Detection of Bisphenol A in dental wastewater after grinding of dental resin composites

Effect of Bleaching Agents on Composite Resins with and without Bis-GMA: An In Vitro Study

The objective was to evaluate the change in color, hardness, and roughness produced by carbamide peroxide (CP) at two different concentrations on two resins. The 16% or 45% CP was applied to 66 resin discs with and without Bis-GMA. The color was measured with a spectrophotometer, and ΔEab and ΔE00 were calculated. Microhardness tester and SEM were used. In both composites, the a* and b* coordinates tended to be red and yellow, respectively, and were significant in the Bis-GMA group (p < 0.05). The ΔEab and ΔE00 were higher in the composite with Bis-GMA, regardless of the treatment received (p < 0.05). The microhardness was reduced in both composites regardless of the PC concentration compared to the control (p < 0.05). The 45% CP reduced the microhardness in the resin group with Bis-GMA compared to 16% CP (p < 0.001) but was not significant in the resin without Bis-GMA (p = 1). An increase in roughness was directly proportional to the concentration of CP, and it was more notable in the composite without Bis-GMA. The composite with Bis-GMA showed a greater tendency to darken than the one without Bis-GMA. The surface hardness of the composite was reduced in both composites and was not influenced by CP concentration in the composite without Bis-GMA. Bleaching is a common procedure nowadays. It is important to know how CP affects composites to establish a prognosis of the treatments in terms of color change, roughness, and hardness.

Impact of bisphenol A and analogues eluted from resin-based dental materials on cellular and molecular processes: An insight on underlying toxicity mechanisms

Dental resin systems, used for artificial replacement of teeth and their surrounding structures, have gained popularity due to the Food and Drug Administration's (FDA) recommendation to reduce dental amalgam use in high-risk populations and medical circumstances. Bisphenol A (BPA), an endocrine-disrupting chemical, is an essential monomer within dental resin in the form of various analogues and derivatives. Leaching of monomers from resins results in toxicity, affecting hormone metabolism and causing long-term health risks. Understanding cellular-level toxicity profiles of bisphenol derivatives is crucial for conducting toxicity studies in in vivo models. This review provides insights into the unique expression patterns of BPA and its analogues among different cell types and their underlying toxicity mechanisms. Lack of a consistent cell line for toxic effects necessitates exploring various cell lines. Among the individual monomers, BisGMA was found to be the most toxic; however, BisDMA and BADGE generates BPA endogenously and found to elicit severe adverse reactions. In correlating in vitro data with in vivo findings, further research is necessary to classify the elutes as human carcinogens or xenoestrogens. Though the basic mechanisms underlying toxicity were believed to be the production of intracellular reactive oxygen species and a corresponding decline in glutathione levels, several underlying mechanisms were identified to stimulate cellular responses at low concentrations. The review calls for further research to assess the synergistic interactions of co-monomers and other components in dental resins. The review emphasizes the clinical relevance of these findings, highlighting the necessity for safer dental materials and underscoring the potential health risks associated with current dental resin systems.

A NiO-nanostructure-based electrochemical sensor functionalized with supramolecular structures for the ultra-sensitive detection of the endocrine disruptor bisphenol S in an aquatic environment

Herein, NiO nanoparticles (NPs) functionalized with a para-hexanitrocalix[6]arene derivative (p-HNC6/NiO) were synthesized by using a facile method and applied as a selective electrochemical sensor for the determination of bisphenol S (BPS) in real samples. Moreover, the functional interactions, phase purities, surface morphologies and elemental compositions of the synthesized p-HNC6/NiO NPs were investigated via advanced analytical tools, such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Additionally, the synthesized p-HNC6/NiO NPs were cast on the surface of a bare glassy carbon electrode (GCE) via a drop casting method, which resulted in uniform deposition of p-HNC6/NiO/GCE over the surface of the GCE. Additionally, the developed p-HNC6/NiO/GCE sensor demonstrated an outstanding electrochemical response to BPS under optimized conditions, including a supporting electrolyte, a Briton-Robinson buffer electrolyte at pH 4, a scan rate of 110 mV s-1 and a potential window of between -0.2 and 1.0 V. The wide linear dynamic range was optimized to 0.8-70 μM to obtain a brilliant linear calibration curve for BPS. The limit of detection (LOD) and limit of quantification (LOQ) of the developed sensor were estimated to be 0.0059 and 0.019 μM, respectively, which are lower than those of reported sensors for BPS. The feasibility of the developed method was successfully assessed by analyzing the content of BPS in waste water samples, and good recoveries were achieved.

