Concentrations Of Triethylene Glycol Dimethacrylate Research Articles

Effect of Incorporating a Dimethacrylate Monomer on the Shear Bond Strength of Two Adhesive Resin Cements to Zirconia Ceramic.

Self-assembled nano-layering resulting from interaction of the phosphate functional group of adhesive monomers with zirconia ceramic surface has been proposed. The purpose of this study was to investigate the bond strengths of two adhesive resin cements (Panavia F 2.0 and BisCem) containing phosphate monomers added with various concentrations (0.0, 1.0, 3.0, and 5.0 wt%) of triethylene glycol dimethacrylate (TEGDMA) to air-abraded zirconia ceramic. The polished/air-abraded zirconia plates (KaVo Everest® ZS-Ronde) were imaged using atomic force microscopy and the average surface roughness (Ra) values were calculated (n = 5). The surface energy parameters of the zirconia plates and the resin cements were calculated based on the extended Fowkes theory. All resin-bonded (diameter: 2.38 mm) zirconia specimens were stored in water at 37 °C for 24 h and then half of them additionally thermocycled 10,000 times before the shear bond strength (SBS) test (n = 10). Air-abrasion of zirconia surface significantly increased the γhS (hydrogen bonding component) value (p < 0.001), as well as greatly increasing the surface area (p < 0.001). For both resin cements, the γhS (dipole-dipole component) gradually increased with increasing incorporated TEGDMA concentrations, whereas the γhS gradually decreased. Overall, the addition of 3.0 wt% of TEGDMA consistently resulted in higher SBS values even after thermocycling. Under the tested condition, reducing the concentration of the adhesive monomers with phosphate functional group by adding the dimethacrylate monomer (up to 3.0 wt%) increased the bond strength between the resin cements and zirconia ceramic.

TEGDMA (Triethylene Glycol Dimethacrylate) Induces Both Caspase-Dependent and Caspase-Independent Apoptotic Pathways in Pulp Cells.

Monomers leached from resin-based composites (RBCs) may reach intrapulpal concentrations of the millimolar (mM) range, which could contribute to inflammation. The aim of this investigation was to assess the cytotoxicity of triethylene glycol dimethacrylate (TEGDMA) monomers on pulp cells as well as to identify molecular mechanisms leading to apoptosis. Pulp cells were harvested from molars extracted for orthodontic reasons and cultured through an explant method. To assess cytotoxicity, cells underwent a 5-day exposure to 0.75, 1.5, and 3 mM TEGDMA and were subject to cell counting and WST-1 staining. Based on the findings, cells were subsequently exposed to 0.1, 0.2, 0.75, 1.5, and 3 mM TEGDMA for 24 h to uncover the details of apoptosis. Changes in the production or cleavage of the apoptosis-specific proteins caspase-8, caspase-9, caspase-3, caspase-12, and Apoptosis-Inducing Factor (AIF) were measured by Western blot. The 5-day study showed concentration- and time-dependent cytotoxicity. Significant cell death was detected after 24 h with TEGDMA concentrations of 1.5 and 3 mM. One-day exposure to TEGDMA led to the activation of caspase-8, -9, -3, and -12 and an increased AIF production. Results suggest that relevant concentrations of TEGDMA monomers, leached from RBCs, induce apoptosis in pulp cells through both caspase-dependent as well as caspase-independent mechanisms. Endoplasmic reticulum stress and the activation of caspase-independent apoptotic pathways may be further mechanisms by which monomers induce apoptosis in pulp cells.

