In vivo bisphenol-a release from dental pit and fissure sealants: a systematic review

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.

Clinical effectiveness of pit and fissure sealants in primary and permanent teeth of children and adolescents: an umbrella review

PURPOSE

This umbrella review aimed to critically appraise the evidence published in systematic reviews (SRs) on the clinical effectiveness of sealants compared with each other/the non-use in primary/permanent teeth of children and adolescents with at least 12-month follow-up.

METHODS

A systematic literature search on 4 electronic databases was conducted up to January 18th, 2023. Following handsearching, two review authors independently screened retrieved articles, extracted data, and assessed the risk of bias (RoB) using the risk of bias in systematic reviews (ROBIS) tool. Based on a citation matrix, the overlap was interpreted by the corrected covered area (CCA).

RESULTS

Of 239 retrieved records, 7 SRs met the eligibility criteria with a moderate overlap among them (CCA = 7.4%). For primary molars, in 1120 1.5- to 8-year-old children, data on the clinical effectiveness of sealants were inconclusive. For permanent molars, 3 SRs found a significant caries risk reduction for sealants versus non-use (≤ 36-month follow-up). There was insufficient evidence to proof superiority of sealants over fluoride varnish for caries prevention (3 SRs), and to rank sealant materials according to the best clinical effectiveness in permanent molars. One study was rated at low and 6 at high RoB, which did not allow for a valid quantitative synthesis.

CONCLUSION

Considering the limitations of this umbrella review, sealants are more effective for caries prevention in children's permanent molars compared to no treatment. Future well-implemented RCTs are needed to draw reliable conclusions on the clinical effectiveness of sealants in primary and permanent teeth of children and adolescents.

Bisphenol A and bisphenol S both disrupt ovine granulosa cell steroidogenesis but through different molecular pathways

BACKGROUND

Ovarian granulosa cells (GC) are essential for the development and maturation of a proper oocyte. GC are sensitive to endocrine disruptors, including bisphenol A (BPA) and its analogue bisphenol S (BPS), plasticisers present in everyday consumer products. BPA exhibits greater binding affinity for the membrane oestrogen receptor (GPER) than for the nuclear oestrogen receptors (ERα and ERβ). Here, we analysed the effects of BPA and BPS on the steroidogenesis of ovine GC in vitro, as well as their early mechanisms of action, the ovine being a relevant model to study human reproductive impairment. Disruption of GC steroidogenesis might alter oocyte quality and consequently fertility rate. In addition, we compared the effects of a specific GPER agonist (G-1) and antagonist (G-15) to those of BPA and BPS. Ewe GC were cultured with BPA or BPS (10 or 50 µM) or G-1 (1 µM) and/or G-15 (10 µM) for 48 h to study steroidogenesis.

RESULTS

Both BPA and BPS (10 µM) altered the secretion of progesterone, however, only BPS (10 µM) affected oestradiol secretion. RNA-seq was performed on GC after 1 h of culture with BPA or BPS (50 µM) or G-1 (10 µM), followed by real-time PCR analyses of differentially expressed genes after 12, 24 and 48 h of culture. The absence of induced GPER target genes showed that BPA and BPS did not activate GPER in GC after 1 h of treatment. These molecules exhibited mainly independent early mechanisms of action. Gene ontology analysis showed that after 1 h of treatment, BPA mainly disrupted the expression of the genes involved in metabolism and transcription, while BPS had a smaller effect and impaired cellular communications. BPA had a transient effect on the expression of CHAC1 (NOTCH signalling and oxidative balance), JUN (linked to MAPK pathway), NR4A1 (oestradiol secretion inhibition), ARRDC4 (endocytose of GPCR) and KLF10 (cell growth, differentiation and apoptosis), while expression changes were maintained over time for the genes LSMEM1 (linked to MAPK pathway), TXNIP (oxidative stress) and LIF (cell cycle regulation) after 12 and 48 h, respectively.

CONCLUSION

In conclusion, although they exhibited similar effects, BPA and BPS impaired different molecular pathways in GC in vitro. New investigations will be necessary to follow the temporal changes of these genes over time, as well as the biological processes involved.

Evaluation of Bisphenol A in Pregnant Women from 10 Caribbean Countries

Bisphenol A (BPA), a phenolic chemical incorporated into many plastic products, has been found to act as an endocrine disruptor that potentially is linked to adverse neurodevelopmental outcomes. Prenatal BPA concentration levels were assessed in 10 English-speaking Caribbean countries by randomly selecting 15 maternal urine samples from approximately 50 pregnant women samples collected in each island and then comparing the findings with comparable data from Canada and the U.S. BPA was detected in all samples ranging from a low geometric mean of 1.46 μg/L (St. Lucia) to a high of 4.88 μg/L (St. Kitts & Nevis). All of the Caribbean islands sampled had geometric mean concentration levels that were higher than those recorded in two Canadian biomonitoring surveys (1.26 μg/L and 0.80 μg/L) and the U.S. NHANES survey (1.39 μg/L). This first biomonitoring survey of BPA concentration levels in maternal urine samples taken from Caribbean countries clearly points to the need for Caribbean governments and public health officials to first engage in legislative and regulatory efforts to ban or minimize the importation and use of BPA products used the Caribbean and, second, to continue to conduct biomonitoring surveys so as to ensure that these laws and regulations are indeed leading to a decrease of BPA concentrations in Caribbean populations.