Electrochemical simultaneous determination of hydroquinone, catechol, bisphenol A, and bisphenol S using a novel mesoporous nickel-modified carbon sensor

The widespread occurrence of endocrine disruptor compounds in wastewater has garnered significant attention owing to their toxicity, even at low concentrations, and their persistence in the water body. Among various analytical techniques, electrochemical sensors become popular for the environmental monitoring of water pollutants due to their low cost, rapid detection, high sensitivity, and selectivity. In this study, the mesoporous Ni (MNi) material was synthesized with an innovative method using Pluronic™ F-127 as a soft template and applied as a modifier for the simultaneous electrochemical sensing of hydroquinone (HQ), catechol (CC), bisphenol A (BPA), and bisphenol S (BPS). MNi with high porosity efficiently enhanced the redox-active surface area and conductivity of the glassy carbon electrode contributing to a significantly improved sensitivity in the detection of target chemicals. The pore size and surface area of MNi were estimated based on atomic force microscopy and Brunauer Emmett and Teller techniques to be ∼14.2 nm and 31.1 m2 g-1, respectively. The limit of detection for HQ, CC, BPA, and BPS was determined to be 5.3, 5.7, 5.6, and 61.5 nM, respectively. The electrochemical sensor presented in this study holds promise as a platform for developing portable and miniaturized tools offering the rapid and sensitive detection of these hazardous phenolic compounds in environmental water samples.

Comparison of three cyclodextrins to optimize bisphenol A extraction from source water: Computational, spectroscopic, and analytical studies

Computationally and spectroscopically assisted analytical comparative investigation into the extraction of bisphenol A using three cyclodextrins, that is, α, β, and γ respectively, were performed. A simple, self-tailored μ-solid-phase extraction podium was used to extract bisphenol A from water samples, and high-performance liquid chromatography-ultraviolet was used for the qualitative and quantitative analysis of bisphenol A. Density functional theory first principle calculations, attenuated total reflectance Fourier-transform infrared spectroscopy and Fourier-transform Raman spectroscopy data supports the analytical selection of β-cyclodextrin as the adsorbent for bisphenol A extraction. Analytical optimization of various parameters including sample volume, sample pH, eluting solvent and its volume was performed to discover the most proper conditions for maximum extraction. Under the optimized conditions, a limit of detection value of 0.70 ng/ml and a limit of quantification value of 2.31 ng/ml was achieved with β-cyclodextrin, with recovery (%) values over 98.40-102.50 in real source water samples. Overall, well assisted by comprehensive computational and spectroscopic studies, a novel, simple, sensitive and economic analytical method was developed for the extraction of bisphenol A from source water using cyclodextrin.

A comparative life cycle assessment of dental restorative materials

OBJECTIVES

Different types of direct-placement dental materials are used for the restoration of structure, function and aesthetics of teeth. The aim of this research investigation is to determine, through a comparative cradle-to-gate life cycle assessment, the environmental impacts of three direct-placement dental restorative materials (DRMs) and their associated packaging.

METHODS

Three direct-placement dental materials; dental amalgam, resin-based composite (RBC) and glass polyalkenoate cements (GIC) are assessed using primary data from a manufacturer (SDI Limited, Australia). The functional unit consisted of 'one dental restoration' of each restorative system under investigation: 1.14 g of dental amalgam; 0.25 g of RBC (plus the adhesive = 0.10 g); and 0.54 g of GIC. The system boundary per restoration included the raw materials and their associated packaging materials for each DRM together with the processing steps for both the materials and packaging. The environmental impacts were assessed using an Egalitarian approach under the ReCiPe method using Umberto software and the Ecoinvent database. Nine different impact categories were used to compare the environmental performance of these materials.

RESULTS

Dental amalgam had the highest impact across most of the categories, but RBC had the highest Global Warming Potential. The highest sources of the environmental impacts for each restorative material were: Amalgam, derived from material use; RBC, derived from energy use in processing material and packaging material; GIC, derived from material and energy use for packaging.

