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PubMed2001

Heterogeneous distribution of single-bottle adhesive monomers in the resin-dentin interdiffusion zone.

OBJECTIVES: The purpose of this study was to investigate whether monomer separation occurs in single-bottle adhesives applied on acid-etched dentin surfaces. METHODS: Smear-layer covered dentin specimens produced from sound premolars, were acid-etched and analyzed by micro-MIR FTIR spectroscopy, before and after treatment with the single-bottle adhesives One-Step, Prime and Bond 2.1, Scotchbond 1 and Syntac-Sprint. The difference spectra (etched, and primed minus etched of the same dentin surfaces) were plotted and compared with original adhesive spectra. The C=C/C...C (aromatic adhesives) and C=C/C=O (aliphatic adhesives) peak area ratios were used to evaluate the extent of monomer separation relative to original adhesive spectra at the uppermost 2 microm of the resin-dentin interdiffusion zone. Three dentin specimens were used for each adhesive. One-way ANOVA and Newman-Keuls tests were performed to assess the statistically significant differences (alpha=0.05). RESULTS: All the adhesives demonstrated separation of monomer components on etched dentin ranging in mean values from 68.7 to 81.9% relative to reference. High molecular weight hydrophobic (i.e. BisDMA, BisGMA, BisGMA adducts) and hydrophilic monomers (i.e. BPDMA) predominated at the region probed. Prime and Bond 2.1 demonstrated the highest extent of monomer separation. SIGNIFICANCE: Heterogeneous monomer distribution following application to etched dentin may affect the curing performance of single-bottle adhesives within the resin infiltrated region and consequently, the mechanical and chemical stability of the network formed.

Acid Etching, Dental↗
PubMed1986

Occupational dermatitis due to an epoxy acrylate.

A dental assistant developed sensitivity to dental restorative materials within 3 months of starting to use them. They contained the epoxy acrylate BIS-GMA, which is the most commonly used dimethacrylate monomer in dental composite restorations. She was positive to a patch test with BIS-GMA, which was the probable allergen, and epoxy resin, but this substance was not present in the materials used, as shown by high performance liquid chromatography. The patient was also allergic to the disinfectant Desimex i containing dodecyl diaminoethyl glycine.

Adult↗
PubMed1991

Occupational skin diseases from epoxy compounds. Epoxy resin compounds, epoxy acrylates and 2,3-epoxypropyl trimethyl ammonium chloride.

Of a total of 3731 patients investigated between 1974 and 1990, 1844 (49.4%) had an occupational skin disease. Of them 142 (7.7%) had an occupational skin disease caused by epoxy compounds--135 patients (95%) had allergic contact dermatitis, five had irritant contact dermatitis, and two had contact urticaria. Apart from dermatoses, two patients had IgE-mediated asthma from exposure to DGEBA epoxy resins. Thus epoxy compounds are one of the main causes of occupational allergic contact dermatoses and can be considered potential causes of occupational asthma. The most frequent causes were epoxy resin compounds, which together induced 93% (132 cases) of all epoxy compound dermatoses. The three most common causative products were epoxy paints and their raw materials (31%, 41 cases), epoxy resin compounds used in electrical insulation (29%, 38 cases) and epoxy glues (18%, 24 cases). Fewer cases were caused by products containing epoxy acrylate and EPTMAC. The present study found that, in addition to contact allergy to DGEBA epoxy resins, contact allergy to epoxy hardeners, non-DGEBA resins and reactive diluents is common. Polyamine hardeners, most frequently MDA, DETA and TETA, rarely IPDA, tris-DMP, EDA, TMD and XDA, were the second commonest causes of contact allergy induced by epoxy resin compounds, after DGEBA epoxy resins. Cycloaliphatic epoxy resins and other non-DGEBA epoxy resins, including heterocyclic dimethyl hydantoin, phenol novolak and brominated epoxy resins, were the third commonest causes, and reactive diluents the fourth commonest cause of allergic dermatitis due to epoxy resin compounds. Most patients sensitized to reactive diluents were allergic to PGE, ortho-CGE, HDDGE and BDDGE, whereas fewer patients were sensitized to AGE, NPGDGE and BGE. Cross-sensitization between reactive diluents was common. Cardura E 10 and Epoxide 8 provoked no reactions. The present study also indicated that DGEBA epoxy resins with a high average MW ought to be regarded as potential sensitizers, and organic solvents probably promote sensitization to DGEBA, even if the amount of DGEBA is low in the causative products. When contact dermatitis induced by epoxy compounds is suspected, an accurate diagnosis is made with the use of detailed data on the patient's exposure and extensive patch testing, including tests with the patient's own products. No chemical can be used alone to screen for sensitization to all different contact allergens of epoxy compounds.(ABSTRACT TRUNCATED AT 400 WORDS)

