Salivary bisphenol A levels and their association with composite resin restoration

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 comprehensive review on advanced trends in treatment technologies for removal of Bisphenol A from aquatic media

Toxic environmental pollutants are considered to be posed a major threat to human and aquatic systems. The fast advancement of the petrochemical and chemical industries has woken up rising worries concerning the pollution of water by contaminants including phenolic Bisphenol A (BPA), an endocrine-disrupting chemical (EDC). The intermediate BPA used in synthesis of certain plastics, polycarbonate polymers, polysulfone, and epoxy resins of various polyesters. Due to potential health risks, severe toxicity, and widespread distribution, there is an urgent need to develop efficient techniques for the removal of BPA. Therefore, advance management for the active elimination of BPA prior to its release into the water sources is of serious concern. Degradation, membrane separation, adsorption, and biological treatments have been extensively examined as they are easy to operate and cost-effective for effective BPA removal. In this review, we summarized the mechanism and performance for removal of BPA by several sorbents, including natural polymers, natural inorganic minerals, porous and carbon-based materials. Comparative results revealed that composite materials and modified adsorbents have good performances for removal of BPA. Furthermore, kinetic study investigating adsorption mechanisms was also discussed. Hazardous quantities of such types of chemicals in various samples have thus been the subject of increasing concern of investigation. This review clarified the extensive literature regarding the major health effects of BPA and its advanced treatment technologies including biological treatment by natural and synthetic materials have been discussed briefly. It delivers regulation for future development and research from the aspects of materials functionalization, development of methods, and mechanism investigation that directing to stimulate developments for removal of emerging contaminants.

Potential hazards of bisphenol A on the male reproductive system: Induction of programmed cell death in testicular cells

A common industrial chemical known as bisphenol A (BPA) has been linked to endocrine disruption and can interfere with hormonal signaling pathways in humans and animals. This comprehensive review aims to explore the detrimental consequences of BPA on reproductive organ performance and apoptosis induction, shedding light on the emerging body of evidence from laboratory animal studies. Historically, most studies investigating the connection between BPA and reproductive tissue function have mainly leaned on laboratory animal models. These studies have provided crucial insights into the harmful effects of BPA on several facets of reproduction. This review consolidates an increasing literature that correlates exposure to BPA in the environment with a negative impact on human health. It also integrates findings from laboratory studies conducted on diverse species, collectively bolstering the mounting evidence that environmental BPA exposure can be detrimental to both humans and animals, particularly to reproductive health. Furthermore, this article explores the fundamental processes by which BPA triggers cell death and apoptosis in testicular cells. By elucidating these mechanisms, this review aids a deeper understanding of the complex interactions between BPA and reproductive tissues.

Water Sorption and Solubility of Highly Aesthetic Single-Shade Nano-Hybrid Resin Composites

Background A single-shade resin composite is a new type of resin composite that was introduced in 2019. There is not much data regarding the water sorption (Wsp) and water solubility (Wsl) of this type of resin composite. Therefore, this study aimed to investigate Wsp and Wsl and their effects on the surface roughness of a single-shade nano-hybrid resin composite in comparison with a conventional nano-hybrid resin composite in accordance with ISO 4049:2019 (Dentistry - Polymer-based Restorative Materials). Material and methods An in vitro study was performed to investigate the Wsp and Wsl of a single-shade supra-nano-hybrid composite (Omnichroma) and a conventional nano-hybrid composite (Filtek™ Z250 XT) in accordance with ISO 4049:2019. Five disks were prepared of each material with dimensions of 15 ± 1 mm in diameter and 1 ± 0.1 mm in thickness, as per ISO 4049:2019. The results were calculated according to the ISO equations for Wsp and Wsl in µg/mm3. Atomic force microscopy (AFM) was used to analyze the surface roughness (Ra) of test specimens. Results The findings showed that the values of Wsl and Wsp of both materials are comparable and revealed no statistically significant difference (P > 0.05). The AFM images showed a higher Ra post-solubility testing, and the statistical analysis indicated a significant difference for both materials. Conclusions The study concluded that the single-shade resin composite (Omnichroma) and the conventional nano-hybrid composite (Filtek™ Z250 XT) are following the requirements of ISO 4049:2019. The AFM analysis indicated that resin composite surfaces are significantly affected when exposed to water for a prolonged period of time. However, the Ra variations of Filtek™ Z250 XT were higher than Omnichroma specimens. These results indicate that resin composite surfaces can be significantly impacted by prolonged water exposure. This knowledge is critical for enhancing the long-term clinical performance and durability of these dental restorative materials.

