Effect of adhesive components in experimental fluoride varnish on fluoride release within 30 days in vitro study

We aimed to determine whether adhesive components could increase the release time of effective fluoride concentration from an experimental fluoride varnish applied to bovine teeth. An experimental fluoride varnish containing 5% sodium fluoride (EX1) was prepared and combined with 35% hydroxyethyl methacrylate (HEMA) (EX2), 5% glutaraldehyde (EX3), or 35% HEMA/5% glutaraldehyde mixture (EX4). Two commercially available fluoride varnishes were used for comparison. Each group was applied to bovine incisors, and the fluoride release and pH were monitored for 30 days. Cell viability analysis, scanning electron microscopy, and energy-dispersive spectroscopy were performed. EX4 released the highest and most effective concentration of fluoride for the longest period and reached neutral pH at the earliest; the release was maintained for up to 30 days without cytotoxicity. In conclusion, EX4 is considered to be the most effective varnish to prevent dental caries.

Fluoride release potential of arginine-incorporated fluoride varnishes

The study aimed to examine the fluoride (F) release potential of arginine (Arg)-incorporated F varnishes. Four commercially available F varnishes were included in the study: Duraphat® (5% NaF), Flúor Protector® (0.9% SiH2F2), Fluor Protector S® (NH4F), and Fluorimax™ (2.5% NaF). L-arginine (2% w/v.) was incorporated in these varnishes to estimate F release at 1 h, 4 h, 6 h, 24 h, 3 days, and 7 days using an F-ion selective electrode. The media pH of eluded varnishes was estimated and primary inorganic F extraction was performed. The main effects pH, F release, and computed integrated mean/cumulative F release for experimental groups were significantly higher than the controls (p<0.01). The primary extracted F concentrations for the Arg-containing groups were significantly lower than the control groups (p<0.001) demonstrating a chemical interplay with Arg incorporation. To conclude, irrespective of the inorganic F content, incorporating Arg in F-containing varnishes increases their F release potential.

Sodium fluoride preserves blood metabolite integrity for biomarker discovery in large-scale, multi-site metabolomics investigations

Background: Metabolite profiling of blood by nuclear magnetic resonance (NMR) is invaluable to clinical biomarker discovery. To ensure robustness, biomarkers require validation in large cohorts and across multiple centres. However, collection procedures are known to impact on the stability of biofluids that may, in turn, degrade biomarker signals. We trialled three blood collection tubes with the aim of solving technical challenges due to preanalytical variation in blood metabolite levels that are common in cohort studies. Methods: We first investigated global NMR-based metabolite variability between biobanks, including the large-scale UK Biobank and TwinsUK biobank of the general UK population, and more targeted biobanks derived from multicentre clinical trials relating to inflammatory bowel disease. We then compared the blood metabolome of 12 healthy adult volunteers when collected into either sodium fluoride/potassium oxalate, lithium heparin, or serum blood tubes using different pre-processing parameters. Results: Preanalytical variation in the method of blood collection strongly influences metabolite composition within and between biobanks. This variability can largely be attributed to glucose and lactate. In the healthy control cohort, the fluoride oxalate collection tube prevented fluctuation in glucose and lactate levels for 24 hours at either 4 °C or room temperature (20 °C). Conclusions: Blood collection into a fluoride oxalate collection tube appears to preserve the blood metabolome with delayed processing up to 24 hours at 4 °C. This method may be considered as an alternative when rapid processing is not feasible.

Impact of pH-adjusted fluoride and stannous solutions on the protective properties on the pellicle layer in vitro and in situ

This study evaluates the ideal pH for anti-erosion and anti-adherent efficacy of fluoride and stannous solutions (sodium fluoride (SF), amine fluoride (AF), sodium monofluorophosphate (SMFP), stannous fluoride (SnF2) with 500 ppm fluoride concentration each and stannous chloride (SnCl2, 1563 ppm stannous)). In vitro, solutions were tested at pH 4.5 and 5.5. The main in situ experiments were carried out at the pH of 4.5: For pellicle formation 6 volunteers wore bovine enamel slabs intraorally for 1 min, rinsed with 8 ml solution for 1 min and continued for up to 30 min/8 h. Physiological pellicle samples served as controls. After incubation in HCl (2.0, 2.3) for 2 min mineral release was determined photometrically. Bacterial counts on 8 h biofilms were determined by fluorescence microscopy (BacLight™ and DAPI with Concanavalin A). Modification of the pellicle ultrastructure was examined by TEM. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney-U tests with Bonferroni-correction (p < 0.05). SnF2 showed a significant erosion protection. AF, SnF2, and SnCl2 were most anti-adherent. SnF2 and SnCl2 caused a pronounced basal pellicle with stannous precipitates. Compared to other fluoride monosubstances, stannous ions offer greater protection against erosive acidic attacks. Stannous ions act as crucial co-factor in this process.

Effect of arginine-fluoride varnish on preventing enamel erosion by paediatric liquid medicaments

BACKGROUND

The study objective was to examine the effect of arginine-sodium fluoride (Arg-NaF) varnish on preventing enamel erosion by acidic paediatric liquid medicaments (PLM).

METHODS

The treatment groups were: 1) 2% Arg-NaF; 2) 4% Arg-NaF; 3) 8% Arg-NaF; 4) NaF; 5) MI (CPP-ACFP) varnishes; and 6) no varnish. The pH of PLM (paracetamol and chlorpheniramine) was measured at baseline and after immersing the Perspex® blocks coated with varnishes at 0 min, 30 min, 1 h, and 4 h. Seventy-two enamel specimens (n = 72) were randomly divided into 2 groups by PLM and further by treatment groups. Then, the specimens were pre-treated with varnishes and subjected to erosive cycles (5 min, 2×/day for 4 days) by PLM. After each erosive challenge, the specimens were stored in artificial saliva. At baseline and after 4 days, the specimens were assessed for surface roughness (Ra) using 2D-surface profilometric analysis (SPA) and atomic force microscopy (AFM). Additionally, the Ca/P ratio was determined using scanning electron microscopy with energy-dispersive X-ray spectroscopy. Paired samples dependent t-test, 1-way ANOVA and 2-way ANOVA with Bonferroni post-hoc tests were used to analyse data with the level of significance set at p < 0.05.

RESULTS

The pH of PLM with 8% Arg-NaF was significantly higher than the other groups at 30 min and 4 h (p < 0.05). With paracetamol, no significant difference was observed between the baseline and post-erosive cycle measured enamel Ra (by SPA/AFM) and Ca/P ratio for all treatment groups (p > 0.05). The Ra determined by AFM, at the post-erosive cycle with chlorpheniramine, when treated with 4 and 8% Arg-NaF was significantly lower than the other groups (p < 0.05); except CPP-ACFP (p > 0.05). With the chlorpheniramine post-erosive cycle, the Ca/P ratio for 4, 8% Arg-NaF and CPP-ACFP treated specimens was significantly higher than the baseline Ca/P (p < 0.05).

CONCLUSION

The 4%/8% Arg-NaF and MI varnish® application exhibit an enhanced preventive effect against low pH (pH < 3.0) PLM-mediated enamel erosive challenges compared to 5% NaF varnish.

Film-Forming Polymers for Inhibition of Hydroxyapatite Dissolution: A Screening Study

The aim of this study was to evaluate the effect of film-forming polymer solutions of different concentrations and pH values, either associated or not with sodium fluoride (F; 225 ppm F-), when applied during the initial stage of salivary pellicle formation, to prevent the dissolution of hydroxyapatite (HA), which was determined by the pH-stat method. Polyacrylic acid (PA), chitosan, sodium linear polyphosphate (LPP), polyvinyl methyl ether/maleic anhydride (PVM/MA), and propylene glycol alginate (PGA) were tested in three concentrations (lower, medium, and higher), two pH values (native or adjusted), and either associated or not with F. Distilled water, F, and stannous ion+fluoride (Sn/F; 225 ppm F- and 800 ppm Sn2+, as SnCl2) solutions were the controls, totalizing 63 groups. HA crystals were pretreated with human saliva for 1 min to allow pellicle formation, then immersed in the experimental solutions (1 min), and exposed to saliva for another 28 min. Subsequently, they were added to a 0.3% citric acid solution (pH = 3.8), connected to a pH-stat system that added aliquots of 28 μL 0.1 N HCl for a total reaction time of 5 min. Data were analyzed with one-way ANOVA and Tukey's tests (α = 0.05). For PA alone, the concentrations of 0.1% (native pH), 0.06%, and 0.08% (both pH adjusted) showed significantly lower HA dissolution than the negative control. PA concentrations of 0.1% and 0.08%, of both pH values, improved the effect of F against HA dissolution to a near-identical value as Sn/F. All solutions containing chitosan and LPP significantly reduced HA dissolution in comparison with the control. For chitosan, the concentration of 0.5% (in both pH values) improved the effect of F. LPP at 0.5% (native pH) and all associations of LPP with F outperformed the effect of F. Some PVM/MA solutions significantly reduced HA dissolution but PVM/MA could not improve the protection of F. PGA was incapable of reducing HA dissolution or improving F effect. It was concluded that chitosan, LPP, and some PA and PVM/MA solutions used alone were capable of reducing HA dissolution. Only PA, chitosan, and LPP were able to enhance fluoride protection, but for PA and chitosan, this was influenced by the polymer concentration.