The Current Findings on the Impact of Prenatal BPA Exposure on Metabolic Parameters: In Vivo and Epidemiological Evidence

Metabolic syndrome (MS) is a multifactorial disease entity and is not fully understood. Growing evidence suggests that early exposure to bisphenol A (BPA) is a significant risk factor for the development of metabolic diseases. BPA is a monomer used in the manufacturing of polycarbonate plastics, thermal receipt paper, and epoxy resins. Owing to its widespread use, BPA has been detected in human fluids and tissues, including blood, placental breast milk, and follicular fluid. In the present review, we aimed to review the impact of prenatal exposure to different doses of BPA on metabolic parameters as determined by in vivo and epidemiological studies. The PubMed, Scopus, and Web of Science electronic databases were searched to identify articles published during a period of 15 years from 2006 to 2021, and 29 studies met the criteria. Most studies demonstrated that prenatal exposure to low BPA concentrations correlated with alterations in metabolic parameters in childhood and an increased risk of metabolic diseases, such as obesity and type 2 diabetes mellitus (T2DM), in adulthood. Therefore, prenatal exposure to low doses of BPA may be associated with an increased risk of obesity and T2DM in a sex-specific manner.

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.

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.

Assessing the estrogenic activity of chemicals present in resin based dental composites and in leachates of commercially available composites using the ERα-CALUX bioassay

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.

FISSURE SEALANT IN A NUTSHELL. EVIDENCE-BASED META-EVALUATION OF SEALANTS' EFFECTIVENESS IN CARIES PREVENTION AND ARREST

OBJECTIVE

This meta-evaluation aimed to summarize all available evidence regarding different fissure sealants on occlusal caries prevention, arrest, retention rate, adverse effect, and cost-effectiveness; when compared with no intervention, other preventive or minimally-invasive procedures.

MATERIALS AND METHODS

The systematic reviews and meta-analyses were identified via four electronic databases and manual searching. Two independent reviewers performed study selection, data extraction, quality assessment with AMSTAR-2.

RESULTS

Among the 366 records yielded, 38 systematic reviews were identified as eligible 24 of them included meta-analyses. Moderate evidence has supported the efficacies of resin-based sealants (RBS) in occlusal caries prevention, arrest and cost-effectiveness compared to no interventions. Low to very low certainty of evidence suggested similar effectiveness of glass-ionomer cements in caries prevention with RBS and more superior performance of resin infiltration in arresting non-cavitated occlusal lesions.

CONCLUSION

This meta-evaluation supports the use of RBS on permanent molars to reduce occlusal caries occurrence, arrest lesion progression and alleviate oral health inequalities between individuals of different socioeconomic status. This meta-evaluation also advocates further research on glass-ionomer cements and resin infiltration with respect to their efficacies in caries prevention and arrest.

An integrative review on the toxicity of Bisphenol A (BPA) released from resin composites used in dentistry

The main aim of this study was to perform an integrative review on the release of bisphenol A (BPA) from resin-matrix composites and potential toxic effects. A bibliographic search was performed on the PubMed platform using the following keywords: "Bisphenol A" OR "BPA" AND "resin composite" OR "composite resin" AND "toxicity" OR "cytotoxicity" OR "release". Inclusion criteria involved in vitro and in vivo studies on the release and toxicity of BPA. Results highlighted the release of BPA from resin-matrix composites due to insufficient polymerization and/or degradation of the polymeric matrix. BPA is part of the organic matrix of resin-matrix composites and may be hydrolysed in human saliva, although studies report that low doses might not be detected by traditional chemical analysis. Studies exposing zebrafish embryos to different concentrations of Bis-GMA, showed 55% mortality at 10 μM Bis-GMA while 30% mortality was recorded at 1 μM Bis-GMA. In patients, a BPA concentration of around 2.09 × 10^-2 μg/ml was found in the saliva after placement of lingual orthodontic retainers with resin-matrix composites. Also, the BPA molecule can be swallowed and absorbed by the oral/gastrointestinal mucosa, which might result in systemic toxicity. The degradation of resin-matrix composites and release of BPA in oral environment are dependent on the organic matrix content and on the polymerization method. A increased release of BPA can lead to the absorption into oral and gastrointestinal mucosa with high risks of local and systemic toxicity.

Isobaric tags for relative and absolute quantitation-based proteomics analysis of the effect of ginger oil on bisphenol A-induced breast cancer cell proliferation

Several chemicals in the environment, particularly those with estrogenic activity and small amounts (micromolar or lower) of environmental estrogen can cause changes in cell function and interfere with endocrine functions of animals and humans. These compounds enter the human body and increase the load of estrogen in the body, leading to an increasing incidence of estrogen-related tumors in breast cancer, ovarian cancer and endometrial cancer. Previous studies have demonstrated that ginger can inhibit the expression of estrogen receptors, while the bioactive ingredients of ginger sig-nificantly inhibit proliferation and promote the apoptosis of breast cancer cells. In the present study, a quantitative proteomics technique based on relative and absolute quanti-tative isobaric labeling was used to determine the effect of ginger essential oil (GEO) and BPA combined treatment on the proteomic characteristics of MCF-7 cells. In total, 5,084 proteins were detected. Proteins that were upregulated >1.2-fold and downregu-lated by >0.8-fold were differentially expressed. Overall, 528 differentially expressed proteins were identified. Compared with the control group, MCF-7 cells treated with GEO, BPA and GEO-BPA resulted in 45 (14 up- and 31 downregulated), 481 (141 up- and 340 downregulated) and 34 (13 up- and 21 downregulated) differentially ex-pressed proteins, respectively. Compared with the BPA group, MCF- 7 cells treated with GEO-BPA resulted in 210 (117 up- and 93 downregulated) differentially expressed proteins, among the 210 differentially expressed proteins in the GEO-BPA group, 10 proteins were associated with oxidative phosphorylation pathways, while succinate dehydrogenase (ubiquinone) iron-sulfur subunit (SDHB), succinate dehydrogenase cytochrome b560 subunit, mitochondrial (SDHC), cytochrome c oxidase subunit 2 and superoxide dismutase (Mn), mitochondrial (SOD2) expression was decreased with GEO-BPA combined treatment. Through the analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, the cellular localization, functional annotation and biological pathways of differentially expressed proteins were ex-amined. The results indicated that GEO-BPA may act through the oxidative phosphory-lation pathway, decreased the expression of SDHB and SDHC, affected the tricarbox-ylic acid cycle and decreased the expression of SOD2. This may have led to oxidative stress and the death of breast cancer cells, and the SDH signaling pathway may be an important mediator of the inhibitory effects of GEO in MCF-7 breast cancer cells. GEO can inhibit the proliferation of breast cancer MCF-7 cells induced by BPA, and the underlying mechanism may be associated with oxidative phosphorylation. These results may aid the development of future treatment strategies for breast cancer caused by environmental estrogen exposure.

