fluoride concentration
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2022 ◽  
Vol 34 (1) ◽  
pp. 134-141
Author(s):  
Tong Lihong ◽  
◽  
Liu Yingjun ◽  
Zhang Shuo ◽  
Liu Xiaowei ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
pp. 321
Author(s):  
Raisa N. Krasikova ◽  
Viktoriya V. Orlovskaya

Incorporation of [18F]fluorine into PET radiotracer structure has traditionally been accomplished via nucleophilic pathways. The [18F]fluoride is generated in an aqueous solution via proton irradiation of oxygen-18 enriched water and must to be introduced into water-free organic solutions in order to generate reactive species. Thus nucleophilic 18F-fluorination traditionally included steps for [18F]fluoride concentration on the anion exchange resin, followed by removal of residual water via azeotropic distillation with MeCN, a time-consuming process associated with radioactivity losses and difficult automation. To circumvent this, several adsorption/elution protocols were developed based on the minimization of water content in traditional kryptofix-based [18F]fluoride eluents. The use of pre-dried KOH/kryptofix solutions, tertiary alcohols, and strong organic bases was found to be effective. Advances in transition metal-mediated SNAr approaches for radiolabeling of non-activated aromatic substrates have prompted development of alternative techniques for reactive [18F]fluoride species generation, such as organic solutions of non-basic alkyl ammonium and pyridinium sulfonates, etc. For radiofluorinations of iodonium salts precursors, a “minimalist” approach was introduced, avoiding the majority of pitfalls common to more complex methods. These innovations allowed the development of new time-efficient and convenient work-up procedures that are easily implementable in modern automated synthesizers. They will be the subject of this review.


2021 ◽  
Author(s):  
Marwa M. Alhothali ◽  
Rob A.M. Exterkate ◽  
Maxim Lagerweij ◽  
A.J.P. Van Strijp ◽  
Mark J. Buijs ◽  
...  

This study compared the effect of topically applied fluoride products on dentine lesions in an in vitro experiment. Demineralized bovine dentine specimens were treated once with either SDF solution (35,400 ppm F), NaF varnish (22,600 ppm F), TiF4 solution (9,200 ppm F), SnF2 gel (1,000 ppm F), no treatment (control) or preserved as baseline lesions. After the application and subsequent removal of the fluoride products, the specimens were subjected to pH-cycling. Calcium loss and uptake in the de- and remineralization buffers were assessed daily. Fluoride release into the buffers was analyzed on day 1, 2, 3, 5, 8 and 13. After the pH-cycling period, mineral distribution throughout the lesion depth was analyzed using transversal microradiography (TMR). X-ray energy-dispersive spectroscopy (EDS) examined the deposition of silver, titanium and tin after application of SDF, TiF4, and SnF2, respectively. Overall, calcium loss and uptake analysis in the de- and remineralization buffers revealed that the SDF product was the most effective in inhibiting lesion progression, followed by the TiF4, NaF, and SnF2 products. Fluoride analysis disclosed a steep reduction of the amount of fluoride released into de- and remineralization buffers with time. The fluoride effects on de- and remineralization continued beyond the days that fluoride was released into the buffers. TMR analysis showed significant remineralization in the outer zone of the dentine lesions for all fluoride products, with SDF giving hyper-mineralization in this zone. In the inner zone, lesions developed in all fluoride groups, with the smallest in the SDF group. EDS showed silver and titanium deposition in depth up to 85 μm and 8 μm, respectively, while no tin deposition was observed. The silver in the dentine lesions did not contribute significantly to the density of the TMR profiles in the SDF group. In conclusion, all topical fluoride products protected the dentine lesions against lesion progression, but at different degrees. SDF showed a superior effect in protection against further demineralization and enhancement of remineralization. This was probably attributed to its fluoride concentration that was the highest among the fluoride products.