SIGNIFICANCE

Less intensive energy sources or more sustainable packaging materials can potentially reduce the impacts associated with RBC and GIC thus making them suitable alternatives to dental amalgam.

Tailoring the monomers to overcome the shortcomings of current dental resin composites - review

Dental resin composites (DRCs) have become the first choice among different restorative materials for direct anterior and posterior restorations in the clinic. Though the properties of DRCs have been improved greatly in recent years, they still have several shortcomings, such as volumetric shrinkage and shrinkage stress, biofilm development, lack of radio-opacity for some specific DRCs, and estrogenicity, which need to be overcome. The resin matrix, composed of different monomers, constitutes the continuous phase and determine the performance of DRCs. Thus, the chemical structure of the monomers plays an important role in modifying the properties of DRCs. Numerous researchers have taken to design and develop novel monomers with specific functions for the purpose of fulfilling the needs in dentistry. In this review, the development of monomers in DRCs were highlighted, especially focusing on strategies aimed at reducing volumetric shrinkage and shrinkage stress, endowing bacteriocidal and antibacterial adhesion activities as well as protein-repelling activity, increasing radio-opacity, and replacing Bis-GMA. The influences of these novel monomers on the properties of DRCs were also discussed.

Metal-organic framework mixed-matrix membrane-based extraction combined HPLC for determination of bisphenol A in milk and milk packaging

The residues of bisphenol A (BPA) in milk packaging may transfer to milk, adversely affecting the human endocrine system. Consequently, to analyse or monitor BPA, it is imperative to develop rapid and effective approaches to BPA extraction from milk and milk packing as BPA is usually present in trace levels. Herein, we developed a rapid, simple, and low-cost dispersive-membrane-solid-phase-extraction (DME) for BPA with MIL-101(Cr) mixed-matrix-membrane (MMM). The MMM had large surface area (1322.09 m²/g) and pore volume (0.65 cm³/g), possessed great extraction efficiency of BPA, and kept more than 90% extraction efficiency after 20 times of reuse. Using the developed MIL-101(Cr)-MMM-based DME coupled with HPLC-fluorescence detector, we received an adequate linearity in the range of 0.1 ∼ 50 μg/L BPA and a limit of detection as low as 16 ng/L under optimized conditions. The recoveries of BPA in milk and milk bottles were from 74.2% to 110.6%, with RSDs less than 9.4%.

Bio-based Non-estrogenic Dimethacrylate Dental Composite from Cloves

Bisphenol A (BPA), as an endocrine disruptor derived from petroleum-based chemicals, has been prohibited by several regulatory agencies for use in a wide variety of consumer products. For the sake of reducing human exposure to BPA derivatives and in the context of sustainability, it is far-reaching to develop high-performance and low-toxic materials from bountiful biomass sources. The objective of this work was to synthesize 2 bio-based dimethacrylate monomers, 2,2'-dially-4,4'-dimethoxy-5,5'-diglycerolate acrylatediphenylmethane (BEF-EA) and 2,2'-dially-4,4'-dimethoxy-5,5'-diglycerolate methacrylatediphenylmethane (BEF-GMA), using eugenol as the raw material. The estrogenic activity of bio-based bisphenol 2,2'-dially-4,4'-dimethoxy-5,5'-dihydroxydiphenylmethane (BEF) was evaluated and compared with estrogen and commercial bisphenols. After photopolymerization of the di(meth)acrylates diluted with tri(ethyleneglycol) dimethacrylate (TEGDMA), bio-based visible light-curing materials were prepared, and their properties were systematically investigated. Notably, di(meth)acrylates BEF-GMA and BEF-EA derived from these nonestrogenic bio-based phenols exhibited improved biocompatibility and low viscosity (down to 220-280 Pa.s). BEF-GMA and BEF-EA resin matrix exhibits lower volumetric polymerization shrinkage (about 8.5%), high photopolymerization reactivity (>50% in 60 s), and mechanical properties (fracture energy >5.5 N mm; flexural strength of 87-91 MPa, etc), which were comparable or superior to commercial Bis-GMA. The respective bio-based composites still exhibit adequate properties. Therefore, introducing eugenol-based visible light-curable dimethacrylate monomers into dental materials is a potential strategy to establish green sustainability and biocompatible dental materials without BPA.

