Effect of topical fluoride applications on residual monomer release from resin-based restorative materials

BACKGROUND

The effects of topical fluoride applications on the release of monomer ingredients from resin-based dental materials by immersion in various extraction solutions are unclear. The aim of this study was to determine the effect of topical fluorides (APF and NaF) on the elution of residual monomers (Bis-GMA, TEGDMA, UDMA, and HEMA) from resin-based materials.

METHODS

Ninety specimens were prepared, 30 bulk-fill composite resin, 30 nanohybrid universal composite resin, and 30 polyacid-modified composite resin (compomer). These were randomly divided into three groups based on fluoride application procedures. Each specimen was kept in 75% ethanol solution, and residual monomers released from materials were analyzed using high-performance liquid chromatography (HPLC) after 10 min, 1 h, 24 h, and 30 days. The groups were compared using the Mann Whitney U and Kruskal Wallis tests. Measurements were analyzed using the Friedman and Wilcoxon signed-rank tests.

RESULTS

Fluoride applications generally had no considerable effect on the amount of residual monomer released from resin-based restorative materials. The amount of monomer release after topical APF application was similar to the release in the control group and was lower than the release in the NaF group. The release of monomers from the resin-based material used in the study did not approach toxic levels at the applied time intervals. The compomer released lower amounts of monomer than other resin-based materials.

CONCLUSIONS

Fluoride applications do not increase monomer release from resin-based restorative materials. However, compomers should be employed by clinicians due to their lower monomer release compared to other resin restorative materials. The release of monomers from all the resin-based materials did not approach toxic levels at the applied time intervals.

Determination of Arsenic(III) and Total Arsenic at Trace Levels in Baby Food Samples via a New Functionalized Magnetic Graphane Oxide Nanocomposite

Baby food safety is an essential issue in health policy. For this reason, a simple, cheap, and fast analytical procedure to developed arsenic(III) and total arsenic determination in baby food samples using functionalized magnetic graphane oxide nanocomposite. A new nanocomposite anchored of tiopronin (TSH) magnetic graphane oxide (GO-PG4@Fe₃O₄-TSH) was first synthesized/characterized and used as an adsorbent to determine arsenic(III) and total arsenic for baby food samples. Arsenic(III) was directly determined on GO-PG4@Fe₃O₄-TSH nanocomposite at pH 4.5. The determination of total arsenic used KI and L( +) ascorbic acid solution as reducing reagents. The parameters influential on arsenic(III) determination in the baby food samples including the sample's pH, adsorption time, amount of GO-PG4@Fe₃O₄-TSH, eluent type, sample volume, reducing reagent type and amount, and also foreign ion effect were investigated. The GO-PG4@Fe₃O₄-TSH carrying As(III) could easily be separated from baby food samples via applying an external magnetic field. The detection limit for arsenic(III) was found as 0.11 μg L^-1, while the limit of quantification values was computed as 0.37 μg L^-1. The precision of results, expressed as relative standard deviation, was always lower than 1.6% at 1 mg L^-1 As(III) levels. The accuracy of this method was confirmed by analysis of certified reference material. The method was successively applied to determine arsenic(III) and total arsenic in baby food samples.

Morphological analysis of aqueous humor drainage using QD nanoparticles and indocyanine green

This study represents the first morphological description of the lymphatic drainage of the ciliary body in vivo by comparative hyperspectral fluorescence imaging techniques of Quantum Qdot655 (QD) nanoparticles and indocyanine green (ICG). A volume of 1.25 μl of QD was injected into the left anterior camera of all rats. Similarly,1.25 μl of ICG diluted at a ratio of one-fourth with physiological saline solution was injected into the right anterior camera of all rats. The thickness of the skin in the mandibular area, connective tissue, and the depth of the mandibular lymph node (MLN) made image retrieval difficult. For QD, 302 nm UV excitation and 605 nm fluorescence peak emission were applied. The detection of QD and ICG used in this study in the MLNs is definitive evidence that aqueous humor (AH) follows a uveolymphatic pathway. Scanning electron microscope and the energy dispersive X-ray analyzer spectrum were used to examine both the Schlemm's canal and the MLN. For the first time, the QD was detected in the cortex of MLN. The QCM analysis of both QD-AH and ICG-AH was used to determine whether there was any interaction between them. This comparative study shows the importance of experimental animal modeling in pharmacological studies regarding eye research and drugs. In a female rat, the signal was taken from the parotid lymph node with QD injections.

