Remineralization potential of dentifrices with calcium sodium phosphosilicate and functionalized tri-calcium phosphate in the deeper incipient carious lesions: An in vitro study

OBJECTIVES

This study evaluated the remineralization potential of calcium sodium phosphosilicate and functionalized tri-calcium phosphate (f-TCP) dentifrices in deeper incipient carious lesions (ICLs).

MATERIALS AND METHODS

Artificial ICLs were created by placing premolars into demineralizing solutions. Teeth were randomly assigned into four groups: calcium sodium phosphosilicate (Group 1), f-TCP (Group 2), 1450 ppm fluoride (Group 3), and distilled water (Group 4), which were subjected to 10-day pH cycling. Mineral density (MD) was assessed using microcomputed tomography (Micro-CT), while hardness (H) and elastic modulus (EM) were assessed using nanomechanical testing.

RESULTS

MD % gain was higher in Groups 1-3 than in Group 4. In addition, Groups 1 and 2 exhibited significantly higher MD % gain than Group 3. Also, Groups 1-3 showed significantly higher EM and H values than Group 4 in the outer enamel area; yet, Groups 1 and 2 displayed significantly higher EM and H values than Groups 3 and 4 in the inner enamel.

CONCLUSIONS

The MD, EM, and H of ICLs significantly increased with the addition of calcium sodium phosphosilicate or f-TCP to fluoridated dentifrices compared to standard fluoride dentifrices. The added active ingredients remineralized the deeper parts of the ICLs, while remineralization at the lesion surface was similar between tested dentifrices.

Diphoterine, an amphoteric rinsing solution, reduces hydrofluoric acid injuries in an ex vivo pigskin model

Hydrofluoric acid (HF) is a ubiquitous industrial chemical that is particularly hazardous because of the potential for systemic effects and the induction of severe cutaneous necrosis after contact with the skin. Minimizing skin injury requires decontaminating the affected area promptly with an emergency rinsing solution. Few experimental studies have objectively characterized rinsing solutions such as Diphoterine (DP). Here we develop an ex vivo pigskin model to study and compare the efficacy of rinsing solutions as initial decontaminating agents to stop the progression of skin lesions after HF splashing. The pigskin model shows an immediate local response to HF at varying concentrations and exposure times. We then exposed the pigskin biopsies to 3.75% HF for 1 min and rinsed them with different solutions, including water, 0.9% NaCl solution (saline), 10% calcium gluconate (CaG), Hexafluorine (HXF), and DP. We found DP to be a more effective agent for decontaminating HF lesions than water, saline, and CaG. DP had a similar efficacy as HXF, an emergency rinsing solution used specifically for decontaminating HF-exposed skin. This study shows that skin exposed to HF must be treated quickly from the first minute of exposure.

Atypical methods for characterization of used photovoltaic panels during their pre- and Post-Thermal treatment assessment

The study presents an innovative approach to the analysis of waste silicon photovoltaic panels prior and after thermal treatment. Using laser-induced breakdown spectroscopy (LIBS), the elemental composition of multilayered panel backsheets was determined, identifying a TiO2-containing coating laminate, a polyvinylidene fluoride (PVDF) layer, and an ethylene vinyl acetate (EVA) encapsulant, while also estimating their thickness. Identifying the fluorine-containing layers allowed their selective removal and safe processing of the used panels. Thermal processing parameters such as temperature (400-550 °C), time (5 - 60 min) and orientation of the busbar relative to the heat source were optimized based on contact angle measurements and CIELAB color space analysis, techniques used to detect organic residues in recovered glass and silicone. The decomposition process was examined by thermal analysis coupled with mass spectroscopy, which revealed that there were no volatile fluorine compounds in the gases released, although fluorine was detected on the recovered glass surface by SEM - EDS examination. After the PVDF layer was removed, fluorine compounds were not found in volatile gases or on the surface of recovered inorganic materials. The study indicated that the orientation of the busbars facilitates the decomposition of organic matter. Methods for reusing recovered secondary materials were also provided, suggesting the potential applications and benefits of recycling components from silicon photovoltaic panels.

