Airborne exposure to gaseous and particle-associated organic substances in resin-based dental materials during restorative procedures.

Dental composite dust has been shown to act as a vehicle for methacrylates in vivo/in vitro. The objective of this study was to assess airborne exposure of dental personnel to gaseous and particle-associated organic constituents from resin-based dental materials in a simulated clinic. Sampling of total aerosol fractions and gaseous substances was performed by dental students carrying particle filters and gas sorbents attached to a personal pump during preclinical restorative procedures in phantom models (n = 13). Water from the phantoms was sampled. Organic substances were extracted from the sampled water, particle filters, and gas sorbents. Qualitative and quantitative analyses were performed by gas chromatography-mass spectrometry (GC-MS) and ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). The methacrylates 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) and the additives camphorquinone (CQ), butylated hydroxytoluene (BHT), and ethyl 4-(dimethylamino)benzoate (DMABEE), were quantified in the gas and particle fractions sampled. A positive-control experiment was conducted. No methacrylates were detected in the gas or particle fractions sampled, whereas strong signals for methacrylates were detected in the positive controls, matching the analysis of the uncured material. In addition, TEGDMA and DMABEE were quantified in the sampled water. Airborne exposure to constituents in resin-based dental materials was below the detection limit. However, the extent of exposure is probably dependent on the procedure, preventive measures, and type of materials used.

Dose- and time-dependent effects of triethylene glycol dimethacrylate on the proteome of human THP-1 monocytes.

Triethylene glycol dimethacrylate (TEGDMA) is commonly used in polymer resin-based dental materials. This study investigated the molecular mechanisms of TEGDMA toxicity by identifying its time- and dose-dependent effects on the proteome of human THP-1 monocytes. The effects of different concentrations (0.07-5 mM) and exposure times (0-72 h) of TEGDMA on cell viability, proliferation, and morphology were determined using a real-time viability assay, automated cell counting, and electron microscopy, and laid the fundament for choice of exposure scenarios in the proteomic experiments. Solvents were not used, as TEGDMA is soluble in cell culture medium (determined by photon correlation spectroscopy). Cells were metabolically labeled [using the stable isotope labeled amino acids in cell culture (SILAC) strategy], and exposed to 0, 0.3 or 2.5 mM TEGDMA for 6 or 16 h before liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses. Regulated proteins were analyzed in the STRING database. Cells exposed to 0.3 mM TEGDMA showed increased viability and time-dependent upregulation of proteins associated with stress/oxidative stress, autophagy, and cytoprotective functions. Cells exposed to 2.5 mM TEGDMA showed diminished viability and a protein expression profile associated with oxidative stress, DNA damage, mitochondrial dysfunction, and cell cycle inhibition. Altered expression of immune genes was observed in both groups. The study provides novel knowledge about TEGDMA toxicity at the proteomic level. Of note, even low doses of TEGDMA induced a substantial cellular response.

Analysis of organic components in resin-modified pulp capping materials: critical considerations.

The purpose of this study was to elucidate the organic composition and eluates of three resin-based pulp-capping materials in relation to their indications and safety data sheets. Uncured samples of Theracal LC, Ultra-Blend Plus, and Calcimol LC were investigated using gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Identification/quantification of 7-d leachables of cured samples was performed using GC-MS for 2-hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), camphorquinone (CQ), ethylene glycol dimethacrylate (EGDMA), ethyl-4-(dimethylamino)benzoate (DMABEE), and triethylene glycol dimethacrylate (TEGDMA). A similar organic composition was found for Ultra-Blend and Calcimol; however, only Ultra-Blend is indicated for direct pulp-capping. In contrast to the other materials analysed, Theracal contained substances of high molecular weight. The safety data sheets of all materials were incomplete. We detected HEMA, CQ, and TEGDMA in eluates from Ultra-Blend and Calcimol, and it was considered that HEMA might have originated from decomposition of diurethane dimethacrylate (UDMA) in the GC-injector. For Theracal, additives associated with light curing (DMABEE and CQ) were detected in higher amounts (4.11 and 19.95 µg mm-2 ) than in the other materials. Pores were quantified in all samples by micro-computed tomography (micro-CT) analysis, which could influence leaching. The organic substances in the investigated materials might affect their clinical suitability as capping agents, especially for direct capping procedures.

Methods and terminology used in cell-culture studies of low-dose effects of matrix constituents of polymer resin-based dental materials.