Unraveling the interaction of bisphenol A with collagen and its effect on conformational and thermal stability

Evidence suggests the association of bisphenol A (BPA) with increased collagen (COL) expression in the development of fibrosis. Ultraviolet and fluorescence spectra on collagen-BPA interaction showed that 100 ng/ml of BPA initiated loosening of protein backbone through unfolding with exposure of tyrosine residues resulting in an intermediate "Molten Globule" state, which later aggregated with 1 μg/ml of BPA indicated with an apparent red-shift. Conformational changes with CD and ATR-FTIR showed disappearance of negative band with broadening and shifting of peptide carbonyl groups. Light scattering findings with TEM images presented initial dissolution followed by unordered thick fibrillar bundles with 30 μg/ml BPA. The complex was pH sensitive, with calorimetric thermogram revealing increased thermal stability requiring 83°C to denature. Hydrogen bonds of 2.8 Å with hydrophobic interactions of BPA in all grooves of collagen molecule with same pattern and binding energy (-4.1 to -3.9 kcal/mol) confirmed the intensity of aggregate formation via in-silico docking.

Current Evidence on Bisphenol A Exposure and the Molecular Mechanism Involved in Related Pathological Conditions

Bisphenol A (BPA) is one of the so-called endocrine disrupting chemicals (EDCs) and is thought to be involved in the pathogenesis of different morbid conditions: immune-mediated disorders, type-2 diabetes mellitus, cardiovascular diseases, and cancer. The purpose of this review is to analyze the mechanism of action of bisphenol A, with a special focus on mesenchymal stromal/stem cells (MSCs) and adipogenesis. Its uses will be assessed in various fields: dental, orthopedic, and industrial. The different pathological or physiological conditions altered by BPA and the related molecular pathways will be taken into consideration.

Evaluation of the bisphenol released in the saliva after residual adhesive removal in orthodontic patients by using ultrasonic scaling and rotary system: A single-center randomized clinical trial

INTRODUCTION

Bisphenol A (BPA) is a substance commonly used in dental materials with noxious properties. Monomers of this substance may be dissolved in the saliva and cause adverse effects. This study aimed to evaluate the amount of BPA released in the saliva after residual adhesive removal in orthodontic patients using an ultrasonic scaler (US) and tungsten carbide bur (TCB).

METHODS

This single-center randomized clinical trial was conducted on 40 subjects whose stainless-steel brackets were bonded directly with light-cured bonding and composite. The subjects were randomly divided into 2 equal groups (n = 20) of TCB or US according to the adhesive removal method. The salivary BPA level was determined using high-performance liquid chromatography-mass spectrometry. And adhesive cleaning time was measured by a stopwatch. Data were analyzed by SPSS using an independent t test and paired-samples t test (P <0.05).

RESULTS

The mean salivary BPA level was significantly lower in the TCB method than in the US method. (1.008 ± 0.061 μg/mL and 2.83 ± 0.24 μg/mL, respectively) (P <0.001). The mean adhesive cleanup time was significantly shorter in the TCB method than in the US method (8.86 ± 0.83 minutes and 13.20±1.02 minutes, respectively) (P <0.001).

CONCLUSIONS

According to the results, residual adhesive removal with TCB released less BPA in saliva and shortened the adhesive cleaning time than the US method.

TRIAL REGISTRATION

The trial was registered at the Iranian Registry of Clinical Trials (IRCT20200702047988N1).

PROTOCOL

The protocol was not published before trial commencement.

Effects of bisphenol A and estradiol in adult rat testis after prepubertal and pubertal exposure

Over the past few decades, male fertility has been decreasing worldwide. Many studies attribute this outcome to endocrine disruptors exposure such as bisphenol A (BPA), which is a chemical compound used in plastics synthesis and exhibiting estrogenic activity. In order to assess how the window of exposure modulates the effects of BPA on the testis, prepubertal (15 dpp to 30 dpp) and pubertal (60 dpp to 75 dpp) male Sprague-Dawley rats were exposed to BPA (50 µg/kg bw/day), 17-β-estradiol (E2) (20 µg/kg bw/day) as a positive control, or to a combination of these compounds. For both periods of exposure, the rats were sacrificed and their testes were collected at 75 dpp. The histological analysis and the quantification of the gene expression of testis cell markers by RT-qPCR confirmed the complete spermatogenesis in all groups for both periods of exposure. However, our results suggest a deleterious effect of BPA on the blood-testis barrier in adults after pubertal exposure as BPA and BPA+E2 treatments induced a decrease in caveolin-1 and connexin-43 gene expression; which are proteins of the junctional complexes. As none of these effects were found after a prepubertal exposure, these results suggested the reversibility of BPA's effects. Caution must be taken when transposing this finding to humans and further studies are needed in this regard. However, from a regulatory perspective, this study emphasizes the importance of taking into account different periods of exposure, as they present different sensitivities to BPA exposure.

