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Objectives: Only little is known about degradation of methacrylate monomers. Therefore, using in vitro chemical and saliva degradation this study aimed to identify the degradation products of organic compounds present in resin-based dental materials., Methods: Ten dental monomers and nine polymerized dental resin-based materials were immersed for 24 h in chemical media (0.1 M HCl, 0.1 M NaOH) and human pooled saliva in order to identify leached monomers and degradation products from chemical and saliva degradation. Samples were analyzed using liquid chromatography coupled to high-resolution mass spectrometry to identify previously unknown degradation products., Results: During in vitro chemical degradation, uncured monomers were rapidly hydrolyzed into mono- and demethacrylated degradation products. During chemical degradation in alkaline conditions of polymerized materials, considered the worst-case scenario, only degradation products could be detected. In acidic conditions, monomers and their degradation products were detected. In addition, different additives such as EDMAB, DMPA and HMBP were present in acidic degradation samples. Degradation in human pooled saliva for 24 h to mimic the in vivo situation, resulted in the identification of both monomers and their degradation products., Clinical Significance: Using state-of-the-art high-resolution mass spectrometry previously unknown degradation products of commonly used monomers were identified for the first time. Results show that patients may be exposed to monomers and their degradation products in the first 24 h after restorative procedures. The results provide a base for further research on the degradation of resin-based dental composites in order to assess their safety using elution and toxicity studies., Competing Interests: Conflicts of interest The authors declare they have no conflict of interest., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objective: The biocompatibility of resin based dental composites has not yet been fully characterized even though certain monomers used in these composites are synthesized from Bisphenol A (BPA), a well-known estrogenic endocrine disruptor. As a result, they show structural relationship to BPA and can contain it as an impurity. Therefore, the estrogenic activity of 9 monomers, 2 photoinitiators, one photostabilizer and leachates of 4 commercially available composites was determined., Methods: The ERα-CALUX bioassay was used to determine both agonistic and antagonistic estrogenic activities of the pure compounds (BPA, BisDMA, BisGMA, BisEMA(3), BisEMA(6), BisEMA(10), TEGDMA, TCD-DI-HEA, BADGE, UDMA, HMBP, DMPA, CQ) and the leachates of cured composite disks. The leachates of 4 commercially available composites (Solitaire 2, Ceram.x Spectra ST, G-ænial Posterior and Filtek Supreme XTE) in water and 0.1 M NaOH (pH = 13, 'worst-case scenario') were tested for estrogenic activity (pooled leachates from 10 cured composite disks)., Results: Agonistic estrogenic activity was found for the monomer BisDMA, the photostabilizer HMBP and photoinitiator DMPA. All leachates from the 4 tested composites showed significant agonistic estrogenic activity higher than the DMSO control, and the highest activity (potency and efficacy) was found for Solitaire 2, followed by Ceram.x Spectra ST. Furthermore, antagonistic estrogenic activity was found in the leachates from G-ænial Posterior., Significance: These results show that significant estrogenic activity was found in all leachates of the cured composite disks, and that this estrogenicity is most likely due to a mixture effect of multiple estrogenic compounds (including BPA, HMBP and DMPA). This indicates that further research into the endocrine activity of all the compounds that are present in these composites (even at low quantities) and their possible mixture effect is warranted to guarantee their safe use., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objectives: BPA release from composites on the short term has been reported in several in-vitro and in-vivo studies. However, it remains unclear whether these materials also leach BPA on the long term. Even though composites may release various (BPA-based) methacrylate monomers up to one year, quantitative data about BPA have not been reported due to the lack of a sensitive method to accurately quantify low levels of BPA. In this context, the aim of the study was to quantify the one-year release of BPA with an optimized analytical method., Methods: Composite disks (n = 6, 6 mm diameter and 2 mm height) from four commercial materials (G-ӕnial Posterior, Venus, Ceram.x mono and Filtek Supreme XTE) were immersed in 1 mL of water or ethanol as extraction solvent and stored in the dark at 37 °C. The extraction solvent was renewed weekly for a period of 52 weeks. Samples were derivatized with pyridine-3-sulfonyl chloride before analysis with ultra-pressure liquid chromatography tandem mass spectrometry (UPLC-MS/MS)., Results: Derivatizing BPA increased the sensitivity of the analytical method and allowed accurate quantification of very low levels of BPA (i.e. 0.78 pmol BPA). BPA eluted continuously in ethanol from all four tested composites over a period of one year. BPA elution was clearly higher when ethanol was used as extraction solution. In water, BPA eluted could be detected up to one year, but levels could not be accurately quantified anymore after several weeks., Significance: Composites can be considered as a potential long-term source of BPA, and thus should not be neglected when assessing the overall exposure to endocrine disrupting chemicals., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objective: