Radiopacity of Methacrylate and Silorane Composite Resins Using a Digital Radiographic System.
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ABSTRACT:
SUBMITTER: Firoozmand LM
PROVIDER: S-EPMC5046049 | biostudies-other | 2016
REPOSITORIES: biostudies-other
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Project description:ObjectivesThis study probes how modifiedapproaches for filler surface treatment in dental composites based on alternative silanes and functional nanogel additives affects physicochemical properties of these materials with a focus on polymerization stress development.MethodsNanogels were synthesized from isobornyl methacrylate, ethoxylated bisphenol-A dimethacrylate and isocyanatoethyl methacrylate followed by partial further reaction with 2-hydroxyethyl methacrylate to provide both isocyanate and methacrylate functionalization. A barium glass filler (˜1 μm particle size) was treated with either γ-methacryloxypropyltrimethoxysilane (MPS), N-methylaminopropyltrimethoxy (MAP) or N-allylaminopropyltrimethoxy (AAP) silanes. The reactive nanogels were then covalently attached to the aminosilane-treated fillers. Surface treatment was characterized by thermogravimetric analysis (TGA) and diffuse reflectance infrared spectroscopy (DR-IR). Composites were formulated with 60 wt% of the various functionalized fillers and the materials were evaluated for polymerization kinetics, polymerization stress (PS), volumetric shrinkage, mechanical properties and photorheology. Data were evaluated by one-way ANOVA and Tukey's test at 5% significance level.ResultsFiller surface treatments were confirmed by TGA and DR-IR analyses. Nanogel-functionalized fillers significantly reduced PS up to 20%, while the degree of conversion and elastic modulus were not compromised. Similar storage modulus development during polymerization was observed among materials by photorheology although the rate of polymerization was significantly increased for nanogel-based treatments. A significant decrease in flexural strength was observed for amino functional silane groups; however, there was no statistical difference in strength for the MPS control group compared with the nanogel-modified composites.SignificanceFiller surface treatment modified with a reactive nanogel enables significant PS reduction, without compromise to degree of conversion or mechanical properties of dental composites.
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Project description:The study aimed to compare the sensitivity and specificity of digital radiographic systems for the diagnosis of proximal carious lesions. Extracted human teeth (3 canines, 3 premolars, and 3 molars) were submitted to one of three types of proximal lesions (demineralized area, cavity affecting the enamel alone, and cavity affecting enamel and dentin). Bitewing radiographs were obtained from each system (Sirona, Kodak, and Schick) and evaluated by 12 raters (4 dental students, 4 radiology specialists, and 4 dentists). The chi-squared test was used to determine the frequency of correct diagnoses among the different systems, raters, teeth, and types of lesion. Sensitivity and specificity regarding demineralized areas were calculated for each system. The frequencies of correct diagnoses were found: Schick (70.8%), Kodak (63.9%), Sirona (59.0%), specialists (69.4%), students (62.5%), dentists (61.8%), premolars (70.1%), canines (65.3%), and molars (58.3%). No significant differences were found among the different systems, raters, or teeth (P > 0.05). Sensitivity and specificity were 0.64 and 0.47 (Schick), 0.56 and 0.50 (Sirona), and 0.48 and 0.58 (Kodak). The most correct diagnoses were achieved using the Schick digital system on premolars and evaluated by specialists in radiology. The systems demonstrated low sensitivity and specificity for the diagnosis of demineralized areas.
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Project description:Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures.
