SiO_(2)-ZrO_(2)-ZnO CNCs with a ratio of 56:10:4 displayed high antibacterial activity(antibacterial ratio>99%)in addition to excellent mechanical properties and radiopacity.Thus,the three-fluid nozzle spray drying technique holds great potential for the efficient construction of multifunctional cluster fillers for DRCs.

Rosuvastatin‑Eluting Gold‑Nanoparticle‑Loaded Perivascular Wrap for Enhanced Arteriovenous Fistula Maturation in a Murine Model

Arteriovenous fistulas(AVFs)are a vital form of AV access for patients requiring hemodialysis,but they link to overall morbidity and mortality when they fail to mature.The most common cause of AVF non-maturation is neointimal hyperplasia(NIH).To minimize the deleterious effects of NIH,a perivascular wrap composed of polycaprolactone(PCL),rosuvastatin(ROSU),and gold nanoparticles(AUNPs)was constructed.This study assessed the impact of ROSU-eluting,radiopaque resorbable perivascular wraps on pathologic NIH in a chronic kidney disease(CKD)rodent model of AVF.Electrospun PCL wraps containing AuNPs and/or ROSU were monitored for in vitro tensile strength,AuNP release,ROSU elution,and effect on cellular viability.The wraps were then implanted around an AVF in a CKD rodent model for in vivo ultrasound(US)and micro-computed tomography(mCT)imaging.AVF specimens were collected for histological analyses.Cell viability was preserved in the presence of both AuNP-and ROSU-containing wraps.In vitro release of ROSU and AuNPs correlated with in vivo findings of decreasing radiopacity on mCT over time.AuNP-loaded wraps had higher radiopacity(1270.0-1412.0 HU at week 2)compared with other wraps(103.5-456.0 HU),which decreased over time.The addition of ROSU decreased US and histologic measurements of NIH.The reduced NIH seen with ROSU-loaded perivascular wraps suggests a synergistic effect between mechanical support and anti-hyperplasia medication.Furthermore,AuNP loading increased wrap radiopacity.Together,our results show that AuNP-and ROSU-loaded PCL wraps induce AVF maturation and suppress NIH while facilitating optimal implanted device visualization.

Immobilized thrombin on X-ray radiopaque polyvinyl alcohol/chitosan embolic microspheres for precise localization and topical blood coagulation

Trans-catheter arterial embolization(TAE)plays an important role in treating various diseases.The available embolic agents lack X-ray visibility and do not prevent the reflux phenomenon,thus hindering their application for TAE therapy.Herein,we aim to develop a multifunctional embolic agent that combines the X-ray radiopacity with local procoagulant activity.The barium sulfate nanoparticles(BaSO4 NPs)were synthesized and loaded into the polyvinyl alcohol/chitosan(PVA/CS)to prepare the radiopaque BaSO4/PVA/CS microspheres(MS).Thereafter,thrombin was immobilized onto the BaSO4/PVA/CS MS to obtain the thrombin@BaSO4/PVA/CS MS.The prepared BaSO4/PVA/CS MS were highly spherical with diameters ranging from 100 to 300μm.In vitro CT imaging showed increased X-ray visibility of BaSO4/PVA/CS MS with the increased content of BaSO4 NPs in the PVA/CS MS.The biocompatibility assessments demonstrated that the MS were non-cytotoxic and possessed permissible hemolysis rate.The biofunctionalized thrombin@BaSO4/PVA/CS MS showed improved hemostatic capacity and facilitated hemostasis in vitro.Additionally,in vivo study performed on a rabbit ear embolization model confirmed the excellent X-ray radiopaque stability of the BaSO4/PVA/CS MS.Moreover,both the BaSO4/PVA/CS and thrombin@BaSO4/PVA/CS MS achieved superior embolization effects with progressive ischemic necrosis on the ear tissue and induced prominent ultrastructural changes in the endothelial cells.The findings of this study suggest that the developed MS could act as a radiopaque and hemostatic embolic agent to improve the embolization efficiency.

In-chain functionalization through the combination of ring opening copolymerization and oxime "Click" reaction towards X-ray opaque polylactide copolymers

X-ray imaging functionalization of biodegradable polyesters is a great demand and challenge in biomedical applications.In this work,a strategy of in-chain functionalization through the combination of ring opening copolymerization and oxime "Click" postfunctionalization was developed towards X-ray opaque polylactide copolymers.A functionalized cyclic carbonate was first synthesized and used as comonomer of polylactide copolymers,which were subjected to postfunctionalization of oxime "Click" reaction towards iodinated polylactide copolymers.The chemical structure and physical properties of the target products were traced and confirmed.In vitro cytotoxicity evaluation with 3T3-Swiss albino by Alamar blue demonstrated a low cytotoxicity.The X-ray radiopacity was analyzed by Micro-CT and quantified by Hounsfield Units value,which could be tailorable by the feedstock.It is a promising X-ray visible implantable biomaterial in biomedical applications.