Comparison between ammonium formate and ammonium fluoride in the analysis of stratum corneum lipids by reversed phase chromatography coupled with high resolution mass spectrometry

Lipids are key constituents of the barrier function in the human stratum corneum (SC), which is the outermost layer of the epidermis and amenable to non-invasive sampling by tape stripping. The three major lipid classes in the SC, i.e., ceramides, fatty acids, and cholesterol, present equimolar concentration. Liquid chromatography coupled with mass spectrometry (LCMS) is elective in profiling lipids in the SC in both positive and negative ion modes. Nevertheless, the latter one allows for the simultaneous detection of the three major epidermal components of the SC. Determination of ceramides in the SC poses analytical challenges due to their wide range of structures and concentrations especially in the case of limited sample amounts. Ammonium formate is a commonly used modifier added to the mobile phase to assist ionization. However, it introduces uncertainty in the identification of ceramides when operating in negative ion mode, even with high resolution MS. We tested the advantages of using fluoride in the lipid profiling of SC and unambiguous identification of ceramides subclasses. The use of fluoride enhanced the ionization of ceramides, regardless the specific substructure, solved misidentification issues, and was successfully applied to the simultaneous detection of all three lipid classes in the human SC.

Fluoro-cotton assisted non-targeted screening of organic fluorine compounds from rice (Oryza sativa L.) grown in perfluoroalkyl substance polluted soil

The toxicity and environmental persistence of perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) are of great concern for food intake in humans. However, PFASs conversion or conjugation to other substances in rice grown on PFASs polluted soil has not been explored clearly. These unknown transformed or conjugated products of PFOA and PFOS could be harmful to human health. The restriction factor in evaluating the possible transformation of PFOA and PFOS is mainly attributed to the lack of an efficient method for screening PFOA and PFOS and their related metabolites. To circumvent this challenge, we established a non-targeted screening method by combining a fluoro-cotton fiber-based solid phase extraction (FC-SPE) and liquid chromatography-high resolution mass spectrometry (LC-HRMS) to monitor the formation of possible organic fluorine compounds from rice (Oryza sativa L.) grown on PFASs. We synthesized fluoro-cotton fibers to serve as the FC-SPE packing material and characterized by field-emission scanning electron-microscope, Fourier transform infrared, and X-ray photoelectron spectroscopy measurements. The optimal extraction conditions for the prepared FC-SPE were investigated. The performance of FC-SPE in LC-MS analysis was validated by linearity, precision, recovery, and matrix effect. Then the FC-SPE combined with LC-HRMS was used to specifically capture organic fluorine compounds from complex matrices via F-F interaction, including rice seedlings grown in PFOA and PFOS polluted soil and soil samples. By the established FC-SPE LC-HRMS method, in total 429 features were found as the possible organic fluorine compounds from rice seedlings grown in PFOA polluted soil among the 1781 features from the rice seedlings. Finally, we employed a¹³C metabolic tracing analysis of organic fluorine compounds in combination with the FC-SPE LC-HRMS method to further identify the features that detected from rice seedlings grown in PFOA polluted soil. The final result indicated that there were not any new organic fluorine metabolites screened out from rice grown in PFOA or PFOS polluted soil.

The influence of environmental pollution with fluorine compounds on the level of fluoride in soil, feed and eggs of laying hens in Central Pomerania, Poland