Benzhydryl Compounds↗
PubMed2000

Are sealants doing more than preventing caries?

Dental sealants are among some of dentistry's most effective tools for preventing tooth decay when applied to pediatric patients' teeth. Yet, a quiet controversy is mounting about some of the chemicals that may be leaching from these powerhouses of prevention. Some scientists hint that sealants may require further study to rule out possible links between some of their components and breast cancer development, prostate enlargement and some as-yet-unknown biological effects. While sealants' preventive power ranks with fluoride, even a remote possibility that they may affect patients' systemic health creates concern.

Benzhydryl Compounds↗
PubMed2007

Biodegradation of bisphenol A and related compounds by Sphingomonas sp. strain BP-7 isolated from seawater.

A bacterium capable of assimilating 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), strain BP-7, was isolated from offshore seawater samples on a medium containing bisphenol A as sole source of carbon and energy, and identified as Sphingomonas sp. strain BP-7. Other strains, Pseudomonas sp. strain BP-14, Pseudomonas sp. strain BP-15, and strain no. 24A, were also isolated from bisphenol A-enrichment culture of the seawater. These strains did not degrade bisphenol A, but accelerated the degradation of bisphenol A by Sphingomonas sp. strain BP-7. A mixed culture of Sphingomonas sp. strain BP-7 and Pseudomonas sp. strain BP-14 showed complete degradation of 100 ppm bisphenol A within 7 d in SSB-YE medium, while Sphingomonas sp. strain BP-7 alone took about 40 d for complete consumption of bisphenol A accompanied by accumulation of 4-hydroxyacetophenone. On a nutritional supplementary medium, Sphingomonas sp. strain BP-7 completely degraded bisphenol A and 4-hydroxyacetophenone within 20 h. The strain degraded a variety of bisphenols, such as 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, and 1,1-bis(4-hydroxyphenyl)cyclohexane, and hydroxy aromatic compounds such as 4-hydroxyacetophenone, 4-hydroxybenzoic acid, catechol, protocatechuic acid, and hydroquinone. The strain did not degrade bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)sulfone, or bis(4-hydroxyphenyl)sulfide.

Benzhydryl Compounds↗
PubMed2002

Chlorination of bisphenol A in aqueous media: formation of chlorinated bisphenol A congeners and degradation to chlorinated phenolic compounds.

The chlorination of bisphenol A (BPA) in aqueous media was investigated in order to describe the degradation profile of this compound and the formation of chlorinated products. Aqueous solutions of BPA (approx. 1 mg/l) were chlorinated by sodium hypochlorite solution at room temperature and under weakly alkaline conditions. Chlorinated compounds were extracted with dichloromethane and determined by gas chromatography/mass spectrometry (GC/MS). BPA was consumed completely within 5 min of chlorination, when the initial chlorine concentration was 10.24 mg/l (molar ratio to BPA, 58.7). On the other hand, when the initial chlorine concentration was 1.03 mg/l (molar ratio, 6.56), 9.3% of BPA still remained after 60 min chlorination. Five chlorinated BPA congeners, 2-chlorobisphenol A (MCBPA), 2,6-dichlorobisphenol A (2,6-D2CBPA), 2,2'-dichlorobisphenol A (2,2'-D2CBPA), 2,2',6-trichlorobisphenol A (T3CBPA) and 2,2', 6,6'-tetrachlorobisphenol A (T4CBPA) were formed in the earlier stages of chlorination. Several chlorinated phenolic compounds, 2,4,6-trichlorophenol (T3CP), 2,6-dichloro-1,4-benzoquinone (D2CBQ), 2,6-dichloro-1,4-hydroquinone (D2CHQ), C9H10Cl2O2, C9H8Cl2O and C10H12Cl2O2, were also formed by further chlorination.