Influence of TEGDMA monomer on MMP-2, MMP-8, and MMP-9 production and collagenase activity in pulp cells

ObjectivesResin-based composites may leach monomers such as triethylene-glycol dimethacrylate (TEGDMA), which could contribute to intrapulpal inflammation. The aim of this investigation was to examine whether various concentrations of TEGDMA are able to influence dentally relevant Matrix metalloproteinase (MMP)-2, MMP-8, and MMP-9 production, total collagenase/gelatinase activity in pulp cells, and suggest possible signaling mechanisms.Materials and methodsPulp cells were cultured, followed by a 1-day exposure to sublethal TEGDMA concentrations (0.1, 0.2, and 0.75 mM). Total MMP activity was measured by an EnzCheck total collagenase/gelatinase assay, while the production of specific MMPs and the relative changes of phosphorylated, i.e., activated signaling protein levels of extracellular signal-regulated kinase (ERK)1/2, p38, c-Jun N-terminal kinase (JNK) were identified by western blot. Immunocytochemistry image data was also plotted and analyzed to see whether TEGDMA could possibly alter MMP production.ResultsAn increase in activated MMP-2, MMP-8, and MMP-9 production as well as total collagenase activity was seen after a 24-h exposure to the abovementioned TEGDMA concentrations. Increase was most substantial at 0.1 (P = 0.002) and 0.2 mM (P = 0.0381). Concurrent p-ERK, p-p38, and p-JNK elevations were also detected.ConclusionsResults suggest that monomers such as TEGDMA, leached from resin-based restorative materials, activate and induce the production of dentally relevant MMPs in pulp cells. Activation of ERK1/2, p38, or JNK and MMP increase may play a role in and/or can be part of a broader stress response.Clinical relevanceInduction of MMP production and activity may further be components in the mechanisms of intrapulpal monomer toxicity.

Bioenergetic Impairment of Triethylene Glycol Dimethacrylate- (TEGDMA-) Treated Dental Pulp Stem Cells (DPSCs) and Isolated Brain Mitochondria are Amended by Redox Compound Methylene Blue †.

Background: Triethylene glycol dimethacrylate (TEGDMA) monomers released from resin matrix are toxic to dental pulp cells, induce apoptosis, oxidative stress and decrease viability. Recently, mitochondrial complex I (CI) was identified as a potential target of TEGDMA. In isolated mitochondria supported by CI, substrates oxidation and ATP synthesis were inhibited, reactive oxygen species production was stimulated. Contrary to that, respiratory Complex II was not impaired by TEGDMA. The beneficial effects of electron carrier compound methylene blue (MB) are proven in many disease models where mitochondrial involvement has been detected. In the present study, the bioenergetic effects of MB on TEGDMA-treated isolated mitochondria and on human dental pulp stem cells (DPSC) were analyzed. Methods: Isolated mitochondria and DPSC were acutely exposed to low millimolar concentrations of TEGDMA and 2 μM concentration of MB. Mitochondrial and cellular respiration and glycolytic flux were measured by high resolution respirometry and by Seahorse XF extracellular analyzer. Mitochondrial membrane potential was measured fluorimetrically. Results: MB partially restored the mitochondrial oxidation, rescued membrane potential in isolated mitochondria and significantly increased the impaired cellular O2 consumption in the presence of TEGDMA. Conclusion: MB is able to protect against TEGDMA-induced CI damage, and might provide protective effects in resin monomer exposed cells.

The self-renewal dental pulp stem cell microtissues challenged by a toxic dental monomer.

Dental pulp stem cells (DPSCs) regenerate injured/diseased pulp tissue and deposit tertiary dentin. DPSCs stress response can be activated by exposing cells to the monomer triethyleneglycol dimethacrylate (TEGDMA) and inducing the DNA-damage inducible transcript 4 (DDIT4) protein expression. The goal of the present study was to determine the impact of TEGDMA on the ability of DPSCs to maintain their self-renewal capabilities, develop and preserve their 3D structures and deposit the mineral. Human primary and immortalized DPSCs were cultured in extracellular matrix/basement membrane (ECM/BM) to support stemness and to create multicellular interacting layers (microtissues). The microtissues were exposed to the toxic concentrations of TEGDMA (0.5 and 1.5 mmol/l). The DPSCs spatial architecture was assessed by confocal microscopy. Mineral deposition was detected by alizarin red staining and visualized by stereoscopy. Cellular self-renewal transcription factor SOX2 was determined by immunocytochemistry. The microtissue thicknesses/vertical growth, surface area of the mineralizing microtissues, the percentage of area covered by the deposited mineral, and the fluorescence intensity of the immunostained cells were quantified ImageJ. DDIT4 expression was determined by a single molecule RNA-FISH technique and the cell phenotype was determined morphologically. DDIT4 expression was correlated with the cytotoxic phenotype. TEGDMA affected the structures of developing and mature microtissues. It inhibited the deposition of the mineral in the matrix while not affecting the SOX2 expression. Our data demonstrate that DPSCs retained their self-renewal capacity although their other functions were impeded. Since the DPSCs pool remained preserved, properties effected by the irritant should be restored by a proper rescue therapy.