To bridge the gap between the current alarming literature on resin-based dental materials and the limited clinical observations, more precise knowledge on the actual quantity of released compounds should be acquired. The objective of this study was to quantify the long-term elution of various compounds from resin-based dental composites during one year., Methods: Eight materials were investigated: G-aenial Anterior, G-aenial Posterior, Venus, Venus Pearl, Venus Diamond, Ceram X mono, Dyract and Filtek Supreme XTE. Cylindrical specimens (6 mm diameter, 2 mm thickness) were immersed in 1mL of three different extraction solutions (water, artificial saliva or ethanol) and stored in the dark at 37°C. Every week, the extraction solution was refreshed. The samples were analyzed using ultra-performance liquid chromatography-tandem mass spectrometry., Results: BisEMA3, BisEMA6, BisEMA10, BisGMA, CQ, HEMA, TCD-DI-HEA, TEGDMA, and UDMA were quantified in the samples. Depending on the composite and the extraction solution, certain monomers (BisGMA, HEMA and UDMA) were able to continuously elute from the materials, up until 52 weeks after initial immersion. Monomer elution was clearly higher when ethanol was used as extraction solution. It could be demonstrated that the tested composites continued to release small quantities of monomers over longer periods when a continuous refreshing protocol is followed., Significance: Even if monomer elution may not lead to a risk at short term, the potential long-term toxicity should be further investigated. Long-term elution and subsequent chronic exposure to monomers from resin-based dental materials should not be neglected when assessing the overall human health risks., (Copyright © 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

There is a growing necessity to acquire more profound knowledge on the quantity of eluates from resin-based dental materials, especially with regard to bisphenol A (BPA). The aim of the present study was to develop a highly sensitive method to characterize the short-term release of BPA in saliva with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), using an extraction step and additional derivatization of BPA with pyridine-3-sulfonyl chloride. Light-cured resin-based composites were incubated at 37 °C in 1 mL artificial saliva, which was refreshed daily for one week. The final protocol allows accurate quantification of very low levels of BPA in samples of artificial saliva (i.e. 1.10 pmol BPA/mL or 250 pg/mL). The daily BPA-release from dental composites, ranging from 1.10 to 7.46 pmol BPA/mL, was characterized over a period of 7 days. The highest total amount of BPA was released from Solitaire 2 (24.72 ± 2.86 pmol), followed by G-ænial Posterior (15.51 ± 0.88 pmol) and Filtek Supreme XTE (12.00 ± 1.31 pmol). In contrast, only trace amounts of BPA were released from Ceram.x Universal. This UPLC-MS/MS method might be used for clinical research focusing on the evaluation of the clinical relevance of BPA release from dental materials.

Objective: Accurate knowledge of the quantity of released monomers from composites is important. To evaluate the elution of monomers, polymerized composites are typically immersed in an extraction solvent. The objective was to determine whether the volume of extraction solvent and the immersion time influences monomer leachability from dental composite materials., Methods: Composite disks of two commercial composites, (Filtek Supreme XTE, 3M ESPE and G-aenial Universal Flo, GC) were prepared. The disks (n=10) were placed in a glass vial with 1ml, 2ml or 3ml of extraction solvent (100% ethanol with deuterated diethylphalate as internal standard). After either 7 or 30 days at 37°C, the supernatant was collected and the amount of released monomers (BisEMA, BisGMA, UDMA, TEGDMA) and bisphenol A was measured with liquid chromatography mass spectroscopy., Results: For both tested composites, the highest amount of released monomers was measured after sample incubation in 3ml, while the lowest amount was measured in 1ml of extraction solvent. Furthermore, 30 days did not result in much more monomer release compared to 7 days, and for most monomers, there was no statistically significant difference in release between 7 and 30 days., Significance: Release kinetics in in-vitro experiments are also influenced by saturation of the extraction solvent with the leached monomers. This is important as it is unlikely that saturation can be reached in an in-vivo situation, where saliva (or pulpal fluid) is continuously refreshed. Saturation of the extraction solvent can be avoided in-vitro by refreshing the extraction medium after equal time intervals., (Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Resin-based dental materials have raised debates concerning their safety and biocompatibility, resulting in a growing necessity of profound knowledge on the quantity of released compounds into the oral cavity. In this context, the aim of this study was to develop a comprehensive and reliable procedure based on liquid chromatography with mass spectrometry for the simultaneous analysis of various leached compounds (including bisphenol A based compounds) in samples from in vitro experiments. Different experiments were performed to determine the optimal analytical parameters, comprising mass spectrometry parameters, chromatographic separation conditions, and sample preparation. Four internal standards were used as follows: deuterated diethyl phthalate and bisphenol A (commercially available), and deuterated analogues of triethylene glycol dimethacrylate and urethane dimethacrylate (custom-made). The optimized method was validated for