A new turn-on fluorimetric method for the rapid speciation of Cr(III)/Cr(VI) species in tea samples with rhodamine-based fluorescent reagent

A new fluorimetric method with rhodamine-based fluorescent agent was developed for the rapid speciation of Cr(III)/Cr(VI) in tea, soil and water samples. The system, which utilizes a fluorescent reagent, was used for the first time after synthesis/characterization of 3',6'-bis(diethylamino)-2-{[(1E)-(2,4-dimethoxyphenyl)methylene] amino}spiro[isoindole-1,9'-xanthen]-3(2H)-one (BDAS). The reagent responds instantaneously at room temperature in a 1:1 stoichiometric manner to the amount of Cr(III). The selectivity of this system for Cr(III) over other metal ions is remarkably high, and its sensitivity is below 0.01mgL^-1 in aqueous solutions which enables a simplification without any pretreatment of the real sample. The method has a wide linear range of 0.1-10mgL^-1 and a detection limit of 0.15μgL^-1 for Cr(III) while the relative standard deviation was 0.1% for 0.1mgL^-1 Cr(III) concentration. The results of detection and recovery experiments for Cr(III) in tea, soil and water were satisfactory, indicating that the method has better feasibility and application potential in the routine determination and speciation of Cr(III)/Cr(VI). The results of analysis of the certified reference material (INCT-TL-1 tea sample and CWW-TM-D waste water) are in good agreement with the certified value.

Grafting of glutathione to magnetic graphene oxide and application for the determination of As(iii)/(v) in food samplesviaa zeta potential analyzer

A new selective method based on magnetic dispersive solid-phase extraction (MDSPE) and a zetasizer system is proposed for the determination of As(iii)/As(v) species in some water and food samples.

Synthesis, characterization and application of a new chelating resin for solid phase extraction, preconcentration and determination of trace metals in some dairy samples by flame atomic absorption spectrometry

In this study, a simple and rapid solid phase extraction/preconcentration procedure was developed for determination of Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Pb(II), and Zn(II) trace metals by flame atomic absorption spectrometry (FAAS). A new chelating resin, poly(N-cyclohexylacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propanesulfonic acid) (NCA-co-DVB-co-AMPS) (hereafter CDAP) was synthesized and characterized. The influences of the analytical parameters such as pH of the sample solution, type and concentration of eluent, flow rates of the sample and eluent, volume of the sample and eluent, amount of chelating resin, and interference of ions were examined. The limit of detection (LOD) of analytes were found (3s) to be in the range of 0.65-1.90μgL(-1). Preconcentration factor (PF) of 200 and the relative standard deviation (RSD) of ⩽2% were achieved (n=11). The developed method was applied for determination of analytes in some dairy samples and certified reference materials.

Dispersive Liquid-Liquid Microextraction of Bismuth in Various Samples and Determination by Flame Atomic Absorption Spectrometry

A dispersive liquid-liquid microextraction method for the determination of bismuth in various samples by flame atomic absorption spectrometry is described. In this method, crystal violet was used as counter positive ion for BiCl4 (-) complex ion, chloroform as extraction solvent, and ethanol as disperser solvent. The analytical parameters that may affect the extraction efficiency like acidity of sample, type and amount of extraction and disperser solvents, amount of ligand, and extraction time were studied in detail. The effect of interfering ions on the analyte recovery was also investigated. The calibration graph was linear in the range of 0.040-1.00 mg L(-1) with detection limit of 4.0 μg L(-1) (n = 13). The precision as relative standard deviation was 3% (n = 11, 0.20 mg L(-1)) and the enrichment factor was 74. The developed method was applied successfully for the determination of bismuth in various water, pharmaceutical, and cosmetic samples and the certified reference material (TMDA-64 lake water).

Determination of some metal ions in various meat and baby food samples by atomic spectrometry

In this paper, we report a simple and rapid solid phase extraction system for the separation/preconcentration and determination of Cd(II), Co(II), Cu(II), Fe(III), Cr(III), Pb(II), and Zn(II) ions by flame atomic absorption spectrometry (FAAS). This method is based upon the retention of metal ions on a column packed with poly[N-(3-methyl-1H-indole-1-yl)]-2-methacrylamide-co-2-acrylamido-2-methyl-1-propane sulphonic acid-co divinylbenzene] (MMAD) resin as a solid-phase extraction (SPE) sorbent at pH 8. At the optimized conditions, the limits of detection (3 s/b) between 0.12 and 1.6 μg L(-1), preconcentration factor of 100, and the relative standard deviation of ⩽1.8% were achieved (n=10). The accuracy of the method was verified by analyzing certified reference materials (CRMs) and performing recovery experiments. The developed method was successfully applied to the various natural water, meat products and baby food samples. The recoveries of analyte ions were found in added real samples and CRMs from 95% to 102%.