Review on fluoride varnishes currently recommended in dental prophylaxis

In dentistry, fluoride compounds play a very important role in the development of teeth hard tissue. They have been modifying the development of the carious process for many years in accordance with the principles of minimally invasive therapy. Studies have confirmed their effectiveness in the prevention and treatment of carious lesions and erosion of deciduous and permanent teeth, as well as in the dentin hypersensitivity treatment. Typically, each varnish consists of 3 basic components, i.e., a resin usually in the form of mastic, shellac and/or rosin, an alcohol-based organic solvent (usually ethanol) and active agents. In the first-generation varnishes, the active agent is fluorine compounds, most often in the form of 5% NaF, while in second-generation varnishes, the composition is further enriched with calcium and phosphorus compounds in the form of CPP-ACP/CPP-ACPF, ACP, TCP, fTCP, CSPS, TMP, CXP, or CaGP. This influences the bioavailability of fluoride in the oral environment by increasing both its release from the product and its subsequent accumulation in enamel and plaque, promotes more efficient closure of dentinal tubules, and facilitates pH buffering in the oral cavity.

Enamel Fluoride Uptake Determined Using the Microbiopsy Technique and Time-of-Flight Secondary Ion Mass Spectrometry: A Pilot Study

This study evaluated the suitability of time-of-flight secondary ion mass spectrometry (ToF-SIMS) to assess enamel fluoride uptake (EFU) in comparison with the microbiopsy technique. Enamel specimens were exposed to equimolar solutions of fluoride prepared from sodium fluoride (NaF), stannous fluoride (SnF2), or amine fluoride (AmF). EFU was quantified by both techniques on the same specimens. EFU was found to be highest for samples treated with AmF, followed by SnF2 and NaF. Both methods yielded clearly interpretable, highly correlating (r = 0.95) data. ToF-SIMS can be considered a promising alternative to the microbiopsy technique for near-surface EFU assessment.

Clinical doses production of pharmaceutical grade Sodium[18F]Fluoride using modified integrated fluidic processor in a SYNTHERA® module

A fully automated large-scale production of sodium [¹⁸F]fluoride ([¹⁸F]NaF) using SYNTHERA module with a modification in integrated fluidic processor (IFP) is reported. This modified IFP module is used to prepare [¹⁸F]NaF with more than 98% non-decay corrected radiochemical yield (RCY) within 5 min with specifications in accordance with United State Pharmacopeia (USP) monograph. The graphical user interface (GUI) is designed to perform the synthesis steps either manually or automatically and give information to the operator during the course of production. The desired clinical results add support to indigenously produced [¹⁸F]NaF as a pharmaceutical grade diagnostic radiopharmaceutical.

Electrochemical Performance of Na3V2(PO4)2F3 Electrode Material in a Symmetric Cell

A NASICON-based Na3V2(PO4)2F3 (NVPF) cathode material is reported herein as a potential symmetric cell electrode material. The symmetric cell was active from 0 to 3.5 V and showed a capacity of 85 mAh/g at 0.1 C. With cycling, the NVPF symmetric cell showed a very long and stable cycle life, having a capacity retention of 61% after 1000 cycles at 1 C. The diffusion coefficient calculated from cyclic voltammetry (CV) and the galvanostatic intermittent titration technique (GITT) was found to be ~10-9-10-11, suggesting a smooth diffusion of Na+ in the NVPF symmetric cell. The electrochemical impedance spectroscopy (EIS) carried out during cycling showed increases in bulk resistance, solid electrolyte interphase (SEI) resistance, and charge transfer resistance with the number of cycles, explaining the origin of capacity fade in the NVPF symmetric cell. Finally, the postmortem analysis of the symmetric cell after 1000 cycles at a 1 C rate indicated that the intercalation/de-intercalation of sodium into/from the host structure occurred without any major structural destabilization in both the cathode and anode. However, there was slight distortion in the cathode structure observed, which resulted in capacity loss of the symmetric cell. The promising electrochemical performance of NVPF in the symmetric cell makes it attractive for developing long-life and cost-effective batteries.

Recent Development of Active Ingredients in Mouthwashes and Toothpastes for Periodontal Diseases

Periodontal diseases like gingivitis and periodontitis are primarily caused by dental plaque. Several antiplaque and anti-microbial agents have been successfully incorporated into toothpastes and mouthwashes to control plaque biofilms and to prevent and treat gingivitis and periodontitis. The aim of this article was to review recent developments in the antiplaque, anti-gingivitis, and anti-periodontitis properties of some common compounds in toothpastes and mouthwashes by evaluating basic and clinical studies, especially the ones published in the past five years. The common active ingredients in toothpastes and mouthwashes included in this review are chlorhexidine, cetylpyridinium chloride, sodium fluoride, stannous fluoride, stannous chloride, zinc oxide, zinc chloride, and two herbs—licorice and curcumin. We believe this comprehensive review will provide useful up-to-date information for dental care professionals and the general public regarding the major oral care products on the market that are in daily use.

Transparent soil microcosms for live-cell imaging and non-destructive stable isotope probing of soil microorganisms

Microscale processes are critically important to soil ecology and biogeochemistry yet are difficult to study due to soil's opacity and complexity. To advance the study of soil processes, we constructed transparent soil microcosms that enable the visualization of microbes via fluorescence microscopy and the non-destructive measurement of microbial activity and carbon uptake in situ via Raman microspectroscopy. We assessed the polymer Nafion and the crystal cryolite as optically transparent soil substrates. We demonstrated that both substrates enable the growth, maintenance, and visualization of microbial cells in three dimensions over time, and are compatible with stable isotope probing using Raman. We applied this system to ascertain that after a dry-down/rewetting cycle, bacteria on and near dead fungal hyphae were more metabolically active than those far from hyphae. These data underscore the impact fungi have facilitating bacterial survival in fluctuating conditions and how these microcosms can yield insights into microscale microbial activities.

Evolution of heterotopic bone in fibrodysplasia ossificans progressiva: An [18F]NaF PET/CT study

Fibrodysplasia ossificans progressiva (FOP) is a rare, autosomal dominant disorder characterized by heterotopic ossification (HO) in muscles, ligaments and tendons. Flare-ups often precede the formation of HO, resulting in immobilization of joints. Due to progression of the disease without signs of a flare-up, co-existence of a chronic progression of HO has been postulated, but conclusive evidence is lacking. Recently, it has been shown that [¹⁸F]NaF PET/CT is able to identify early ossifying disease activity during flare-ups. Therefore, the purpose of the present study was to assess whether [¹⁸F]NaF PET/CT might also be able to identify the possible presence of chronic progressive HO in FOP. A total of thirteen [¹⁸F]NaF PET/CT scans from five FOP patients were analysed. Scans were acquired over a period of 0.5 to 2 years. Volumes of HO and standardized uptake values (SUV) were obtained based on manual segmentation of CT images. SUV_peak values, defined as the average SUV value of a 1 mL sphere containing the hottest voxel pixels, were obtained. Two out of five patients experienced ≥1 active clinical flare-ups at the time of the [¹⁸F]NaF PET/CT scan. In addition, in four out of five patients, serial scans showed radiological progression of HO (3 to 8 cm³), as assessed by CT volume, in the absence of a clinical flare-up. This volumetric increase was present in 6/47 (12.8%) of identified HO structures and, in all cases, was accompanied by increased [¹⁸F]NaF uptake, with SUV_peak ranging from 8.4 to 17.9. In conclusion, HO may progress without signs of a flare-up. [¹⁸F]NaF PET/CT is able to identify these asymptomatic, but progressive HO lesions, thereby demonstrating the presence of chronic activity in FOP. Consequently, future drugs should not only target new HO formation, but also this chronic HO progression.