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.

Monomer release from dental restorative materials containing dimethacrylate resin after bleaching

OBJECTIVE

The aim of this study is to determine the type and amount of monomer released over time after bleaching was applied to dental restorative materials containing dimethacrylate resin.

MATERIALS AND METHODS

Thirteen different restorative materials containing dimethacrylate resin were used in this study. Twenty samples were prepared from each material and the samples were randomly divided into 4 subgroups, namely, office bleaching, home bleaching, and separate control group for each of the bleaching methods. After bleaching, the samples were stored in 75% ethanol solution for 1, 14, and 28 days. Analysis of the samples collected to determine the type and amount of residual monomer released from the materials was performed using a liquid chromatography-tandem mass/mass spectrometer (LC-MS/MS). Data were analyzed using Friedman and Kruskal-Wallis tests. Statistical significance level was taken as p < 0.05.

RESULTS

In terms of bleaching groups, mostly no significant difference was found between the groups in each time period in restorative materials (p > 0.05). In terms of time periods, it was determined that the amount of release of all monomers was decreased over time. In terms of restorative materials, the highest monomer release was detected in composite resin groups and the least monomer release was detected in CAD/CAM blocks.

CONCLUSION

Although monomers were released from all materials, bleaching did not affect the amount of released monomer. Amounts of released monomers were generally below toxic limits.

CLINICAL RELEVANCE

Within the limits of this study, bleaching does not significantly affect monomer release in restorative materials containing dimethacrylate resin.

Influence of BPA exposure, measured in saliva, on childhood weight

INTRODUCTION

Endocrine disruptors such as bisphenol A (BPA), BPA glycidyl methacrylate, and other BPA acrylate-based derivatives have been related to type 2 diabetes, the metabolic syndrome, and obesity, among other metabolic disorders. The objective of this study is to examine the influence of BPA exposure by saliva analysis and daily physical activity on the risk of overweight/obesity in schoolchildren from southern Spain.

METHODS

The study included 300 children (53.5% girls) aged 7-10 years. Participants completed a questionnaire with four sections: participant data, including demographic information and life and family habits; semi-quantitative food frequency questionnaire; anthropometric variables; and physical activity variables. All participants underwent dental examination, when the presence of sealants/composites in each tooth and other dental alterations was recorded, and samples of whole saliva were collected for UHPLC-MS/MS analyses.

RESULTS

Risk of overweight/obesity was significantly influenced by body fat composition (OR = 10.77), not walking to and from school (OR = 1.38), lesser energy expenditure in sedentary activities (OR = 12.71), greater energy expenditure in sports (OR =1.62), and exposure to BPA from dental sealants/composites (OR = 1.38; p = 0.058).

DISCUSSION

Further research is warranted on this issue in children, who may be especially vulnerable to the negative health effects of endocrine disruption.

Bisphenol A Release from Dental Composites and Resin-Modified Glass Ionomers under Two Polymerization Conditions

Bisphenol A (BPA)-based monomers are commonly contained in dental resin-based materials. As BPA is an endocrine disruptor, its long-term release from restorative composites and resin-modified glass ionomers (RM-GICs) under two polymerization conditions was measured in this study. Specimens of two conventional composites containing BPA-based monomers, two “BPA-free” composites, and two RM-GICs were polymerized from one side for 20 s at 1300 mW/cm² or for 5 s at 3000 mW/cm². The amounts of BPA released in artificial saliva and methanol after 1, 4, 9, 16, 35, 65, 130, and 260 days were measured using liquid chromatography–tandem mass spectrometry. The highest amounts of BPA were released from conventional composites, followed by RM-GICs, while the least was released from “BPA-free” composites. Amounts of released BPA were significantly higher in methanol and decreased gradually after the first day. Fast polymerization (5 s at 3000 mW/cm²) resulted in a significantly higher release of BPA after 1 day, but the effect of polymerization conditions was not significant overall. In conclusion, fast polymerization increased the initial release of BPA, but the released amounts were significantly lower than the current tolerable daily intake (4 μg/kg body weight/day) even in methanol, representing the worst-case scenario of BPA release.

