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Background: Marginal adaptation is one of biggest challenges in restorative dentistry, mainly in restoration of composite resin. Even with development of lower shrinkage materials, like those which use the polymer silorane, it is necessary a faithful clinical protocol in order to obtain better results and more clinical durability of restorative procedure. The purpose of this study was investigated if different polymers can influence on marginal adaptation of different composite resin restorations. Material and methods: Twenty class V cavities were confectioned in twenty human molars in a standardized way. Ten dentists received one tooth each and a questionnaire to describe their own clinical protocol. The other 10 teeth were restored by one researcher as control group. The cavities received the adhesive system than increments of composite resin, and so the restorations were finished with finishing bur (KG Sorensen, São Paulo, SP, Brazil) to remove the excess, followed by sof-lex discs (3M ESPE). After this stage, all of specimens were embedded in 1% Methylene blue (Prolabo, Paris, France) during 48 h. The evaluation of pigment penetration into the interfaces was performed after specimens were washed in distilled water and longitudinally sectioned with steel Diamond disc in low velocity. Results: There was significant statistical difference between the different techniques using compose resin. Conclusions: it was possible conclude that the clinical protocol to perform dental restoration interfere dramatically in the final results of restorative procedure. [ABSTRACT FROM AUTHOR]

Resin composites may release bisphenol A (BPA) due to impurities present in the monomers. However, there is a lack of knowledge regarding the leaching characteristics of BPA from resin composites. Therefore, experimental resin composites were prepared with known amounts of BPA. The objective of this study was (1) to determine which amount of BPA initially present in the material leaches out in the short term and, (2) how this release is influenced by the resin composition. BPA (0, 0.001, 0.01, or 0.1 wt%) was added to experimental resin composites containing 60 mol% BisGMA, BisEMA(3), or UDMA, respectively, as base monomer and 40 mol% TEGDMA as diluent monomer. Polymerized samples (n = 5) were immersed at 37 °C for 7 days in 1 mL of water, which was collected and refreshed daily. BPA release was quantified with UPLC-MS/MS after derivatization with pyridine-3-sulfonyl chloride. Between 0.47 to 0.67 mol% of the originally added BPA eluted from the resin composites after 7 days. Similar elution trends were observed irrespective of the base monomer. Two-way ANOVA showed a significant effect of the base monomer on BPA release, but the differences were small and not consistent. The released amount of BPA was directly proportional to the quantity of BPA present in the resin composite as an impurity. BPA release was mainly diffusion-based, while polymer composition seemed to play a minor role. Our results underscore the importance for manufacturers only to use monomers of the highest purity in dental resin composites to avoid unnecessary BPA exposure in patients. [ABSTRACT FROM AUTHOR]

BisGMA, a crucial component of dental resin widely employed in oral care, undergoes an in-depth computational investigation in this study. Employing advanced computational tools such as Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) and General Utility Lattice Program (GULP), we explore a wide range of physical parameters. These encompass the stress–strain variations, Young's and linear moduli, pair distribution functions, RMSD trajectory analysis, enthalpy, entropy, elastic constants, self-energy, zero-point energy and optical and dielectric constants. This multifaceted analysis enhances our understanding on intricate correlation of this material, offering insights that are frequently challenging to obtain. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the influence of weight ratio, the shape of the precursor particles, and the application of a phosphate-monomer-containing primer on the mechanical properties of polymer infiltrated ceramic networks (PICNs) using zinc oxide. Two different types of zinc oxide particles were used as precursors to produce zinc oxide networks by sintering, each with two different densities resulting in two different weight ratios of the PICNs. For each of these different networks, two subgroups were built: one involving the application of a phosphate-monomer-containing primer prior to the infiltration of Bis-GMA/TEGDMA and one without. Elastic modulus and flexural strength were determined by using the three-point bending test. Vertical substance loss determined by the chewing simulation was evaluated with a laser scanning microscope. There was a statistically significant influence of the type of precursor particles on the flexural strength and in some cases on the elastic modulus. The application of a primer lead to a significant increase in the flexural strength and in most cases also in the elastic modulus. A higher weight ratio of zinc oxide led to a significantly higher elastic modulus. Few statistically significant differences were found for the vertical substance loss. By varying the shape of the particles and the weight fraction of zinc oxide, the mechanical properties of the investigated PICN can be controlled. The use of a phosphate-monomer-containing primer strengthens the bond between the infiltrated polymer and the zinc oxide, thus increasing the strength of the composite. [ABSTRACT FROM AUTHOR]

A new eugenyl dimethacrylated monomer (symbolled BisMEP) has recently been synthesized. It showed promising viscosity and polymerizability as resin for dental composite. As a new monomer, BisMEP must be assessed further; thus, various physical, chemical, and mechanical properties have to be investigated. In this work, the aim was to investigate the potential use of BisMEP in place of the BisGMA matrix of resin-based composites (RBCs), totally or partially. Therefore, a list of model composites (CEa0, CEa25, CEa50, and CEa100) were prepared, which made up of 66 wt% synthesized silica fillers and 34 wt% organic matrices (BisGMA and TEGDMA; 1:1 wt/wt), while the novel BisMEP monomer has replaced the BisGMA content as 0.0, 25, 50, and 100 wt%, respectively. The RBCs were analyzed for their degree of conversion (DC)-based depth of cure at 1 and 2 mm thickness (DC1 and DC2), Vickers hardness (HV), water uptake (WSP), and water solubility (WSL) properties. Data were statistically analyzed using IBM SPSS v21, and the significance level was taken as p < 0.05. The results revealed no significant differences (p > 0.05) in the DC at 1 and 2 mm depth for the same composite. No significant differences in the DC between CEa0, CEa25, and CEa50; however, the difference becomes substantial (p < 0.05) with CEa100, suggesting possible incorporation of BisMEP at low dosage. Furthermore, DC1 for CEa0–CEa50 and DC2 for CEa0–CEa25 were found to be above the proposed minimum limit DC of 55%. Statistical analysis of the HV data showed no significant difference between CEa0, CEa25, and CEa50, while the difference became statistically significant after totally replacing BisGMA with BisMEP (CEa100). Notably, no significant differences in the WSP of various composites were detected. Likewise, WSL tests revealed no significant differences between such composites. These results suggest the possible usage of BisMEP in a mixture with BisGMA with no significant adverse effect on the DC, HV, WSP, and degradation (WSL). [ABSTRACT FROM AUTHOR]

The long history of bisphenol A glycidyl dimethacrylate (Bis GMA) as a major component in resin-based composites is also associated with numerous reports of its toxicity. Since one of the substrates used in the production of BisGMA is bisphenol A (BPA), the question of its release from materials containing this monomer is also raised. Due to the widespread use of BisGMA in modern dentistry, the aim of this narrative review is to provide and summarize information on its toxicity based on the current literature. It covers the chemical structure and possible synthesis pathways of BisGMA, as well as the toxicity of its substrates. The toxicity of the BisGMA monomer is also discussed, in particular its effect on pulp cells, the release of composite components in the gastrointestinal tract, and its metabolic degradation. BisGMA and BPA are eluted from resin composites in the oral cavity. Acute toxicity is unlikely due to the small amounts of amounts eluted, but knowledge of chronic exposure is very limited. In addition, the amount of BPA released from dental materials is incomparably low, considering the environmental exposure levels in everyday life. Composite resins provide a highquality treatment that outweighs the potential complications. [ABSTRACT FROM AUTHOR]