linearity of the calibration curves and the associated correlation coefficient, lower limit of quantification, higher limit of quantification, and intra- and interassay accuracy and precision. Additionally, the developed liquid chromatography with tandem mass spectrometry method was applied to the analysis of leaching compounds from four resin-based dental materials. The results indicated that this method is suitable for the analysis of different target compounds leaching from dental materials. This method might serve as a valuable basis for quick and accurate quantification of leached compounds from resin-based dental materials in biological samples., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Objectives: The aim of this study was to determine the degree of conversion (DC) and the monomer release of three composite types when employed following a layer- and bulk-filling technique., Methods: The release of monomers from a 'conventional paste-like' (Filtek Z250), a 'conventional flowable' (Filtek Supreme XTE Flowable) and a 'bulk-fill' flowable composite (Filtek Bulk Fill Flowable) from the same manufacturer (3M ESPE, Seefeld, Germany) was determined. Ten cylindrical specimens per composite were built, either in two 2-mm layers or in one 4-mm bulk. DC was measured at the specimen top and bottom surface using micro-Raman spectroscopy, after which the specimens were immersed in 2 ml absolute ethanol for 24 h at 37 °C. This solution was refreshed weekly during six weeks and the concentration of BisGMA, BisEMA(6), BisPMA, UDMA, TEGDMA and BPA was determined by liquid chromatography/mass spectroscopy., Results: DC at the specimen top and bottom was similar except for the bulk-fill technique, which resulted in significantly lower DC at the specimen bottom. The release of BisGMA and TEGDMA was initially very high, but rapidly dropped in the second week. In contrast, the release of BisPMA and UDMA increased initially, but then declined towards the sixth week. BisEMA(6) release was relatively steady over time. All composites released small amounts of BPA. The total monomer release was significantly lower for the layer- than the bulk-filling technique., Conclusions: The slightly reduced degree of conversion at 4-mm depth resulted in a higher monomer elution when the composite was applied following a bulk-fill application method., Clinical Significance: Applying a flowable and a bulk-fill composite following a bulk-fill application method resulted in a significantly reduced degree of conversion at the bottom of polymerized composite specimens when compared to a layer-application method. This reduced polymerization degree was reflected in significantly increased monomer release., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objectives: Resin-based dental materials are not inert in the oral environment, and may release components, initially due to incomplete polymerization, and later due to degradation. Since there are concerns regarding potential toxicity, more precise knowledge of the actual quantity of released eluates is necessary. However, due to a great variety in analytical methodology employed in different studies and in the presentation of the results, it is still unclear to which quantities of components a patient may be exposed. The objective of this meta-analytical study was to review the literature on the short- and long-term release of components from resin-based dental materials, and to determine how much (order of magnitude) of those components may leach out in the oral cavity., Methods: Out of an initial set of 71 studies, 22 were included. In spite of the large statistical incertitude due to the great variety in methodology and lack of complete information (detection limits were seldom mentioned), a meta-analytical mean for the evaluated eluates was calculated. To relate the amount of potentially released material components with the size of restorations, the mean size of standard composite restorations was estimated using a 3D graphical program., Results: While the release of monomers was analyzed in many studies, that of additives, such as initiators, inhibitors and stabilizers, was seldom investigated. Significantly more components were found to be released in organic than in water-based media. Resin-based dental materials might account for the total burden of orally ingested bisphenol A, but they may release even higher amounts of monomers, such as HEMA, TEGDMA, BisGMA and UDMA. Compared to these monomers, similar or even higher amounts of additives may elute, even though composites generally only contain very small amounts of additives. A positive correlation was found between the total quantity of released eluates and the volume of extraction solution., Significance: There is a clear need for more accurate and standardized analytical research to determine the long-term release from resin-based materials. Several guidelines for standardization are proposed., (Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Objectives : Dental composites remain under scrutiny regarding their (long-term) safety. In spite of numerous studies on the release of monomers both in vitro and in vivo, only limited quantitative data exist on the in vivo leaching of degradation products from monomers and additives. The aim of this observational study was for the first time to quantitatively and qualitatively monitor the release of parent compounds and their degradation products in saliva from patients undergoing multiple restorations. Materials and methods: Five patients in need of multiple large composite restorations (minimally 5 up to 28 restorations) due to wear (attrition, abrasion, and erosion) were included in the study, and they