Comparison of 18F-NaF PET/CT and 18F-FDG PET/CT for Detection of Skull-Base Invasion and Osseous Metastases in Nasopharyngeal Carcinoma

Our study aimed at comparing the diagnostic value of 18F-NaF positron emission tomography-computed tomography (PET/CT) and 18F-fluorodeoxyglucose (FDG) PET/CT for detection of skull-base invasion and osseous metastases in patients with nasopharyngeal carcinoma (NPC). Our study retrospectively analyzed 45 patients with pathologically proven NPC. They all underwent both 18F-NaF PET/CT and 18F-FDG PET/CT within a 7-day interval. Bone metastases were confirmed by follow-up using PET/CT, enhance-contrast computed tomography (CT), and magnetic resonance image (MRI). These two examinations were compared using per-patient-based analysis and per-lesion-based analysis. 18F-NaF PET/CT detected 27 patients with skull-base invasion, whereas 18F-FDG PET/CT detected 17 patients. 18F-NaF PET/CT and 18F-FDG PET/CT differed significantly in diagnosing skull-base invasion (p=0.02) and sensitivity (p=0.008). The sensitivity, specificity, and agreement rate of 18F-NaF PET/CT for detecting bone metastatic lesions were 98.3%, 65.7%, and 92.9%, respectively; these values were 42.9%, 97.1%, and 51.9%, respectively, for 18F-FDG PET/CT. 18F-NaF PET/CT and 18F-FDG PET/CT differed significantly in the number of osseous metastases detected (t=2.45, p=0.18) sensitivity (p < 0.0001) and specificity (p=0.003). In patients with nasopharyngeal carcinoma, 18F-NaF PET/CT assessed invasion of the skull base better and detected more osseous metastases than 18F-FDG PET/CT.

Proteomic identification of sperm from mice exposed to sodium fluoride

Fluoride is a widespread environmental pollutant which can induce low sperm quality and fertilizing ability. However, effect of fluoride on proteomic changes of sperm is unknown. In this study, two-dimensional electrophoresis (2DE) and mass spectrometry (MS) were used to investigate the differently expressed proteins of sperm from mice exposed to fluoride. 180 male mice were randomly divided into three groups, and were administrated with the distilled water containing 0, 25, and 100 mg L^-1 NaF, respectively. After 45, 90 and 180 day's exposure, mice were sacrificed and sperm from the cauda epididymis and vas deferens were collected for 2DE. 16 differently expressed spots were picked up to identify using MS, 15 of which were successfully identified. Many of them are associated with the sperm function such as sperm motility, maturation, capacitation and acrosome reaction, lipid peroxidation, detoxification, inflammation, and stability of membrane structure. These results could contribute to the explanation and further research of mechanisms underlying sperm damage induced by fluoride.

Blood Glucose Determination: Effect of Tube Additives

The measurement of fasting plasma glucose may be biased by a time-dependent decrease of glucose in blood tubes, mainly attributable to blood cell metabolism when glycolysis is not rapidly inhibited or blood cells cannot be rapidly separated from plasma. Although glycolysis inhibitors such as sodium fluoride (NaF) in combination with potassium oxalate (KOx) are currently used for overcoming this drawback, their efficacy for stabilizing blood glucose is seemingly limited, and probably lower than that of newer additives such as the citrate buffer. Therefore, we performed a critical analysis of the current scientific literature aimed to generate evidence-based information about the advantages of using citrate buffer in blood tubes compared to the more conventional NaF additive. The results of our systematic overview of the literature show that citrate blood tubes represent a considerable step forward in achieving more accurate and reliable plasma glucose measurements, thereby limiting the risk of underdiagnosing diabetes due to spurious decrease of glucose concentration in uncentrifuged blood specimens, ensuring higher stability of glucose levels over time, while simultaneously producing less hemolysis compared to NaF blood tubes. Therefore, we suggest that the use of this new mixture should be encouraged for achieving a higher degree of accuracy and standardization of plasma glucose measurements.

Rapid Mechanistic Evaluation and Parameter Estimation of Putative Inhibitors in a Single-Step Progress-Curve Analysis: The Case of Horse Butyrylcholinesterase

Highly efficient and rapid lead compound evaluation for estimation of inhibition parameters and type of inhibition is proposed. This is based on a single progress-curve measurement in the presence of each candidate compound, followed by the simultaneous analysis of all of these curves using the ENZO enzyme kinetics suite, which can be implemented as a web application. In the first step, all of the candidate ligands are tested as competitive inhibitors. Where the theoretical curves do not correspond to the experimental data, minimal additional measurements are added, with subsequent processing according to modified reaction mechanisms.

The Effect of Fluoride Varnish on Enamel Shear Bond Strength of Pit and Fissure Sealants

PURPOSE

The purpose of this study was to determine the effects of fluoride varnish on the enamel shear bond strength of pit and fissure sealants.

METHODS

Ninety-six teeth were divided into three duplicated test groups: sealant (S)/sealant thermocycle (ST) received Clinpro Sealant only; varnish sealant (VS)/varnish sealant thermocycle (VST) received five percent sodium fluoride (NaF) varnish plus sealant (VPS); and VPS/VPS thermocycle (VPST) received NaF, polish with Clinpro Prophy Paste, plus sealant. One set of each group (ST, VST, VPST) was thermocycled to represent aging, and one set (S, VS, PVS) was not. The shear bond strengths for the thermocycled groups and nonthermocycled groups were determined, and two-way analysis of variance tested the effects of thermocycling and varnish.

RESULTS

Thermocycling did not have a significant effect on the peak stresses of the groups (P=0.0552), so sets were combined. The peak stress for S/ST was significantly higher than for VS/VST (P<0.0001). The peak stress for VPS/VPST was significantly higher than for VS/VST (P<0.0001). The peak stress for S/ST was significantly higher than VPS/VPST (P=0.025).

CONCLUSION

Fluoride varnish applied immediately before pit and fissure sealant placement negatively affected the shear bond strength of the sealant. Mechanically cleaning a fluoride varnish-coated tooth with prophy paste did not provide pit and fissure sealant enamel shear bond strengths comparable to those of untreated enamel.

Candida albicans survival, growth and biofilm formation are differently affected by mouthwashes: an in vitro study

Candida albicans is the most common cause of oral mycoses. The aim of the present study was to investigate in vitro the susceptibility of C. albicans to mouthwashes, in terms of growth, survival and biofilm formation. Candida albicans, laboratory strain SC5314, and 7 commercial mouthwashes were employed: 3 with 0.2% chlorhexidine digluconate; 1 with 0.06% chlorhexidine digluconate and 250 ppm F- sodium fluoride; 3 with fluorine-containing molecules. None of the mouthwashes contained ethanol in their formulations. The anti-Candida effects of the mouthwashes were assessed by disk diffusion, crystal violet and XTT assays. By using five protocols combining different dilutions and contact times the mouthwashes were tested against: 1) C. albicans growth; 2) biofilm formation; 3) survival of fungal cells in early, developing and mature Candida biofilm. Chlorhexidine digluconate-containing mouthwashes consistently exhibited the highest anti-Candida activity, irrespective of the protocols employed. Fungal growth, biofilm formation and survival of Candida cells within biofilm were impaired, the effects strictly depending on both the dilution employed and the time of contact. These in vitro studies provide evidence that mouthwashes exert anti-Candida activity against both planktonic and biofilm fungal structures, but to a different extent depending on their composition. This suggests special caution in the choice of mouthwashes for oral hygiene, whether aimed at prevention or treatment of oral candidiasis.

Kinetic and isotherm studies on adsorption of fluoride by limonite with batch technique

Fluoride in drinking water has an intense effect on bones and teeth. The concentration of fluoride >1.5 mg l-1 in drinking water is harmful for human health. In the present study the naturally occurring geomaterial limonite (Iron Ore) has been used as the adsorbent for the investigation of defluoridation capacity by Batch adsorption technique in aqueous condition. Various parameters such as contact time, adsorbent dose, adsorbate concentration, adsorbent particle size and agitation speed at room temperature (298K) and pH (7?0.3), has been optimization for the adsorption of F- onto limonite. The initial rate of the adsorption was very fast and after 120 minutes it attained equilibrium. Three known Isotherm Models (Langmuir, Freundlich and Temkin) used to study the mechanism and nature of adsorption onto the surface of limonite. The experimental results are best fitted into the Langmuir and Temkin isotherm models (R2> 0.99). The average monolayer adsorption capacity (Qm) obtained for limonite is 0.269 mg g-1. The experimental data highlights that surface sites of adsorbent (limonite) are heterogeneous in nature and fits into a heterogeneous site binding model. The kinetic study revealed that the adsorption process followed Pseudo 2nd order model. The removal efficiency of limonite for the naturally high F- water sample (4.12 mg l-1) under optimized condition obtained 66.9%. The maximum adsorption capacity Qe (F- adsorbed) at equilibrium is calculated 2.208 mg g-1. The isotherm and kinetic studies reveal that limonite can be used as an adsorbent for fluoride removal. The OH-group of limonite acts as ion exchange with F- ion confirm by Fourier Transmission-IR spectroscopy analysis (FT-IR). XRD (X-ray Refraction Dispersive) peaks also give good evidence of surface adsorption onto limonite and surface morphology by Scanning electron microscopy (SEM) image. In the future we can use this technology for fluoride removal in large scale by using limonite which is cost-effective, eco-friendly, minimal processing and easily available in the study area.