Bisphenol A‐glycidyl methacrylate (BisGMA) is a methacrylate monomer that is mainly used in three‐dimensional structures to reconstruct dental and bony defects. BisGMA has toxic and proinflammatory effects on macrophages. Rutin is a natural flavonol glycoside that is present in various plants and has useful biological effects, such as anti‐inflammatory, anticancer, and antioxidative effects. The aim of this study was to investigate the anti‐inflammation of rutin in macrophages after exposure to BisGMA. Pretreatment of the RAW264.7 macrophage with rutin at 0, 10, 30, and 100 μM for 30 min before being incubated with BisGMA at 0 or 3 μM. Proinflammatory cytokines and prostaglandin (PG) E2 were detected by enzyme‐linked immunosorbent assay (ELISA). Nitric oxide (NO) was detected by the Griess assay. Expression and phosphorylation of proteins were measured by Western blot assay. Pretreatment with rutin inhibited the BisGMA‐induced generation of proinflammatory cytokines, including tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, IL‐6, and PGE2, in macrophages. Rutin also suppressed the BisGMA‐induced secretion of NO and expression of inducible nitric oxide synthase (iNOS) in a concentration‐dependent manner. Furthermore, rutin suppressed the mitogen‐activated protein kinase (MAPK) phosphorylation in a concentration‐dependent manner. Finally, rutin suppressed the BisGMA‐induced phosphorylation of nuclear factor (NF)‐κB p65 and degradation of inhibitor of κB (IκB). These results indicate that the concentration of rutin has an inhibitory effect on proinflammatory mediator generation, MAPK phosphorylation, NF‐κB p65 phosphorylation, and IκB degradation. In conclusion, rutin is a potential anti‐inflammatory agent for BisGMA‐stimulated macrophages through NF‐κB p65 phosphorylation and IκB degradation resulting from MAPK phosphorylation. [ABSTRACT FROM AUTHOR]

Composites, resins, and sealants that are commonly used in orthopedics and dentistry are based on 2,2‐bis[p‐(2′‐hydroxy‐3′‐methacryloxypropoxy)phenylene]propane (BisGMA), which induces proinflammatory responses in macrophages. The present study aimed to explore the anti‐inflammatory responses of wogonin, which is a natural dihydroxyl flavonoid compound, in BisGMA‐treated macrophages. According to the findings, wogonin exhibits anti‐inflammatory, antiallergic, anticancer, and antioxidative properties. The generation of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) were noted to be inhibited by wogonin in BisGMA‐treated macrophages. Furthermore, the production of proinflammatory cytokines including tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, and IL‐6 was reduced. In addition, BisGMA‐induced nuclear factor (NF)‐κB p65 phosphorylation and inhibitor of κB (IκB) degradation were inhibited. Finally, the BisGMA‐induced phosphorylation of mitogen‐activated protein kinases (MAPKs), including p38 MAPK, extracellular signal‐regulated kinase (ERK), c‐Jun N‐terminal kinase (JNK) was inhibited. All these effects were induced by wogonin in the macrophages in a concentration‐dependent manner. Similar inhibitory effects of wogonin were observed on the production of NO and proinflammatory cytokines, expression of iNOS, phosphorylation of NF‐κB p65 and MAPK, and degradation of IκB. These results indicated that rutin is a potential anti‐inflammatory agent for BisGMA‐treated macrophages that undergo NFκB p65 phosphorylation and IκB degradation through upstream MAPK phosphorylation. Therefore, wogonin inhibits BisGMA‐induced proinflammatory responses in macrophages through the regulation of the NFκB pathway and its upstream factor, MAPK. [ABSTRACT FROM AUTHOR]

Bisphenol‐A‐glycidyldimethacrylate (BisGMA) is a resin monomer frequently used in dentin restorative treatments. The leakage of BisGMA monomer from BisGMA‐based polymeric resins can lead to cytotoxicity in macrophages. Rutin has various beneficial bioeffects, including antioxidation and antiinflammation. In this study, we found that pretreatment of RAW264.7 macrophages with rutin‐inhibited cytotoxicity induced by BisGMA in a concentration‐dependent manner. BisGMA‐induced apoptosis, which was detected by levels of phosphatidylserine from the internal to the external membrane and formation of sub‐G1, and genotoxicity, which was detected by cytokinesis‐blocked micronucleus and single‐cell gel electrophoresis assays, were inhibited by rutin in a concentration‐dependent manner. Rutin suppressed the BisGMA‐induced activation of caspase‐3 and ‐9 rather than caspase‐8. Rutin inhibited the activation of the mitochondrial apoptotic pathway, including cytochrome C release and mitochondria disruption, after macrophages were treated with BisGMA. Finally, BisGMA‐induced reactive oxygen species (ROS) generation and antioxidant enzyme (AOE) deactivation could be reversed by rutin. Parallel trends were observed in the elevation of AOE activation and inhibition of ROS generation, caspase‐3 activity, mitochondrial apoptotic pathway activation, and genotoxicity. These results suggested that rutin suppressed BisGMA‐induced cytotoxicity through genotoxicity, the mitochondrial apoptotic pathway, and relatively upstream factors, including reduction of ROS generation and induction of AOE. [ABSTRACT FROM AUTHOR]

• Niobium silicate particles were produced by sol-gel route and used as filler dor dental composites • The addition of niobium silicate particles did not interfere on the physicomechanical properties of developed composites • The biological properties were enhanced for niobium silica-containing composite resins • Increased cell viability and mineral deposition were observed for the composite resins with niobium silicate addition. This study aimed to evaluate the influence of niobium silicate (SiNb) particles in the physicomechanical and biological properties of an experimental composite resin. The SiNb particles were incorporated (50 wt%) into a polymeric matrix formulated with 70 wt% Bisphenol A-Glycidyl Methacrylate and 30 wt% Triethylene Glycol Dimethacrylate to formulate an experimental composite resin. A control group was formulated with barium silicate glass (SiBa) as filler for the same polymeric matrix. The composite resins were tested for their refractive index, polymerization kinetics, flexural strength, radiopacity, softening in solvent, pH, cytotoxicity and mineral deposition. The SiBa group presented refractive index results between 1.50 and 1.52 and the SiNb between 1.43−1.45. No statistically significant difference in the degree of conversion, flexural strength, and softening in solvent was observed between different groups. Radiopacity was lower for SiNb, while the addition of these particles increased cell viability. The pH was increased for all groups after immersion. The mineral deposition analysis resulted in increased deposition above specimens after the immersion in SBF. Niobium silicate particles may be used as an alternative inorganic filler to achieve an adequate balance between physical-chemical and biological properties for the development of bioactive composite resins. [ABSTRACT FROM AUTHOR]