An alternate methodology for studying diffusion and elution kinetics of dimethacrylate monomers through dentinal tubules

ObjectiveEthoxylated bisphenol A dimethacrylate (bisEMA) is a base monomer in several dental resin composites. It was the main aim of the present study to determine if bisEMA can reach the dental pulp by generally passive diffusion through the coronal dentinal tubules stimulated via eluent liquids surrounding the root structures only. MethodsIn 20 human third molar teeth, standard Class-I occlusal cavities were prepared and provided either with an adhesive system alone or additionally with a composite restoration, according to the instructions of the manufacturer. The teeth were placed in an elution chamber such that the elution media only came into contact with the tooth root/tooth base where they were incubated at 37 °C for up to 7 d. Samples were taken after 1, 2, 4 and 7 d. Gas chromatography/mass spectrometry was used to identify bisEMA and other monomers in ethanol/water (3:1) and aqueous eluates. ResultsbisEMA was only found in ethanol/water eluates, where the teeth had received a composite restoration. Traces of bisEMA with up to three ethylene oxide units could be detected in these eluates. Depending on the dentin thickness, different elution kinetics of bisEMA were determined. Regardless of the treatment of teeth, triethylene glycol dimethacrylate (TEGDMA) and tetraethylene glycol dimethacrylate (TEEGDMA) were found in ethanolic/aqueous eluates in equal amounts. Most TEGDMA and TEEGDMA diffused through the dentin within the first 24 h. SignificanceDepending on the dentin layer thickness, bisEMA was released for varied time periods, resulting in varied concentrations and exposure times for the different cells of the dental pulp. The concentrations of TEGDMA and TEEGDMA were greatest for cells of the dental pulp within the first 24 h.

Morphological and kinetic study of oral keratinocytes assembly on reconstituted basement membrane: Effect of TEGDMA

ObjectiveOpen wounds of oral cavity require rapid healing. The cytotoxic monomer, triethylene glycol dimethacrylate (TEGDMA) can leach out from dental restoratives, reach the oral epithelial barrier and trigger an immune response. It is speculated that low and moderate concentrations of TEGDMA (0.5 and 1.5 mmol/L, respectively) influence the assembly kinetics and morphology of the keratinocyte layers overlying the extracellular matrix (ECM) in vivo. A three-dimensional cell system composed of immortalized oral keratinocytes (iMOK) cultured on reconstituted basement membrane (ECM) was used to investigate the development of epithelial layers upon exposure to TEGDMA. MethodsAdherence and opposing movement of adjacent keratinocytes using actin protrusions (lamellipodia and filopodia) to create spheroids, and their fusion capacity to establish subsequent layers were tested at different time points. Fluorescent, confocal, differential interference contrast microscopy and image processing were employed to quantify the morphological modifications over time. ResultsIncreasing concentrations of TEGDMA decreased the number of viable cells that utilized the actin protrusions and led to a delay in the communication/interaction among cells. Consequently, cells assembly was affected and the formation of more than a single layer prevented. Areas of basal-like proliferating cells were replaced with the increasing areas of non-replicating large cell population and extended gaps. ConclusionsThese findings suggest that TEGDMA may prevent rapid sealing of open wounds by keratinocytes and suppress the establishment of a resistant and impermeable barrier against pathogen internalization. The iMOK-ECM-based platform facilitated the validation and quantification of solubilized dental materials impact on the reconstitution of epithelial layer.

Evaluation of Monomer Leaching from a Resin Cement Through Dentin.