Imaging Chronic Tuberculous Lesions Using Sodium [(18)F]Fluoride Positron Emission Tomography in Mice

PURPOSE

Calcification is a hallmark of chronic tuberculosis (TB) in humans, often noted years to decades (after the initial infection) on chest radiography, but not visualized well with traditional positron emission tomography (PET). We hypothesized that sodium [(18)F]fluoride (Na[(18)F]F) PET could be used to detect microcalcifications in a chronically Mycobacterium tuberculosis-infected murine model.

PROCEDURES

C3HeB/FeJ mice, which develop necrotic and hypoxic TB lesions, were aerosol-infected with M. tuberculosis and imaged with Na[(18)F]F PET.

RESULTS

Pulmonary TB lesions from chronically infected mice demonstrated significantly higher Na[(18)F]F uptake compared with acutely infected or uninfected animals (P < 0.01), while no differences were noted in the blood or bone compartments (P > 0.08). Ex vivo biodistribution studies confirmed the imaging findings, and tissue histology demonstrated microcalcifications in TB lesions from chronically infected mice, which has not been demonstrated previously in a murine model.

CONCLUSION

Na[(18)F]F PET can be used for the detection of chronic TB lesions and could prove to be a useful noninvasive biomarker for TB studies.

Which sample tube should be used for routine glucose determination?

BACKGROUND

Glucose is one of the most frequently requested analytes in clinical laboratory. Blood glucose analysis is affected from in vitro glycolysis. In order to determine the most suitable blood collection tube for this purpose we have compared different tubes: sodium fluoride, lithium heparin, sodium fluoride/citrate buffer containing tubes and serum with clot activator tube for the measurement of glucose when the tube has been kept at room temperature (RT) for up to 4h.

METHODS

Venous blood was collected from 49 healthy volunteers into Sarstedt S-Monovettes for glucose analysis. Reference plasma glucose was determined in a lithium heparin tube and immediately placed in an ice/water slurry. Within 10min it was centrifuged at 4°C and plasma was separated from the blood cells. Samples have been preserved at RT for 1, 2 and 4h after drawing. Glucose has been determined using a hexokinase method.

RESULTS

Glucose levels tested in a serum with clot activator tube, in lithium heparin and in sodium fluoride/sodium EDTA tubes when compared with lithium-heparin reference plasma did not meet the desirable bias for glucose (±1.8%) when kept at RT for up to 4h. GlucoEXACT tubes, when corrected by the Sarsted recommended factor of 1.16, showed a mean (95% CI) bias of +0.96% (0.45-1.47) at 1h, +1.40% (0.88-1.93) at 2h and +0.95% (0.44-1.46) at 4h, reaching the analytical goal for the desirable bias.

CONCLUSIONS

Samples collected into GlucoEXACT tubes containing sodium fluoride/citrate buffer liquid mixture are equivalent to those collected in reference plasma tubes avoiding glycolysis completely and within a 4h delay in plasma separation.

[Fluorescent Indices of Bean Leaves Treated with Sodium Fluoride]

It is shown that the treatment of bean leaves with NaF in concentration of 10(-2) M resulted in the alteration of fluorescent indices registered by the method of pulse fluorimetry. Fluorescent parameters F(0) and F(m) decreased, but the ratio F(v)/F(m) = (F(m) - F(0))/F(m), characterizing the maximal photochemical activity of photosystem II remained invariable. Photochemical fluorescence quenching (qP) was higher than in control during the first minutes of illumination with the actinic light, and it markedly decreased with the following illumination. Nonphotochemical quenching (qN), in contrary, decreased at the beginning of illumination, and then increased. Photosynthetic activity as characterizing by the ratio (F(M) - F(T))/F(T) reduced after the leaf treatment with NaF. Results obtained are interpreted proceeding, on the one hand, from the influence of NaF on redistribution of excitation energy between photosystem II and photosystem I and its inhibitory effect on the ATPase complex and Kalvin-Benson cycle, on the other.

Identifying active vascular microcalcification by (18)F-sodium fluoride positron emission tomography

Vascular calcification is a complex biological process that is a hallmark of atherosclerosis. While macrocalcification confers plaque stability, microcalcification is a key feature of high-risk atheroma and is associated with increased morbidity and mortality. Positron emission tomography and X-ray computed tomography (PET/CT) imaging of atherosclerosis using (18)F-sodium fluoride ((18)F-NaF) has the potential to identify pathologically high-risk nascent microcalcification. However, the precise molecular mechanism of (18)F-NaF vascular uptake is still unknown. Here we use electron microscopy, autoradiography, histology and preclinical and clinical PET/CT to analyse (18)F-NaF binding. We show that (18)F-NaF adsorbs to calcified deposits within plaque with high affinity and is selective and specific. (18)F-NaF PET/CT imaging can distinguish between areas of macro- and microcalcification. This is the only currently available clinical imaging platform that can non-invasively detect microcalcification in active unstable atherosclerosis. The use of (18)F-NaF may foster new approaches to developing treatments for vascular calcification.

Fluoride Varnishes--Is There a Correlation Between Fluoride Release and Deposition on Enamel?

PURPOSE

Fluoride uptake of enamel after application of fluoride varnishes was compared with fluoride release into artificial saliva. The hypothesis was that fluoride uptake is higher for products exhibiting faster fluoride release.

MATERIALS AND METHODS

Fluoride varnishes, i.e. Fluor Protector S, Duraphat, MI Varnish, Clinpro White Varnish, Profluorid Varnish and Enamel Pro Varnish were applied on bovine enamel specimens. Subsequently, specimens were incubated in artificial saliva. After removal of the varnishes, surface bound fluoride was extracted with potassium hydroxide and measured with an ion-selective electrode. Structurally bound fluoride was etched from the same specimens with perchloric acid. Fluoride release of varnish films into artificial saliva was measured for comparison.

RESULTS

After 4 h in artificial saliva, the highest total enamel fluoride uptake of 47.9 μg F·cm-² was found with Fluor Protector S, followed by Enamel Pro Varnish with 22.1 μg F·cm-². The other products ranged between 12-16 μg F·cm-². This was several times higher than the negative control. Fluoride uptake did not correlate with release into artificial saliva. During the first 4 h, Duraphat released the lowest and MI Varnish the highest amount of fluoride with 7.7 and 249 μg F·cm-², respectively. The fluoride uptake of these two products was not statistically different.

CONCLUSION

Enamel fluoride uptake cannot be predicted from the fluoride release rate of a product. Hence, based on the results of this study, fluoride release into artificial saliva is no measure for the efficacy of a fluoride varnish.

Fluoride Affects Calcium Homeostasis by Regulating Parathyroid Hormone, PTH-Related Peptide, and Calcium-Sensing Receptor Expression

Parathyroid hormone (PTH), PTH-related peptide (PTHrP), and calcium-sensing receptor (CaSR) play important roles in maintaining calcium homeostasis. Here, we study the effect of fluoride on expression of PTH, PTHrP, and CaSR both in vitro and in vivo. MC3T3-E1 cells and Sprague-Dawley rats were treated with different concentrations of fluoride. Then, the free calcium ion concentration in cell culture supernatant and serum were measured by biochemical analyzer. The expression of PTH, PTHrP, and CaSR was analyzed by qRT-PCR and Western blot. We found that the low dose of fluoride increased ionized calcium (i[Ca(2+)]) and the high dose of fluoride decreased i[Ca(2+)] in cell culture supernatant. The low dose of fluoride inhibited the PTH and PTHrP expression in MC3T3-E1 cells. The high dose of fluoride improved the PTHrP expression in MC3T3-E1 cells. Interestingly, we found that NaF decreased serum i[Ca(2+)] in rats. Fluoride increased CaSR expression at both messenger RNA (mRNA) and protein levels in MC3T3-E1 cells and rats. The expression of PTHrP protein was inhibited by fluoride in rats fed regular diet and was increased by fluoride in rats fed low-calcium diet. Fluoride also increased the expression of PTH, NF-kappaB ligand (RANKL), and osteoprotegerin (OPG) in rats. The ratio of RANKL/OPG in rats fed low-calcium food in presence or absence of fluoride was significantly increased. These results indicated that fluoride might be able to affect calcium homeostasis by regulating PTH, PTHrP, and CaSR.