Water sorption, high volumetric shrinkage, polymerization stress, and potential estrogenic effects triggered by leached compounds are some of the major concerns related to BisGMA-TEGDMA co-monomer systems used in dental composites. These deficiencies call for the development of alternative organic matrices in order to maximize the clinical lifespan of resin composite dental restorations. This study proposes BisGMA-free systems based on the combination of UDMA and a newly synthesized diurethane dimethacrylate, and evaluates key mechanical and physical properties of the resulting materials. 2EMATE-BDI (2-hydroxy-1-ethyl methacrylate) was synthesized by the reaction between 2-hydroxy-1-ethyl methacrylate with a difunctional isocyanate (1.3-bis (1- isocyanato-1-methylethylbenzene) – BDI). The compound was copolymerized with UDMA (urethane dimethacrylate) at 40 and 60 wt%. UDMA copolymerizations with 40 and 60 wt% TEGDMA (triethylene glycol dimethacrylate) were tested as controls, as well as a formulation based in BisGMA (bisphenol A-glycidyl methacrylate)-TEGDMA 60:40% (BT). The organic matrices were made polymerizable by the addition of DMPA (2.2-dimethoxyphenoxy acetophenone) and DPI-PF6 (diphenyliodonium hexafluorophosphate) at 0.2 and 0.4 wt%, respectively. Formulations were tested as composite with the addition of 70 wt% inorganic content consisting of barium borosilicate glass (0.7 μm) and fumed silica mixed in 95 and 5 wt%, respectively. All photocuring procedures were carried out by a mercury arc lamp filtered to 320–500 nm at 800 mW/cm2. The experimental resin composites were tested for kinetics of polymerization and polymerization stress in real time. Flexural strength, elastic modulus, water sorption, and solubility were assessed according to ISO 4049. Biofilm formation was analyzed after 24 h by luciferase assay. Data were statistically analyzed by one-way ANOVA and Tukey's test (α ≤ 0.05). In general, the addition of 2EMATE-BDI into the formulations decreased the maximum rate of polymerization (RP MAX), the degree of conversion at RP MAX (DC at RP MAX), and the final degree of conversion (final DC). However, these reductions did not compromise mechanical properties, which were comparable to the BT controls, especially after 7-day water incubation. The incorporation of 60 wt% 2EMATE-BDI reduced water sorption of the composite. 2EMATE-BDI containing formulations showed reduction in polymerization stress of 30% and 50% in comparison to BT control and TEGDMA copolymerizations, respectively. Biofilm formation was similar among the tested groups. The use of the newly synthesized diurethane dimethacrylate as co-monomer in dental resin composite formulations seems to be a promising option to develop polymers with low-shrinkage and potentially decreased water degradation. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to characterize low-shrinkage dental composites containing methacrylethyl-polyhedral oligomeric silsesquioxane (ME-POSS). Four experimental composites were manufactured, two of which contained organic matrixes of BisGMA-TEGDMA (70/30 wt% - BGC) and BisEMA-TEGDMA (80/20 wt% - BEC). The two other experimental composites replaced BisGMA and BisEMA with 25 wt% of ME-POSS (BGP and BEP). The composites also contained 70 wt% of 0.7 µm silanized BaBSi particles. The following properties were evaluated: Degree of conversion (DC%), volumetric polymerization shrinkage (VS%), polymerization shrinkage stress (Pss), flexural strength (FS), Flexural modulus (FM), hardness (KHN), water sorption (W sp), water solubility (W sl), diffusion coefficient (D), and wear. The DC% was not influenced by the presence of ME-POSS, with BEC (75.6%) and BEP (74.8%) presenting higher DC% than BGC (60.6%) and BGP (55.6%). The ME-POSS-containing composites (BGP and BEP) presented significantly lower VS% and Pss. The FS ranged from 92.7 to 142.0 MPa and the FM from 3.6 to 10.3 GPa. ME-POSS did not influence the KHN. BEC and BEP presented lower W sp and W sl when compared to BGC and BGP. D ranged from 1.0 × 10−6 to 7.4 × 10−6 cm2 m−1. Incorporation of ME-POSS significantly decreased the wear for both binary matrices (p < 0.05). With the exception of FS and FM for BGP, the incorporation of ME-POSS decreased the VS% and Pss without jeopardizing the other properties of the experimental dental composites. Graphical abstract fx1 Highlights • The Degree of conversion was not influenced by the presence of ME-POSS. • Incorporation of ME-POSS decreased the wear. • Incorporation of ME-POSS decreased the polymerization shrinkage stress. • Incorporation of ME-POSS decreased the volumetric polymerization shrinkage. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract An esterase from S. mutans UA159, SMU_118c, was shown to hydrolyze methacrylate resin-based dental monomers. Objective To investigate the association of SMU_118c to the whole cellular hydrolytic activity of S. mutans toward polymerized resin composites, and to examine how the bacterium adapts its hydrolytic activity in response to environmental stresses triggered by the presence of a resin composites and adhesives biodegradation by-product (BBP). Materials and Methods Biofilms of S. mutans UA159 parent wild strain, SMU_118c knockout strain (ΔSMU_118c), and SMU_118c complemented strain (ΔSMU_118cC) were incubated with photo-polymerized resin composite. High performance liquid chromatography was used to quantify the amount of a universal 2,2-Bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bisGMA)-derived BBP, bishydroxy-propoxy-phenyl-propane (bisHPPP) in the media. Fluorescence in situ hybridization (FISH) and quantitative proteomic analysis were used to measure SMU_118c gene expression and production of SMU_118c protein, respectively, from biofilms of S. mutans UA159 wild strain that were cultured with bisHPPP. Results The levels of bisHPPP released from composite were similar for ΔSMU_118c and media control, and these were significantly lower compared to the parent wild-strain UA159 and complemented strain (ΔSMU_118cC) (p < 0.05). Gene expression of SMU_118c and productions of SMU_118c protein were higher for bisHPPP incubated biofilms (p < 0.05). Significance This study suggests that SMU_118c is a dominant esterase in S. mutans and capable of catalyzing the hydrolysis of the resinous matrix of polymerized composites and adhesives. In turn, the bacterial response to BBP was to increase the expression of the esterase gene and enhance esterase production, potentially accelerating the biodegradation of the restoration, adhesive and restoration-tooth interface, ultimately contributing to premature restoration failure. Statement of Significance We recently reported (Huang et al., 2018) on the isolation and initial characterization of a specific esterase (SMU_118c) from S. mutans that show degradative activity toward the hydrolysis of dental monomers. The current study further characterize this enzyme and shows that SMU_118c is a dominant degradative esterase activity in the cariogenic bacterium S. mutans and is capable of catalyzing the hydrolysis of the resinous matrix of polymerized composites and adhesives. In turn, the bacterial response to biodegradation by-products from composites and adhesives was to increase the expression of the esterase gene and enhance esterase production, accelerating the biodegradation of the restoration, adhesive and the restoration-tooth interface, potentially contributing to the pathogenesis of recurrent caries around resin composite restorations. [ABSTRACT FROM AUTHOR]

Restorative composites have evolved significantly since they were first introduced in the early 1960s, with most of the development concentrating on the filler technology. This has led to improved mechanical properties, notably wear resistance, and has expanded the use of composites to larger posterior restorations. On the organic matrix side, concerns over the polymerization stress and the potential damage to the bonded interface have dominated research in the past 20 y, with many "low-shrinkage" composites being launched commercially. The lack of clinical correlation between the use of these materials and improved restoration outcomes has shifted the focus more recently to improving materials' resistance to degradation in the oral environment, caused by aqueous solvents and salivary enzymes, as well as biofilm development. Antimicrobial and ester-free monomers have been developed in the recent past, and evidence is mounting for their potential benefit. This article reviews literature on the newest materials currently on the market and provides an outlook for the future developments needed to improve restoration longevity past the average 10 y. [ABSTRACT FROM AUTHOR]

The Bisphenol A glycidyl methacrylate (BisGMA) was used as binder to fix the free cross wire nodes in the entangled porous titanium for enhancement. The entangled titanium with 60% porosity after infiltrated with 5–20 vol.% BisGMA had the pore size in the range of 100 μm–400 μm. The enhanced materials with the real porosity of 40–55% exhibited the elastic modulus in the range of 0.4–1.4 GPa and the yielding strength in the range of 12.9–52.5 MPa. Such mechanical properties were comparable with those of cancellous bones, suggesting potentials for load-bearing bio applications. [ABSTRACT FROM AUTHOR]

Highly transparent and tough graft-interpenetrating polymer networks (graft-IPNs) were synthesized using an elastomeric polyurethane phase (PU) and a highly stiff acrylate-base copolymer phase. The grafting points between the two networks were generated with the purpose of minimizing the phase separation process of the polymeric systems. In order to generate the grafting between the networks, an acrylic resin capable of undergoing both free radical and poly-addition polymerization was employed. The thermo-mechanical properties, fracture toughness properties as well as network and surface phase morphology of the graft-IPNs synthesized were evaluated in this work. Data obtained suggested that the minimization of the phase separation was achieved by the generation of crosslinking points between both networks. High transparency was obtained in all samples as an indication of the high level of interpenetration achieved. The relative high values obtained for the fracture toughness tests suggest that generating chemical crosslinks between networks is a good approach for increasing the fracture toughness of polymeric materials. [ABSTRACT FROM AUTHOR]

Objective To study the effect of a low-shrinkage methacrylate monomer and monoacylphosphine oxide photoinitiator on color, translucency, and color stability of model resin-based composites (RBCs). Methods Four micro-hybrid RBCs were prepared containing barium-glass fillers in bisphenol A-glycidyl-methacrylate (BisGMA) and triethyleneglycol-dimethacrylate (TEGDMA) or urethane-based low-shrinkage monomer FIT-852 (FIT; Esstech Inc.) and TEGDMA matrix. Camphorquinone (CQ)/amine or Lucirin TPO were used as photoinitiators. Commercial low-shrinkage RBCs (Charisma Diamond, Heraeus Kulzer and N’Durance, Septodont) and conventional RBCs (Tetric EvoCeram, Ivoclar Vivadent and Filtek Z250, 3M ESPE) were used as controls. Color and translucency were measured using Thermo Scientific Evolution (Thermo Fisher Scientific) and SpectroShade™ Micro (MHT Optic Research) spectrophotometers. Color stability was evaluated after immersion in black tea (pure, with milk or lemon) and distilled water. Data were analyzed using analyses of variance with Tukey's post-test ( α = 0.05). Results Photoinitiators had no significant effect on baseline color. Initially whiter FIT-based RBCs showed greater staining in all staining solutions than BisGMA-based RBCs. TPO-containing RBCs showed better color stability than CQ-containing RBCs irrespective of the base monomer. Tea and tea with lemon induced greatest color changes. Adding milk to tea significantly reduced material staining. Significance Urethane-based low-shrinkage monomer FIT and conventional BisGMA affected color, translucency and color stability of their respective RBCs. Despite being used in posterior teeth, low-shrinkage RBCs are expected to have favorable optical and esthetic properties. Manufacturers are urged to provide information on optical properties of monomers and monomer mixtures in their low-shrinkage RBCs to allow understanding of interaction with fillers and photoinitiators. [ABSTRACT FROM AUTHOR]