The aim of the study was to evaluate the elution of Triethylene glycol dimethacrylate (TEGDMA), Urethane dimethacrylate (UDMA), Bisphenol A glycerolate dimethacrylate (BisGMA), and Bisphenol A (BPA), from a dual-cured resin cement through human dentin, under constant positive pulpal pressure. Ten human dentin disks were adjusted into a custom made testing device and transparent glass slabs were luted with Variolink II cement, under a steady pressure. The device was filled with Ringer's solution and a pressure of 14.1 cm H₂O was applied. Eluates were retrieved from each one of the ten specimens at 9 time interval. All the samples were analyzed by High Performance Liquid Chromatography (HPLC). TEGDMA was detected from the second and UDMA was detected from the fourth time interval and then. The highest average concentration of TEGDMA and UDMA was detected in the 3 day time interval. Time had a significant effect on their elution. BPA and BisGMA were not detected in any sample of any time interval. The clinical relevance of the present study is that the concentration of the eluted monomers, under the conditions that were chosen, did not reach toxic levels for the pulp.

Impaired angiogenic differentiation of dental pulp stem cells during exposure to the resinous monomer triethylene glycol dimethacrylate

ObjectiveDental pulp stem cells (DPSCs) can differentiate into tissue specific lineages to support dental pulp regeneration after injuries. Triethylene glycol dimethacrylate (TEGDMA) is a widely used co-monomer in restorative dentistry with adverse effects on cellular metabolism. Aim of this study was to analyze the impact of TEGDMA on the angiogenic differentiation potential of DPSCs. MethodsDPSCs were characterized by flow cytometry. Short-term (max. 72h) cytotoxicity of TEGDMA was assessed by MTT assay. To evaluate TEGDMA effects on angiogenic differentiation, DPSCs were cultivated in angiogenic differentiation medium (ADM) in the presence or absence of short-term non-toxic TEGDMA concentrations (0.1mM and 0.25mM). Subsequently, angiogenic differentiation was analyzed by qRT-PCR analysis of mRNA markers and in vitro spheroid sprouting assays. ResultsDPSCs treated with 0.25mM TEGDMA revealed downregulation of angiogenesis-related marker genes PECAM1 (max. 3.8-fold), VEGF-A (max. 2.4-fold) and FLT1 (max. 2.9-fold) compared to respective untreated control. In addition, a reduction of the sprouting potential of DPSCs cultured in the presence of 0.25mM TEGDMA was detectable. Larger spheroidal structures were detectable in the untreated control in comparison to cells treated with 0.25mM TEGDMA. In contrast, TEGDMA at 0.1mM was not affecting angiogenic potential in the investigated time period (up to 28 days). SignificanceThe results of the present study show that TEGDMA concentration dependently impair the angiogenic differentiation potential of DPSCs and may affect wound healing and the formation of granulation tissue.

Synthesis and characterization of thermally expandable PMMA-based microcapsules with different cross-linking density

Triethylene glycol dimethacrylate (TEGDMA) crosslinked poly(methyl methacrylate) (PMMA) hollow particles with a core/shell structure containing an inert hydrocarbon (pentane) as a blowing agent were prepared by a suspension polymerization. From the synthesized microspheres, the sieved particles having sizes in the range of 44–149 μm were selected for further investigations and the effect of TEGDMA (as a cross-linker) content on the properties of synthesized particles was studied. In addition, the gel point, shell composition, particle size and its distribution, pentane content, thermal expansion properties, and particle morphology were studied. The results showed that a small change in TEGDMA concentration had a significant influence on the properties of synthesized microballoons. Kinetic studies showed that decreasing in the TEGDMA content shifted the gel point to higher reaction times. According to scanning electron microscopy (SEM) images, the shell thickness increased and particle size decreased with a decreased cross-linker concentration. The results of SEM analysis also proved the decrement of average particle size for lower TEGDMA contents. The expansion behavior of the prepared samples was investigated by means of SEM analysis. The density measurements were performed to study how the density of the particles was affected by cross-linker concentration. All samples were able to be expanded at 160 °C but the particles synthesized with lower cross-linker concentrations exhibited better expansion.