Influence of various fluoride agents on working properties and surface characteristics of uncoated, rhodium coated and nitrified nickel-titanium orthodontic wires

OBJECTIVE

To analyze the effect of various fluoride formulations in commercially available agents on working properties of various nickel-titanium orthodontic wires.

MATERIALS AND METHODS

Uncoated (NiTi), rhodium coated (RhNiTi) and nitrified (NNiTi) wires were immersed to dH2O, MiPaste, Elmex and Mirafluor for 1 h. Unloading slope characteristics (average force, bending action of the force and average plateau length) and the percentage of useable constant force during unloading were observed. Surface roughness (Ra) was measured. SEM and EDS were used for observation of the surface.

RESULTS

NiTi had decreased loading and unloading elastic modulus (E) and yield strength (YS) after immersion to MIPaste and Mirafluor. The unloading YS decreased in the RhNiTi by the MIPaste. The loading and unloading YS of the NNiTi increased in Elmex and increased average plateau force. RhNiTi showed higher average plateau length and the percentage of useful constant force during unloading in Mirafluor and the average plateau force lowered after immersion to MIPaste. The unloading slope characteristics for NiTi were affected by all three prophylactic agents, mostly by Mirafluor, and produced significantly lower forces during both loading and unloading, similarly to the NNiTi wires. The RhNiTi had the lowest forces during both loading and unloading in MIPaste. All results were at significance; p<0.05. Difference in Ra was observed for RhNiTi after immersion to the MI Paste (p<0.001; η2=0.761).

CONCLUSION

The NiTi and NNiTi wires lose less working force when combined with Elmex. The RhNiTi improve their working properties with Mirafluor and deteriorate when combined with MiPaste.

Effects of different pre-treatment methods on the shear bond strength of orthodontic brackets to demineralized enamel

OBJECTIVE

To compare the effects of different treatment methods used for the enamel damage, on the shear bond strength (SBS) and fracture mode of orthodontic brackets.

MATERIALS AND METHODS

Freshly-extracted 140 premolars were randomly allocated to seven groups: Group I was considered as the control of other groups. The remaining groups were exposed to demineralization. In group II, brackets were directly bonded to the demineralized enamel surface. CPP-ACP paste (GC Tooth Mousse), fluoride varnish (Bifluorid 12), microabrasion with a mixture prepared with 18% hydrochloric acid and fine pumice powder, microabrasion with an agent (Opalustre) and resin infiltrant (Icon®) were applied in Groups III, IV, V, VI and VII, respectively. The specimens were tested for SBS and bond failures were scored according to the Adhesive Remnant Index (ARI). Analysis of variance and Tukey tests were used to compare the SBS of the groups. ARI scores were compared with G-test. The statistical significance was set at p < 0.05 level.

RESULTS

Statistically significant differences were found among seven groups (F = 191.697; p < 0.001). The SBSs of groups I (mean = 18.8 ± 2.0 MPa) and VII (mean = 19.1 ± 1.4 MPa) were significantly higher than the other groups. No statistically significant difference was found between groups IV (mean = 11.5 ± 1.2 MPa) and V (mean = 12.6 ± 1.5 MPa). The differences in ARI scores of the groups were statistically significant (p < 0.01).

CONCLUSIONS

All demineralization treatment methods improve bonding to demineralized enamel. Resin infiltrant application after demineralization showed similar bond strength values as intact enamel.

Effect of halide salts on development of surface browning on fresh-cut 'Granny Smith' (Malus × domestica Borkh) apple slices during storage at low temperature

BACKGROUND

The postharvest life of fresh-cut apple slices is limited by browning on cut surfaces. Dipping in halide salt solutions was examined for their inhibition of surface browning on 'Granny Smith' apple slices and the effects on biochemical factors associated with browning.

RESULTS

Delay in browning by salts was greatest with chloride = phosphate > sulfate > nitrate with no difference between sodium, potassium and calcium ions. The effectiveness of sodium halides on browning was fluoride > chloride = bromide > iodide = control. Polyphenol oxidase (PPO) activity of tissue extracted from chloride- and fluoride-treated slices was not different to control but when added into the assay solution, NaF > NaCl both showed lower PPO activity at pH 3-5 compared to control buffer. The level of polyphenols in treated slices was NaF > NaCl > control. Addition of chlorogenic acid to slices enhanced browning but NaCl and NaF counteracted this effect. There was no effect of either halide salt on respiration, ethylene production, ion leakage, and antioxidant activity.

CONCLUSION

Dipping apple slices in NaCl is a low cost treatment with few impediments to commercial use and could be a replacement for other anti-browning additives. The mode of action of NaCl and NaF is through decreasing PPO activity resulting in reduced oxidation of polyphenols.

Exploratory Randomized Clinical Trial of an Experimental Gel-to-Foam Fluoride Dentifrice Formulation Using an In Situ Caries Model

OBJECTIVE

To evaluate the in situ caries performance and safety of two experimental fluoride dentifrice formulations (1450 ppm fluoride) with and without 2% isopentane as an excipient, in comparison to a positive control, currently marketed dentifrice (1450 ppm fluoride) and a negative control dentifrice (0 ppm fluoride).

METHODS

This was a single-center, examiner-blind, randomized, controlled, four-treatment cross-over study. During each treatment period, the subject wore a modified mandibular partial denture fitted with two gauze-covered, partially demineralized human enamel specimens, and brushed at home for one timed minute, twice daily, for two weeks. At the end of each treatment period, the enamel specimens were removed from the dentures for analysis. During the week between treatment periods, subjects returned to their usual dental hygiene practices for four to five days, received a dental prophylaxis, and used a study-designated non-fluoride dentifrice for two to three days before starting the next treatment. Treatment effect on enamel specimen remineralization was assessed by surface microhardness (SMH). Enamel fluoride uptake was assessed using microdrill enamel biopsy.

RESULTS

All fluoride-containing dentifrices demonstrated significant, superior SMH recovery and levels of fluoride uptake compared to the negative control dentifrice. No significant differences were observed for either efficacy variable between the experimental dentifrice formulations and the positive control dentifrice. No significant difference was observed between the 2% isopentane dentifrice and the 0% isopentane dentifrice for SMH recovery.

CONCLUSION

The addition of 2% isopentane did not positively or negatively affect fluoride efficacy in this model.

Influence of the Relative Enamel Abrasivity (REA) of Toothpastes on the Uptake of KOH-soluble and Structurally Bound Fluoride

PURPOSE

To determine the influence of the relative enamel abrasivity (REA) of fluoridated toothpaste on the uptake of KOH-soluble and structurally bound fluoride into enamel.

MATERIALS AND METHODS

Bovine enamel samples were randomly allocated to 6 groups (n=36 per group). Groups A to C were treated with sodium fluoride (NaF) toothpastes and groups D to F with amine fluoride (AmF) toothpastes (1500 ppm F each). The REA in groups A and D was 2, in groups B and E it was 6 and in groups C and F it was 9. Twice a day, 18 samples of each group were immersed for 2 min in a slurry (toothpaste:artificial saliva=1:3), while the remaining samples were brushed with the respective slurry (2.5 N force; 60 strokes/min; 2 min). All samples were stored at 37°C and 100% humidity. After five days, the amount of KOH-soluble and structurally bound fluoride was determined and statistically compared by Scheffe's post-hoc tests.

RESULTS

REA value and mode of application (immersion or brushing) had no significant influence on the amount of either kind of fluoride from NaF toothpastes. Only for the NaF toothpaste with REA 6 was the amount of KOH-soluble fluoride significantly higher after brushing. With AmF toothpastes, KOH-soluble and structurally bound fluoride concentrations were significantly higher when the samples were brushed. Furthermore, in the REA-2 group, the amounts of KOH-soluble fluoride (brushed or immersed) and structurally bound fluoride (brushed) were significantly higher than in the other groups.

CONCLUSION

The REA dependency of KOH-soluble and structurally bound fluoride was found only for the AmF toothpastes. Using AmF toothpaste, the mode of application influenced the uptake of KOH-soluble and structurally bound fluoride into enamel.

Hidden physics in molecular rovibrational spectrum

An algebraic method for rotational energies (AMr) is proposed to unearth the rotational spectrum {ɛJ} and the rovibrational interaction energies ευJint that are hidden in the rovibrational energies EυJ. The applications to the excited electronic state a3Σu+ of 7Li2 and the ground state X1Σ+ of NaF molecules show that: (1) the rotational energies ɛJ of the lighter 7Li2 molecule have better accuracies than the widely used rigid rotor rotational energies εJrr particularly for the lowest two rotational states, while the rigid rotor model produces satisfied rotational energies for the heavier NaF molecule and (2) the attractive rovibrational interaction energies ευJint stabilize a molecular rovibrational system.