ABSTRACT Bisphenol-A-glycidyldimethacrylate (BisGMA) is a frequently used monomer in dental restorative resins. However, BisGMA could leach from dental restorative resins after polymerization leading to inflammation in the peripheral environment. Wogonin, a natural flavone derivative, has several benefits, such as antioxidative, anti-inflammatory and neuroprotective properties. Pretreatment of macrophage RAW264.7 cells with wogonin inhibited cytotoxicity which is induced by BisGMA in a concentration-dependent manner. BisGMA induced apoptotic responses, such as redistribution of phosphatidylserine from the internal to the external membrane and DNA fragmentation, were decreased by wogonin in a concentration-dependent manner. In addition, BisGMA-induced genotoxicity, which detected by cytokinesis-blocked micronucleus and single-cell gel electrophoresis assays, were inhibited by wogonin in a concentration-dependent manner. Furthermore, wogonin suppressed BisGMA-induced activation of intrinsic caspase pathways, such as caspases-3 and −8. Parallel trends were observed in inhibition of caspase-3 and −8 activities, apoptosis, and genotoxicity. These results indicate wogonin suppressed the BisGMA-induced apoptosis and genotoxicity mainly via intrinsic caspase pathway in macrophages. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 176-184, 2016. [ABSTRACT FROM AUTHOR]

Camphorquinone (CQ) and resin monomers are included in dentin bonding agents (DBAs) and composite resin to restore tooth defects due to abrasion, crown fracture, or dental caries. DBAs, CQ, and bisphenol A-glycidyl methacrylate (BisGMA) applications influence the biological activities of the dental pulp. The current investigation aimed to delineate the effect of DBAs, CQ, and BisGMA on cathepsin L production/expression, lysosomal activity, and autophagy induction in human dental pulp cells (HDPCs). HDPCs were exposed to DBAs, CQ, or BisGMA with/without inhibitors for 24 h. Enzyme-linked immunosorbent assay was employed to determine the cathepsin L level in culture medium. The cell layer was utilized to measure cell viability by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl -tetrazolium bromide (MTT) assay. Real-time PCR was used to evaluate the mRNA expression. Western blotting or immunofluorescent staining was used to study protein expression. Lysosomal density was evaluated by lysotracker red staining. We found that DBAs, CQ, and BisGMA stimulated cathepsin L mRNA, protein expression, and production in HDPCs. In addition, CQ and BisGMA induced lysosomal activity, Beclin1, ATG12, LC3B, Bax, and p53 expression in HDPCs, indicating the stimulation of autophagy. Glutathione (GSH) prevented CQ- and BisGMA-induced cytotoxicity. Moreover, E64d, cathepsin L inhibitor (two cathepsin inhibitors), and Pifithrin-α (a p53 inhibitor) showed little preventive effect toward CQ- and BisGMA-induced cytotoxicity. Autophagy inhibitors (NH4Cl, Lys05) mildly enhanced the CQ- and BisGMA-induced cytotoxicity. These results indicate that DBAs stimulated cathepsin L, possibly due to their content of CQ and BisGMA that may induce cathepsin L in HDPCs. CQ and BisGMA stimulated lysosomal activity, autophagy, and apoptosis, possibly via induction of Beclin 1, ATG12, LC-3B, Bax, and p53 expression. In addition, CQ and BisGMA cytotoxicity was related to redox change and autophagy. These events are important role in pulpal changes after the restoration of tooth decay using CQ- and BisGMA-containing DBAs and resin composite., Competing Interests: Declaration of competing interest The authors declare that no conflict of competing interest for this manuscript submission., (Copyright © 2022. Published by Elsevier B.V.)

Purpose – This paper aims to focus on the development and study properties of bisphenol-A glycidyldimethacrylate (BisGMA) and ethylene–propylene–diene monomer (EPDM) blend-based nanocomposites containing amine-functionalised multi-walled carbon nanotubes (MWCNT-NH2) as a compatibiliser. Design/methodology/approach – First, BisGMA was synthesised from epoxy and methacrylic acid followed by the amine functionalisation of MWCNTs. A novel two-roll milling technique was then conducted to prepare nanocomposite specimens with MWCNT-NH2 as compatibiliser. Effect of MWCNT-NH2 content on the mechanical, thermal, electrical, corrosive and water absorption properties of the nanocomposites was investigated and results have been reported. Findings – The results of the present work reveal that MWCNT-NH2 acts as a potential compatibiliser and nanofiller in BisGMA/EPDM blend-based nanocomposites. The authors report here that the nanocomposites exhibit improved mechanical, thermal and electrical properties with increased addition of MWCNT-NH2. Moreover, desirable results are obtained at 5 phr of nanofiller loading beyond which the properties deteriorate due to particle agglomeration. The nanocomposites display negligible corrosion and water absorption characteristics. Thus, the above fabricated nanocomposites with optimum compatibiliser content can serve as low-cost structural, thermal and electrical materials which can also be utilised in corrosive and moist environments. Research limitations/implications – The present investigation has come up with the successful and cost-effective fabrication of BisGMA/EPDM blend-based nanocomposites with optimum nanofiller/compatibiliser (MWCNT-NH2) content that can be used for a wide range of structural, thermal and electrical projects, as it is corrosion and moisture resistant. It is also the most durable from the mechanical point of view. Originality/value – The above nanocomposites have never been designed before. [ABSTRACT FROM AUTHOR]

Objectives The ester linkages contained within dental resin monomers (such as Bisphenol A-glycidylmethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA)) are susceptible to hydrolytic degradation by salivary esterases, however very little is known about the specific esterase activities implicated in this process. The objective of this work was to isolate and identify the dominant proteins from saliva that are associated with the esterase activities shown to be involved in the degradation of BisGMA. Methods Human whole saliva was collected and processed prior to separation in a HiPrep 16/60 Sephacryl S-200 HR column. The fraction with the highest esterase activity was further separated by an anion exchange column (Mono-Q (10/100G)). Isolated fractions were then separated by gel electrophoresis, and compared to a common bench marker esterase, cholesterol esterase (CE), and commercial albumin which has been reported to express esterase activity. Proteins suspected of containing esterase activity were analyzed by Mass Spectroscopy (MS). Commercially available proteins, similar to the salivary esterase proteins identified by MS, were used to replicate the enzymatic complexes and confirm their degradation activity with respect to BisGMA. Results MS data suggested that the enzyme fraction with the highest esterase activity was contained among a group of proteins consisting of albumin, Zn-α2-glycoprotein, α-amylase, TALDO1 protein, transferrin, lipocalin2, and prolactin-induced protein. Studies concluded that the main esterase bands on the gels in each fraction did not overlap with CE activity, and that albumin activity emerged as a lead candidate with significant esterase activity relative to BisGMA degradation, particularly when it formed a complex with Zn-α2-glycoprotein, under slightly basic conditions. Significance These enzyme complexes can be used as a physiologically relevant formulation to test the biostability of composite resins. [ABSTRACT FROM AUTHOR]

Composite resin restorative materials were developed to overcome the disadvantages of amalgam restorative materials. Dental amalgams are unesthetic, and toxic. Composite resins are filled resins and they exhibit high compressive strength, abrasion resistance, ease of application and high translucency. Depending on the filler size and shapes, various composites have been developed till now. This article is a review of various types of composites and their properties. [ABSTRACT FROM AUTHOR]