The Influence of Irradiation Time and Layer Thickness on Elution of Triethylene Glycol Dimethacrylate from SDR® Bulk-Fill Composite.

Objective. This study aimed to evaluate triethylene glycol dimethacrylate (TEGDMA) elution from SDR bulk-fill composite. Methods. Three groups of samples were prepared, including samples polymerized in a 4 mm layer for 20 s, in a 4 mm layer for 40 s, and in a 2 mm layer for 20 s. Elution of TEGDMA into 100% ethanol, a 75% ethanol/water solution, and distilled water was studied. The TEGDMA concentration was measured using HPLC. Results. The TEGDMA concentration decreased in the following order: 100% ethanol > 75% ethanol > distilled water. Doubling the energy delivered to the 4 mm thick sample caused decrease (p < 0.05) in TEGDMA elution to distilled water. In ethanol solutions, the energy increase had no influence on TEGDMA elution. Decreasing the sample thickness resulted in decrease (p < 0.05) in TEGDMA elution for all the solutions. Conclusions. The concentration of eluted TEGDMA and the elution time were both strongly affected by the hydrophobicity of the solvent. Doubling the energy delivered to the 4 mm thick sample did not decrease the elution of TEGDMA but did decrease the amount of the monomer available to less aggressive solvents. Elution of TEGDMA was also correlated with the exposed sample surface area. Clinical Relevance. Decreasing the SDR layer thickness decreases TEGDMA elution.

Effect of Opalescence® bleaching gels on the elution of bulk-fill composite components

ObjectivesBleaching treatments can affect release of components from conventional composites. In this continuing study the influence of two different bleaching gels on the elution of bulk-fill composite components was investigated. MethodsThe composites Tetric EvoCeram® Bulk Fill, QuiXFil™ and X-tra fil were treated with the bleaching gels Opalescence PF 15% (PF 15%) for 5h and PF 35% (PF 35%) for 30min and then stored in methanol and water for 24h and 7d. The eluates were analyzed by gas chromatography/mass spectrometry (GC/MS). Unbleached specimens were used as control group. ResultsA total of 7 different elutable substances have been identified from the investigated composites after bleaching-treatment. Three of them were methacrylates: 2-hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA) and trimethylolpropane trimethacrylate (TMPTMA). Compared to the unbleached controls an increase in elution after PF 15%-treatment of following compounds was found: HEMA (Tetric EvoCeram® Bulk Fill), TEGDMA (QuiXFil™, X-tra fil) and 4-N,N-dimethylaminobenzoic acid butyl ethoxy ester (DMABEE) (Tetric EvoCeram® Bulk Fill, QuiXFil™, X-tra fil). Following compounds showed a reduction in elution after PF 35%-treatment compared to controls: TEGDMA (QuiXFil™) and DMABEE (Tetric EvoCeram® Bulk Fill). The highest concentration of HEMA was 0.22mmol/l (Tetric EvoCeram® Bulk Fill, methanol, 7d, PF 15%), the highest concentration of TEGDMA was 0.3mmol/l (X-tra fil, water, 7d, PF 15%) and the highest concentration of DMABEE was 0.05mmol/l (QuiXFil™, water, 7d, PF 35%). SignificancePF 15% and PF 35% can lead to reduced and/or increased elution of some bulk-fill components, compared to unbleached bulk-fill composites.

Assessment of HEMA and TEGDMA induced DNA damage by multiple genotoxicological endpoints in human lymphocytes