Analytical Methods for Determination of BPA Released from Dental Resin Composites and Related Materials: A Systematic Review

Knowing the impacts of bisphenol A (BPA) on human health, this systematic review aimed to gather the analytical methods for the quantification of BPA release of BPA in dental materials in in vitro and in vivo (biological fluids) studies. A brief critical discussion of the impacts of BPA on human health and the possible association with BPA in dental materials was also presented. The research was carried out by three independent researchers, (according to PRISMA guidelines) in PUBMED and SCOPUS databases, by searching for specific keywords and articles published between January 2011 and February 2022. Seventeen articles met the eligibility criteria and were included in this systematic review: 10 in vitro and 7 in vivo. In in vitro studies, the highest amounts of BPA released were from flowable to conventional resins, followed by resin-modified glass ionomer. In contrast, the smallest amount was released from "BPA-free" composites and CAD-CAM blocks. Regarding in vivo studies, a higher concentration of BPA were found in saliva than urine or blood. The best analytical method for trace quantifying BPA is LC-MS/MS (Liquid Chromatography with Tandem Mass Spectrometry) due to its selectivity, low quantification limits, and the unequivocal identification. However, further studies are required to develop faster and more sensitive methods, in order to obtain more reliable results.

Resin-based composite materials: elution and pollution

Pollution arises from all human activity and the provision of oral healthcare using resin-based composite restorative materials (RBCs) should be considered. This paper aims to provide a comprehensive review of the potential pollutant risk to the environment from the chemical compounds found in resin-based restorative materials, by including: 1) the principal pollutant compounds present in the resin matrix; 2) the degradation process of RBCs and its consequences; 3) the methods used for the detection and quantification of monomer elution and RBC microparticles; and 4) a review of the release mechanisms of eluates and RBC microparticles into the environment.

RBCs are pollutants by virtue of the compounds created during the degradation processes. These are in the form of the constituent eluted monomers and microparticles. Their impact on the environment and biodiversity is unknown. These materials are currently one of the main direct-placement restorative materials and their success is unquestionable when used and maintained correctly. Mitigation strategies for reducing the impact of pollution on the environment should be considered and implemented by all stakeholders and processes in the supply chain, from manufacturing, clinical use and waste management.

All the constituent components of resin-based composites have the potential to act as environmental pollutants as a consequence of their breakdown and subsequent elution.

Microparticles have a pollution potential as they are easily dispersed in solution and have an increased surface area that potentiates the elution of monomers.

Strategies to reduce their pollution impact should include: a) development of innovative direct-placement restorative materials; b) minimising waste; and c) providing good-quality preventive dentistry that minimises restoration failure and requirement for replacement.

Characteristics of wastewater originating from dental practices using predominantly mercury-free dental materials

Dental materials are currently undergoing a revolution. Mercury use, including traditional amalgam (mercury-containing) material used in dental fillings, is now being widely regulated under the Minamata convention, and dental amalgam is currently being replaced by resin formulations in dentistry. These resin-based materials can be tuned to offer varying material properties by incorporation of a range of nano- and micro-particle based 'fillers' for different dental properties and applications. However, these innovations may have a concomitant effect on the waste streams associated with common dental applications, in particular the potential for higher concentrations of novel micro- and nanomaterials within wastewater streams, and a potential route for novel nanomaterials into the wider Environment. These new materials may also mean that wastewater filtering apparatus commonly deployed at present, such as amalgam separators, may be less efficient or insufficient to capture these new filler materials in dental facility wastewater. In this work, we analyse dental wastewater streams from three dental facilities in Ireland with differing amalgam separators in place. The potential overall toxicity, particulate load and physicochemical properties are analysed. The overall risk posed by these new materials is also discussed.