The reproductive toxicity potential of the dental resin monomer bisphenol A glycidyl methacrylate (BisGMA; CASRN 1565-94-2) was investigated in male and female Crl: CD1(ICR) mice, 4 dosage groups, and 25 mice/sex/group. Formulations of BisGMA (0, 0.008, 0.08, or 0.8 mg/kg/d) in 0.8% ethanol in deionized water were intubated once daily beginning 28 days before cohabitation and continuing through mating (males) or through gestation day 17. The following parameters were evaluated: viability, clinical signs, body weights, estrous cyclicity, necropsy observations, organ weights, sperm concentration/motility/morphology, cesarean sectioning and litter observations, and histopathological evaluation of select tissues. No deaths or clinical signs related to BisGMA occurred. No significant changes in male and female body weights and body weight gains were recorded at any of the administered dosages of BisGMA. All mating and fertility parameters, and all litter and fetal data, were considered to be unaffected by dosages of BisGMA as high as 0.8 mg/kg/d. Gross or histopathologic tissue changes attributable to the test article were not observed. Reproductive and developmental no observed effect levels (NOAELs) for BisGMA were 0.8 mg/kg/d, the highest dose tested. Comparison of this NOAEL value to published probabilistic estimates of human BisGMA exposure from dental products suggests a margin of safety of at least 280- to nearly 2000-fold. Under the conditions of this study, BisGMA is not a reproductive toxicant. [ABSTRACT FROM AUTHOR]

Abstract: Objective: (Co)monomers from dental resin composites have cytotoxic and genotoxic potential. In previous studies it has been demonstrated that antioxidants can decrease the cytotoxicity of various dental (co)monomers. In this study the effects of the antioxidants N-acetylcysteine (ACC) and ascorbic acid (Asc) on the number of DNA double-strand breaks (DSBs) in human gingiva fibroblasts (HGFs) were tested. Methods: HGF was incubated with the (co)monomers bisphenol-A-glycidyl methacrylate (BisGMA), urethandimethacrylate (UDMA), ethylene glycol dimethacrylate (EGDMA) or 1,3-glyceroldimethacrylate (GDMA) with and without addition of antioxidants ACC and Asc. DNA-DSBs were determined using the γ-H2AX assay. Results: Asc induced at 500μM significant more DNA-DSBs in HGFs compared with controls (4.92 (1.28) vs. 1.62 (0.67); foci/cell mean (standard deviation), n =3). Most DNA-DSBs were found after incubation of HGFs with 90μM BisGMA (4.05 (0.56)) and 2720μM EGDMA (5.36 (1.59)). The addition of 100μM Asc or 500μM ACC leaded to a statistical significant reduction of DNA-DSBs in HGFs for all tested (co)monomers. After incubation of HGFs with 2720μM EGDMA and 500μM ACC the foci/cell decrease from 5.36 (1.59) to 1.9 (1.17) (controls: 1.12 (0.24)). After incubation of HGFs with 90μM BisGMA and 100μM Asc the foci/cell decrease from 4.05 (0.56) to 1.96 (0.59) (controls: 1.12 (0.24)). Significance: All tested (co)monomers can induce DNA-DSBs but addition of antioxidants (Asc or ACC) leads to reduction of DNA-DSBs. [Copyright &y& Elsevier]

Abstract: Aim: Bisphenol A-glycidyl-methacrylate (BisGMA), a dental composite resin and dentin bonding agent, might prompt inflammatory effects to adjacent tissues. Macrophages are a major cellular component of the inflammatory sites. Little is known about the mechanisms of BisGMA on macrophages activation. The aim of this study was to evaluate BisGMA on proinflammatory mediators generation of murine macrophage RAW264.7 cells. Methods: IL-1β and IL-6 were analyzed by enzyme-linked immunosorbent assay. Nitric oxide, extracellular superoxide anion, and intracellular reaction oxygen species were measured by Griess assay, ferricytochrome c, and 2′,7′-dichlorofluorescein assay, respectively. Expression of iNOS, p-p65, IκB, and p-Akt was analyzed by Western blotting. Results: BisGMA augmented the generation of IL-1β, IL-6, nitric oxide and the expression of iNOS in a time- and dose-dependent manner (p <0.05). BisGMA enhanced the generation of intracellular and extracellular ROS in a dose-dependent manner (p <0.05). The levels of p65 phosphorylation, IκB degradation, and Akt phosphorylation were found to be increased in a time- and dose-dependent manner (p <0.05). Conclusions: These results indicate that BisGMA could induce nitric oxide, ROS, and inflammatory cytokines in macrophages. In addition, BisGMA may active macrophage via NF-κB activation, IκB degradation, and p-Akt activation. [Copyright &y& Elsevier]

Li Y-C, Kuan Y-H, Huang F-M, Chang Y-C. The role of DNA damage and caspase activation in cytotoxicity and genotoxicity of macrophages induced by bisphenol-A-glycidyldimethacrylate. International Endodontic Journal, 45, 499-507, 2012. Abstract Aim To evaluate the potential toxicological implications of BisGMA on murine macrophage cell line RAW264.7. Methodology Lactate dehydrogenase release, flow cytometry, Western blot and fluorometric assays were used to detect cell viability, mode of cell death and caspase activities, respectively. In addition, alkaline single-cell gel electrophoresis and cytokinesis-block micronucleus assays were applied to detect genotoxicity. Statistical analyses were performed using anova followed by the Bonferroni's t-test for multi-group comparisons test. Results BisGMA demonstrated a cytotoxic effect on RAW264.7 cells in a dose-dependent and a time-dependent manner ( P < 0.05). BisGMA was found to induce two modes of cell death. The mode of cell death changed from apoptosis to necrosis as the concentrations of BisGMA elevated. Caspase-3, caspase-8 and caspase-9 activities were significantly induced by BisGMA in a dose-dependent manner ( P < 0.05). Moreover, BisGMA exhibited genotoxicity via a dose-related increase in the numbers of micronucleus and DNA strand breaks ( P < 0.05). Conclusions Cytotoxicity and genotoxicity induced by BisGMA are mediated by DNA damage and caspase activation. [ABSTRACT FROM AUTHOR]

Abstract: Biocompatibility of dentin bonding agents (DBA) and composite resin may affect the treatment outcome (e.g., healthy pulp, pulpal inflammation, pulp necrosis) after operative restoration. Bisphenol-glycidyl methacrylate (BisGMA) is one of the major monomers present in DBA and resin. Prior studies focused on salivary esterase for metabolism and degradation of resin monomers clinically. This study found that human dental pulp cells expressed mainly carboxylesterase-2 (CES2) and smaller amounts of CES1A1 and CES3 isoforms. Exposure to BisGMA stimulated CES isoforms expression of pulp cells, and this event was inhibited by catalase. Exogenous addition of porcine esterase prevented BisGMA- and DBA-induced cytotoxicity. Interestingly, inhibition of CES by bis(p-nitrophenyl) phosphate (BNPP) and CES2 by loperamide enhanced the cytotoxicity of BisGMA and DBA. Addition of porcine esterase or N-acetyl-l-cysteine prevented BisGMA-induced prostaglandin E2 (PGE2) and PGF2α production. In contrast, addition of BNPP and loperamide, but not mevastatin, enhanced BisGMA-induced PGE2 and PGF2α production in dental pulp cells. These results suggest that BisGMA may induce the cytotoxicity and prostanoid production of pulp cells, leading to pulpal inflammation or necrosis via reactive oxygen species production. Expression of CES, especially CES2, in dental pulp cells can be an adaptive response to protect dental pulp against BisGMA-induced cytotoxicity and prostanoid release. Resin monomers are the main toxic components in DBA, and the ester group is crucial for monomer toxicity. [Copyright &y& Elsevier]

