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• A method is described that compares elution directly from RBC and elution indirectly from teeth with restored cavities. • Direct comparison of eluates from bulk fill restoratives was achieved. • Critical substances including TINUVIN® 328 were found in the eluates. • Elution from restored carious lesions gives new insights into amounts of elutable substances. • Due to synergistic effects between teeth and restoratives, multiple models are important for toxicological assessments. To compare elutable substances directly released from bulk-fill (BF) resin-based composites (RBCs) with indirect elution from teeth restored with a BF composite. In addition to (co)monomers, the analytical focus was on other potentially toxic ingredients or impurities. Furthermore, the barrier function of the residual dentin/adhesive layer was studied. Six BF-RBC materials were studied. For each material subgroup, ten human third molar teeth with standard Class-I occlusal cavities were prepared and provided with a three-step adhesive system and the respective composite restoration (tooth groups). Same sized control specimens of the restorative material were prepared ('direct BF-RBC' groups). Each specimen was placed in an elution chamber such that the elution media (ethanol/water, 3:1) only contacted the tooth root or ¾ height of each specimen. They were incubated at 37 °C for up to 7 d. Samples of eluate were taken after 1, 2, 4 and 7 d and were analysed by high-temperature gas chromatography/mass spectrometry. (Co)monomers such as Bisphenol A ethoxylate dimethacrylate (bisEMA) or tetraethylene glycol dimethacrylate (TEEGDMA) were mostly found in the eluates of the 'direct BF-RBC' groups in statistically significantly greater amounts than in the eluates of the 'tooth groups'. The residual dentin and/or adhesive layers acted as a diffusion barrier for most of the substances except for triethylene glycol dimethacrylate (TEGDMA) or diethylene glycol dimethacrylate (DEGDMA). For TEGDMA up to 3 orders of magnitude more were found in the 'tooth groups' compared to the 'direct BF-RBC' groups, evidently released by the adhesive system. Substances of Very High Concern (SVHC) including TINUVIN® 328 and BPA were found mainly in the eluates of 'direct BF-RBC' groups. For estimation of biocompatibility, a total system, specifically BF-RBC + adhesive, should always be investigated since individual considerations, such as only elution from a BF-RBC, do not correctly reflect the total clinical situation. The focus of elution tests should not only be on the co(monomers), but also on other ingredients or impurities that may be released. [ABSTRACT FROM AUTHOR]

• A method is described that allows direct comparisons between elution from RBC specimens and from RBC-restored teeth prepared with cavities. • A direct comparison was made of elutable substances from an RBC product family. • GC/MS methods have been used to detect and quantify a range of dimethacrylate monomers in the eluent media and the kinetics of elution. • In addition to elutable (co)monomers, substantial amounts of plasticizers and a UV-stabilizer were found. • An overall assessment of the treatment with regard to elutable substances is recommended, considering the restorative material and adhesive. To develop a model for quantitative comparison of elutable substances by direct elution from resin-bonded composite (RBC) test specimens versus indirect elutability of substances from RBC-restored teeth. Furthermore, it was to be investigated whether the different composites of the Tetric® RBC product family release different types and amounts of substances. Four different composite materials from the Tetric® product family were studied. For each material subgroup ten human third molar teeth were prepared with standard Class-I occlusal cavities. These 'tooth group' specimens were provided with a three-step adhesive system (incorporating TEGDMA) and the respective composite restoration. Same sized control specimens, of each RBC restorative material, were prepared ('direct RBC' groups). All specimens were placed in individual elution chambers such that the elution media (ethanol/water, 3:1) only came into contact with either the tooth root or ¾ height of the 'direct RBC' materials. They were incubated at 37 °C for up to 7 d. Samples of the eluant were taken after 1, 2, 4 and 7 d and were analysed by high-temperature gas chromatography/mass spectrometry. Bisphenol A ethoxylate dimethacrylate (bisEMA), bisphenol A glycidyldimethacrylate (bisGMA), tetraethylene glycol dimethacrylate (TEEGDMA), decan-1,10-diol dimethacrylate (DDDMA) were mostly found in the eluates of the 'direct RBC' groups in statistically significantly greater amounts than in the eluates of the 'tooth groups'. Such quantitative differences were also the case with eluates containing bisphenol A (BPA), dicyclohexyl phthalate (DCHP) and drometrizole, which are common in the environment. In contrast to the behavior found with all the other monomers, up to 3 orders of magnitude more triethylene glycol dimethacrylate (TEGDMA) was found in the 'tooth groups' compared to the 'direct RBC' groups, evidently released by the adhesive system. The release of most of the substances was clearly delayed in the 'tooth groups' indicative of their chronic, rather than acute, elution to the oral environment. A barrier function of the residual dentin layer and the adhesion layer can be inferred. The different release patterns of substances from the various composites of the RBC product family is a manifestation of their different and indication-specific compositions. Consideration of an overall restorative care (RBC plus adhesive) system, when assessing the total amount of released substances, is emphasized. [ABSTRACT FROM AUTHOR]