Preparation and optimization of calcium fluoride particles for dental applications

Fluorides are used in dental care due to their beneficial effect in tooth enamel de-/remineralization cycles. To achieve a desired constant supply of soluble fluorides in the oral cavity, different approaches have been followed. Here we present results on the preparation of CaF2 particles and their characterization with respect to a potential application as enamel associated fluoride releasing reservoirs. CaF2 particles were synthesized by precipitation from soluble NaF and CaCl2 salt solutions of defined concentrations and their morphology analyzed by scanning electron microscopy. CaF2 particles with defined sizes and shapes could be synthesized by adjusting the concentrations of the precursor salt solutions. Such particles interacted with enamel surfaces when applied at fluoride concentrations correlating to typical dental care products. Fluoride release from the synthesized CaF2 particles was observed to be largely influenced by the concentration of phosphate in the solution. Physiological solutions with phosphate concentration similar to saliva (3.5 mM) reduced the fluoride release from pure CaF2 particles by a factor of 10-20 × as compared to phosphate free buffer solutions. Fluoride release was even lower in human saliva. The fluoride release could be increased by the addition of phosphate in substoichiometric amounts during CaF2 particle synthesis. The presented results demonstrate that the morphology and fluoride release characteristics of CaF2 particles can be tuned and provide evidence of the suitability of synthetic CaF2 particles as enamel associated fluoride reservoirs.

Sodium fluoride activates ERK and JNK via induction of oxidative stress to promote apoptosis and impairs ovarian function in rats

The toxicity of sodium fluoride (NaF) to female fertility is currently recognized; however, the mechanisms are unclear. Previously, we reported a reduction in successful pregnancy rates, ovarian atrophy and dysfunction following exposure to NaF. The purpose of this study was to elucidate the underlying molecular mechanisms. Female Sprague-Dawley rats (10 rats/group) received 100 or 200mg/L NaF in their drinking water for 6 months or were assigned to an untreated control group. Apoptotic indices and oxidative stress indicators in blood and ovarian tissue were analyzed following sacrifice. The results confirmed the NaF-induced ovarian apoptosis, with concomitant activation of oxidative stress. Further investigations in ovarian granular cells showed that exposure to NaF activated extracellular regulated protein kinase (ERK) and c-Jun NH2 kinase (JNK), disrupting the ERK and JNK signaling pathways, while p38 and PI3K remained unchanged. These data demonstrated that oxidative stress may play a key role in NaF-induced ovarian dysfunction by activating the apoptotic ERK and JNK signaling pathways.

Citric/citrate buffer: an effective antiglycolytic agent

BACKGROUND

In order to minimize the influence of glycolysis on diabetes mellitus (DM) diagnostic tests, we have compared the behavior of citric/citrate, fluoride additives and gel-serum with plasma-heparin under careful preanalytical conditions. Subsequently, we compared the effectiveness of both fluoride and citric additives at different pre-centrifugation times. Finally, the influence of citric/citrate collection tube on diagnostic tests results was evaluated.

METHODS

The first study of 80 voluntary patients assessed the glucose bias of citric/citrate, fluoride additive tubes and gel-serum tubes versus plasma-heparin tubes at several medical decision cut-offs (MDC). The second study performed with 72 volunteers evaluated additives, simulating transport times to the laboratory and centrifugation delay periods. Final evaluation compares the proportion of positive tests in total tests carried out in two different periods.

RESULTS

When citric/citrate (n=79) and fluoride tubes (n=60) were compared with plasma-heparin under controlled preanalytical conditions, both met the bias specification for plasma glucose (±1.8%) at seven MDC. On the contrary, serum samples (n=15) did not meet it at five MDC. In the second study, differences in glucose values at distinct pre-centrifugation times were not statistically significant for citric/citrate tubes, but significant for fluoride tubes and also for comparison of fluoride and citric/citrate tubes. Hemolysis in fluoride tubes was higher. Citric/citrate tube implementation in our laboratory caused an increase in positive diagnostic tests that were only statistically significant for gestational diabetes mellitus (GDM) screening.

CONCLUSIONS

Citric/citrate additive tube is equivalent to plasma-heparin avoiding glycolysis completely and immediately under careful preanalytical conditions even with a 3-h delay in plasma separation. According to used MDC we have not statistically significantly increased the diagnoses of DM cases.

Antibacterial property expressed by a novel calcium phosphate glass

We have developed a calcium phosphate glass (CPG) doped with Zn(2+) or F(-) or combined Zn(2+) and F(-) ions, which are naturally found in the human body and play a dual role in bone formation and antibacterial activity. Previously, we have demonstrated that this family of CPGs has superior osteoconductive and resorbable properties in vivo. This study aimed to investigate the antibacterial property of CPGs incorporating Zn(2+) and/or F(-) . We used Streptococcus mutans as a model organism because it is one of the major human oral pathogens and an early colonizer, and it has been associated with several oral infections, such as dental caries, periodontitis, and peri-implantitis. CPGs of 0.01 and 0.05 g were incubated with S. mutans for 0, 2, 4, and 6 h. Serial dilutions were plated in triplicate and colony forming units were determined. The antimicrobial effect of CPG incorporating Zn(2+) or F(-) was greater than CPG incorporating both these ions. CPG without doping produced a moderate antimicrobial effect. This family of CPGs, previously shown to promote new bone formation in vivo, is demonstrated to have superior bactericidal properties.

A new perspective on metals and other contaminants in fluoridation chemicals

BACKGROUND

Fluoride additives contain metal contaminants that must be diluted to meet drinking water regulations. However, each raw additive batch supplied to water facilities does not come labeled with concentrations per contaminant. This omission distorts exposure profiles and the risks associated with accidents and routine use.

OBJECTIVES

This study provides an independent determination of the metal content of raw fluoride products.

METHODS

Metal concentrations were analyzed in three hydrofluorosilicic acid (HFS) and four sodium fluoride (NaF) samples using inductively coupled plasma-atomic emission spectrometry. Arsenic levels were confirmed using graphite furnace atomic absorption analysis.

RESULTS

Results show that metal content varies with batch, and all HFS samples contained arsenic (4·9-56·0 ppm) or arsenic in addition to lead (10·3 ppm). Two NaF samples contained barium (13·3-18·0 ppm) instead. All HFS (212-415 ppm) and NaF (3312-3630 ppm) additives contained a surprising amount of aluminum.

CONCLUSIONS

Such contaminant content creates a regulatory blind spot that jeopardizes any safe use of fluoride additives.

In-beam Mössbauer spectroscopy of (57)Fe/(57)Mn in MgO and NaF at Heavy-Ion Medical Accelerator in Chiba

Development of efficient ion supply of (58)Fe from (58)Fe(C5H5)2, and quick switching between therapy and material science at the Heavy-Ion Medical Accelerator in Chiba realized a new (57)Mn in-beam emission Mössbauer spectroscopy measurement system. Application to simple binary chemical compounds, MgO and NaF, proved the usefulness of the system to probe chemical and physical behaviors of trace impurities in solids. Annealing of lattice defects produced by the implantation and β-decay of (57)Mn and/or γ-ray emission recoil was observed by a local probe.

Comparison of the enamel solubility reduction from Various prescription and OTC fluoride toothpastes and gels

OBJECTIVE

The purpose of this in vitro study was to determine if a novel 970 ppm F ion SnF2OTC gel (Enamelon Preventive Treatment Gel) and a 1150 ppm F- ion SnF2OTC Enamelon Toothpaste, each delivering amorphous calcium phosphate (ACP), can significantly reduce the effect of an acid challenge to enamel as compared to two prescription (Rx) strength 5000 ppm F- ion (NaF) dentifrices containing tri-calcium phosphate (TCP), and an Rx 900 ppm F- ion (NaF) paste with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). The effect will be determined by measuring the resistance of enamel specimens to an acid challenge before and after treatment with the test dentifrices.