Author(s):  
Lídia Audrey Rocha Valadas ◽  
Ana Laura Sorazabal ◽  
Paulo Andres Salgado ◽  
Angela Beatriz Argentieri ◽  
Aldo Squassi

2021 ◽  
Vol 16 (2) ◽  
pp. 177-189
Author(s):  
Aira Syazleen Ahmad ◽  
Nor Azlida Mohd Nor ◽  
Nadia Afiqah Ahmad ◽  
Zamros Yuzadi Mohd Yusof ◽  
Ivor G. Chestnutt

This study aimed to determine the fluoride and pH levels of beverages likely to be consumed by children in Malaysia and to estimate daily fluoride intake from consumption of these beverages. A convenience sampling of 120 ready-to-drink beverages were purchased and categorised into 11 groups (UHT recombined milk, fresh milk [pasteurised], cultured milk [probiotic], yogurt beverages, fresh fruit juices, fruit flavoured beverages, soy-based beverages, malt-based beverages, tea, carbonated beverages and bottled waters). Fluoride concentration was measured using a fluoride ion-selective electrode while the pH level was measured using a pH meter. The fluoride concentration in the beverages ranged from 0.02±0.00 mg/L to 2.77±0.06 mg/L. Tea was found to have the highest fluoride concentration. The intake of fluoride from consumption of other types of beverages is below the lowest-observed-adverseeffect level (except tea). The pH of the beverages included in the study ranged from 2.20±0.01 to 7.76±0.00. Carbonated beverages (mean pH: 2.98±0.50) were found to be extremely acidic followed by fresh fruit juices (mean pH: 3.38±0.34) and fruit flavoured beverages (mean pH: 3.90±0.92). The correlation between fluoride and pH levels was weak, τ = 0.058 and not statistically significant (p


2021 ◽  
Author(s):  
Mauro Antonio Dall Agnol ◽  
Carla Battiston ◽  
Livia Maria Andalo Tenuta ◽  
Jaime Aparecido Cury

Although fluoride varnish (FV) and acidulated phosphate fluoride gel (APF-gel) are considered clinically effective to reduce caries, in vitro studies have shown that FV reacts slowly with enamel because most NaF present in the formulation is not solubilized in the FV. Therefore, we conducted a clinical study to evaluate if the time that FV remains on dental surfaces could overcome its slower chemical reactivity when compared with APF-gel. Sixty-eight volunteers were randomly allocated into four groups: Negative control (Control, no treatment), APF -gel application (1.23% F applied for 4 min), and FV application (Duraphat®, 2.26 % F) for 4 h (FV-4h) or 24 h (FV-24h). To evaluate fluoride formed and retained on enamel, acid biopsies were made on the buccal surfaces of the maxillary central incisors before, at the end of the application of fluoride products (immediately after gel application, or after 4 or 24 h of varnish application) and after 7 and 28 days. Fluoride concentration in dental biofilm was also analyzed before and up to 28 days after initial application. The data were analyzed by 2-way ANOVA, considering treatment and time as factors. The APF-gel and FV-24h groups formed greater fluoride concentration on enamel than the FV-4h and the control group at the end of application (p=0.0001), with no difference from each other (p=0.99). The groups did not differ regarding fluoride in biofilm, fluid (p=0.73) and solids (0.40). In conclusion, fluoride varnish needs to remain in contact with the teeth for prolonged times (>4 h) to reach the same reactivity obtained by a 4-min application of APF-gel.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Chao Ren ◽  
Peng Zhang ◽  
Xiao-Yan Yao ◽  
Hui-Hua Li ◽  
Rui Chen ◽  
...  

Abstract Objective To evaluate cognitive impairment and risk factors of elders in high fluoride drinking water areas and investigate whether DKK1 is involved in this disorder. Methods MoCA-B and AD-8 were used to measure the cognitive functions of 272 and 172 subjects over the age of 60 came from the high and normal fluoride drinking water areas respectively, general information and peripheral blood were collected, the level of SOD, GSH and MDA were measured, mRNA level of DKK1, the concentration of blood fluoride and the polymorphism of APOE were tested. Results The blood fluoride concentration, mRNA level of DKK1 and ratio of abnormal cognitive function of subjects in high fluorine drinking water areas were higher than those in normal areas. The level of SOD of subjects in high fluorine drinking water was low compared with those in normal areas. The level of MDA and GSH had no difference between the two crowds in different fluorine drinking water areas. There were differences in cigarette smoking, education, dental status, hypertension, hyperlipidaemia and APOE results between the two crowds in different fluorine drinking water areas. The mRNA level of DKK1 and the level of cognitive function showed a positive correlation and DKK1 was one of five risk factors involved in cognitive impairment of older people living in high fluorosis areas. Conclusions The cognitive functions could be impaired in the older people living in high fluoride drinking water areas, and DKK1 may as a potential intervention point of this brain damage process need attention.