• An alternative methodology is described to study passive diffusion of residual monomers through the coronal dentinal tubules stimulated via eluent liquids surrounding the root structures only. • Measurements have been conducted at 37 -->°C over a 7 d period and key variables including residual dentin thickness and eluent media have been considered. • GC/MS methods have been used to detect and quantify a range of dimethacrylate monomers in the eluent media and the kinetics of elution. • Critical periods post-restoration for exposure of different monomers to pulp cells have been identified. Ethoxylated 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. In 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. bisEMA 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. Depending 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. [ABSTRACT FROM AUTHOR]

The aim is to recommend a fast and cost-effective screening procedure for UK/SA SARS-CoV-2 variants in a routing diagnostic setting. A rapid procedure using qPCR is described to provide clinicians with information about the two currently most prevalent variants (B1.1.7 and B1.351) that harbour receptor binding domain mutation N501Y. The N501Y specific assay only delivers an amplification signal if the Y501 variant is present. 436 samples initially screened positive for SARS-CoV-2 were randomly selected. Only one of these samples showed a fluorescence signal increase indicative for the Y501 variant. The remaining 435 samples had a melting peak at 54 °C indicating the N501 wildtype. The screening of a broad population base can still be performed with the established test system. In case of a positive test for SARS-CoV-2 and corresponding clinical and anamnestic indications, a second qPCR for the mutation N501Y can follow and deliver the result to public health authorities and to the treating physician within a few hours. [ABSTRACT FROM AUTHOR]

Objectives Ethoxylated bisphenol A dimethacrylate (bisEMA) is a basis monomer in several dental resin composites. It was the aim of the present study to develop a method allowing detection of bisEMA and its different degrees of ethoxylation eluted from polymerized resin composites. Methods High-temperature gas chromatography/mass spectrometry (HT-GC/MS) by direct on-column injection was used to identify ethoxylated bisEMA in ethanol/water (3:1) eluates from polymerized specimen of four bulk-fill resin composites – Venus ® bulk fill, Surefil ® SDR™ flow, Filtek™ Bulk Fill and Sonic Fill™. Additionally, the unpolymerised pastes were analysed. Results The developed method allowed identification of a homologous series of bisEMA up to twelve ethoxy groups in the unpolymerised materials. The molecular masses of the homologous bisEMA varied between 452 g/mol and 892 g/mol and were detected for retention times from 9.43 min to 13.36 min. Analysis of eluates from polymerised materials identified bisEMA monomers with less than 6 ethoxy groups. Chromatograms showed larger peak areas for the lower volatile bisEMA with 4–6 ethoxy groups compared with higher volatile bisEMA with 2 or 3 ethoxy groups, thus indicating that the amounts of these homologues in the pastes were higher. Significance Ethoxylated bisEMA with up to twelve ethoxy groups can be identified by HT-GC/MS. In all eluates bisEMA was found. The higher the number of ethoxy groups the lower are the peak areas from bisEMA in the gas chromatogram. These findings may be significant for toxicological analysis of resin-composites incorporating bis-EMA. [ABSTRACT FROM AUTHOR]