The hazardous threat of Bisphenol A: Toxicity, detection and remediation

Bisphenol A (or BPA) is a toxic endocrine disrupting chemical that is released into the environment through modern manufacturing practices. BPA can disrupt the production, function and activity of endogenous hormones causing irregularity in the hypothalamus-pituitary-gonadal glands and also the pituitary-adrenal function. BPA has immuno-suppression activity and can downregulate T cells and antioxidant genes. The genotoxicity and cytotoxicity of BPA is paramount and therefore, there is an immediate need to properly detect and remediate its influence. In this review, we discuss the toxic effects of BPA on different metabolic systems in the human body, followed by its mechanism of action. Various novel detection techniques (LC-MS, GC-MS, capillary electrophoresis, immunoassay and sensors) involving a pretreatment step (liquid-liquid microextraction and molecularly imprinted solid-phase extraction) have also been detailed. Mechanisms of various remediation strategies, including biodegradation using native enzymes, membrane separation processes, photocatalytic oxidation, use of nanosorbents and thermal degradation has been detailed. An overview of the global regulations pertaining to BPA has been presented. More investigations are required on the efficiency of integrated remediation technologies rather than standalone methods for BPA removal. The effect of processing operations on BPA in food matrices is also warranted to restrict its transport into food products.

Quantification of Single Use Plastics Waste Generated in Clinical Dental Practice and Hospital Settings

OBJECTIVES

To quantify (by number and mass) single use plastic waste generated from the provision of oral healthcare in primary and secondary care clinical dental settings in the UK.

METHODS

An observational study of four dental practices and the clinics of a UK undergraduate dental teaching hospital was conducted. A range of routine common procedures were observed by trained and calibrated observers; these were: Examinations, endodontics, periodontics, direct placement restorations, fixed and removable prosthodontics and oral surgery. The PPE items used before and during the COVID-19 pandemic were also included.

RESULTS

Routine 'surgery set up' generic items present a significant proportion of SUP plastic waste as these are used in every instance of patient treatment. An average of twenty-one (n=21) SUP plastic waste items are used for every procedure with a mean mass of 354g per procedure (including set up and clean up). The use of PPE increased from 14 items (pre-COVID -19) to 19 items during the pandemic. SUP items are constructed from a single plastic or from multiple plastics forming compound structures (heteropolymers); with an approximate 50:50 distribution.

CONCLUSIONS

The dental profession, at the point of care, uses a high volume of single use plastic that becomes clinical waste. The use of personal protective equipment (PPE) significantly increased during the COVID 19 pandemic and this accounts for the single greatest contribution of single use plastic, as this is used for every clinical procedure.

CLINICAL SIGNIFICANCE

Manufacturers, distributors and oral healthcare providers have an opportunity to consider and implement approaches that include effective waste management with reduction, recovery and recycling at its core, towards transforming oral healthcare to a circular plastics economy.

Bisphenol A and Its Analogues Deteriorate the Hormones Physiological Function of the Male Reproductive System: A Mini-Review

BPA is identified as an endocrine-disrupting chemical that deteriorates the physiological function of the hormones of the male reproductive system. Bisphenol F (BPF), bisphenol S (BPS), and bisphenol AF (BPAF) are actively explored as substitutes for BPA and are known as BPA analogues in most manufacturing industries. These analogues may demonstrate the same adverse effects as BPA on the male reproductive system; however, toxicological data explaining the male reproductive hormones' physiological functions are still limited. Hence, this mini-review discusses the effects of BPA and its analogues on the physiological functions of hormones in the male reproductive system, focusing on the hypothalamus-pituitary-gonad (HPG) axis, steroidogenesis, and spermatogenesis outcomes. The BPA analogues mainly show a similar negative effect on the hormones' physiological functions, proven by alterations in the HPG axis and steroidogenesis via activation of the aromatase activity and reduction of spermatogenesis outcomes when compared to BPA in in vitro and in vivo studies. Human biomonitoring studies also provide significant adverse effects on the physiological functions of hormones in the male reproductive system. In conclusion, BPA and its analogues deteriorate the physiological functions of hormones in the male reproductive system as per in vitro, in vivo, and human biomonitoring studies.