Bisphenol A-glycidyl methacrylate (BisGMA) is monomer of dental filling composites, which can be released from these materials and cause adverse biologic effects in human cells. In the present work, we investigated genotoxic effect of BisGMA on human lymphocytes and human acute lymphoblastic leukemia cell line (CCRF-CEM) cells. Our results indicate that BisGMA is genotoxic for human lymphocytes. The compound induced DNA damage evaluated by the alkaline, neutral, and pH 12.1 version of the comet assay. This damage included oxidative modifications of the DNA bases, as checked by DNA repair enzymes EndoIII and Fpg, alkali-labile sites and DNA double-strand breaks. BisGMA induced DNA-strand breaks in the isolated plasmid. Lymphocytes incubated with BisGMA at 1 mM were able to remove about 50% of DNA damage during 120-min repair incubation. The monomer at 1 mM evoked a delay of the cell cycle in the S phase in CCRF-CEM cells. The experiment with spin trap-DMPO demonstrated that BisGMA induced reactive oxygen species, which were able to damage DNA. BisGMA is able to induce a broad spectrum of DNA damage including severe DNA double-strand breaks, which can be responsible for a delay of the cell cycle in the S phase. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The objectives of this study are to investigate the properties of high aspect-ratio hydroxyapatite (HAP) nanofibers and the reinforcing effect of such fibers on bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental resins (without silica microparticle filler) and dental composites (with silica microparticle filler) with various mass fractions (loading rates). Methods: HAP nanofibers were synthesized using a wet-chemical method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermal gravimetric analysis (TGA). Biaxial flexural strength (BFS) of the HAP nanofibers reinforced dental resins without any microsized filler and dental composites with silica microparticle filler was tested and analysis of variance (ANOVA) was used for the statistically analysis of acquired data. The morphology of fracture surface of tested dental composite samples was examined by SEM. Results: The HAP nanofibers with aspect-ratios of 600 to 800 can be successfully fabricated with a simple wet-chemical method in aqueous solution. Impregnation of small mass fractions of the HAP nanofibers (5wt% or 10wt%) into the BisGMA/TEGDMA dental resins or impregnation of small mass fractions of the HAP nanofibers (2wt% or 3wt%) into the dental composites can substantially improve the biaxial flexural strength of the resulting dental resins and composites. A percolation threshold of HAP nanofibers, beyond which more nanofibers will no longer further increase the mechanical properties of dental composites containing HAP nanofibers, was observed for the dental composites with or without silica microparticle filler. Our mechanical testing and fractographic analysis indicated that the relatively good dispersion of HAP nanofibers at low mass fraction is the key reason for the significantly improved biaxial flexural strength, while higher mass fraction of HAP nanofibers tends to lead to bundles that cannot effectively reinforce the dental resins or composites and may even serve as defects and thus degrade the resulting dental resin and composite mechanical properties. Significance: The incorporation of small mass fraction of HAP nanofibers with good dispersion can improve the mechanical property of dental resins and dental composites. [Copyright &y& Elsevier]

Abstract: Biocompatibility of dentin bonding agents (DBAs) and resin composite is important to preserve the pulp vitality after operative restoration. Bisphenol-glycidyl-methacrylate (BisGMA) is one common monomer adding into DBAs and resin. In this study, we found that exposure of human dental pulp cells to BisGMA (>0.1 mm) led to cytotoxicity, G2/M cell cycle arrest and apoptosis as analyzed by propidium iodide (PI) and PI/annexin V dual fluorescent flow cytometry. These events were associated with a decline of cdc2, cdc25C and cyclinB1 expression at both mRNA and protein levels. BisGMA also induced the expression of hemeoxygenase-1 (HO-1), an oxidative stress responsive gene, in pulp cells. Catalase could prevent the BisGMA-induced alteration of cell cycle-related genes (cdc2, cdc25C, cyclinB1) and HO-1 expression in dental pulp cells. Interestingly, Zn-protoporphyrin (2.5–5 μm), a HO inhibitor, enhanced the BisGMA-induced reactive oxygen species (ROS) production and cytotoxicity. These results suggest that exposure to higher concentrations of BisGMA may stimulate ROS production, cell cycle arrest, apoptosis and cell death. Inducing the expression of HO-1 in dental pulp cells by BisGMA is mediated by ROS production and important to protect dental pulp against the toxicity by monomers present in composite resin and DBAs. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Aim of this study was by continuous monitoring to assay the proliferative capacity of human gingival fibroblasts (HGFs), to investigate cytotoxicity of the most common monomers/comonomers in dental resin composites: bisphenol-A-glycidylmethacrylate (BisGMA), hydroxyethylenemethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), and urethanedimethacrylate (UDMA) in HGFs during 24h exposure using the xCELLigence system. Methods: xCELLigence cell index (CI) impedance measurements were performed according to the instructions of the supplier. HGFs were resuspended in medium and subsequently adjusted to 400,000, 200,000, 100,000, and 50,000cells/mL. After seeding 100μL of the cell suspensions into the wells of the E-plate 96, HGFs were monitored every 15min for a period of up to 18h by the xCELLigence system. Results: Half maximum effect concentrations (EC50) were determined based on the dose–response curves derived by xCELLigence measurements. Following real-time analysis, significantly increased EC50 values of HGFs exposed for 24h to the following substances were obtained: HEMAa, TEGDMAb, UDMAc. The EC50 values (mean [mmol/L]±S.E.M.; n =5) were: HEMA 11.20±0.3, TEGDMAa 3.61±0.2, UDMAa,b 0.20±0.1, and BisGMAa,b,c 0.08±0.1. These results are similar to the EC50 values previously observed with the XTT end-point assay. Significance: Our data suggests that the xCELLigence live cell analysis system offers dynamic live cell monitoring and combines high data acquisition rates with ease of handling. Therefore, the xCELLigence system can be used as a rapid monitoring tool for cellular viability and be applied in toxicity testing of xenobiotics using in vitro cell cultures. [Copyright &y& Elsevier]

Abstract: Objectives: The purpose of this study was to investigate the effect of the resin matrix composition on the translucency of experimental dental composite resins. Methods: Three types of unfilled resin matrices (TEGDMA-, UDMA- and BisGMA-based) were formulated and light cured. In addition, six different experimental dental composite resins with constant filler loading but varying in the type of monomer and the content of BisGMA were fabricated. Discs of each test material with 15.5mm diameter and 1.0mm thickness were prepared (N =3) and light cured. Total and diffuse transmittance values for each sample were measured using a UV/VIS spectrophotometer with the range of readings from 380 to 700nm. Difference in color was measured using the CIE Lab system. Results: Statistical analysis by one-way ANOVA followed by Tukey''s test showed that there was no statistically significant difference in transmittance values between the three unfilled resins. However, with the addition of filler, BisGMA-containing composite resins showed significantly higher transmittance values than the UDMA- and TEGDMA-based composite resins. Regression analysis revealed that there was a linear correlation between the percentage of BisGMA in the resin matrix and the total and diffuse translucency. Significance: The amount of BisGMA used in the resin matrix has a significant effect on the translucency of silica filler-containing dental composite resins. [Copyright &y& Elsevier]

Abstract: Objectives: The degree of conversion (DC) and polymerization shrinkage of resin composites are closely related manifestations of the same process. Ideal dental composite would show an optimal degree of conversion and minimal polymerization shrinkage. These seem to be antagonistic goals, as an increase in monomer conversion leads to a high polymerization shrinkage. This paper aims to determine the effect of opaque mineral fillers and monomer ratios on the DC and the shrinkage-strain of experimental composites based on (BisGMA/TEGDMA) monomers (traditionally used monomers). A relationship between the shrinkage-strain and the degree of conversion values was also investigated. The radiopacity of these experimental composites has been investigated in a previous paper. Methods: Experimental resin composites were prepared by mixing different monomer ratios of (BisGMA/TEGDMA) with Camphoroquinone and dimethyl aminoethyl methacrylate (DMAEMA) as photo-initiator system. Five different radiopacifying filler agents: La2O3, BaO, BaSO4, SrO and ZrO2 at various volume fractions ranging from 0 to 80wt.% were added to the mixture. The degree of conversion of experimental composites containing different opaque fillers contents was measured using FTIR/ATR spectroscopy. The shrinkage-strain of specimens, photopolymerized at circa 500mW/cm2, was measured using the bonded-disk technique at room temperature with respect to time. Results: The result revealed that the DC and the shrinkage-strain decrease slightly with the increasing of opaque fillers loadings, but this decrease is not significant. However, these two properties are closely related to the monomer concentration of the organic matrix. The results have also showed a linear correlation between the shrinkage-strain and DC of experimental composites investigated. Significance: The nature and the volume effects of the opaque fillers on the DC and shrinkage of the experimental composites investigated were not significant. However, this study has confirmed the importance of viscosity in the system and shrinkage behavior of dimethacrylate monomers studied. Then we confirmed that direct relationships linked the shrinkage and the DC of filled dental resin composites. [Copyright &y& Elsevier]