Safety Considerations for Thermoplastic-Type Appliances Used as Orthodontic Aligners or Retainers. A Systematic Review and Meta-Analysis of Clinical and In-Vitro Research

Use of thermoplastic material in orthodontics, either as aligner or as retainer appliances, is common practice and is likely to increase in the years to come. However, no systematic assessment on safety considerations of these adjuncts has been implemented up to date. The aim of this systematic review was to collectively appraise the existing evidence from both clinical and laboratory studies, on whether these appliances are associated with any estrogenic/cytotoxic effects or bisphenol-A (BPA) and monomer leaching. Eight electronic databases were searched with no limits in December 22, 2019, for published and unpublished research. Eligibility criteria comprised of studies of any design, describing use of any type of thermoplastic aligner. Study selection, data extraction and risk of bias (RoB) assessment was done independently, either in duplicate or confirmed by a second reviewer. Random effects meta-analyses of weighted mean differences (WMD) with associated 95% Confidence Intervals (CIs) were planned. Quality of the evidence was evaluated with Grading of Recommendations Assessment, Development and Evaluation (GRADE). A total of 58 articles were initially identified, while 5 were included in qualitative synthesis and 2 of those contributed to the quantitative syntheses. Four studies were in-vitro, while one was a randomized controlled trial; all assessed some type of orthodontic aligner or retainer, either as-received or retrieved. Risk of bias recordings ranged between unclear and high for all studies. Proliferation induction capacity of thermoplastic appliances' eluents on MCF-7 cells failed to be confirmed compared to beta-estradiol (2 studies: 5% v/v, WMD: -182.08; 95% CI: -198.83, -165.33; p-value < 0.001; and 20% v/v, WMD: -184.53; 95% CI: -206.17, -162.88; p-value < 0.001). No cytotoxic activity was detected as well. In addition, although evidence from in-vitro studies was indicative of no traceable detection of BPA or other monomers, the findings from a single clinical trial were allied to increased levels of BPA in whole stimulated saliva, after up to 30 days of thermoplastic retainer usage, compared to standard Hawley retainer. The quality of the evidence overall was low to medium. Current data from in-vitro research are indicative of an absence of an estrogenic or cytotoxic effect of thermoplastic aligners or retainers. Regarding BPA or monomer release, evidence from clinical and laboratory studies appear inconsistent.

Dawn of a New Age Fissure Sealant? A Study Evaluating the Clinical Performance of Embrace WetBond and ART Sealants: Results from a Randomized Controlled Clinical Trial

OBJECTIVES

 The main purpose of this article is to evaluate the clinical performance of atraumatic restorative treatment (ART) sealant versus Embrace WetBond sealant in terms of retention and fissure caries prevention among a section of school children in the southern Indian state of Karnataka (ClinicalTrials.gov NCT02716558).

MATERIALS AND METHODS

 After obtaining consent from the parents and screening the children against the inclusion cum exclusion criteria, 90 school children whose mandibular first molars were caries free and with a well-defined pit and fissure system were recruited for this spilt mouth trial. The respective molars were allocated either to the ART sealant or the embrace group after the randomization process. The sealants were applied according to the manufacturer's instructions and followed up at the end of 3rd, 6th, and 12th month, respectively. The outcome measures assessed were the retention and the caries preventive effects of the materials.

RESULTS

 At the end of the 6th month, about one-fourth of the sealants in either group remained totally intact, without evidence of caries. No significant differences were seen between the sealants either in terms of retention or caries preventive benefits at the end of 12 months.

STATISTICAL ANALYSIS

 The chi-squared test was used to check differences in proportions. The significance value was set at <0.05. Kappa test was performed to assess the intraexaminer reproducibility with respect to retention and caries status.

CONCLUSION

 The moisture-tolerant resin sealant could not replicate the physical properties usually associated with conventional resin sealants. The usage of ART sealants was deemed to be less cumbersome in an outreach setting as observed in this trial.

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.

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.

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 Systematic Review of Exposure to Bisphenol A from Dental Treatment

INTRODUCTION

Dental composite restorations and dental sealants containing bisphenol A glycidyl methacrylate (BisGMA) are commonly used materials in dentistry. Bisphenol A (BPA) is used to manufacture BisGMA and can be a by-product in BisGMA-based dental materials. BPA is an endocrine-disrupting chemical that may affect reproductive, psychological, cognitive, and endocrine-related health. We conducted a systematic review of clinical studies that measured urinary BPA (uBPA) concentrations before and after dental treatment to evaluate the extent to which individuals are exposed to BPA from dental treatment.

METHODS

Eligibility included studies that measured uBPA concentrations before and after dental treatment with any type of resin-based dental material. We searched PubMed, Cochrane, Web of Science, Virtual Health Library, Science Direct, ProQuest, and Clinical Trials with no date or language restrictions to identify published studies. We summarized eligible studies across participant characteristics, amount of treatment, and time of follow-up measures. Because methods of measuring uBPA varied, our primary outcome was the direction and percentage change between baseline and 24 h posttreatment and at later time points as available.