A fabric phase sorptive extraction method for the LC-UV determination of bisphenol A and leaching monomers from dental materials in human saliva

A rapid and simple fabric phase sorptive extraction (FPSE) procedure is developed for the simultaneous extraction of four monomers (Bisphenol A, BPA; Triethylene glycol dimethacrylate, TEGDMA; Urethane dimethacrylate, UDMA; Bisphenol A-glycidyl methacrylate, BisGMA) in human saliva, prior to the determination by high pressure liquid chromatography with an ultraviolet-visible detector. FPSE is a green sample preparation technique, harmonized with the principles of Green Analytical Chemistry (GAC), which utilizes a flexible surface, such as cellulose, chemically coated with a polymeric material using sol-gel technology. FPSE membranes are characterized by superior chemical stability and any solvent or solvent mixture can be used for elution. Among twelve different sol-gel coated membranes, an FPSE membrane coated with sol-gel polytetrahydrofuran (sol-gel PTHF) was found optimum to extract four target compounds from saliva samples, which were first centrifuged. Parameters with most significant impact on the extraction efficiency of FPSE including elution solvent, utilization of magnetic stirring, extraction time have been comprehensively studied and optimized. The studied compounds' separation was carried out by a Perfect Sil 120 ODS-2 chromatographic column (250 mm × 4.0 mm, 5 μm), using a mobile phase constituting of acetonitrile-water 70:30 % v/v (isocratic elution). The total analysis time was 10 min. Detection was achieved by an ultraviolet-visible detector at 220 nm. The method was validated in terms of sensitivity, linearity, trueness, precision, selectivity and stability of samples. For all four compounds, the limit of detection and the limit of quantification were 0.075 ng/μL and 0.25 ng/μL, respectively. Relative recovery rates were between 90.0 and 106.7%, while RSD values were <8.1 and 12% for interday and intraday repeatability, respectively. Youden & Steiner approach was applied to study method's ruggedness and reusability of the media was tested, which enhanced the green nature of technique.

Effects of high-dose bisphenol A on the mouse oral mucosa: A possible link with oral cancers

Bisphenol A (BPA) is an endocrine disrupting chemical able to promote hormone-responsive tumors. The major route of BPA contamination being oral, the aim of the present study was to investigate BPA effects on oral cells. Here, we evaluated the impact of sub-chronic in vivo exposure to BPA and its in vitro effects on neoplastic and non-neoplastic oral cells. We evaluated the oral mucosa of mice chronically exposed to BPA (200 mg/L). The response of keratinocytes (NOK-SI) and Head and Neck (HN) Squamous Cell Carcinoma (SCC), HN12 and HN13 cell lines to BPA was examined. In vivo, BPA accumulated in oral tissues and caused an increase in epithelial proliferative activity. BPA disrupted the function of keratinocytes by altering pro-survival and proliferative pathways and the secretion of cytokines and growth factors. In tumor cells, BPA induced proliferative, invasive, pro-angiogenic, and epigenetic paths. Our data highlight the harmful effects of BPA on oral mucosa and, tumorigenic and non-tumorigenic cells. Additionally, BPA may be a modifier of oral cancer cell behavior by prompting a functional shift to a more aggressive phenotype.

Investigation of the Impact of Dental Care via Composite Resin Restoration among Children with Attention Deficit Hyperactivity Disorder: A Registry-Based Nested Case-Control Study

Attention deficit hyperactivity disorder (ADHD) is one of the most common psychiatric conditions. Many studies have shown that exposure to low-dose bisphenol-A (BPA) can contribute to ADHD. The relationship between ADHD and composite resin is still unclear. We designed a nested case-control study to investigate the relationship between ADHD and composite resin restorations among children from the Taiwan's National Health Insurance Research Database. We included 85,503 people whose birth years were between 1998 and 2005 and who received resin restoration from January 2000 to December 2008. A 1:2 matched control sample without ADHD was randomly selected from the database by propensity score matching based on birth year and sex. We identified 4984 individuals as ADHD patients. The average diagnostic age of ADHD was 7.45 years old. The patients who received composite resin restorations had higher risk of ADHD than those who had never received them (aOR (adjusted odds ratio) = 1.25; 95% CI (confidence interval) = 1.13-1.38). Males had a higher risk of ADHD (aOR = 1.29; 95% CI = 1.14-1.43). Taken together, this nested case-control study demonstrated a positive association between ADHD and dental care via composite resin restoration in Taiwanese children. Prospective clinical studies of the relationship between ADHD and composite resin are warranted.