Objectives: To analyse the influence of irradiation time, aging before bleaching, and bleaching technique (home bleaching vs. in-office bleaching) on the amount of elutable substances from modern nano-hybrid resin-based composites (RBCs). Methods: Specimens (n =5) of three nano-hybrid RBCs (Venus® Diamond, Tetric EvoCeram® and Filtek™ Supreme XTE) were irradiated for 5, 10, 20 and 40s. The degree of conversion (DC) was measured in real-time with Fourier transform infrared spectroscopy (FTIR). Specimens were bleached either directly after irradiation or after aging (1.5 or 6 month in distilled water at 37°C) with Opalescence® PF15% for 6h (simulation of home bleaching) or PF35% for 0.5h (simulation of in-office bleaching) and incubated in ethanol/water (3:1) at 37°C for 7d. The eluates were analyzed by gas chromatography/mass spectrometry. Unbleached specimens at the above mentioned irradiation times were used as controls. Results: Bleaching increases the amount of elutable substances. This amount is generally stronger influenced by aging than by polymerization time or concentration of the gel. 2-Hydroxyethyl methacrylate was found in amounts up to 334.14 (106.91) μmol/l (Tetric EvoCeram®, irradiation time 5s; bleaching with 15% CP) as a destruction product. Diethoyxdimethylsilane was found in all eluates from bleached specimens, but not in the control groups. This substance may be formed by oxidation of 3-methacryloxy-propyltrimethoxysilane, indicating that the bond between inorganic filler and organic matrix might be weakened after bleaching. Significance: Bleaching gels might alter the physical properties of resin-based composites, especially at low irradiation times and fresh placed restorations. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The public interest steadily increases in the biological adverse effects caused by components released from resin-based dental restorations. Objective: In this study, the cytotoxicity and the genotoxicity were investigated of following released components from dental resin restorations in human gingival fibroblasts (HGF): tetraethyleneglycol dimethacrylate (TEEGDMA), neopentylglycol dimethacrylate (Neopen), diphenyliodoniumchloride (DPIC), triphenyl-stibane (TPSB) and triphenylphosphane (TPP). Methods: XTT based cell viability assay was used for cytotoxicity screening of substances. γ-H2AX assay was used for genotoxicity screening. In the γ-H2AX assay, HGFs were exposed to the substances for 6h. Induced foci represent double DNA strand breaks (DSBs), which can induce ATM-dependent phosphorylation of the histone H2AX. Cell death effects (apoptosis and necrosis), induced by the substances were visually tested by the same investigator using the fluorescent microscope. Results: All tested substances induced a dose-dependent loss of viability in HGFs. Following toxicity ranking among the substances at EC50-concentration were found in the XTT assay (mM, mean±SEM; n =5): DPIC>Neopen>TPSB>TPP>TEEGDMA. DSB-foci per HGF-cell were obtained, when HGFs were exposed to the EC50-concentration of each substance in the following order (mean±SEM; n =3): DPIC>Neopen>TPSB>TPP>TEEGDMA. Multi-foci cells (cells that contain more than 40 foci each) in 80 HGF-cells at EC50-concentration of each substance were found as follow (mean±SEM; n =3): DPIC>Neopen>TPP>TPSB>TEEGDMA. Cell apoptosis contained in each substance at EC50-concentration in the following order (mean±SEM; n =3): DPIC>Neopen>TPSB>TPP >TEEGDMA. Cell necrosis contained in each substance at EC50-concentration in the following order (mean±SEM; n =3): DPIC>Neopen>TPSB>TPP>TEEGDMA. Conclusion: Leached components from dental resin restorations can induce DNA DSBs and cell death effects in HGFs. [Copyright &y& Elsevier]