METHODS

The procedure used in this study was the FDA Test Method #33 for the determination of the effect of different test dentifrices on enamel solubility reduction. Twelve sets of three extracted human teeth were unprotected and etched prior to treatment with 0.1 M lactic acid buffer solution. The amount of phosphate dissolved from the teeth was quantified via measuring the phosphate in the retained lactate buffer solution with phosphorous analysis (pre-treatment phosphorous levels). The teeth sets were then exposed to the following treatments (diluted 1:3 parts in preheated [37 degrees C] distilled water): 5000 ppm F- ion, sodium fluoride (NaF) Rx dentifrice containing TCP; 5000 ppm F- ion, NaF Rx dentifrice; 900 ppm F- ion, NaF Rx paste with CPP-ACP; 1150 ppm F- ion, stannous fluoride (SnF2) OTC toothpaste delivering ACP Enamelon Toothpaste; and 970 ppm F- ion, SnF2 OTC gel delivering ACP (Enamelon Preventive Treatment Gel). The teeth sets were rinsed with distilled water and then exposed to 0.1 M buffered lactic acid solution. The amount of phosphate in the lactic acid buffer was determined for a second time (post-treatment phosphorous levels). The percent of enamel solubility reduction was then computed as the difference between the amount of phosphorous in the pre- and post-treatment lactic acid solutions divided by the amount of phosphorous in the pre-treatment solution, and multiplied by 100.

RESULTS

The percent reduction in enamel solubility recorded in this study was as follows: 60.14 ± 0.79 for the Enamelon Toothpaste; 56.91 ± 1.05 for the Enamelon Preventive Treatment Gel; 18.78 ± 3.20 for the 5000 ppm F- ion, NaF prescription dentifrice "A' with TCP; 6.84 ± 1.20 for the 900 ppm F- ion, NaF paste with CPP-ACP; 5.82 ± 3.10 for the 5000 ppm F- ion, NaF prescription dentifrice "B" with TCP; and -5.45 ± 1.86 for the negative control. The differences between all the products tested were statistically significant (p < 0.05), except for the Enamelon products that were not statistically different. The 900 ppm F- ion, NaF paste with CPP-ACP and the 5000 ppm F- ion, NaF toothpaste results were also not statistically different.

CONCLUSION

The Enamelon products (970 ppm and 1150 ppm F- ion, SnF2 OTC dentifrices) delivering ACP were statistically significantly more effective in reducing enamel solubility than two Rx strength 5000 ppm F- ion NaF toothpastes containing TCP and the Rx 900 ppm F- ion NaF paste containing CPP-ACP.

Influence of sodium halides (NaF, NaCl, NaBr, NaI) on the photocatalytic performance of hydrothermally synthesized hematite photoanodes

It has been suggested that a high concentration of Fe(3+) in solution, a low pH, and noncomplexing ions of high ionic strength are all essential for developing a high-quality hematite array. Our curiosity was piqued regarding the role of the electrolyte ions in the hydrothermal synthesis of hematite photoanodes. In this study, we prepared hematite photoanodes hydrothermally from precursor solutions of 0.1 M FeCl3 at pH 1.55 with a background electrolyte of 1.0 M sodium halide (NaF, NaCl, NaBr, or NaI). We compared the structures and properties of the as-obtained hematite photoanodes with those of the material prepared in 1.0 M NaNO3, the most widely adopted electrolyte in previous studies. Among our studied systems, we found that the hematite photoanode prepared in NaCl solution was the only one possessing properties similar to those of the sample obtained from the NaNO3 solution-most importantly in terms of photoelectrochemical performance (ca. 0.2 mA/cm(2) with +0.4 V vs SCE). The hematites obtained from the NaF, NaBr, and NaI solutions exhibited much lower (by approximately 2 orders of magnitude) photocurrent densities under the same conditions, possibly because of their relatively less ordered crystallinity and the absence of rodlike morphologies. Because the synthetic protocol was identical in each case, we believe that these two distinct features reflect the environments in which these hematite photoanodes were formed. Consistent with the latest studies reported in the literature of the X-ray photoelectron spectra of fast-frozen hematite colloids in aqueous solutions, it appears that the degree of surface ion loading at the electrolyte-hematite interface (Stern layer) is critical during the development of hematite photoanodes. We suspect that a lower ion surface loading benefits the hematite developing relatively higher-order and a rodlike texture, thereby improving the photoelectrochemical activity.

Effect of resin composites with sodium trimetaphosphate with or without fluoride on hardness, ion release and enamel demineralization

PURPOSE

To evaluate the effect of the addition of sodium trimetaphosphate (TMP) with or without fluoride on enamel demineralization, and the hardness and release of fluoride and TMP of resin composites.

METHODS

Bovine enamel slabs (4 x 3 x 3 mm) were prepared and selected based on initial surface hardness (n = 96). Eight experimental resin composites were formulated, according to the combination of TMP and sodium fluoride (NaF): TMP/NaF-free (control), 1.6% sodium fluoride (NaF), and 1.5%, 14.1% and 36.8% TMP with and without 1.6% NaF. Resin composite specimens (n = 24) were attached to the enamel slabs with wax and the sets were subjected to pH cycling. Next, surface and cross-sectional hardness and fluoride content of enamel as well as fluoride and TMP release and hardness of the materials were evaluated. Data were statistically analyzed using ANOVA (P < 0.05).

RESULTS

The presence of fluoride in enamel was similar in fluoridated resin composites (P > 0.05), but higher than in the other materials (P < 0.05). The combination of 14.1% TMP and fluoride resulted in less demineralization, especially on lesion surface (P < 0.05). The presence of TMP increased fluoride release from the materials and reduced their hardness.

A pilot-scale study of cryolite precipitation from high fluoride-containing wastewater in a reaction-separation integrated reactor

Fluoride removal by traditional precipitation generates huge amounts of a water-rich sludge with low quality, which has no commercial or industrial value. The present study evaluated the feasibility of recovering fluoride as low water content cryolite from industrial fluoride-containing wastewater. A novel pilot-scale reaction-separation integrated reactor was designed. The results showed that the seed retention time in the reactor was prolonged to strengthen the induced crystallization process. The particle size of cryolite increased with increasing seed retention time, which decreased the water content. The recovery rate of cryolite was above 75% under an influent fluoride concentration of 3500 mg/L, a reaction temperature of 500C, and an influent flow of 40 L/hr. The cryolite products that precipitated from the reactor were small in volume, large in particle size, low in water content, high in crystal purity, and recyclable.

Influence of two different methods of delivering fluoride on bond strength and degree of conversion of an adhesive after bleaching

PURPOSE

To evaluate the influence of fluoride delivery and restoration time point on the microshear bond strength (mSBS) and degree of conversion (DC) values of an adhesive applied on bleached enamel.

MATERIALS AND METHODS

Fifty-four enamel specimens were submitted to bleaching and divided into 3 groups of n = 18: group HP: 35% hydrogen peroxide (HP); group HPF: HP + 1.23% sodium fluoride application (F); group PF: 38% HP with F. A control group of n = 6 was neither bleached nor fluoridated. Subsequently, each group except the control was subdivided into 3 subgroups (n = 6) to be restored immediately, or at 7 or 14 days. Tygon tubes were filled with composite resin and placed on enamel surfaces, then the mSBS test was performed. The DC of the interface was observed with Raman spectroscopy. The data were submitted to two-way ANOVA and Tukey's and Dunnet's post-hoc test (α = 0.05).

RESULTS

The mSBS results showed higher values for groups HP and HPF at 14 days compared with immediate and 7 days (p < 0.05). Lower DC values were obtained in the immediately restored groups HP and HPF, which were significantly different from 7 and 14 days (p < 0.05). mSBS and DC for group PF was similar at all restoration time points and to the control group (p > 0.05).

CONCLUSION

Only the use of a fluoridated in-office bleaching agent (Opalescence Boost PF) proved to be effective for immediately reversing the side effects of low mSBS and DC values when in-office bleaching is used.

Surface roughness of fluoride-releasing restorative materials after topical fluoride application

AIM

The aim of this study was to assess the effect of a single application of two topical fluoride agents: NNaF and APF (2% neutral sodium fluoride gel and 1.23% acidulated phosphate fluoride gel, respectively) on the surface roughness (Ra) of Fuji IX GP, Ketac N100, Vitremer, Dyract AP, Compoglass F and Filtek Ultimate.

STUDY DESIGN

The effect of NNaF and APF on the surface roughness of fluoride-releasing restorative materials was tested on disk-shaped material specimens with a surface profilometer.

METHODS

All materials were handled according to manufacturer's instructions. ISO standardised specimens were prepared for each material and then stored in distilled water for 24 hr. Each sample was polished with 600 and 1200 grit sandpaper on both sides while keeping the material surface wet. Ra measurements were performed on untreated specimens initially and after 1 min, 4 min and simulated 2-years for both fluoride applications, respectively. The mean Ra values for all specimens were measured using a surface profilometer.

STATISTICS

Differences in surface roughness values were assessed using paired t-test. The differences between the experimental groups were analysed with one-way ANOVA; p<0.05 was accepted as statistically significant.