The present study was aimed at evaluating fluorine contamination of the eggs of free-ranging laying hens in Northern Poland, in the Central Pomerania region, in relation to the distance from the emission sources. Fluorine levels in the soil, feed, and the shells, and contents of the eggs were assayed with the potentiometric method using an ion-selective electrode from ORION Ion Meter. The sampled eggs were subjected to pressure microwave digestion with the use of a Milestone MLS-1200 microwave. All the samples were digested in 5 ml of supra-pure grade concentrated HNO₃ from Merck. The mean level of fluorine in the studied soils ranged from 3.79 mg kg^-1 of DM in typical river alluvial soil to 126.19 mg kg^-1 of DM in lessive soil. The study revealed an average fluorine content in the feeds administered to the hens on the farms in zone 1 (17.29 mg kg^-1 of DM), it being 3.5 times higher than the corresponding content in zone 2 (4.92 mg kg^-1 of DM). A statistically significantly higher mean fluorine level was identified in the eggshells of hens on zone 1 farms, located closer to the pollution emission sources (17.52 mg kg^-1 of DM), the value being more than 3-fold higher than that in zone 2 (5.47 mg kg^-1 of DM). The present study revealed an almost twice as high fluorine mean content in the hen eggs collected on farms in zone 1 (1.488 mg kg^-1 of DM) compared with the hen egg contents in the experimental zone 2 (0.640 mg kg^-1 of DM), the difference being statistically significant.

Radical Chlorodifluoromethylation: Providing a Motif for (Hetero)arene Diversification

A method for the radical chlorodifluoromethylation of (hetero)arenes using chlorodifluoroacetic anhydride is reported. This operationally simple protocol proceeds under mild photochemical conditions with high functional group compatibility and complements the large body of literature for the trifluoromethylation of (hetero)arenes. Introduction of the chlorodifluoromethyl motif enables rapid diversification to a wide array of aromatic scaffolds. This work showcases the chlorodifluoromethyl group as an attractive entryway to otherwise synthetically challenging electron-rich difluoromethyl(hetero)arenes. Furthermore, facile conversion of the CF2Cl moiety into the corresponding aryl esters, gem-difluoroenones, and β-keto-esters is demonstrated.

Membrane-Derived Fluorinated Radicals Detected by Electron Spin Resonance in UV-Irradiated Nafion and Dow Ionomers: Effect of Counterions and H2O2

Electron spin resonance (ESR) spectroscopy was used to detect and identify radicals formed by UV irradiation of Nafion and Dow perfluorinated membranes partially or fully neutralized by Cu(II), Fe(II), and Fe(III). This method allowed the monitoring of ESR signals from the paramagnetic counterions together with the appearance of membrane-derived radical species. The most surprising aspect of this study was the formation of membrane-derived radical species only in the neutralized membranes, and even in the absence of H2O2 in the case of Nafion/Cu(II) and Nafion/Fe(III). In Nafion/Cu(II), ESR spectra from radicals exhibiting hyperfine interactions with three equivalent 19F nuclei (the "quartet") and with four equivalent 19F nuclei (the "quintet") were detected. In Nafion/Fe(II) exposed to H2O2 solutions, the formation of Fe(III) was detected. Upon UV irradiation, strong signals from the chain-end radical ROCF2CF2* were detected first, followed by the appearance, upon annealing above 200 K, of the quartet signal observed in Nafion/Cu(II). In subsequent experiments with Nafion and Dow membranes neutralized by Fe(III), the ROCF2CF2* radicals were formed even in the absence of H2O2, indicating that the role of H2O2 is oxidation of Fe(II) to Fe(III); moreover, in these systems small amounts of the chain-end radicals were detected even without UV irradiation. This result validates the method used to form the radicals: the role of UV irradiation is to accelerate the formation of a signal that is produced, albeit slowly, even in the dark, and possibly during fuel cell operation. The major conclusion is that cations are involved in degradation processes; the point of attack appears to be at or near the pendant chain of the ionomer. Therefore when studying membrane stability, it is important to consider not only the formation of oxygen radicals, such as HO*, HOO*, and O2*-, that can attack the membrane but also the specific reactivity of counterions.

Fluoride concentration in superficial enamel layers of permanent teeth in children residing in areas with different levels of environmental pollution with fluorine compounds

The concentration of fluoride in superficial layers of enamel of permanent teeth was studied in 14-year-old children residing in Szczecin and Bialystok-two cities differing regarding the level of environmental fluorine pollution. It was found that higher environmental pollution with fluorine favors the accumulation of this element in superficial layers of enamel in the form of structural fluoride. Total and structural fluoride concentration decreased with layer depth.