RESULTS

We identified 1,190 abstracts and 7 eligible studies: 4 in children and 3 in adults. In all studies, BPA concentrations increased 24 h after treatment. The 2 studies with the largest sample sizes found statistically significant increases >40% in uBPA concentrations at 24 h posttreatment (both P values <0.01). The 1 study to examine uBPA concentrations beyond 1 mo posttreatment found that concentrations returned to baseline by 14 d after treatment and remained at baseline 6 mo after treatment.

CONCLUSIONS

Our findings suggest that uBPA concentrations increase 24 h after dental treatment. One study showed that uBPA concentrations return to baseline by 14 d. Additional research is needed to determine the magnitude of change from pre- to post-dental treatment and the trajectory of uBPA concentrations posttreatment.

KNOWLEDGE TRANSFER STATEMENT

BPA is an endocrine-disrupting chemical that may have negative human health effects. Our findings suggest that urinary BPA concentrations increase in the short term after dental treatment. The extent to which such an increase may affect the health of patients remains an open question, particularly since there are no established thresholds for safety or harm related to BPA exposure.

Presence and leaching of bisphenol a (BPA) from dental materials

BPA has been reported to leach from some resin based dental restorative materials and materials used for orthodontic treatment. To confirm and update previous findings, especially in light of the new temporary lower threshold value for tolerable daily BPA intake, we have investigated the leaching of BPA from 4 composite filling materials, 3 sealants and 2 orthodontic bonding materials. The materials were either uncured and dissolved in methanol or cured. The cured materials were kept in deionized water for 24 hours or 2 weeks. Samples were subsequently analyzed by ultra-performance liquid chromatography coupled to mass spectrometry (UPLC-MS-MS). The composite filling material Tetric EvoFlow^® and the fissure sealant DELTON^® showed significantly higher levels of BPA leaching compared to control samples for all test conditions (uncured, 24 h leaching and 2 weeks leaching). There were no significant differences in amount of leached BPA for any of the tested materials after 24 hours compared to 2 weeks. These results show that BPA is still released from some dental materials despite the general concern about potential adverse effects of BPA. However, the amounts of BPA were relatively low and most likely represent a very small contribution to the total BPA exposure.

Assessment of monomer release from 3 different fissure sealants

Background:

Light-activated resin-based dental fissure sealants are the most widely accepted among clinicians. The objective of this study was to determine monomer release of 3 different light-curing fissure sealants in vitro: Control Seal (Voco, Germany), Fissurit FX (Voco, Germany) and R&D Series Fıssured Nova (Imicrly, Turkey).

Methods:

Each material was polymerized with a curing light: Valo Cordless (Ultradent) LED in standard mode for 20 seconds (n = 27) and 40 seconds (n = 27) and in Xtra power mode (plasma arc) for 3 seconds (n = 27). High-performance liquid chromatography (HPLC) was used to measure the amount of monomers released over 1, 3 and 7 days.

Results:

Plasma arc groups showed the highest release of monomers at 1, 3 and 7 days in the 3 fissure sealant groups (p<0.001). The greatest release of bisphenol A glycidyl methacrylate (bis-GMA) determined for R&D Series Fissured Nova both with LED 20 seconds and LED 40 seconds and for Control Seal was with the plasma arc. With time, release of the monomer was reduced for all polymerization systems.

Conclusions:

Efficiency of the polymerization system and applying the recommended curing time for light-activated resin-based dental materials are very important to protect the patient from potential hazards of residual monomers.

The Use of Pit and Fissure Sealants-A Literature Review

This paper reviews the literature and discusses the latest updates on the use of pit and fissure sealants. It demonstrates the effectiveness of pit and fissure sealants in preventing caries and the management of early carious lesions. It compares the use of different sealant materials and their indications. It describes the application technique for sealants. It also reviews the cost-effectiveness of sealants as a preventive strategy. From this review and after the discussion of recently published studies on pit and fissure sealants, it is evident that sealants are effective in caries prevention and in preventing the progression of incipient lesions. It is therefore recommended that pit and fissure sealant be applied to high-caries-risk children for optimum cost-effectiveness. It is a highly sensitive technique that needs optimum isolation, cleaning of the tooth surface, etching, and the application of a thin bonding layer for maximum benefit. Recall and repair, when needed, are important to maximize the effectiveness of such sealant use.

Performance of pit and fissure sealants according to tooth characteristics: A systematic review and meta-analysis

OBJECTIVE

Aim of this systematic review was to assess the clinical performance of sealants on various teeth in an evidence-based manner.

SOURCES

Five databases were searched from inception to February 2017.

DATA

Randomized clinical studies on humans.

METHODS

After duplicate study selection, data extraction, and risk of bias assessment according to the Cochrane guidelines, Paule-Mandel random-effects meta-analyses of Relative Risks (RRs) and their 95% confidence intervals (CIs) were calculated.

RESULTS

A total of 16 randomized clinical trials with 2778 patients (male/female 49.1%/50.9%) and an average age of 8.4 years were included. No significant difference in either caries incidence of sealed teeth or sealant retention could be found according to (i) mouth side (right versus left), (ii) jaw (upper versus lower), (iii) and tooth type (1st permanent molar versus 2nd permanent molar/1st permanent molar versus 2nd deciduous molar/1st deciduous molar versus 2nd deciduous molar), based on evidence of very low to low quality. On the other side, compared to 1st permanent molars, sealed premolars were significantly less likely to develop caries (3 trials; RR=0.12; 95% CI=0.03 to 0.44; P=0.001) and less likely to experience loss of the sealant (5 trials; RR=0.33; 95% CI=0.20 to 0.54; P=0.001), both based on low to moderate quality evidence.