ObjectivesResidual unbound resin monomers of 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) are known to diffuse in the saliva and through dentin and pulp into the blood and may affect cellular integrity. The current study was performed to investigate the genotoxic potential of both monomers in distinctly lower concentrations than known to cause cytotoxic damage. MethodsLymphocytes from 10 healthy volunteers were treated with HEMA (10μM–1mM) and TEGDMA (1μM–100μM) for 24h. Cell viability, apoptosis and influence on cell cycle kinetics were assessed by flowcytometry. DNA damage was determined by the alkali version of the comet assay in combination with the FPG protein and by the cytokinesis-block micronucleus (CBMN) test. Additionally, the chromosome aberration (CA) test and sister chromatid exchange (SCE) test were performed. ResultsA slight decrease in cell viability was detected only at the highest concentration of TEGDMA. Genotoxic effects were measurable in the comet assay at 1mM of HEMA and 100μM of TEGDMA, with and without FPG protein, but not in the CBMN test or the cell cycle analysis. Contrary to these findings, a significant dose-dependent increase in the frequency of CAs and SCEs could be demonstrated in all tested concentrations. SignificanceThis is the first time clastogenic responses to HEMA and TEGDMA have been detected in concentrations distinctly lower than those reported for causing cytotoxic or even genotoxic effects. These findings underline the importance of using test batteries with different genotoxicological endpoints to describe the multiple effects of both resin monomers.

The Effect of UDMA/TEGDMA Mixtures and Bioglass Incorporation on the Mechanical and Physical Properties of Resin and Resin-Based Composite Materials

Incorporating Bioglass into dental composites may improve biocompatibility and aid tooth and bone tissue remineralisation. This study aimed to determine the impact of Bioglass and silica filler on the mechanical and physical properties of cured photopolymers. Hardness (Vickers microhardness test), flexural strength (FS), and flexural modulus (FM) (three-point bend test) of resins containing various urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) and bisphenol A-glycidyl methacrylate (bisGMA)/TEGDMA concentrations (20–80 mass%) were tested. Degree of conversion (DC), FS, and FM of resin composites containing nonsilanised irregular 45S5-Bioglass (50 μm; 5–40 mass%) and/or silanised silicate glass filler particulates (0.7 μm; 30–70 mass%) were tested. Data was analysed using one-way ANOVA. UDMA/TEGDMA resins exhibited increased hardness and FM compared with bisGMA/TEGDMA resins. Addition of Bioglass particles to 60/40 wt% UDMA/TEGDMA or bisGMA/TEGDMA resins may enable the development of new materials that exhibit higher or at least equivalent values of DC, FS, and FM compared with conventional resin composites.

Gene Expression Change in Human Dental Pulp Cells Exposed to a Low‐Level Toxic Concentration of Triethylene Glycol Dimethacrylate: An RNA‐seq Analysis

Dental composite resin restoration for defective tooth may lead unpolymerized resin monomers to be leached into dental pulp tissue. The aim of this study was to investigate the early gene expression change over time of human dental pulp cells (HDPCs) treated with a low-level toxic concentration of Triethylene Glycol Dimethacrylate (TEGDMA), a common dental resin monomer, by adopting the novel high-throughput transcriptome analysis of RNA-seq. The low-level toxic concentration of TEGDMA was determined through MTT assays with serially diluted concentrations. After the HDPCs were exposed to TEGDMA for 6, 12, 24 or 48hr, the total RNA of the samples was prepared for RNA-seq. qRT-PCR for several genes was performed for validation of RNA-seq results. In the treated group, 1280 genes were differentially expressed compared with the control group. Five patterns of time-series gene expression profiles were identified through k-means clustering analysis. Angiogenesis, cell adhesion and migration, extracellular matrix organization, response to extracellular stimulus, inflammatory response and mineralization-related process were major gene ontology terms in functional annotation clustering. HMOX1, OSGIN1, SMN2, SRXN1 AKR1C1, SPP1 and TOMM40L were highly up-regulated genes, and WRAP53 and CCL2 were highly down-regulated genes over time. qRT-PCR for several genes exhibited a high level of agreement with RNA-seq. TEGDMA induced the HDPCs to show massive and dynamic gene expression changes over time. The previously suggested toxic mechanism of TEGDMA was not only verified, but new genes whose functions have yet to be determined were also found.