Enhancement of fluorouracil uptake in human colorectal and gastric cancers by interferon or by high-dose methotrexate: An in vivo human study using noninvasive (19)F-magnetic resonance spectroscopy

PURPOSE

To study whether two modulators, high-dose methotrexate (MTX) and interferon alfa-2a (IFNalpha-2a) will alter the intratumoral pharmacokinetics of fluorouracil (5-FU).

PATIENTS AND METHODS

Five patients, two with gastric cancer and three with colorectal cancer, who had metastatic tumor nodules in their livers were studied dynamically in vivo after 5-FU injection. In a magnetic resonance imaging unit, noninvasive (19)F-magnetic resonance spectroscopy (MRS) was used to detect (19)F signals from 5-FU and its metabolites.

RESULTS

The intratumoral half-life (t(1/2)) of 5-FU in these tumors ranged from 18.8 minutes to 42.3 minutes. Four of the five patients exhibited increases in the t(1/2) of 5-FU after intravenous (IV) administration of MTX or IFNalpha-2a. In the two patients with gastric cancer who received IV high-dose MTX followed by IV 5-FU, increases were seen in either the total t(1/2) of 5-FU (41.8%) or in the t(1/2) of the alpha phase (150%). In the three patients with colorectal cancer who received IV IFNalpha-2a followed by IV 5-FU, the two patients with partial responses had increases in the t(1/2) of 5-FU of 41% and 30.2%, whereas the nonresponder had a nonsignificant increase (5.6%) in the t(1/2) of 5-FU.

CONCLUSIONS

These results document that the in vivo modulation of the tumoral pharmacokinetics of 5-FU can be measured noninvasively by (19)F-MRS and suggest that such information correlates with subsequent clinical outcomes. The findings also indicate that IFNalpha-2a and high-dose MTX can increase the intratumoral 5-FU in some patients. Such information, obtained prospectively in vivo, may assist in better individual cancer patient management and in developing novel drug combinations.

Mass spectral fragmentation pathways of propranolol related beta-fluorinated amines studied by electrospray and electron impact ionization

Propranolol, its 1"-mono-, di-, and trifluorinated analogs, and other related compounds were analyzed under electrospray ionization ion trap collision-induced dissociation (ESI-CID) and electron impact (EI) conditions. Interesting trends were observed in the fragment ions formed in both cases. Under ESI conditions, the abundances of product ions easily explained by protonation on the amine nitrogen decreased relative to the abundances of those formed from the ether-protonated species as the number of fluorines increased from zero to three. Under EI conditions, the distribution of fragment ions was shifted away from those arising from a nitrogen-centered cation radical and toward those arising from an ether oxygen-centered cation radical. The changes observed in apparent molecular sites of protonation and of ion radical formation in the mass spectra are consistent with the electron-withdrawing effects of the sequentially added fluorines. These effects are correlated with changes in solution phase pK( a)'s of the fluorinated amines.

Fluorinated phospholipid-based vesicles as potential drug carriers: encapsulation/sustaining of drugs and stability in human serum

The release of entrapped 5(6)-carboxyfluorescein from fluorinated vesicles in a buffer or in human serum is considerably less than that from hydrogenated liposomes. The presence of a fluorinated core inside the liposomal membrane definitely reduces its permeability. In some cases, the stability of liposomes made from fluorinated phospholipids alone is better than that of egg phosphatidylcholine cholesterol 1/1 vesicles, which are among the least permeable and most stable hydrogenated liposomes.

Absorption of various fluorine compounds from the gastrointestinal tract of the rat

The absorption of variously bonded fluorine compounds from the gastrointestinal tract of the rat was determined. NaF, Na2SiF6, Na2PO3F and SnF2 were absorbed to the same extent (48%), whereas KPF6, EtNPF6 and KBF4 were absorbed to a significantly greater degree (74%). The results suggest that covalently held fluorine compounds are absorbed at a greater rate than the fluoride ion.