Benzhydryl Compounds↗
PubMed2002

Phenylphenols, biphenols, bisphenol-A and 4-tert-octylphenol exhibit alpha and beta estrogen activities and antiandrogen activity in reporter cell lines.

We previously demonstrated the interactions of different chemical compounds with estrogen receptors ERalpha and ERbeta and the androgen receptor (AR) using different reporter cell lines. In this study, we characterize the ERalpha, ERbeta and AR activity of different biphenyls using the same tools. We provide evidence that several phenyl derivatives present both estrogenic and antiandrogenic activity. The extent of hydroxylation and the position of the hydroxyl function were important in determining their estrogenicity and antiandrogenicity. Of the tested compounds, bisphenol-A and 4,4' biphenol had very high estrogenic activity, although it was lower than that of the strong estrogenic alkylphenol, 4-tert-octylphenol. Bisphenol-A and 4,4' biphenol were able to activate ERs at concentrations lower than 1 microM, whereas the other compounds only activated at concentrations above 1 microM. Interestingly, 4,4' biphenol was a better agonist for ERbeta than for ERalpha. No androgenic activity was detected for any of these compounds. Bisphenol-A, 3-OH phenylphenol, 4-OH phenylphenol and 4,4' biphenol exhibited antiandrogenic activity close to that of 4-tert-octylphenol (IC(50) approximately 5 microM). In whole cell binding assays, these compounds displaced [3H] R1881 with Ki = 10 microM. Although these Ki values seem high in comparison with that of hydroxyflutamide (0.4 microM), one must keep in mind that environmental chemicals can accumulate in adipose tissues for several years. In conclusion, these environmental chemicals may have a negative impact on androgen action during fetal and post-natal life.

Androgen Receptor Antagonists↗
PubMed2000

Determination of bisphenol A and related aromatic compounds released from bis-GMA-based composites and sealants by high performance liquid chromatography.

Most of the composites and sealants used in dentistry are based on bisphenol A diglycidylether methacrylate (Bis-GMA). Reports revealed that in situ polymerization is not complete and that free monomers can be detected by different analytic methods. Concerns about the estrogenicity of bisphenol A (BPA) and other aromatic components leached from commercial products have been expressed. We studied biphenolic components eluted from seven composites and one sealant before and after in vitro polymerization using HPLC and gas chromatography/mass spectrometry and we investigated how pH modifications affect the leaching of these components. We found BPA (maximal amount 1.8 microg/mg dental material), its dimethacrylate derivative (Bis-DMA, 1.15 microg/mg), bisphenol A diglycidylether (6. 1 microg/mg), Bis-GMA (2.0 microg/mg), and ethoxylate and propoxylate of bisphenol A in media in which samples of different commercial products were maintained under controlled pH and temperature conditions. Our results confirm the leaching of estrogenic monomers into the environment by Bis-GMA-based composites and sealants in concentrations at which biologic effects have been demonstrated in in vivo experimental models. The main issue with implications for patient care and dentist responsibility is to further determine the clinical relevance of this estrogenic exposure.

Benzhydryl Compounds↗
PubMed2002

Endocrine disruptors and dental materials: health implications associated with their use in Brazil.

This study analyzes international historical trends in the use of different types of materials in dental practice. The author describes the chemical properties of their ingredients and the potential and observed adverse effects in patients and dental technicians resulting from clinical or occupational exposure to various metals like beryllium, used to produce metal alloys. The growing use of various products (resin cements, ionomer cements, aesthetic restorative materials, resins, endodontal cements, and others) based on the compound bisphenol-A, whose chemical structure is similar to that of estrogen. Considering the demographic and contemporary work force characteristics of those involved in dental practice in the Brazil, the study highlights the possible effect of the use of these materials in both male and female patients and all age strata, as well as in health professionals with occupational exposure to products containing bisphenol-A.

Benzhydryl Compounds↗
PubMed2004

Identification of juvenile hormone-active alkylphenols in the lobster Homarus americanus and in marine sediments.