Epigallocatechin-3-gallate Blocks Triethylene Glycol Dimethacrylate–induced Cyclooxygenase-2 Expression by Suppressing Extracellular Signal-regulated Kinase in Human Dental Pulp and Embryonic Palatal Mesenchymal Cells

IntroductionMethacrylate resin–based materials could release components into adjacent environment even after polymerization. The major components leached include triethylene glycol dimethacrylate (TEGDMA). TEGDMA has been shown to induce the expression of cyclooxygenase-2 (COX-2). However, the mechanisms are not completely understood. The aims of this study were to investigate the molecular mechanism underlying TEGDMA-induced COX-2 in 2 oral cell types, the primary culture of human dental pulp (HDP) cells and the human embryonic palatal mesenchymal (HEPM) pre-osteoblasts, and to propose potential strategy to prevent or ameliorate the TEGDMA-induced inflammation in oral tissues. MethodsTEGDMA-induced COX-2 expression and its signaling pathways were assessed by Western blot analyses in HDP and HEPM cells. The inhibition of TEGDMA-induced COX-2 protein expression using various dietary phytochemicals was investigated. ResultsCOX-2 protein expression was increased after exposure to TEGDMA at concentrations as low as 5 μmol/L. TEGDMA-induced COX-2 expression was associated with reaction oxygen species, the extracellular signal-regulated kinase 1/2, and the p38 mitogen-activated protein kinase signaling pathways in HDP and HEPM cells. The activation of p38 mitogen-activated protein kinase was directly associated with reactive oxygen species. Epigallocatechin-3-gallate suppressed TEGDMA-induced COX-2 expression by inhibiting phosphorylation of extracellular signal-regulated kinase 1/2. ConclusionsCells exposed to low concentrations of TEGDMA may induce inflammatory responses of the adjacent tissues, and this should be taken into consideration during common dental practice. Green tea, which has a long history of safe beverage consumption, may be a useful agent for the prevention or treatment of TEGDMA-induced inflammation in oral tissues.

Triethylene Glycol Dimethacrylate Induction of Apoptotic Proteins in Pulp Fibroblasts

Monomers such as triethylene glycol dimethacrylate (TEGDMA) can leach from dental composites. TEGDMA-induced apoptosis in human pulp has been reported. However, the apoptotic (pro or anti) proteins involved in this process remain unclear. Therefore, the purpose of this study was to determine which apoptotic proteins are enhanced or suppressed during TEGDMA-induced apoptosis. Human pulp fibroblasts (HPFs) were incubated with different TEGDMA concentrations (0.125-1.0 mM) and cytotoxicity was determined. TEGDMA was shown to be cell cytotoxic at concentrations of 0.50 mM and higher. The highest concentration with no significant cytotoxicity was then incubated (0.25 mM TEGDMA) with the HPFs. Cell lysates were then prepared and the protein concentrations determined. Human Apoptosis Array kits were utilized to detect the relative levels of 43 apoptotic proteins. HPFs exposed to TEGDMA showed significant increases in multiple pro-apoptotic proteins such as Bid, Bim, Caspase 3, Caspase 8, and Cytochrome c at 24 hours. Some anti-apoptotic proteins were also altered. The results indicated that TEGDMA activates both the extrinsic and intrinsic apoptotic pathways.

In vitro cellular detoxification of triethylene glycol dimethacrylate by adduct formation with N-acetylcysteine

ObjectiveVarious protective effects of N-acetylcysteine (NAC) against triethylene glycol dimethacrylate (TEGDMA)-induced cell damage have been demonstrated, but so far there is no evidence on NAC direct monomer detoxification mechanism. Here, we hypothesized that NAC might reduce TEGDMA cytotoxicity due to direct NAC adduct formation. MethodsWe measured the cytotoxic effects of TEGDMA in presence and in absence of NAC by MTT test. Then we analyzed the presence of TEGDMA–NAC adduct formation in extracellular and intracellular compartments by capillary electrophoresis–UV detection (CE–UV) and capillary electrophoresis–mass spectrometry (CE–MS) analytical techniques. Moreover, we quantified the effective intracellular and extracellular TEGDMA concentrations through HPLC in the presence and absence of 10mmol/L NAC. ResultsTEGDMA reduced 3T3 cell vitality in a dose- and time-dependent manner, while NAC decreased monomer cytotoxicity and extracellular monomer concentrations by a direct reaction with TEGDMA. The adducts between the two molecules were detected both in the presence and absence of cell. Moreover a signal ascribed to the methacrylic acid was present in the CE–UV electropherogram of cellular lysates obtained after incubation with TEGDMA. SignificanceOur results suggest that in vitro detoxification capability of NAC against TEGDMA-induced cell damage might occur also through the formation of NAC–TEGDMA adduct.