received adhesive restorative treatment according to the standard procedures in the university clinic for Restorative Dentistry. Saliva was collected at different time points, starting before the restoration up until 24 h after the treatment with composite restorations. Saliva extracts were analyzed by liquid chromatography–mass spectrometry. Results: Leaching of monomers and degradation products was highest within 30 min after the placement of the restorations. The highest median concentrations of monomers were recorded for UDMA, BisEMA-3, and TEGDMA; yet, besides BisEMA-3 and TEGDMA, no monomers could be detected after 24 h. Mono- and demethacrylated degradation products remained present up to 24 h and concentrations were generally higher than those of monomers. In patients with multiple restorations, degradation products were still present in the sample taken before the next operation, several weeks after the previous operation. Conclusions: Exposure to residual monomers and degradation products occurs in the first hours after restoration. Monomers are present in saliva shortly after restoration, but degradation products can be detected weeks after the restoration confirming a long-term release. Clinical significance: Future research should focus more on the release of degradation products from monomers and additives from resin-based materials given their prolonged presence in saliva after restoration. [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]

• Traces of BPA were present as an impurity in the monomer batches of BisGMA and BisEMA-3. • Increased BPA quantities were detected upon salivary and bacterial challenge, indicating degradation of the monomers. • Dental monomers in acidic or alkaline solutions did not degrade into BPA. There is still much debate about the release of bisphenol-A (BPA) from dental materials. Therefore, this study aimed to quantify BPA present as an impurity in both BPA-based and non-BPA-based monomers and to evaluate whether these monomers may degrade to BPA upon salivary, bacterial, and chemical challenges. BPA was determined in three different amounts (1, 2, and 3 μmol) of each monomer (TEGDMA, UDMA, mUDMA, BisGMA, BisEMA-3, -6, -10, -30, BisPMA, EBPADMA urethane, BADGE, and BisDMA). Next, the monomers (3 μmol) were immersed in whole human pooled saliva collected from adults, Streptococcus mutans (2 × 107 CFU/mL), and acidic (0.1 M HCl), alkaline (0.1 M NaOH), and control media. The amount of BPA was quantified using a specific and highly sensitive UPLC–MS/MS method including derivatization of BPA by pyridine-3-sulfonyl chloride. The monomers BisGMA and BisEMA-3 contained trace amounts (0.0006% and 0.0025%, respectively) of BPA as impurities of their synthesis process. BPA concentrations increased when the monomers BisGMA, BisEMA-3, BisEMA-6, BisEMA-10, BisPMA and BADGE were exposed to saliva and S. mutans, indicating degradation of a small amount of monomer into BPA. In addition, BisPMA and BADGE degraded into BPA under alkaline conditions. The conversion rate of the monomers into BPA ranged between 0.0003% and 0.0025%. Impurities and degradation of BPA-based monomers may account for the release of BPA from resin-based dental materials. Even though the detected amounts of BPA due to monomer impurity were small, manufacturers of dental materials can reduce the BPA content by using only monomers of the highest purity. Considering the overall current trend towards BPA-free materials, it may be recommendable to investigate whether non-BPA based monomers can be used in dental resin-based materials. [ABSTRACT FROM AUTHOR]

• A novel approach for collection of respirable fraction of composite dust. • Respirable fraction of composite dust can induce both cytotoxic and mild genotoxic effect in 16HBE cells. • Initial DNA damage and impairment of normal cell cycle is observable in subtoxic concentrations. • Respirable particles of all tested composites were taken by the cells. To determine the cytotoxic and genotoxic potential of the respirable fraction of composite dust (<4 μm) on human bronchial epithelial cells. Composite sticks of three commercial dental composites (Filtek Supreme XTE, Grandio, Transbond XT) were ground in an enclosed plexiglass chamber with a rough dental bur (grain-size 100 μm) and the generated airborne respirable dust was collected in a personal cyclone on a teflon filter (pore size 5 μm). Immediately after particle collection, the dust was quantified gravimetrically and the particles were suspended in cell culturing medium. Next, human bronchial epithelial cells (16HBE14o-) were exposed to the suspensions (3 μg/ml–400 μg/ml). After 24 h, cell viability (WST-1 assay) and membrane integrity (LDH assay) were evaluated. Furthermore, the genotoxic effect of a sub-cytotoxic concentration (50 μg/ml) of composite dust was evaluated by the comet assay after 3 h exposure and cell cycle disturbances were analyzed by flow cytometry. Cellular uptake of particles was evaluated by transmission electronic microscope (TEM). For all three tested composite materials, a decrease in metabolic activity of 10–35% was observed when the cells were exposed to the highest concentrations (100 μg/ml–400 μg/ml). Toxicity was partially linked to membrane disruption especially after 72 h exposure. All tested composites provoked a mild genotoxic effect after short-term exposure compared to the control groups. TEM revealed that respirable particles of all tested composites were taken up by the cells. The respirable fraction of composite dust only showed cytotoxic effects at the highest concentrations, whereas mild genotoxicity was observed after exposure to a sub-cytotoxic concentration. [ABSTRACT FROM AUTHOR]