We have identified, by gas chromatography/mass spectrometry, four alkylphenols that are present in the hemolymph and tissues of the American lobster Homarus americanus and in marine sediments. These alkylphenols are used industrially in antioxidant formulations for plastic and rubber polymer manufacturing, and are similar in structure to a known endocrine disruptor, bisphenol A. The compound 2-t-butyl-4-(dimethylbenzyl)phenol was present at concentrations of 0.02 to 1.15 microg/ml in hemolymph and 8.95 to 21.58 microg/g in sediments. A second compound, 2,4-bis-(dimethylbenzyl)phenol, was present at concentrations between 0.07 and 19.78 microg/ml in hemolymph and 138.94 to 224.89 microg/g in sediment, while a third compound, 2,6-bis-(t-butyl)-4-(dimethylbenzyl)phenol, was found at concentrations between 0.01 and 13.00 microg/ml in hemolymph, 2.55 and 6.11 microg/g in hepatopancreas, and 47.85 and 74.66 microg/g in sediment. A fourth compound, 2,4-bis-(dimethylbenzyl)-6-t-butylphenol, was found at concentrations of 0.20 to 70.71 microg/ml in hemolymph, 23.56 to 26.89 microg/g in hepatopancreas, and 90.68 to 125.58 microg/g in sediment. These compounds, along with bisphenol A, 4-dimethylbenzylphenol, and nonylphenol, display high juvenile hormone activity in bioassays. Alkylphenols at high concentrations are toxic to crustaceans and may contribute significantly to lobster mortality; at lower concentrations, they are likely to have endocrine-disrupting effects.

Animals↗
PubMed2002

Acute toxicity, mutagenicity, and estrogenicity of bisphenol-A and other bisphenols.

Although abundant data are available on the toxicity of bisphenol-A (2,2-bis (4-hydroxydiphenyl)propane; BPA), little is known about the toxicities of the structurally similar compounds, namely bisphenols (BPs). A variety of BPs were examined for their acute toxicity against Daphnia magna, mutagenicity, and estrogenic activity using the Daphtoxkit (Creasel Ltd.), the umu test system, and the yeast two-hybrid system, respectively, in comparison with BPA. BPA was moderately toxic to D. magna (48-h EC50 was 10 mg/l) according to the current U.S. EPA acute toxicity evaluation standard, and it was weakly estrogenic with 5 orders of magnitude lower activity than that of the natural estrogen 17 beta-estradiol in the yeast screen, while no mutagenicity was observed. All seven BPs tested here showed moderate to slight acute toxicity, no mutagenicity, and weak estrogenic activity as well as BPA. Some of the BPs showed considerably higher estrogenic activity than BPA, and others exhibited much lower activity. Among the tested BPs, two compounds, i.e., bisphenol-S (bis(4-hydroxydiphenyl)sulfone) and bis(4-hydroxyphenyl)sulfide, have never been reported for their estrogenic activity previously.

Animals↗
PubMed1997

A study of component release from resin pit and fissure sealants in vitro.

OBJECTIVE: A recent study reported that an estrogenic chemical, bisphenol-A, was released from a fissure sealant. The aim of this study was to identify and quantify the major (or detectable) components released from any of seven commercially-available, light-cured pit and fissure sealants in vitro. METHODS: The fissure systems of ten extracted, third molar teeth were filled with sealant, light-activated and immersed in separate containers of distilled water. Separate, cylindrical stainless steel molds were filled with sealant which was then light-activated and immersed. Each mold or tooth with sealant was moved to a new container of water at defined times and each remaining water sample (eluate) then analyzed by high performance liquid chromatography (HPLC). RESULTS: Triethylene glycol dimethacrylate (TEGDMA) was present in all eluates from each of the sealants tested. 2,2-bis[4'-(2'-hydroxy-3'-methacryloyloxy)phenyl]propane (BisGMA) was detected at much lower levels (about one thousand-fold less) in eluates from one sealant only. Bisphenol-A was not detected in any eluates. The rates of TEGDMA and BisGMA release were highest on first immersion and decreased thereafter. The total amount of TEGDMA released was on the order of 0.25 mg per tooth. Most release occurred during the first day. SIGNIFICANCE: Because bisphenol-A release could not be detected from any of the seven sealants tested, these results call into question earlier concerns expressed about possible adverse effects of bisphenol-A released from resin sealants.

Air Pollutants, Occupational↗