| S-EPMC4870681 | biostudies-literature
Project description:The creation of biodegradable and biocompatible shape memory polymers amenable to biofabrication techniques remains a challenge. The ability to create shape-changing biodegradable objects that are triggered at body temperature opens up possibilities in tissue engineering, minimally invasive surgery, and actuating bioimplants. Merging Digital Light Processing (DLP) printing with shape memory polymers brings us closer to new smart biomedical outcomes. Previously, we developed a poly(caprolactone-co-trimethylenecarbonate) urethane acrylate resin for the DLP fabrication of biodegradable 3D objects. In further studies, we observed that some of these resins possessed shape memory properties, triggered by body temperature (37 °C). In this subsequent study, we explored the shape memory properties and tunability of this resin family via changes in copolymer composition, molecular weight, and identity of the acrylate end-capping unit. We found that we could create a library of shape memory resins, amenable to DLP printing, which allowed the creation of shape-actuating structures with some tunability over the speed of shape memory and mechanical properties. We observed that increased mole fraction of caprolactone in the copolymer and increased molecular weight of the polymer led to a decrease in speed of the shape memory switch. Furthermore, we observed a trade-off between the composition and the end-capping moiety on the mechanical properties of the polymers. These polymeric resins were able to be processed into shapes that were able to perform work, including the release of cargo and grabbing/lifting of an object. This platform now provides a way to tune the speed and mechanical properties of a shape memory DLP object created from common and scalable polymerization techniques. This work ultimately provides a new platform to develop customizable and biodegradable devices capable of actuating and delivery devices for numerous biomedical applications.
| S-EPMC11322996 | biostudies-literature
Project description:The aim of the study was to evaluate the cytotoxic and genotoxic potential of five commercially available dental composite resins (CRs), investigating the effect of their quantifiable bisphenol-A-glycidyl-methacrylate (Bis-GMA) and/or triethylene glycol dimethacrylate (TEGDMA) release. Experiments were performed using the method of soaking extracts, which were derived from the immersion of the following CRs in the culture medium: Clearfil-Majesty-ES-2, GrandioSO, and Enamel-plus-HRi (Bis-GMA-based); Enamel-BioFunction and VenusDiamond (Bis-GMA-free). Human Gingival Fibroblasts (hGDFs) were employed as the cellular model to mimic in vitro the oral cavity milieu, where CRs simultaneously release various components. Cell metabolic activity, oxidative stress, and genotoxicity were used as cellular outcomes. Results showed that only VenusDiamond and Enamel-plus-HRi significantly affected the hGDF cell metabolic activity. In accordance with this, although no CR-derived extract induced a significantly detectable oxidative stress, only VenusDiamond and Enamel-plus-HRi induced significant genotoxicity. Our findings showed, for the CRs employed, a cytotoxic and genotoxic potential that did not seem to depend only on the actual Bis-GMA or TEGDMA content. Enamel-BioFunction appeared optimal in terms of cytotoxicity, and similar findings were observed for Clearfil-Majesty-ES-2 despite their different Bis-GMA/TEGDMA release patterns. This suggested that simply excluding one specific monomer from the CR formulation might not steadily turn out as a successful approach for improving their biocompatibility.
| S-EPMC8468467 | biostudies-literature
Project description:The paper reviews the environmental factors affecting ageing processes, and the degradation of resins, filler, and the filler-matrix interface. It discusses the current methods of testing materials in vitro. A review of literature was conducted with the main sources being PubMed. ScienceDirect, Mendeley, and Google Scholar were used as other resources. Studies were selected based on relevance, with a preference given to recent research. The ageing process is an inherent element of the use of resin composites in the oral environment, which is very complex and changes dynamically. The hydrolysis of dental resins is accelerated by some substances (enzymes, acids). Bonds formed between coupling agent and inorganic filler are prone to hydrolysis. Methods for prediction of long-term behaviour are not included in composite standards. Given the very complex chemical composition of the oral environment, ageing tests based on water can only provide a limited view of the clinical performance of biomaterial. Systems that can reproduce dynamic changes in stress (thermal cycling, fatigue tests) are better able to mimic clinical conditions and could be extremely valuable in predicting dental composite clinical performance. It is essential to identify procedure to determine the ageing process of dental materials.