Abstract: Objectives: This study''s purpose was to measure and compare the degree of conversion (DC) and the amount of elutable substances from modern resin-based composites (RBCs) as function of polymerization time. One nano-hybrid RBC based on tricyclodecane-(TCD)-urethane (Venus® Diamond) and two conventionally formulated RBCs (TetricEvo Ceram®, Filtek™ Supreme XTE) were considered. Method: DC (n =5) was investigated in real time for 5min by Fourier transform infrared spectroscopy (ATR-FTIR) in a filling depth of 2mm at varied irradiation times (5, 10, 20, 40s). After storing the specimens in ethanol/water for 7 d at 37°C the eluates were analyzed by gas chromatography/mass spectrometry. Results were statistically analyzed using a multivariate analysis (α =0.05) an independent t-test (p <0.05) and a Pearson correlation analysis. Results: In all groups increasing curing time resulted in a significant increase in DC. For TetricEvo Ceram® a high significant inverse correlation was found between DC and the amount of eluted camphorquinone (CQ, Pearson correlation coefficient=−0.88), ethylene glycol dimethacrylate (EGDMA, −0.73), 4-N,N-dimethylaminobenzoic acid ethylester (DMABEE, −0.87), triethylene glycol dimethacrylate (TEGDMA, −0.68), Tinuvin P (−0.71) and bisphenol-A-polyetheylene glycol dimethacrylate (BisEMA, −0.84). Unexpectedly DC and the amount of eluted methyl acrylate (MAA) correlated directly (0.72). In the specimens of Venus® Diamond a significant inverse correlation was found between DC and the amount of eluted CQ (−0.69) and TEGDMA (−0.50), whereas in the specimen of Filtek™ Supreme XTE DC correlated with CQ (−0.96), EGDMA (−0.70), DMABEE (−0.87), TEGDMA (−0.92) and MAA (−0.92). Significance: This study demonstrated a strong inverse correlation between DC and elutable substances in RBCs. Both evaluation methods emphasis the importance of an adequate polymerization (20, 40s), since short curing-times (5, 10s) resulted in lower DC and higher amount of eluted substances with toxic potential. [Copyright &y& Elsevier]

Abstract: Introduction: On extrusion, endodontic sealers might come into close contact with the periapical tissues for long periods. The objective of this study was to test possible mutagenicity of resin-based endodontic sealers by evaluating their potential to induce DNA double-strand breaks (DSBs). Methods: Human gingival fibroblasts were exposed to subtoxic concentrations of eluates from 1 epoxy resin–based endodontic sealer (AH Plus Jet) and 2 methacrylate-based endodontic sealers (EndoRez and Real Seal). As control, Calcicur, a Ca(OH)2-based sealer, was used. The γ-H2AX immunofluorescence assay was used to microscopically detect DNA DSBs, and a custom algorithm was developed to quantify them. Results: The cytotoxicity of the 24-hour eluates could be ranked in the following order: AH Plus Jet > Real Seal > EndoRez >> Calcicur. The γ-H2AX assay revealed that 1.3%–4.3% of the cell nucleus was occupied by foci when the cells were exposed to the eluates of the endodontic sealers. This was not significantly different from the negative control group in which the cells had been exposed to medium (2.1%). Conclusions: No indications for increased risk of genotoxicity of resin-based root canal sealers caused by the induction of DNA DSBs were found in this study. [Copyright &y& Elsevier]

Abstract: Objectives: Silver containing materials have been used for years as antimicrobial materials. Silver particles were also added to experimental dental composites to reduce caries. The aim of our study was to show whether silver nanoparticles can lead to higher amounts of elutable substances. Methods: 0.0125, 0.025, 0.05, 0.1 and 0.3% by weight silver nanoparticles were added to the commercial composite Tetric Flow®. After light curing of the specimen, they were stored up to 7 days in methanol. The eluate was analyzed by gas chromatography/mass spectrometry. Results: Compared to controls more camphorquinone (CQ), ethoxylated bisphenol-A-dimethacrylate (BisEMA) and triethylene glycol dimethacrylate (TEGDMA) will be eluted when silver nanoparticles were added to the composite. Twenty-four hours after the beginning of the experiment 132μmol/l of CQ, 33.9μmol/l BisEMA and 4.5mmol/l TEGDMA were found in the eluate of the specimens containing 0.3% Ag. Significance: Silver nanoparticles may influence the polymerization process in dental materials and lead to an increase in elutable substances. Four possible mechanisms of interaction are discussed: (1) reflection and scattering of the photons, (2) absorption of photons, (3) electron transfer from or to the silver nanoparticles and (4) formation of complexes with Ag+-ions. [Copyright &y& Elsevier]