Effect of the Degree of Conversion on Mechanical Properties and Monomer Elution from Self-, Dual- and Light-Cured Core Composites

The objective of this work was to measure and correlate the degree of conversion (DC), mechanical properties and monomer elution from self-, dual- and light-cured core composites. Five samples of each of the following materials were prepared for each test: Clearfil (Core, Photo Core, Automix), Bisco (Core-Flo, Light-Core and Bis-Core). DC was determined using FTIR, compressive and flexural strength and modulus of elasticity using a universal testing machine and microhardness using Vickers hardness. Elution was measured using HPLC. One-way ANOVA with Tukey's post-test and Pearson's correlation were used to statistically analyze the data. DC of Clearfil-Dual (70.1%) and Clerafil-Photo (66.8%) were higher than Clearfil-Self (55.4%) and all Bisco materials (51.4-55.3%). Flexural strength of Clearfilwas higher than that of Bisco composites. The Microhardness of Clearfil-Dual (119.8VHN) and Clearfil-Photo (118.0VHN) were higher compared to other materials. The greatest elution was detected from self-cured materials. DC positively correlated to microhardness and compressive/flexural strength and negatively to BisGMA elution. Clearfil-Photo and Automix showed higher conversion, lower monomer elution and, generally, better mechanical properties. Self-cured composites should not be recommended for routine clinical use as their performance was inferior to dual- and light-cured composites. Microhardness may be used as an indicator of elution.

Characterisation of Microparticle Waste from Dental Resin-Based Composites

Clinical applications of resin-based composite (RBC) generate environmental pollution in the form of microparticulate waste. Methods: SEM, particle size and specific surface area analysis, FT-IR and potentiometric titrations were used to characterise microparticles arising from grinding commercial and control RBCs as a function of time, at time of generation and after 12 months ageing in water. The RBCs were tested in two states: (i) direct-placement materials polymerised to simulate routine clinical use and (ii) pre-polymerised CAD/CAM ingots milled using CAD/CAM technology. Results: The maximum specific surface area of the direct-placement commercial RBC was seen after 360 s of agitation and was 1290 m²/kg compared with 1017 m²/kg for the control material. The median diameter of the direct-placement commercial RBC was 6.39 μm at 360 s agitation and 9.55 μm for the control material. FTIR analysis confirmed that microparticles were sufficiently unique to be identified after 12 months ageing and consistent alteration of the outermost surfaces of particles was observed. Protonation-deprotonation behaviour and the pH of zero proton charge (pH_zpc) ≈ 5–6 indicated that the particles are negatively charged at neutral pH7. Conclusion: The large surface area of RBC microparticles allows elution of constituent monomers with potential environmental impacts. Characterisation of this waste is key to understanding potential mitigation strategies.

Cytotoxicity and estrogenicity in simulated dental wastewater after grinding of resin-based materials

OBJECTIVE

This study evaluated the cytotoxic and estrogenic effects of dust and eluates released into simulated wastewater after grinding of dental resin-based materials.

METHODS

Four materials were used: ceram.x® universal, Filtek™ Supreme XTE, Lava™ Ultimate and Core-X™ flow. From each composite material, samples (5 × 2 mm, n = 50) were prepared according to the manufacturers' instructions. Lava™ Ultimate was used as blocks. All samples were ground to dust with a diamond bur (106 μm) and suspended in distilled water at 60 mg/mL. After storage for 72 h, the suspensions were separated into a soluble (eluate) and a particulate (dust) fraction. Eluates and dusts were evaluated for inhibition of Vibrio fischeri bioluminescence and cytotoxicity on human A549 lung cells (WST-1-Assay). The estrogenic activity was assessed by YES-Assay using Saccharomyces cerevisiae. Additionally, dental monomers (BisGMA, BisEMA, UDMA, TEGDMA, HEMA) and Bisphenol A were investigated.

RESULTS

All eluates showed inhibition of V. fischeri bioluminescence at concentrations above 1.1 mg/mL (p < 0.05). The activity of the eluates of ceram.x® universal and Filtek™ Supreme XTE was significantly higher than Lava™ Ultimate and Core-X™ flow (p < 0.05). In the WST-1-Assay, all materials induced cytotoxic effects at concentrations of 0.1 mg/mL (p < 0.05), while no significant differences were detected among them. The tested materials revealed no estrogenic activity. All dental monomers and Bisphenol A showed concentration dependent cytotoxic effects (p < 0.05), whereas only Bisphenol A induced an estrogenic effect (p < 0.01).

SIGNIFICANCE

Dust and eluates of resin-based dental materials released into wastewater exert bactericidal and cytotoxic effects in vitro. However, they reveal no estrogenic effect.