CONCLUSIONS

The performance of pit and fissure sealants does not seem to be negatively affected by mouth side, jaw, and tooth type, apart from the exception of a favorable retention on premolars.

CLINICAL SIGNIFICANCE

Based on existing evidence, pit and fissure sealants can be effectively applied on any deciduous or permanent posterior teeth without adverse effects on their clinical performance.

Adverse reactions to orthodontic materials

Adverse effects can arise from the clinical use of orthodontic materials, due to the release of constituent substances (ions from alloys and monomers, degradation by-products, and additives from polymers). Moreover, intraoral aging affects the biologic properties of materials. The aim of this review is to present the currently identified major adverse effects of the metallic and polymeric components found in orthodontic appliances and materials. Corrosion in metallic orthodontic attachments releases metal ions, mainly iron, chromium, and nickel. The latter has received the greatest attention because of its reported potential for an allergic response. The formation of an oxide layer may inhibit the outward movement of ions, thereby acting as an obstacle for release. Titanium alloys have superior corrosion resistance than stainless steel. The efficiency of polymerisation is considered an essential property for all polymers. A poor polymer network is susceptible to the release of biologically reactive substances, such as bisphenol-A (BPA), which is capable of inducing hormone-related effects. The close proximity of a light-curing tip to the adhesive, pumice prophylaxis after bonding, indirect irradiation and mouth rinsing during the first hour after bonding may decrease BPA release. The adverse effects of some orthodontic materials should be considered during material selection and throughout orthodontic treatment, in order to minimise possible undesirable implications.

Pit and fissure sealants for preventing dental decay in permanent teeth

BACKGROUND

Dental sealants were introduced in the 1960s to help prevent dental caries, mainly in the pits and fissures of occlusal tooth surfaces. Sealants act to prevent bacteria growth that can lead to dental decay. Evidence suggests that fissure sealants are effective in preventing caries in children and adolescents compared to no sealants. Effectiveness may, however, be related to caries incidence level of the population. This is an update of a review published in 2004, 2008 and 2013.

OBJECTIVES

To compare the effects of different types of fissure sealants in preventing caries in occlusal surfaces of permanent teeth in children and adolescents.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched: Cochrane Oral Health's Trials Register (to 3 August 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 7), MEDLINE Ovid (1946 to 3 August 2016), and Embase Ovid (1980 to 3 August 2016). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials to 3 August 2016. No restrictions were placed on language or date of publication.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing sealants with no sealant or a different type of sealant material for preventing caries of occlusal surfaces of premolar or molar teeth in children and adolescents aged up to 20 years. Studies required at least 12 months follow-up. We excluded studies that compared compomers to resins/composites.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results, extracted data and assessed risk of bias of included studies. We presented outcomes for caries or no caries on occlusal surfaces of permanent molar teeth as odds ratio (OR) or risk ratio (RR). We used mean difference (MD) for mean caries increment. All measures were presented with 95% confidence intervals (CI). We conducted meta-analyses using a random-effects model for comparisons where there were more than three trials; otherwise we used the fixed-effect model. We used GRADE methods to assess evidence quality.

MAIN RESULTS

We included 38 trials that involved a total of 7924 children; seven trials were new for this update (1693 participants). Fifteen trials evaluated the effects of resin-based sealant versus no sealant (3620 participants in 14 studies plus 575 tooth pairs in one study); three trials with evaluated glass ionomer sealant versus no sealant (905 participants); and 24 trials evaluated one type of sealant versus another (4146 participants). Children were aged from 5 to 16 years. Trials rarely reported background exposure to fluoride of trial participants or baseline caries prevalence. Resin-based sealant versus no sealant: second-, third- and fourth-generation resin-based sealants prevented caries in first permanent molars in children aged 5 to 10 years (at 24 months follow-up: OR 0.12, 95% CI 0.08 to 0.19, 7 trials (5 published in the 1970s; 2 in the 2010s), 1548 children randomised, 1322 children evaluated; moderate-quality evidence). If we were to assume that 16% of the control tooth surfaces were decayed during 24 months of follow-up (160 carious teeth per 1000), then applying a resin-based sealant would reduce the proportion of carious surfaces to 5.2% (95% CI 3.13% to 7.37%). Similarly, assuming that 40% of control tooth surfaces were decayed (400 carious teeth per 1000), then applying a resin-based sealant would reduce the proportion of carious surfaces to 6.25% (95% CI 3.84% to 9.63%). If 70% of control tooth surfaces were decayed, there would be 19% decayed surfaces in the sealant group (95% CI 12.3% to 27.2%). This caries-preventive effect was maintained at longer follow-up but evidence quality and quantity was reduced (e.g. at 48 to 54 months of follow-up: OR 0.21, 95% CI 0.16 to 0.28, 4 trials, 482 children evaluated; RR 0.24, 95% CI 0.12 to 0.45, 203 children evaluated). Although studies were generally well conducted, we assessed blinding of outcome assessment for caries at high risk of bias for all trials (blinding of outcome assessment is not possible in sealant studies because outcome assessors can see and identify sealant). Glass ionomer sealant versus no sealant: was evaluated by three studies. Results at 24 months were inconclusive (very low-quality evidence). One sealant versus another sealant: the relative effectiveness of different types of sealants is unknown (very low-quality evidence). We included 24 trials that directly compared two different sealant materials. Comparisons varied in terms of types of sealant assessed, outcome measures chosen and duration of follow-up. Adverse events: only four trials assessed adverse events. No adverse events were reported.