Abstract: Objectives: Less data are available about the effects of hydrogen peroxide on the three-dimensional polymer network of polymerized composites. Therefore the study was performed to test the effects of hydrogen peroxide on the three-dimensional polymer network in composites. Methods: Polymerized specimens from Tetric Flow®, Tetric Ceram® and Filtek™ Supreme XT were bleached with Opalescence® PF 15% for 5h or PF 35% for 0.5h, respectively, and then stored in methanol for 1d and 7d. Controls were unbleached specimens. The eluates were analyzed by gas chromatography/mass spectrometry. Results: More methacrylic acid (MAA), bisphenol-A (BPA), ethoxylated bisphenol-A-dimethacrylate (BisEMA), hydroquinone monomethyl ether (HQME), 1,10-decanediol dimethacrylate (DDDMA) and/or triethylene glycol dimethacrylate (TEGDMA) were eluted from bleached specimens compared with non bleached controls (1d). The highest DDDMA amount of 419.8μmol/l was found in the eluates after 7d in Tetric Flow® specimens treated with PF 15. The highest HQME amount of 159.6μmol/l was found in eluates from Tetric Ceram® specimens treated with PF after 7d. The highest TEGDMA amount of 178.7μmol/l was found in eluates from Filtek™ Supreme XT specimens treated with PF 35 after 7d. Significance: Bleaching with hydrogen peroxide has an effect on the three-dimensional polymer network in polymerized composites leading to an increase in the release of unpolymerized monomers, additives and unspecific oxidative products. [Copyright &y& Elsevier]

Abstract: Previous in vivo studies have shown that the comonomers triethylene glycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) from dental materials can be metabolised to CO2 by two postulated pathways: an epoxide and a valine pathway. In the epoxide pathway the formation of pyruvate is postulated and in valine pathway the formation of l-malate. The aim of this investigation was to quantify the formation of the intermediates pyruvate and l-malate to show which pathway may be preferred in A549 cells. Therefore A549 cells were incubated with TEGDMA or HEMA (with a tracer dose 14C-TEGDMA or 14C-HEMA) and afterwards 14C-TEGDMA or 14C-HEMA, 14C-methacrylate, 14C-l-malate and 14C-pyruvate were identified and quantified by thin layer chromatography at different time intervals from the extracellular and intracellular fluid. Our results show that in the metabolism of both comonomers more 14C-pyruvate was formed compared to 14C-l-malate for 14C-HEMA metabolisation during 0.5 up to 6h after 14C-HEMA exposure and for 14C-TEGDMA metabolisation >4h after 14C-TEGDMA exposure. Therefore the epoxide pathway with formation of the epoxy-intermediate 2,3-epoxymethacrylic acid is the main route of metabolisation of HEMA and TEGDMA. [Copyright &y& Elsevier]

Abstract: Objectives: Components released from resin-based dental materials are important factors in the assessment of the biocompatibility of these materials. The study was performed to investigate the elution of substances from unpolymerized and polymerized composites (Tetric® =TET; Arabesk® =ARA), ormoceres (Admira® =ADM; Definite® =DEF) and the compomere (Hytac® =HYT). Methods: Specimens were polymerized and immersed in either water or methanol. Besides the unpolymerized specimens were dissolved in methanol. Eluted substances were detected by gas chromatography/mass spectroscopy. The Nernst partition coefficient (DC) of 64 substances, eluted from various resin-based dental materials was determined. Results: Only in methanolic and aqueous eluates from unpolymerized and polymerized specimens of DEF and ADM, the comonomere 1,2/1,3-glycerol dimethacrylate was measured. Triethylene glycol dimethacrylate was eluted into the aqueous and methanolic phase from polymerized specimens from TET and ARA. 2-Hydroxyethyl methacrylate was eluted into the methanolic phase from polymerized specimen from TET and HYT. Residuals of monomer synthesis like triphenyl stibane were found in unpolymerized specimens of TET and ARA. Camphorquinone was eluted into the methanolic eluate from polymerized and unpolymerized specimens from all tested dental materials. Highest DC of 20.8 was found for 1/2-cyclohexene methacrylate. DC of urethane dimethacrylate and bisphenol-A-glycidyldimethacrylate varies from different manufacturers. Significance: Impurities from manufacturing process were found in some resin-based materials. Various well-known substances causing allergic reactions were found in aqueous or methanolic elutes. Patients, dental and manufacturing personnel are exposed to these substances. [Copyright &y& Elsevier]