Abstract: After operative restoration, some monomers released from dentin bonding agents or composite resin may induce tissue inflammation and affect the vitality of dental pulp. Whether BisGMA, a major monomer of composite resin, may induce prostaglandin release and cytotoxicity to pulp cells and their mechanisms awaits investigation. We found that BisGMA induced cytotoxicity to human dental pulp cells at concentrations higher than 0.075mm as analyzed by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. BisGMA (0.1mm) also stimulated ERK phosphorylation, PGE2 production, COX-2 mRNA and protein expression as well as ROS production (as indicated by an increase in cellular DCF fluorescence) in dental pulp cells. Catalase (500 and 1000U/ml) and U0126 (10 and 20μm, a MEK inhibitor) effectively prevented the BisGMA-induced ERK activation, PGE2 production and COX-2 expression. Moreover, catalase can protect the pulp cells from BisGMA cytotoxicity, whereas aspirin and U0126 lacked of this protective activity. These results suggest that BisGMA released from composite resin may potentially affect the vitality of dental pulp and induce pulpal inflammation via stimulation of ROS production, MEK/ERK1/2 activation and subsequent COX-2 gene expression and PGE2 production. Cytotoxicity of BisGMA to dental pulp cells is related to ROS production, but not directly mediated by MEK activation and PGE2 production. [Copyright &y& Elsevier]

Abstract: Objective: BisGMA, a widely used component in dentin adhesive has very good mechanical properties after curing, but is relatively hydrophobic and thus, does not adequately infiltrate the water wet demineralized dentin collagen. Developing techniques that would lead to optimum infiltration of the hydrophobic component into the demineralized dentin matrix is very important. The purpose of this study was to evaluate interfacial morphological and chemical characteristics of the resultant adhesive–dentin interface when the ethanol wet bonding technique is used with hydrophobic adhesives. Materials and methods: The occlusal one-third of the crown was removed from six unerupted human third molars; a uniform smear layer was created with 600 grit SiC. The dentin surface was etched with 35% phosphoric acid for 15s before applying BisGMA/HEMA model adhesive using either water wet or ethanol wet bonding technique. Five-micro-thick sections of adhesive/dentin interface specimens were cut and stained with Goldner''s trichrome for light microscopy. Companion slabs were analyzed with SEM and micro-Raman spectroscopy. Results: The presence of ethanol in the demineralized dentin increased adhesive collagen encapsulation as indicated by trichrome staining. The SEM results confirmed that the ethanol wet bonding improved the quality of the interface. Micro-Raman spectral analysis of the dentin/adhesive interface indicated there was a gradual decrease in penetration of BisGMA component for specimens using water wet bonding, while relatively homogeneous distribution of the hydrophobic BisGMA component was noted in the interface with ethanol wet bonding. Significance: Wet bonding with ethanol instead of water permits better BisGMA infiltration improving the quality of interface. We speculate that the higher infiltration of hydrophobic BisGMA and better collagen encapsulation observed from the specimens using ethanol wet bonding would lead to more durable bonds because of improved resistance to hydrolytic attack. [Copyright &y& Elsevier]

Abstract: Objective: Monomers like BisGMA (Bisphenol-A-glycidyldimethacrylate) and comonomers like TEGDMA (triethyleneglycoldimethacrylate) are used in dental restorative materials in order to build up the three-dimensional network of filling materials. Since earlier investigations revealed uptake and subsequent metabolism of unpolymerized remainders of (co)monomers, the present experiment investigates the metabolic urine pattern of guinea pigs (n =4) after application of TEGDMA or BisGMA (each dose=0.02mmol/kg body weight=100%), respectively. Methods: For the investigations BisGMA was pre-dissolved in DMSO and subsequently diluted with 0.9% NaCl solution (final DMSO concentration 1%) and TEGDMA was dissolved in 0.9% NaCl solution. The solutions were administered with a gastric tube into the animals. Control animals received either 0.9% NaCl or 0.9% NaCl solution with 1% DMSO solution. Results: After 24h in collected urine the following metabolites were identified. After administration of TEGDMA (mean relative concentration of administered substances)±s.d. [%]; n =4): unchanged TEGDMA: 12±1.5%, MA: 2.4±0.8%, and triethyleneglycol: 35±2.2%. After administration of BisGMA (mean±s.d. [%]; n =4): unchanged BisGMA: 11.4±2.7%, MA: 2.2±0.6%, and bisphenol-A-bis(2,3-dihydroxypropyl)ether: 60.1±5.2%). Conclusion: No further metabolites like the previously identified intermediate 2,3-epoxymethacrylic acid and derived reaction products were identified in the urine, indicating that these metabolites must have reacted further. [Copyright &y& Elsevier]

Abstract: Objective: The fundamental optical characteristics of dental polymers as a function of curing time are exiguously reported in the literature. In this work the refractive index and the extinction coefficient of bisphenol-A-glycidyldimethacrylate–triethyleneglycoldimethacrylate (BisGMA/TEGDMA)-based polymers of different volume fractions have been studied as a function of the curing time. A comparison between the measured index of refraction and theoretical calculation based on molar refraction is made. Also the temporal behavior of both the refractive index and extinction coefficient is compared. Methods: Index of refraction: BisGMA/TEGDMA monomer samples were cured with a commercial light-curing unit by using camphorquinone and DMAEMA as the photoinitiator system. Curing times of 0, 40, 60, 300, 900 and 1800s were used. The refractive indices were determined with a refractometer at 470nm wavelength, where the peak absorption of the camphorquinone photoinitiator is located. Extinction coefficient: BisGMA/TEGDMA samples having different lengths were cured and the relative attenuation of light at 470nm was measured as a function of the curing time (0, 40, 60, 300, 900, 1800s). Results: The results show that in general the index of refraction increases during the photopolymerization process in a time frame from 0 to 40s and then approaches a steady-state value, which depends on the original composition of the admixture. The detailed refractive index change depends on the volume fractions of the constituent substances. The extinction coefficient decreases in a time frame from 60 to 900s and reaches a steady-state value thereafter. Significance: Knowledge of the fundamental optical characteristics of commonly used dental polymers is essential in the development of advanced light-initiated curing methods. [Copyright &y& Elsevier]

Toxicity potentiation of two monomers [bisphenol-A-glycidyldimethacrylate (BisGMA) and urethanedimethacrylate (UDMA)] as well as two comonomers [triethyleneglycoldimethacrylate (TEGDMA) and 2-hydroxyethylmethacrylate (HEMA)], each in combination with H2O2, was investigated on the viability on human gingival fibroblasts (HGF) and human pulpal fibroblasts (HPF). The applied concentration of H2O2 was 0.06 or 0.1 mmol/l, respectively, corresponding to the EC0 of H2O2 in HGF or HPF. The cell viability was assessed by the XTT test. From this test the half maximum effect concentrations (EC50) were calculated from fitted sigmoidale curves. EC50 values were (HGF; mmol/l; mean ± s.e.m.; n = 5): HEMA 11.9 ± 0.9, TEGDMA 3.7 ± 0.3, H2O2 0.36 ± 0.04, UDMA 0.27 ± 0.08, and BisGMA 0.11 ± 0.03. No significant ( P < 0.05) differences in the EC50 values were observed when HGF was exposed to substances, as compared to HPF. No significant decrease of the EC50 values was found when HGF or HPF, respectively, was exposed to HEMA or BisGMA in addition with H2O2 up to the concentration of 0.1 mmol/l, as compared to those EC50 values of each compound without H2O2 addition. A significant decrease of the TEGDMA EC50 value from 3.7 to 2.1 or 0.4 mmol/l, respectively, was found when cells were exposed to TEGDMA in combination with H2O2 (0.06 or 0.1 mmol/l), as compared to that TEGDMA EC50 value without H2O2 addition. A significant decrease of the UDMA EC50 value from 0.27 to 0.11 or 0.08 mmol/l, respectively, was found when HGF or HPF was exposed to UDMA in combination with H2O2 (0.06 or 0.1 mmol/l), as compared to that UDMA EC50 value without H2O2 addition. The addition of H2O2 (0.06 or 0.1 mmol/l) resulted in a toxicity potentiation of TEGDMA and UDMA, but not of HEMA and BisGMA, on HGF or HPF. [ABSTRACT FROM AUTHOR]