AUTHORS' CONCLUSIONS

Resin-based sealants applied on occlusal surfaces of permanent molars are effective for preventing caries in children and adolescents. Our review found moderate-quality evidence that resin-based sealants reduced caries by between 11% and 51% compared to no sealant, when measured at 24 months. Similar benefit was seen at timepoints up to 48 months; after longer follow-up, the quantity and quality of evidence was reduced. There was insufficient evidence to judge the effectiveness of glass ionomer sealant or the relative effectiveness of different types of sealants. Information on adverse effects was limited but none occurred where this was reported. Further research with long follow-up is needed.

Bisphenol A release from orthodontic adhesives measured in vitro and in vivo with gas chromatography

INTRODUCTION

The objectives of this study were to quantify in vitro the Bisphenol A (BPA) release from 5 orthodontic composites and to assess in vivo the BPA level in patients' saliva and urine after bracket bonding with an orthodontic adhesive system.

METHODS

For the in-vitro portion of this study, 5 orthodontic composites were evaluated: Eagle Spectrum (American Orthodontics, Sheboygan, Wis), Enlight (Ormco, Orange, Calif), Light Bond (Reliance Orthodontic Products, Itasca, Ill), Mono Lok II (Rocky Mountain Orthodontics, Denver, Colo), and Transbond XT (3M Unitek, Monrovia, Calif). Simulating intraoral conditions, the specimens were immersed in a water/ethanol solution, and the BPA (ng.g^-1) liberation was measured after 30 minutes, 24 hours, 1 day, 1 week, and 1 month by the gas chromatography system coupled with mass spectrometry. Twenty patients indicated for fixed orthodontic treatment participated in the in-vivo study. Saliva samples were collected before bracket bonding and then 30 minutes, 24 hours, 1 day, 1 week, and 1 month after bonding the brackets. Urine samples were collected before bonding and then at 1 day, 1 week, and 1 month after bonding. The results were analyzed statistically using analysis of variance and Tukey posttest, with a significance level of 5%.

RESULTS

All composites evaluated in vitro released small amounts of BPA. Enlight composite showed the greatest release, at 1 month. Regarding the in-vivo study, the mean BPA level in saliva increased significantly only at 30 minutes after bonding in comparison with measurements recorded before bonding.

CONCLUSIONS

All orthodontic composites released BPA in vitro. Enlight and Light Bond had, respectively, the highest and lowest BPA releases in vitro. The in-vivo experiment showed that bracket bonding with the Transbond XT orthodontic adhesive system resulted in increased BPA levels in saliva and urine. The levels were significant but still lower than the reference dose for daily ingestion.

Release of monomers from orthodontic adhesives

INTRODUCTION

Most composite resins release both bisphenol A (BPA), which disrupts the endocrine balance, and triethylene glycol dimethacrylate (TEGDMA), which has high risks for human health: eg, allergies and cytotoxicity. The aim of this study was to characterize monomers released from orthodontic adhesives.

METHODS

We studied samples of orthodontic adhesives by associating 2 techniques: gas phase chromatography and mass spectrometry.

RESULTS

The in-vitro analysis detected significant quantities of BPA, TEGDMA, and other monomers in orthodontic adhesives used in daily practice: Transbond XT, Transbond Supreme LV (both, 3M Unitek, Monrovia, Calif), Blugloo (Ormco, Orange, Calif), and MonoLok 2 (Rocky Mountain Orthodontics, Denver, Colo).

CONCLUSIONS

Clinicians should consider that orthodontic adhesives contain BPA, an endocrine disruptor; TEGDMA, an allergic and a cytotoxic compound; and carcinogenic genotoxic compounds. These molecules are not mentioned in the material safety data sheets. Manufacturers should declare all components of dental composites to identify these substances that may result in allergic or undesirable side effects for patients and dental staff.

Human exposure to endocrine disrupting compounds: Their role in reproductive systems, metabolic syndrome and breast cancer. A review

Endocrine disrupting chemicals (EDCs) are released into the environment from different sources. They are mainly used in packaging industries, pesticides and food constituents. Clinical evidence, experimental models, and epidemiological studies suggest that EDCs have major risks for humans by targeting different organs and systems in the body (e.g. reproductive system, breast tissue, adipose tissue, pancreas, etc.). Due to the ubiquity of human exposure to these compounds the aim of this review is to describe the most recent data on the effects induced by phthalates, bisphenol A and parabens in a critical window of exposure: in utero, during pregnancy, infants, and children. The interactions and mechanisms of toxicity of EDCs in relation to human general health problems, especially those broadening the term of endocrine disruption to 'metabolic disruption', should be deeply investigated. These include endocrine disturbances, with particular reference to reproductive problems and breast, testicular and ovarian cancers, and metabolic diseases such as obesity or diabetes.

Synthetic phenolic antioxidants, including butylated hydroxytoluene (BHT), in resin-based dental sealants

Resin-based dental sealants (also referred to as pit-and-fissure sealants) have been studied for their contribution to bisphenol A (BPA) exposure in children. Nevertheless, little attention has been paid to the occurrence of other potentially toxic chemicals in dental sealants. In this study, the occurrence of six synthetic phenolic antioxidants (SPAs), including 2,6-di-tert-butyl-4-hydroxytoluene (BHT), 2,6-di-tert-butyl-4-(hydroxyethyl)phenol (BHT-OH), 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), 2,6-di-tert-butylcyclohexa-2,5-diene-1,4-dione (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH) and 2-tert-butyl-4-methoxyphenol (BHA), was examined in 63 dental sealant products purchased from the U.S. market. BHT was found in all dental sealants at median and maximum concentrations of 56.8 and 1020µg/g, respectively. The metabolites of BHT and BHA were detected in 39-67% of samples, at concentration ranges of <LOQ to 242µg/g. BHT is likely used in sealants to inhibit oxidative reactions, remove free radicals, and inhibit potential polymerization, which would eventually prolong the shelf-life of the products. The estimated daily intake (EDI) of BHT, following sealant placement, based on a worst-case scenario (application on eight teeth at 8mg each tooth), was 930 and 6510ng/kg bw/d for adults and children, respectively. The EDI of BHT from dental sealants was several orders of magnitude lower than the current acceptable daily intake (ADI) proposed by the European Food Safety Authority (EFSA).