Risk assessment of predicted serum concentrations of bisphenol A in children and adults following treatment with dental composite restoratives, dental sealants, or orthodontic adhesives using physiologically based pharmacokinetic modeling

Bisphenol A (BPA) is a chemical used to manufacture bisphenol A glycidyl methacrylate (BisGMA). BisGMA has been used for decades in dental composite restoratives, sealants, and adhesives. Based on published studies, exposure to low concentrations of BPA are possible from dental and orthodontic devices. The serum BPA concentrations arising from such devices and oral doses were predicted using a PBPK model in children and adult females based on 1) published extraction data for cured and uncured 3M ESPE Filtek Supreme Ultra Flowable, 3M ESPE Filtek Bulk Fill Restorative, and 3M ESPE Clinpro Sealant and 2) published 20% ethanol/water and water rinsate data following orthodontic application with 3M ESPE Transbond MIP Primer and 3M ESPE Transbond XT Adhesive. Predicted oral exposure to BPA arising from these dental and orthodontic devices is low (median <10 ng/treatment) and predicted serum BPA concentrations were also low (<10^-4 nM). Even the maximum predicted exposure in this study (533.2 ng/treatment) yields a margin of exposure of 7.5 relative to the EFSA t-TDI (4 μg/kg-day) and is only 2.8% of the daily BPA exposure for the US population in a 58-kg woman (15,660 ng/day). Therefore, the exposure to BPA arising from the 3M ESPE dental and orthodontic devices evaluated in this study is negligible relative to daily BPA exposure in the general population and these potential BPA sources do not constitute a risk to patients.

Bisphenol A in human saliva and urine before and after treatment with dental polymer-based restorative materials

The aim of this study was to quantify bisphenol A (BPA) concentrations in saliva and urine before and after treatment with dental polymer-based restorative materials to assess if placement of this material is associated with increased BPA levels in saliva and urine. Twenty individuals in need of at least one dental restoration with polymer-based restorative material were included in this study. The participants were instructed to abstain from eating, drinking, and brushing their teeth for at least 10 h prior to sampling. Saliva and urine were collected before and 10 min (saliva only), 1 h, 24 h, and 1 wk after treatment. Samples were stored at -80°C before analyses. BPA in saliva and urine was determined with liquid chromatography/mass spectrometry. Linear mixed effects regression models were used for statistical analyses. There was a statistically significant increase of salivary BPA concentration directly after placement of the dental polymer-based restorations. Following placement, the concentration of BPA decreased exponentially with time. One week after treatment the BPA level in saliva was only marginally higher than before treatment. In urine, no statistically significant change of the BPA concentration was detected after treatment.

The adverse health effects of bisphenol A and related toxicity mechanisms

Bisphenol A (BPA) is an industrial component commonly used in synthesis of polycarbonate plastics, epoxy resin and other polymer materials. Due to its mass productions and widespread applications, the presence of BPA is ubiquitous in the environment. BPA can enter the body via different ways such as digestive tract, respiratory tract and dermal tract. As an endocrine disruptor, BPA has estrogen-like and anti-androgen effects causing damages to different tissues and organs, including reproductive system, immune system and neuroendocrine system, etc. Recently, it has been shown that BPA could induce carcinogenesis and mutagenesis in animal models. Here, the underlying mechanisms of BPA-induced multi-organ toxicity were well summarized, involving the receptor pathways, disruption of neuroendocrine system, inhibition of enzymes, modulation of immune and inflammatory responses, as well as genotoxic and epigenetic mechanisms. The aim of this review is to compile the available current research data regarding BPA and provide an overview of the current status of BPA exposure and relevant health effects covering reproductive, developmental, metabolic, immuno, respiratory, hepatic and renal toxicity and carcinogenesis of BPA. This review provides comprehensive data of BPA toxicity on human health and related mechanisms. We also identify any missing data which should be addressed by further studies.