Objective. The resin monomer triethyleneglycoldimethacrylate (TEGDMA) is used as a diluent in many resin-based bonding, cementing and direct tooth filling materials.Methods. In the present study the uptake and the clearance of 14C-TEGDMA applied via different routes were examined in vivo in guinea pigs. TEGDMA (0.02 mmol/kg by weight labeled with a tracer dose 14C-TEGDMA 0.7 Bq/g by weight) was administered by gastric tube or by subcutaneous injection. Urine, feces, and exhaled carbon dioxide were collected for 24 h after administration. The animals were killed 24 h after the beginning of the experiment and various organs removed and 14C-radioactivity measured.Results. It was apparent that 14C-TEGDMA was taken up rapidly from the stomach and small intestine after gastric administration and was widely distributed in the body following administration by each of the routes. Clearance from most tissues following gastric and intradermal administration was essentially complete within one day. Low fecal 14C-levels (<1% of the administered dose) and urinary levels of about 15% after 24 h were noted with each route of administration. Direct measurement of exhaled carbon dioxide showed that 60–65% of the administered dose of 14C left the body via the lungs during 24 h. It is likely that 14C-pyruvate is formed in vivo resulting possibly in the formation of toxic 14C-TEGDMA-intermediates.Significance. Despite using a high administered dose, the peak TEGDMA levels in all tissues examined after 24 h were at least 100,000-fold less than known toxic levels. [Copyright &y& Elsevier]

• Proficiency testing results were analyzed for calprotectin and pancreatic elastase. • Pancreatic elastase assays gave comparable results across different manufacturers. • Calprotectin assays high variation in results across the different manufacturers. Fecal calprotectin and fecal pancreatic elastase assays are not standardized because of a lack of suitable reference material. Laboratories may have difficulty in switching assays because different manufacturers do not compare well with each other despite having similar reference intervals. Data from proficiency testing performed in Germany (Fecal Diagnostics 01 Survey, INSTAND eV) were investigated to understand how results differed across eight calprotectin and five pancreatic elastase manufacturers. Data were collected from participating laboratories in external quality assessment schemes from 2015 to 2020 for calprotectin and 2017 to 2020 for pancreatic elastase. The manufacturer group mean values and standard deviations were calculated. Reference points were created for each external quality assessment scheme by calculating the average of all manufacturer group means. Deming regression analyses were used to observe the differences across manufacturers. The slopes of the Deming regression spanned 0.37–1.91 for calprotectin and 0.84–1.33 for pancreatic elastase. The calprotectin assays had a high degree of variability in quantitative results by manufacturer. However, pancreatic elastase assays appear to be harmonized across the different manufacturer when considering the qualitative interpretation. Both calprotectin and pancreatic elastase assays could be improved by standardization efforts. Given the clinical utility and our data demonstrating high inter-manufacturer variability, calprotectin should be prioritized over pancreatic elastase in standardization efforts. [ABSTRACT FROM AUTHOR]

Fast and reliable detection of infection is a key to control the SARS-CoV-2 pandemic. Lateral flow antigen tests (LFATs) are inexpensive, easy to use, but have to be verified, as they are rather unspecific and can produce both, false positive and false negative results. Our objective was to combine the speed of LFAT for SARS-CoV-2 with the reliability of qPCR tests. A serial dilution of a patient sample positive for SARS-CoV-2 was prepared and added to LFAT wells from two manufacturers. After evaluation, the devices were opened, the strips removed and extracted in a solution. Amplification was performed using point of care PCR systems (cobas® Liat®, ID NOW™) or on a LightCycler after extraction by MagNAPure 96. The nucleic acid amplification systems yielded higher sensitivity to LFAT. Thus, all samples determined positive by LFAT from the serial dilution were also positive in the subsequent amplification reactions. Sensitivity using extracted eluates was 10–100 times higher. The usage of LFAT is highly recommended for single samples in emergency dental or emergency clinical settings, for smaller cohorts, or even for larger population screening, as it is inexpensive and fast. Positive results can be conveniently verified directly from the test devices using either point of care test equipment or more complex laboratory equipment thus making a major impact on efficient management of infections and isolations. [ABSTRACT FROM AUTHOR]