Changes in urinary bisphenol A concentrations associated with placement of dental composite restorations in children and adolescents

BACKGROUND

Bisphenol A-glycidyl methacrylate (bis-GMA)-based dental composite restorations may release bisphenol A (BPA). The authors assessed changes in urinary BPA concentrations over a 6-month follow-up period in children and adolescents who received bis-GMA-based restorations.

METHODS

The authors collected data from 91 study participants aged 3 to 17 years who needed composite restorations. Participants provided urine samples and information on BPA-related exposures before and at approximately 1 day, 14 days, and 6 months after treatment. The authors used multivariable linear regression models to test associations between the number of surface restorations placed and the changes in urinary BPA concentrations.

RESULTS

Participants had a mean (standard deviation [SD]) of 1.4 (1.0) for surfaces restored with composite at the first treatment visit and 2.3 (1.6) for surfaces restored during the entire study period. Mean (SD) change in urinary BPA concentrations between pretreatment and day 1 was 1.71 (9.94) nanograms per milliliter overall and 0.87 (5.98) after excluding 1 participant who had 8 surfaces restored at the visit. Overall, the authors observed an association between a greater number of composite surface restorations placed and higher urinary BPA concentrations in the 1-day sample (posterior-occlusal exponentiated coefficients [e(β)] = 1.47; 95% confidence interval [CI], 1.18-1.83; P < .001), but the association was attenuated after the authors restricted the sample to the 88 participants who had up to 4 restorations (e(β) = 1.19; 95% CI, 0.86-1.64), and they did not observe any association using 14-day (e(β) = 0.94; 95% CI, 0.75-1.18) or 6-month (e(β) = 0.88; 95% CI, 0.74-1.04) samples.

CONCLUSIONS

Placement of bis-GMA-based restorations in children and adolescents may produce transient increases in urinary BPA concentrations that are no longer detectable in urine samples taken approximately 14 days or 6 months after treatment. After placement of a few restorations, increases in urinary BPA concentrations may not be detectable, owing to a high level of variation in background BPA exposure.

PRACTICAL IMPLICATIONS

These results suggest that leaching of BPA from newly placed composite restorations ceases to be detectable in urine within 2 weeks after restoration placement. The potential human health impact of such short-term exposure remains uncertain.

Bond Strength of a Bisphenol-A-Free Fissure Sealant With and Without Adhesive Layer under Conditions of Saliva Contamination

Dental sealants are important for prevention of carious lesions, if they have good shear strength. The aim of this study was to evaluate the shear bond strength (SBS) of two sealants to saliva-contaminated and non-contaminated enamel with and without an intermediate adhesive layer underneath the sealant. Ninety flat enamel surfaces from human third molars were randomly assigned to 6 groups (n=15): F (control): Fluroshield(tm) sealant; EWB (control): Embrace(tm) WetBond(tm); SB/F: Single Bond adhesive system + F; SB/EWB, s-SB/F and s-SB/EWB. In the s-SB/F and s-SB/EWB groups, the acid-etched enamel was contaminated with 0.01 mL of fresh human saliva for 20 s. Sealant cylinders were bonded to enamel surface with and without an intermediate adhesive system layer. The shear tests were performed using a universal testing machine (0.5 mm/min). Data were analyzed statistically by Kruskal-Wallis and Mann-Whitney tests (α=0.05). F presented higher mean SBS than EWB in all experimental conditions. The lowest SBS mean was obtained for EWB on contaminated enamel (p<0.05). In conclusion, an adhesive system layer should be used prior to sealant placement, in both dry and saliva-contaminated enamel. F had the best performance in all experimental conditions. EWB sealant showed very low results, but an adhesive layer underneath the sealant increased its SBS even after salivary contamination.

Development and testing of novel bisphenol A-free adhesives for lingual fixed retainer bonding

AIM

To comparatively evaluate the properties of two BPA-free experimental adhesives (EXA, EXB) for lingual fixed retainer bonding versus a commercially available reference material (Transbond LR-TLR) based on BPA-compound.

MATERIALS AND METHODS

The experimental materials were a flowable 60 per cent glass filler-filled UEDMA/TEGDMA flowable composite (EXB) and a 70 per cent glass filler-filled paste composite with PCDMA/UEDMA/TEGDMA co-monomers. The properties tested were degree of conversion (DC%), mechanical properties (Martens hardness-MH, elastic modulus-E_IT, elastic index-n_IT), effect of prolonged (6 months) water storage (changes in Vickers microhardness-VHN) and pull-out strength employing a multi-stranded wire.

RESULTS

EXB showed the highest DC% (63.6 per cent), followed by EXA (50.5 per cent) and TRL (44.1 per cent), with all means differences being statistically significant (P < 0.05). The statistical rankings of MH (MPa) and E_IT (GPa) means were TLR (76.1MPa; 17.3GPa) > EXA (53MPa; 12.9GPa) > EXB (12.9MPa; 6.7GPa), whereas for n_IT, EXB (40 per cent) > EXA (34.9 per cent), TLR (33.6 per cent). All materials were affected by prolonged water storage with significant differences among them in VHN. TLR was the most affected material (ΔVHN = -11 per cent), followed by EXA (ΔVHN = -6.8 per cent) and EXB (ΔVHN = -4.2 per cent). No statistically significant differences were found in the pull-out strength testing (24-24.2 N range) and failure mode (70-77 per cent mixed).

CONCLUSION

Considering the differences between the two experimental materials, it may be concluded that the material containing the PCDMA/UEDMA/TEGDMA co-monomers may be used as an alternative to the control.