Cosmetics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 113
Author(s):  
Ammar Abdulrahman Jairoun ◽  
Sabaa Saleh Al-Hemyari ◽  
Moyad Shahwan ◽  
Obaida Jairoun ◽  
Sa’ed H. Zyoud

Background: While there is much scientific evidence supporting the benefits of fluoride for oral health, the concentration of fluoride in over-the-counter fluoride toothpaste should meet United Arab Emirates (UAE) regulations of a fluoride concentration not exceeding 0.15%. Objectives: The current study examines the fluoridated toothpaste products available on the UAE market and aims to quantify their total fluoride content. Methods: A total of 50 toothpaste products were collected and analyzed in this study. Ion Chromatography (IC) conductivity analysis was performed to determine the total fluoride content. Results: Among the 50 products tested, 10 exceeded the recommended concentration of total fluoride of less than 0.15%, while 12 had a total fluoride concentration that was less than was declared on their labels. Moreover, this study has revealed that 22 of the sampled products had a total fluoride concentration below 1000 ppm fluoride. An increased risk of higher total fluoride content was observed in the toothpaste products with monofluorophosphate active ingredients than in products with potassium nitrate/sodium fluoride and sodium fluoride (p = 0.011). Conclusions: There is a need to reassess the effectiveness of current regulations in the UAE to ensure that all fluoridated toothpastes available on the market are safe and effective for the consumer. Specifically, appropriate guidelines should be established on the basis of the risks and benefits inherent in fluoride exposure. Moreover, fluoridated toothpastes need to be subject to stricter monitoring and control regarding their safety and quality through good manufacturing practices (GMPs), education, research, and adverse event reporting.


Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3343
Author(s):  
Bo Yang ◽  
Guirong Sun ◽  
Bingxu Quan ◽  
Jiawei Tang ◽  
Chunhui Zhang ◽  
...  

The emerging interest in fluoride-removal from wastewater has attracted attention to zeolite since it has been considered as a natural adsorbent. However, the fluoride-removal efficiency of natural zeolite is generally low. As part of the effort to improve the zeolite adsorption efficiency, we have produced and tested the Mn-Ti modified zeolite. In the current work, the material preparation is discussed, and prepared materials were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy, and Fourier transform infrared (FTIR) spectra. Both static and dynamic experiments were conducted to examine the effects of independent variables. In the static adsorption section, sensitivity analysis experiments were conducted for independent variables, such as adsorbent dosage, pH, temperature, and competitive ions. The maximum adsorption capacity is 2.175 mg/g, which was obtained at PH = 7, temperature = 25 °C, and initial fluoride concentration = 10 mg/L. For adsorption kinetics, both Lagergren and Pseudo-second order models predict the experiments very well, which probably demonstrates that the current process is a combination of physical sorption and chemisorption. For adsorption isotherms, the Freundlich model performs better than the Langmuir model since it is usually applied to illustrate adsorption on inhomogeneous surfaces. In the dynamic adsorption section, sensitivity analysis experiments were also conducted for independent variables, such as adsorbent thickness, flow velocity, initial fluoride concentration, and PH. Additionally, the adsorption mechanism is also discussed. The main reason is the hydrated metal fluoride precipitate formation. As we know, the current work provides the first quantified comparison of the natural zeolite and the Mn-Ti modified zeolite regarding fluoride-removal efficiency.


Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7112
Author(s):  
Adane Woldemedhin Kalsido ◽  
Beteley Tekola Meshesha ◽  
Beshah M. Behailu ◽  
Esayas Alemayehu

Using small-scale batch tests, various researchers investigated the adsorptive removal of fluoride using low-cost clay minerals, such as Bentonite. In this study, Column adsorption studies were used to investigate the removal of fluoride from aqueous solution using acid-treated Bentonite (ATB). The effects of initial fluoride concentration, flow rates, and bed depth on fluoride removal efficiency (R) and adsorption capability (qe) in continuous settings were investigated, and the optimal operating condition was determined using central composite design (CCD). The model’s suitability was determined by examining the relationship between experimental and expected response values. The analysis of variance was used to determine the importance of independent variables and their interactions. The optimal values were determined as the initial concentration of 5.51 mg/L, volumetric flow rate of 17.2 mL/min and adsorbent packed-bed depth of 8.88 cm, with % removal of 100, adsorptive capacity of 2.46 mg/g and desirability of 1.0. This output reveals that an acid activation of Bentonite has made the adsorbent successful for field application.


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