Once Resin Composites and Dental Sealants Release Bisphenol-A, How Might This Affect Our Clinical Management?-A Systematic Review

(1) Background: Bisphenol A (BPA) based dental resins are commonly used in preventive and reparative dentistry. Since some monomers may remain unpolymerized in the application of dental resin, they dissolve in the saliva. (2) Methods: The literature search was carried out in Pubmed, Cochrane and Embase databases. Randomized controlled trials, cohort studies and case-control studies that evaluated BPA levels in human urine, saliva and/or blood were included. (3) Results: The initial search had 5111 results. A total of 20 studies were included in the systematic review. Most studies showed an increase of the levels of bisphenol A 1 h after treatments with composite resins and dental sealants. One week after treatments the levels were decreased. (4) Conclusions: Some clinical precautions should be taken to decrease the release of BPA, namely the use of rubber dam, the immediate polishing of all resins used, or the use of glycerin gel to avoid non-polymerization of the last resin layer, and mouthwash after treatment. Another preventive measure in addition to the above-mentioned is the use of the smallest possible number of restorations or sealants, a maximum of four per appointment. These measures are even more important in children, adolescents and pregnant women.

Supramolecular solvent-based microextraction of emerging bisphenol A replacements (colour developers) in indoor dust from public environments

Bisphenol A (BPA) is present in a wide variety of materials and it is a well-known endocrine disruptor that is widespread in indoor and outdoor environments. For this reason, industry has introduced a variety of replacements, such as Bisphenol S (BPS) or Bisphenol F (BPF), and other less known structural analogs, such as BPS-MAE, D-8 or TGSA. These emerging potential contaminants have been identified in thermal paper products, according to recent studies, but their potential toxic effects and their migration into the environment remain unclear. In this study, we report for the first time the presence of emerging BPA replacements in indoor dust from public environments (shops, restaurants, etc.). For this purpose, we optimized a novel supramolecular solvent (SUPRAS)-based microextraction method. SUPRAS are multi-target solvents made up of self-assembled amphiphiles. They offer multiple extraction interactions (dispersion, polar, hydrophobic, etc.) and they constitute excellent candidates to develop generic and fast sample treatment procedures at low cost. By this method, emerging BPA replacements (BPS-MAE, D-8 and TGSA) were detected in dust at median concentrations in the range 6-22 ng g^-1 (around ten times lower than BPS) with detection frequencies in the range 50-90%. These results constitute a first insight into the migration of emerging BPA replacements into the environment via indoor dust, which is a common route of human exposure to contaminants.

Bisphenol A in dental materials - existence, leakage and biological effects

OBJECTIVE

Recently, questions have been raised concerning the potential endocrine disrupting effects of bisphenol A (BPA). This substance is a constituent in many different products which we frequently come into contact with, such as food containers and receipts. Resin-based dental filling materials are another source of exposure, although according to previous studies the amount and potential risks are not clear. Thus, the aims of the present study were (1) to identify if direct dental filling materials are liable to leak BPA and (2) to investigate if this leakage could lead to any adverse effects on health.

MATERIALS AND METHODS

A literature search was made with PubMed as the primary source, subsequently complemented with reference tracking.

RESULTS

A total of 26 articles were included, 24 of which were used for the first aim (leakage) and 2 for the second aim (health risks). The majority of studies, including all in vivo studies, showed leakage of BPA from dental materials in various amounts and during different time intervals. The findings showed a contradiction in results regarding the connection between dental materials and adverse health effects.

CONCLUSIONS

There is leakage of BPA from some dental materials, but critical levels are not evident. Bis-DMA contents might convert to BPA in the oral cavity. There is a contradiction between in vitro and in vivo studies concerning BPA leakage and finally, there is a lack of studies investigating the association between BPA exposure and its adverse effects on human health.

A novel high sensitivity UPLC-MS/MS method for the evaluation of bisphenol A leaching from dental materials

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.

Polymer-Based Direct Filling Materials

After a brief review of current restorative materials and classifications, this article discusses the latest developments in polymer-based direct filling materials, with emphasis on products and studies available in the last 10 years. This will include the more recent bulk fill composites and self-adhesive materials, for which clinical evidence of success, albeit somewhat limited, is already available. The article also introduces the latest cutting edge research topics on new materials for composite restorations, and an outlook for the future of how those may help to improve the service life of dental composite restorations.

Four or More Amalgam Fillings Correlate With Higher Blood Mercury Levels in Pregnant Women but Not High Enough to be of Health Concern

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Dental associations with blood mercury in pregnant women. Golding J, Steer CD, Gregory S, Lowery T, Hibbeln JR, Taylor CM. Community Dent Oral Epidemiol 2016; 44: 216-22.

SOURCE OF FUNDING

This study was funded by a combination of government (UK Medical Research Council), foundation/nonprofit (the Welcome Trust) and university (University of Bristol, UK) grants.

TYPE OF STUDY/DESIGN

Cross-sectional.