General comprehension of terms and confounding factors associated with in vitro experiments can maximize the potential of in vitro testing of substances. In this systematic review, we present an overview of the terms and methods used to determine low-dose effects of matrix constituents in polymer resin-based dental materials in cell-culture studies and discuss the findings in light of how they may influence the comprehension and interpretation of results. Articles published between 1996 and 2015 were identified by searches in the Scopus, Web of Science, MEDLINE, PubMed, and Embase databases using keywords associated with low-dose effects, polymer resin-based materials, in vitro parameters, and dental materials. Twenty-nine articles were included. Subtoxic (n = 11), sublethal (n = 10), and nontoxic (n = 6) were the terms most commonly used to describe the low-dose effects of methacrylates. However, definition of terms varied. Most (82%) studies employed only one method to define the exposure scenario, and no agreement was seen between studies on the use of solvents. Prophylactic use of antibiotics was widespread, and mycoplasma screening was not reported. In conclusion, cell-culture conditions and tests used to define exposure scenarios have changed little in the last decades, despite development in recommendations. Nomenclature alignment is needed for a better understanding of possible biohazards of methacrylates.

Detection and quantification of monomers in unstimulated whole saliva after treatment with resin-based composite fillings in vivo.

Resin-based dental restorative materials contain allergenic methacrylate monomers, which may be released into saliva after restorative treatment. Monomers from resin-based composite materials have been demonstrated in saliva in vitro; however, studies analyzing saliva after restorative therapy are scarce. The aim of this study was to quantify methacrylate monomers in saliva after treatment with a resin-based composite filling material. Saliva was collected from 10 patients at four start points--before treatment, and 10 min, 24 h, and 7 d after treatment--and analysed by combined chromatography/mass spectrometry. The monomers bisphenol-A diglycidyl methacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), and urethane dimethacrylate (UDMA) were detected and quantified in the samples collected shortly (10 min) after treatment. The amounts detected ranged from 0.028 to 9.65 µg ml(-1) for Bis-GMA, from 0.015 to 0.19 µg ml(-1) for HEMA, and from 0.004 to 1.2 µg ml(-1) for UDMA. Triethyleneglycol dimethacrylate (TEGDMA) was detected in four of the samples. Ethoxylated bisphenol-A dimethacrylate (Bis-EMA) was not detected. Monomers were not detected in saliva samples collected before treatment, or 24 h or 7 d after treatment, with the exception of one sample, 24 h after treatment, in which HEMA was detected. In conclusion, monomers from the investigated resin-based composite and adhesive system were present in saliva shortly after treatment. One week after treatment, no monomers could be detected in patients' saliva samples.

Quantitative analysis of TEGDMA and HEMA eluted into saliva from two dental composites by use of GC/MS and tailor-made internal standards.

OBJECTIVES: The use of resin-based dental restorative materials is rapidly increasing, concurrently the biocompatibility of the materials is under investigation. Attention has been placed on studies addressing the cytotoxic, genotoxic and estrogenic potential of these materials. Therefore, the degree of exposure to eluted compounds from the dental materials is of high interest. The aim of this study was to assess the amounts of 2-hydroxyethyl methacrylate (HEMA) and triethyleneglycol dimethacrylate (TEGDMA), released from two composites, eluting into human saliva. To improve the method of quantification, three tailor-made internal standards were synthesized. METHODS: Specimens made from two composites (Tetric EvoCeram and Filtek Z250) were polymerized and immersed in human saliva for 24h. Eluted TEGDMA and HEMA were identified and quantified. The quantitative analyses were performed by use of combined gas chromatography-mass spectrometry (GC/MS) with tailor-made internal standards synthesized by dissolving HEMA or TEGDMA in methanol and reducing the double bond of the methacrylate group by hydrogenation with 1H2 and 2H2 (D2) gas. RESULTS: HEMA was released from both materials, whereas TEGDMA eluted from Filtek Z250 only. Full scan GC-MS analysis of each tailor-made internal standard demonstrated one peak only, which was well separated from the corresponding analyte's peak and with no traces of HEMA or TEGDMA. SIGNIFICANCE: The quantification method seems well suited for in vivo analysis, and the three standards synthesized represent an improved tool for quantification of the eluted monomers. The synthesis may be applied to other methacrylate monomers to produce tailor-made standards for quantification.