Objectives: To assess the effect of irradiation time and distance of the light tip on the micro-mechanical properties and polymerisation kinetics of two bulk-fill resin-based composites at simulated clinically relevant filling depth. Methods: Micro-mechanical properties (Vickers hardness (HV), depth of cure (DOC) and indentation modulus (E)) and polymerisation kinetics (real-time increase of degree of cure (DC)) of two bulk-fill resin-based composites (Tetric EvoCeram® Bulk Fill, Ivoclar Vivadent and x-tra base, Voco) were assessed at varying depth (0.1-6 mm in 100 mm steps for E andHV and 0.1,2,4 and 6 mm for DC), irradiation time (10,20 or 40 s, Elipar Freelight2) and distances from the light tip (0 and 7 mm). Curing unit's irradiance was monitored in 1 mm steps at distances up to 10 mm away from the light tip on a laboratory-grade spectrometer. Results: Multivariate analysis (a = 0.05), Student's t-test and Pearson correlation analysis were considered. The influence of material on the measured mechanical properties was significant (η² = 0.080 for E and 0.256 for HV), while the parameters irradiation time, distance from the light tip and depth emphasise a stronger influence on Tetric EvoCeram® Bulk Fill. The polymerisation kinetics could be described by an exponential sum function, distinguishing between the gel and the glass phase. The above mentioned parameters strongly influenced the start of polymerisation (gel phase), and were of less importance for the glass phase. Conclusions: Both materials enable at least 4 mm thick increments to be cured in one step under clinically relevant curing conditions. Clinical significance: The susceptibility to variation in irradiance was material dependent, thus properties measured under clinically simulated curing conditions might vary to a different extent from those measured under ideal curing conditions. [ABSTRACT FROM AUTHOR]

Objectives First, to analyse the in vitro release of BPA and Bis-GMA from an orthodontic resin composite (Transbond XT, 3M Unitek), stored in various conditions, by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS); then to extrapolate the data to the clinical situation. Secondly, to explore the thermal stability of Bis-GMA. Methods Cylinders of resin composite were prepared and stored according to 3 different protocols: (1) they were light-cured 20 s, then placed in artificial saliva; (2) they were light-cured 2 s, then placed in acetonitrile; (3) they were light-cured 2 s, then placed in methanol. For each group, BPA and Bis-GMA release were determined with GC/MS and/or LC/MS at least after one week. Besides, 120 brackets (10 of each type) were bonded over metal teeth, then debonded, and the weight and the surface of resin composite residues were measured. BPA and Bis-GMA release of adhesive residues were extrapolated from the data obtained with the cylinders. Besides, BPA release from a heated Bis-GMA solution was measured. Results With GC/MC, BPA was detected in all samples. With LC/MS, BPA was detected only from samples immersed in MeOH; Bis-GMA was detected, in varying amount according to the extraction media and the light-curing time. BPA was found after heating of the Bis-GMA solution. Significance Contamination risk and the heat applied in GC/MS may overestimate the BPA release from resin composite. Based on the LC/MS results, the risk of BPA release after orthodontic bonding would be more than 42 000 times lower than the TDI for a 30-kg child. [ABSTRACT FROM AUTHOR]