RESULTS

The results of the present study indicated that Ra values for Fuji IX GP and Vitremer increased significantly after all APF, but not NNaF applications. All tested materials exhibited increased Ra values for both treatment regimes, but this was not found statistically significant.

CONCLUSION

APF gel application significantly increased the surface roughness of both Fuji IX GP and Vitremer for all time periods.

Comparison of glucose determinations on blood samples collected in three types of tubes

Because of the metabolism of serum glucose in collection tubes containing blood samples, serum glucose levels may be found to decrease over time. Several types of collection tubes have been designed to, at least partially, block glucose metabolism by red blood cells in blood collection tubes that may not be analyzed immediately after blood collection. These include red-top collection tubes with serum separator, grey-top tubes with a fluoride glycolysis inhibitor, and heparin-containing green-top tubes which prevent clot formation. As part of a quality assurance project, we investigated whether glucose levels differed in the three tube types from each of 18 volunteers on a prolonged standing of 4 hours. We then determined the glucose concentrations of all three tubes from each of the 18 volunteers. We used refrigerated samples over a five-day period to determine if the initial values were reproducible. Surprisingly, after standing for four hours at room temperature, we found that the glucose levels in the three tubes from each volunteer were statistically indistinguishable from one another using the two-tailed paired t-test. Also, a linear regression analysis showed that the values of glucose for the three pairs of two tube types were closely correlated with one another, with correlation coefficients of >0.97, slopes close to 1, and Y-intercepts close to 0. These results suggest that blood collection in any of these tubes will render similar values for serum glucose even after standing for four hours. The tubes were then refrigerated at 4°C and re-analyzed after another six hours and then once per day for the next four days. Beginning at the first day at the six-hour determination, the glucose levels in the red- and grey-top tubes were statistically indistinguishable from one another but not in the red- and green-top tubes and in the grey- and green-top tubes. This was due to a steady decrease in the glucose levels in the green-top tubes. The glucose levels in the red- and grey-top tubes from each volunteer remained constant over the five-day period so that the coefficients of variation (CV) were low. In contrast, due to the decrease of glucose levels in the green-top tubes, the CVs for repeated glucose determinations in these tubes were high. Interestingly, a regression analysis of the glucose values for all three sets of paired tubes showed high (> 0.97) correlation coefficients and slopes close to 1. However, a regression analysis of the glucose values in the red- and green-top and grey- and green-top tubes at day five showed Y-intercepts of about -32 suggesting that there is a constant decrease of glucose in the green-top tubes that amounts to approximately 6 mg/dL per day over five days. These results suggest that red-top tubes with serum separator or grey-top tubes with a fluoride glycolysis inhibitor may be used for reproducible glucose determinations.

Facile synthesis of multifunctional beta-NaGdF4:Yb3+/Er3+ nanoparticles in oleylamine

Multifunctional beta-NaGdF4:Yb3+/Er3+ nanoparticles (NPs) were successfully synthesized using oleylamine as both solvent and stabilizer via the thermolysis method. They have uniform morphology with a mean size of 12.7 nm and show efficient up-conversion emission when excited by a 980 nm laser. The up-conversion NPs demonstrated a nearly quadratic dependence of the photoluminescence intensity on the excitation power, which indicated a two-photon induced process. In addition, these NPs exhibit paramagnetic characteristics at both 300 and 77 K. The magnetic properties of beta-NaGdF4:Yb3+/Er3+ NPs are intrinsic to the Gd3+ ions. The measured mass magnetic susceptibility value of 0.79 x 10(-4) em mu/g x Oe at room temperature is close to reported values of other NPs for bioseparation and optical-magnetic dual modal nanoprobes in biomedical imaging.

Formulation and characterization of antibacterial fluoride-releasing sealants

PURPOSE

The purpose of this study was to formulate and characterize experimental antibacterial fluoride-releasing sealants and compare them with commercial sealants for fluoride release, recharge, adhesion, and microleakage.

METHODS

Two experimental sealants (Exp-1, Exp-2) containing a synthesized antibacterial fluoride-releasing monomer and fluoride-releasing filler were formulated. Exp-2 also contained NovaMin nanoparticles. Commercial sealants Clinpro (CL) FluroShield (FS), and SeLECT Defense (E34) were also included. Fluoride release from disk samples in deionized water was measured daily using an ion-selective electrode for 14 days, and after recharging with Neutra-Foam (2.0% sodium fluoride), fluoride was measured for 5 days. Microtensile bonding strengths (MTBS) to enamel were tested after 24-hour storage in water at 37°C or thermocycling 5-55°C for 1,000 cycles. A microleakage test was conducted on extracted teeth using a dye-penetration method. The data were analyzed using analysis of variance with the Tukey's honestly significant difference test and Kruskal-Wallis test.

RESULTS

Exp-1 and Exp-2 had significantly higher fluoride release and recharge capabilities than CL and FL (P<.05). All tested sealants had similar MTBS before and after thermocycling. Exp-2 and Exp-1 had significantly lower microleakage scores (P<.05) than other groups.

CONCLUSION

The experimental sealants had higher fluoride release and recharge capabilities and similar or better retention than commercial sealants.

Inhibition of acidogenicity in dental plaque by sodium fluoride solution after sucrose rinse

OBJECTIVE

To evaluate the effect of sodium fluoride rinse on sucrose-induced decrease in plaque pH with interdental plaque pH telemetry.

METHODS

Six participants wearing partial lower prostheses incorporating a miniature glass pH electrode were included. The measurement of plaque pH was performed after 6 days of plaque accumulation. Three experiments were performed to test the effects of fluoride administered before (experiment I) or 10 min after (experiment II) and 25 min after (experiment III) a sucrose rinse. In experiment I, the subjects rinsed with 0.05% NaF solution before rinsing with 10% sucrose to examine the effect of fluoride on the sucrose-induced pH drop. In experiment II, the subjects first rinsed with 10% sucrose and then followed no subsequent rinsing or rinsing with tap water 10 min after sucrose expectoration, or 0.05%, 0.02% or 0.01% NaF solution for 2 min. In experiment III, the subjects first rinsed with 10% sucrose and then 25 min after sucrose expectoration, they rinsed with 0.05% NaF for 2 min. The plaque pH was continuously recorded for about 120 min.

RESULTS

Without any subsequent rinses, the plaque pH decreased at 10 min to 4.36 and stayed below the critical pH 5.7 for about 85 min after the sucrose rinse. Subsequent water rinses showed little effect on the sucrose-induced decrease in plaque pH. Pretreatment of 0.05% NaF solution showed no effect on the subsequent sucrose-induced pH drop. Subsequent rinses with NaF solutions at 10 min after the sucrose rinse inhibited the sucrose-induced pH drop in a dose-dependent manner. Subsequent rinses with NaF solutions after the sucrose rinse also significantly reduced the time below pH 5.7 and the area of plaque pH curve under 5.7 (AUC5.7). Furthermore, the AUC5.7 value (3.99) of 0.05% NaF rinse at 10 min after the sucrose rinse was much smaller than that (57.01) of 0.05% NaF rinse at 25 min after the sucrose rinse.

CONCLUSION

Rinsing with 0.05% fluoride after carbohydrate consumption effectively reduced the acidogenicity of the plaque and could enhance the anticaries functions of fluoride.

The effect of fluoride exposure on the load-deflection properties of superelastic nickel-titanium-based orthodontic archwires

BACKGROUND

It has been demonstrated that fluoride prophylactic agents may cause hydrogen absorption in NiTi wires and degrade their mechanical properties.

AIMS

To investigate the effect of a fluoride mouthwash on load-deflection characteristics of three types of nickel-titanium-based orthodontic archwires.

METHODS

Twenty maxillary 0.016 inch round specimens from each of the single-strand NiTi (Rematitan 'Lite'), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) wires were selected. The specimens were kept in either 0.2% NaF or artificial saliva solutions at 37 degrees C for 24 hours (N = 10). The wire load-deflection properties were measured by a Zwick testing machine, using a three-point bending test. An un-paired student's t-test, a one-way ANOVA and a Tukey post-hoc test were used to assess statistical significance.

RESULTS

Immersion in NaF solution affected the load-deflection properties of NiTi wires. The unloading forces at 0.5 and 1.0 mm deflections were significantly lower in fluoride-treated specimens compared with the control groups (p < 0.05). Unloading forces at 1.5, 2.0 and 2.5 mm deflections were not statistically different between fluoride- and saliva-treated specimens (p > 0.05).

CONCLUSIONS

The results suggested that subjecting NiTi wires to fluoride agents decreased associated unloading forces, especially at lower deflections, and may result in delayed tooth alignment.