| S-EPMC7240588 | biostudies-literature
Project description:We describe an approach for the discrete and reversible assembly of tunable and actively deformable structures using modular building block parts for robotic applications. The primary technical challenge addressed by this work is the use of this method to design and fabricate low density, highly compliant robotic structures with spatially tuned stiffness. This approach offers a number of potential advantages over more conventional methods for constructing compliant robots. The discrete assembly reduces manufacturing complexity, as relatively simple parts can be batch-produced and joined to make complex structures. Global mechanical properties can be tuned based on sub-part ordering and geometry, because local stiffness and density can be independently set to a wide range of values and varied spatially. The structure's intrinsic modularity can significantly simplify analysis and simulation. Simple analytical models for the behavior of each building block type can be calibrated with empirical testing and synthesized into a highly accurate and computationally efficient model of the full compliant system. As a case study, we describe a modular and reversibly assembled wing that performs continuous span-wise twist deformation. It exhibits high performance aerodynamic characteristics, is lightweight and simple to fabricate and repair. The wing is constructed from discrete lattice elements, wherein the geometric and mechanical attributes of the building blocks determine the global mechanical properties of the wing. We describe the mechanical design and structural performance of the digital morphing wing, including their relationship to wind tunnel tests that suggest the ability to increase roll efficiency compared to a conventional rigid aileron system. We focus here on describing the approach to design, modeling, and construction as a generalizable approach for robotics that require very lightweight, tunable, and actively deformable structures.
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Project description:In this work, nanocomposites of poly(methyl methacrylate) (PMMA) with cellulose nanofiber (CNF) were prepared by a solution casting technique. CNF was modified by propionic anhydride (PA) to form surface-propionylated CNF (CNFp) to improve its compatibility with the PMMA matrix. CNF, CNFp, and acetylated CNF were compared with respect to their influence as fillers in PMMA composite films by ultraviolet-visible transmittance, haze values, tensile strength testing, and water contact angle measurement. It was demonstrated that 1 wt % of CNFp has good compatibility and uniform dispersion in the PMMA matrix, as demonstrated by the formation of a smooth surface composite film with good transparency, enhanced tensile properties, improved toughness, and lower wettability. Therefore, PMMA/CNFp composite films have great potential for use in several applications such as lightweight transparent materials, window substitutes, and see-through packaging.
| S-EPMC8153788 | biostudies-literature
Project description:Introduction:This in vitro study compared the shear strength of three composite resin systems to fluorosed and normal dentin. Methods:Silorane FiltekTM P90, FiltekTMZ250 XT in combination with the adhesive system AdperTM Single bond 2, and Amelogen® Plus in association with Peak Universal Bond® were tested. Fifteen normal and 15 fluorosed dentine disks were prepared per material. The shear bond strength test was performed using a universal machine. Results:One-way ANOVA revealed significant differences in bond strength between the tested composite resins. All tested materials had significantly different adhesion at the fluorosed and the nonfluorosed interface. FiltekTM Z250 XT and Silorane had lower adhesion values to fluorosed than to normal dentin. In contrast, Amelogen® Plus presented a better average resistance at the fluorosed interface. Conclusion:Amelogen® Plus presented a better average shear bond strength on the fluorosed dentine. FiltekTMZ250 XT showed the best adhesion forces and shear bond strength with sound dentine. Further studies are needed to better understand the sealing of these systems.
| S-EPMC7171611 | biostudies-literature
Project description:The introduction of 3D printing technology in dentistry has opened new treatment options. The ongoing development of different materials for these printing purposes has recently enabled the production of definitive indirect restorations via 3D printing. To identify relevant data, a systematic search was conducted in three databases, namely PubMed, Scopus, and Web of Science. Additionally, a manual search using individual search terms was performed. Only English, peer-reviewed articles that encompassed in vitro or in vivo research on the mechanical properties of 3D-printed composite materials were included, provided they met the predefined inclusion and exclusion criteria. After screening 1142 research articles, 14 primary studies were selected. The included studies mainly utilized digital light processing (DLP) technology, less commonly stereolithography (SLA), and once PolyJet printing technology. The material properties of various composite resins, such as VarseoSmile Crown Plus (VSC) and Crowntec (CT), were studied, including Vickers hardness, flexural strength, elastic modulus, compressive strength, tensile strength, fracture resistance, and wear. The studies aimed to compare the behavior of the tested additive composites to each other, conventional composites, and subtractive-manufactured materials. This scoping review examined the mechanical properties of composites used for 3D printing of definitive restorations. The aim was to provide a comprehensive overview of the current knowledge on this topic and identify any gaps for future research. The findings suggest that 3D-printed composites are not yet the first option for indirect restorations, due to their insufficient mechanical properties. Due to limited evidence, more research is needed in this area. Specifically, there is a need for clinical trials and long-term in vivo research.
| S-EPMC11355578 | biostudies-literature