Objectives: Constituents of dental composites can be released from dental fillings after polymerization. The aim of this study was to examine the time-related elution and breakdown of separable constituents of polymerized composites using deuterated solvents. Method: Elution and breakdown of constituents were investigated with deuterated solvents methanol and water by gas chromatography/mass spectrometry of following composites for 180 days: Filtek™ Supreme XT, Filtek™ Supreme XT Flow, Tetric Ceram®, Tetric Flow®, Grandio®, Grandio® Flow. Results: Within 180 days no compounds were formed as the products of breakdown. 19 compounds were identified as elution products: Bis-EMA, TEGDMA, DDDMA, EGDMA, MAA, BPA, CQ, HQME, DMABEE, CSA, BL, TEG, BHT, TINP, TPP, TPSB, DEDHTP, DCHP, ß-PHEA. The highest concentration of Bis-EMA was measured for Tetric Flow® in deuterated methanol on day 90 at 36.993mmol/l and in deuterated water also on day 90 at 0.031mmol/l. The highest TEGDMA concentrations were measured for Grandio® Flow in deuterated methanol on day 60 at 1.322mmol/l and for Filtek™ Supreme XT Flow in deuterated water on day 3 at 0.689mmol/l. The highest BPA concentration was measured for Tetric Flow® in deuterated methanol on day 90 at 1.469mmol/l. The highest BPA concentration was measured for Grandio® in deuterated water on day 180 at 0.007mmol/l. Significance Examination of time-related elution indicates that various elution products (e.g. Bis-EMA, BPA) were only released in small quantities during the first 90 days, but in high quantities between day 90 and day 180. [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: Objectives: In this study the amount of TEGDMA and HEMA eluted from several adhesive systems was quantified. Methods: The adhesive systems were applied according to manufacturers’ instructions in an analytic vial. The adhesive systems used were (abbreviation and producer in parenthesis): cmf adhesive system® (CMF) (Saremco), ENAbond (EB) (Micerium), Optibond FL (OB) (Kerr), Adper Scotchbond Multi-Purpose (SB) (3M ESPE), Silorane System Adhesive (SSA) (3M ESPE), Syntac Classic (SC) (Ivoclar Vivadent) and XP Bond (XPB) (Dentsply). After preparation the specimens were immersed in methanol or distilled water for a period from 1d to 30d at 37°C. Eluted TEGDMA and HEMA were determined by gas chromatographic–mass spectrometry (GC–MS). Results: Following TEGDMA elution from adhesives was found (μg/ml; mean and standard deviation(sd); 1d/30d; methanol): SC 0.93(0.8)/0.68(0.5), SSA 0.27(0.09)/0.16(0.04) and XPB 0.25(0.1)/0.19(0.09). TEGDMA eluted from EB, CMF, OB, and SB was always below detection limit. TEGDMA water elution from each adhesive was about 1/5 lower, compared to the corresponding TEGDMA methanol elution. Following HEMA elution was found (μg/ml; mean(sd); 1d/30d; methanol): SB 3.42(0.9)/2.02(1.2), EB 3.07(2.2)/2.15(2.2), XPB 2.47(1.6)/1.89(1.1), OB 1.4(0.7)/0.82(0.2) and SSA 0.44(0.2)/0.17(0.07). HEMA eluted from CMF and SC was always below detection limit. HEMA water elution from each adhesive was about 1/10 lower, compared to the corresponding HEMA methanol elution. Significance: SC, SSA, and XPB eluted TEGDMA. SB, EB, XPB, OB, and SSA eluted HEMA. CMF eluted neither HEMA nor TEGDMA. [Copyright &y& Elsevier]

Abstract: Objectives: Methacrylate-based (co)monomers released from dental composites can be, metabolized in vivo to methacrylic acid (MA). MA can be further oxidized to the toxic 2,3-epoxymethacrylic acid (2,3-EMA) by cytochrome P450 (CYP450) enzymes. The subform CYP450-2E1, can metabolize xenobiotics with low-molecular weight to epoxides. Oral cells are highly exposed to (co)monomers released from composites. Therefore in this study the, expression of CYP450-2E1 in human oral (and other) cells was investigated as well as the formation of 2,3-EMA in cells exposed to MA. Methods: Following human oral cells were used: human gingiva fibroblasts (HGF), human pulp fibroblasts (HPF), and human tumor buccal keratinocytes (SqCC/Y1). As negative control V79 cells without CYP450-2E1 expression were used. As positive controls V79 cells with CYP450-2E1 expression (V79-CYP450-2E1) and pooled human liver microsomes were used. The expression of CYP450-2E1 in cells was analyzed with the real-time polymerase chain reaction (RT-PCR). 2,3-EMA was quantified by the use of the method of gas chromatography/mass spectrometry (GC/MS). Results: The highest expression of CYP450-2E1 was found in human liver microsomes, followed by SqCC/Y1 cells, V79-CYP450-2E1 cells, HGF, and HPF. The highest amount of 2,3-EMA (μmol/L; mean±SEM, n =3) was found in human liver microsomes (5.0±1.0), followed by SqCC/Y1 cells (2.5±0.8), V79-CYP450-2E1 cells (1.5±0.6), HPF (0.3±0.3), and HGF (0.2±0.2). Significance: It is concluded that the formation of the toxic epoxide 2,3-EMA, as intermediate in the metabolism of dental materials, can occur also in human oral cells which can express the CYP450-2E1 enzyme system. [ABSTRACT FROM AUTHOR]