Abstract: Objective: The aim of this study was to determine the elution of monomers of two conventional resin composite materials after different polymerization and storage times. Methods: Two resin composites (a hybrid and a flowable) were used. Four groups (n =10, diameter: 4.5mm, thickness: 2mm) of each material were fabricated, one for each polymerization time of: 0s, 20s, 40s, and 80s. The samples were stored in 1ml of 75% ethanol at room temperature, and the storage medium was renewed after 24h, 7 days, and 28 days. From the storage medium that was removed, samples were prepared and evaluated, with LC–MS/MS. Results: Bisphenol A and UDMA were not detected in the samples. Regardless of the polymerization time, the material or the storage time, a higher amount of BisGMA was eluted compared to TEGDMA. The amount of monomer that was released from the polymerized samples of the hybrid resin composite (Tetric Ceram®) was significantly higher (p <0.0001) compared to the flowable (Tetric Flow®). No significant difference was found between samples polymerized for 20s compared to 40s concerning the elution of monomers. Only a polymerization time of 80s resulted in a decreased release of monomers. The release of TEGDMA decreased after 28 days; however, the elution of BisGMA remained at high levels. Significance: The release of monomers remains at a high level for a long time (7–28 days) after polymerization. The 40s that are usually used for the polymerization of resin composites seems insufficient in order to prevent a high release of monomers. [Copyright &y& Elsevier]

BisGMA (Bisphenol-A-glycidyldimethacrylate) resin had been modified by incorporating TiO2 nanoparticles (0.5-2% by weight). An ultrasonic mixing process was used to disperse the particles into the resin system prior to casting and curing test specimens. TEM investigation showed that the particles were nano size (5-60 nm) and dispersed throughout the entire volume of the resin. In dynamic mechanical analysis, nanophase resin showed increase in storage modulus and glass transition temperature from neat resin system. Thermogravimetric analysis revealed better thermal stability. Flexural loading, Tg and flexural modulus of the nanocomposites were enhanced as the particle volume fraction was enhanced and than decreased. [ABSTRACT FROM AUTHOR]

Abstract: Incomplete conversion, an ongoing challenge facing photopolymerized methacrylate-based polymers, affects leachables as well as the resulting polymer network. As novel polymers and composites are developed, methods to efficiently screen cell response to these materials and their properties, including conversion, are needed. In this study, an in vitro screening methodology was developed to assess cells cultured directly on cross-linked polymer networks. A gradient in methacrylate double bond conversion was used to increase the experimental throughput. A substrate of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl] propane (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) was prepared with a conversion ranging from 43.0% to 61.2%. Substrates aged for 7 days had no significant differences in surface roughness or hydrophilicity as a function of conversion. Leachables were detectable for at least 7 days using UV absorption, but their global cytotoxicity was insignificant after 5 days of aging. Thus, RAW 264.7 macrophage-like cells were cultured on aged substrates to evaluate the cell response to conversion, with possible contributions from the polymer network and local leachables. Conversions of 45% and 50% decreased viability (via calcein/ethidium staining) and increased apoptosis (via annexin-V staining). No significant changes (p >0.05) in tumor necrosis factor-α and interleukin-1β gene expression, as measured by quantitative, real-time reverse transcription-polymerase chain reaction, were seen as conversion increased. Thus, conversions greater than 50% are recommended for equimolar BisGMA/TEGDMA. The ability to distinguish cell response as a function of conversion is useful as an initial biological screening platform to optimize dental polymers. [Copyright &y& Elsevier]

Aim of this study was to investigate the effects of the resin monomer BisGMA on the glutathione concentration (monobromobimane assay) and apoptosis (Annexin V/PI-assay) of cultured primary human gingival fibroblasts. Cells were treated for up to 24 h with 0.001–0.25 mm BisGMA to determine growth curves using the DNA stain H33342. Subsequent Annexin V/PI-assays revealed that fibroblasts exposed to concentrations of 0.005–0.01 mm (non-cytotoxic) and 0.05 mm (ED10-concentration) showed no increase of the share of apoptotic cells compared to non-treated controls (5–8%), while 0.1 mm BisGMA (∼ ED50-concentration) caused a significant increase of the percentage of apoptotic cells (50%). Simultaneously to the induction of apoptosis, 0.1 and 0.25 mm of BisGMA caused a significant depletion of the intracellular GSH content after 18 h of incubation. Our results indicate that BisGMA at concentrations >0.1 mm causes an extreme depletion of the intracellular GSH pool as well as apoptosis. [Copyright &y& Elsevier]

Unpolymerized dental monomers can leach out into the oral biophase and are bioavailable for metabolism. We hypothesize that metabolites would be less toxic than parent monomers. We first identified the formation of metabolites from bisphenol F diglycidyl ether (BFDGE) and Bisphenol A glycidyl methacrylate (BISGMA) after their exposure to liver S9 fractions. Then, the metabolites and parent compounds were subjected to in vitro cytotoxicity, mutagenicity, and estrogenicity studies. Bisphenol A bis(2,3-dihydroxypropyl) ether and bisphenol F bis(2,3-dihydroxypropyl) ether were the hydroxylated metabolites of BISGMA and BFDGE, respectively. Cytotoxicity against L929 cells showed that the metabolites were significantly (p < 0.05) less cytotoxic than the parent monomers. Only BFDGE was mutagenic in the Ames assay with strain TA100 of Salmonella typhimurium. Parent and metabolite compounds did not stimulate estrogen-dependent MCF-7 cell proliferation above solvent controls. These results indicated that the hydroxylated metabolites were non-mutagenic, non-estrogenic, and less cytotoxic than their parent monomers. [ABSTRACT FROM AUTHOR]

The effect of matrix selection, filler composition, filler silanization, operator variations, and test site (dental clinic) on the wear rate of eight composites were evaluated. The wear was measured on replicas using both a microscopic and a laser scanning measuring method. The average wear rate on contact‐free surfaces was 9.2±4.2 µm/month with the microscopic measurement and 8.5±3.7 µm/month with the laser scanner over the 36‐month period. The urethane‐based composites performed significantly better than those which were bisGMA‐based. Restorations placed at one dental clinic showed significantly lower initial wear. There was also a significant difference between the operators that was most pronounced during the first 6 months. The other variable (filler composition and silane treatment) did not affect the wear rate significantly. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify through quantum mechanical quantitative structure activity relationships (Q-QSARs) chemical structures in dental monomers that influence their mutagenicity. AMPAC, a semiempirical computer program that provides quantum mechanical information for chemical structures, was applied to three series of reference chemicals: a set of methacrylates, a set of aromatic and a set of aliphatic epoxy compounds. QSAR models were developed using this chemical information together with mutagenicity data (Salmonella TA100, Ames Test). CODESSA, a QSAR program that calculates quantum chemical descriptors from information generated by AMPAC and statistically matches these descriptors with observed biological properties was used. QSARs were developed which had r[sup 2] values exceeding 0.90 for each study series. These QSARs were used to accurately predict the mutagenicity of BISGMA, a monomer commonly used in dentistry, and two epoxy monomers with developing use in dentistry, GY-281 and UVR-6105. The Q-QSAR quantum mechanical descriptors correctly predicted the level of mutagenicity for all three compounds. The descriptors in the correlation equation pointed to components of structure that may contribute to mutagenesis. The QSARs also provided 'dose windows' for testing mutagenicity, circumventing the need for extensive dose exploration in the laboratory. The Q-QSAR method promises an approach for biomaterials scientists to predict and avoid mutagenicity from the chemicals used in new biomaterial designs. [ABSTRACT FROM AUTHOR]

The degree of polymerization for dimethacrylate resin-based materials (BisGMA, TEGDMA, UDMA, HEMA) ranges from 55 to 75%. Literature data indicate that polymerization efficacy depends, among other factors, on the type of methacrylate resin comprising the material. The aim of this study was to evaluate the polymerization efficacy of four dental cement materials characterized by different polymerization mechanisms using FTIR analysis. In the present study, the FTIR method was adopted to analyze the degree of polymerization efficacy of four resin-based dental cement materials, two of which were self-cured and two were dual-cured cements. The IR spectral analysis was performed 24 h after the polymerization of the cementitious material. RelyX ARC cement exhibits the lowest polymerization efficacy (61.3%), while that of Variolink II (85.8%) and Maxcem Elite is the highest (90.1%). Although the efficacy of self-cured cements appears to be superior, the difference is not statistically significant (p = 0.280). Polymerization efficacy largely depends on the chemical structure of the material in terms of the presence of a particular methacrylate resin and less on the polymerization mechanism itself, i.e., whether it is a self-cured or dually cured dental cement. Thus, in clinical practice, cementitious materials with a higher proportion of TEGDMA compared with BisGMA are recommended. [ABSTRACT FROM AUTHOR]