Prenatal bisphenol A exposure and maternally reported behavior in boys and girls

Prenatal exposure to gonadal hormones plays a major role in the normal development of the male and female brain and sexually dimorphic behaviors. Hormone-dependent differences in brain structure and function suggest that exposure to exogenous endocrine disrupting chemicals may be associated with sex-specific alterations in behavior. Bisphenol A (BPA) is an environmental chemical that has been shown to alter estrogen, androgen, and thyroid hormone signaling pathways. Epidemiological and experimental studies suggest associations between prenatal exposure to BPA and child behavior, however data are inconsistent, and few studies have examined school age children. We examined BPA concentration in spot urine samples from women at mean 27 weeks of pregnancy in relation to child behavior assessed at age 6-10 years using the parent-completed Child Behavior Checklist (CBCL). We report associations between maternal BPA urinary concentrations and several CBCL scores in 153 children (77 boys and 76 girls). We observed a significant interaction between maternal urinary BPA and sex for several behaviors (externalizing, aggression, Anxiety Disorder, Oppositional/Defiant Disorder and Conduct Disorder traits), but no significant associations between BPA and scores on any CBCL scales. However in analyses restricted to children of mothers with detectable prenatal urinary BPA (n=125), BPA was associated with moderately increased internalizing and externalizing behaviors, withdrawn/depressed behavior, somatic problems, and Oppositional/Defiant Disorder traits in boys. In addition we observed a significant interaction between BPA and sex for several behaviors (externalizing, withdrawn/depressed, rule-breaking, Oppositional/Defiant Disorder traits, and Conduct Disorder traits). These results suggest that prenatal exposure to BPA may be related to increased behavior problems in school age boys, but not girls.

Phthalate and bisphenol A exposure among pregnant women in Canada--results from the MIREC study

Bisphenol A (BPA) and phthalates are endocrine disruptors possibly linked to adverse reproductive and neurodevelopmental outcomes. These chemicals have commonly been measured in urine in population surveys; however, such data are limited for large populations of pregnant women, especially for the critical first trimester of pregnancy. The aim of the study was to measure BPA and phthalate metabolites in first trimester urine samples collected in a large national-scale pregnancy cohort study and to identify major predictors of exposure. Approximately 2000 women were recruited in the first trimester of pregnancy from ten sites across Canada. A questionnaire was administered to obtain demographic and socio-economic data on participants and a spot urine sample was collected and analyzed for total BPA (GC-MS/MS) and 11 phthalate metabolites (LC-MS/MS). The geometric mean (GM) maternal urinary concentration of total BPA, uncorrected for specific gravity, was 0.80 (95% CI 0.76-0.85) μg/L. Almost 88% of the women had detectable urinary concentrations of BPA. An analysis of urinary concentrations of BPA by maternal characteristics with specific gravity as a covariate in the linear model showed that the geometric mean concentrations: (1) decreased with increasing maternal age, (2) were higher in current smokers or women who quit during pregnancy compared to never smokers, and (3) tended to be higher in women who provided a fasting urine sample and who were born in Canada, and had lower incomes and education. Several of the phthalate metabolites analyzed were not prevalent in this population (MCHP, MMP, MiNP, MOP), with percentages detectable at less than 15%. The phthalate metabolites with the highest measured concentrations were MEP (GM: 32.02 μg/L) and MnBP (GM: 11.59 μg/L). MBzP urinary concentrations decreased with maternal age but did not differ by time of urine collection; whereas the DEHP metabolites tended to be higher in older women and when the urine was collected later in the day. This study provides the first biomonitoring results for the largest population of pregnant women sampled in the first trimester of pregnancy. The results indicate that exposure among this population of pregnant women to these chemicals is comparable to or even lower than that observed in a Canadian national population-based survey.

Glass ionomer ART sealant and fluoride-releasing resin sealant in fissure caries prevention--results from a randomized clinical trial

Background

The relative performance of ART sealant and fluoride-releasing resin sealant in preventing fissure caries in permanent molars was compared in a randomized clinical trial conducted in southern China (ClinicalTrials.gov NCT01829334).

Methods

After obtaining ethical approval, healthy schoolchildren who had permanent first molars with occlusal fissures which were sound but deep or presented with only incipient caries were recruited for the study. Included molars were randomly allocated into one of four parallel study groups in units of left/right teeth per mouth. Two of the four groups adopted the methods of ART or fluoride-releasing resin sealant placement while the other two groups adopted the topical fluoride application methods. Fissure status of the molars in each group was evaluated every 6 months. Development of dentine caries and sealant retention over 24 months in the molars in the two sealant-using groups was compared in this report. Outcome on cost-effectiveness of all four groups over 36 months will be reported elsewhere.

Results

At baseline, a total of 280 children (383 molars) with mean age 7.8 years were involved for the two sealant groups. After 24 months, 261 children (357 molars) were followed. Proportions of molars with dentine caries were 7.3% and 3.9% in the ART sealant and fluoride-releasing resin sealant groups, respectively (chi-square test, p = 0.171). Life-table survival analysis showed that sealant retention (full and partial) rate over 24 months for the resin sealant (73%) was significantly higher than that (50%) for the ART sealant (p < 0.001). Molar survival (no development of dentine caries) rates in the ART sealant (93%) and fluoride-releasing resin sealant (96%) groups were not significantly different (p = 0.169). Multilevel logistic regression (GEE modeling) accounting for the effects of data clustering and confounding factors confirmed this finding.

Conclusions

Though the retention of fluoride-releasing resin sealant was better than that of the ART sealant, their effectiveness in preventing fissure caries in permanent molars did not differ significantly over 24 months. ART sealants could be a good alternative when and where resources for resin sealant placement are not readily available.