Effects of ethanol and dimethyl sulfoxide on solubility and cytotoxicity of the resin monomer triethylene glycol dimethacrylate

Several in vitro studies have reported contrasting values for triethylene glycol-dimethacrylate (TEGDMA) concentrations shown to induce cytotoxic effects. The aim of this study was to evaluate the effective concentrations of TEGDMA reached under the routine experimental conditions used in biocompatibility in vitro tests and determines changes in cytotoxicity and the associated production of reactive oxygen species (ROS) based on different TEGDMA solutions. TEGDMA was added to cell culture medium either directly or previously dissolved in dimethyl sulfoxide (DMSO) or ethanol (EtOH), both in the presence and absence of cells. Intracellular and extracellular TEGDMA concentrations were determined by high performance liquid chromatography (HPLC). The cytotoxicity effects of TEGDMA preparations were determined in 3T3-fibroblasts by 3-(4,5 dimethyiazol-2-1)-2-5-diphenyl tetrazolium bromide assay. The production of ROS was measured by flow cytometry. In the absence of cells the effective final TEGDMA concentrations obtained in Dulbecco's Modified Eagle Medium were significantly lower than the nominal one. When 2 mmol/L TEGDMA was first solubilized in DMSO or EtOH, a significant decrease in cell viability, and an increase in ROS production-compared to pure TEGDMA-was observed. After 2 h of incubation, TEGDMA previously dissolved in DMSO or ETOH was reduced by 15% and 20%, respectively, whereas otherwise it remained unaffected. Our results demonstrate that the effective concentration of TEGDMA dissolved in culture medium (in the presence or absence of solvents) does not concur with the nominal one. Therefore, the presence of the utilized solvents does not substantially alter the monomer solubility but eases its entrance into the cells thus improving its cytotoxic potency.

Effects of the iron‐chelating agent deferoxamine on triethylene glycol dimethacrylate, 2‐hydroxylethyl methacrylate, hydrogen peroxide‐induced cytotoxicity

Triethylene glycol dimethacrylate (TEGDMA) and 2-hydroxylethyl methacrylate (HEMA) are known to deplete glutathione in mammalian cells, generate reactive oxygen species (ROS), and cause oxidative stress. In this study, we investigated whether hydroxyl radicals (·OH), the most lethal and genotoxic ROS, and the Fenton reaction are involved in the cytotoxicity of resin monomers to four different cell types, namely MC3T3-E1 preosteoblasts, human dental pulp cells (HDPCs), human gingival fibroblasts, and L929 mouse fibroblasts. Deferoxamine (DFO), an iron chelating agent, effectively protected MC3T3-E1 cells from resin monomer-induced cytotoxicity, indicating that cytotoxicity was caused primarily by hydroxyl radicals. However, DFO only had a protective effect against relatively high concentrations of TEGDMA and HEMA in HDPCs and human gingival fibroblasts, and resin monomer-induced cytotoxicity in L929 was not attenuated by DFO. A labile iron pool (LIP) was detectable only in MC3T3-E1 cells among the four cell types. This indicates that the generation of hydroxyl radicals induced by resin monomers is likely dependent on LIP levels. In contrast to resin monomers, hydrogen peroxide (H(2)O(2))-induced cytotoxicity was not prevented by DFO in any of the cell types examined, although hydroxyl radicals were detected in MC3T3-E1 cells and HDPCs on exposure to exogenous H(2)O(2). This result suggests that generation of hydroxyl radicals is not always the primary cause of cytotoxicity in H(2)O(2)-treated cells.