The main drivers for this body of work were a systematic review on water fluoridation by the NHS Centre for Research Dissemination (known as the York Report) and a report by the Medical Research Council entitled 'Water Fluoridation & Health'. Both documents highlighted shortcomings in the evidence base on water fluoridation. Two major projects form the basis of this thesis in an attempt to address some of the issues raised. The first project in Chiang Mai, Thailand aimed to determine the ability of QLF to discriminate between populations with differing exposures to fluoride. Populations with differing exposures to fluoride were identified through the analysis of drinking water and cooking water. Subjects were examined for fluorosis with standardized photographs and QLF to evaluate software techniques for fluorescence image analysis. The results in Thailand demonstrated that QLF was able to discriminate between populations with differing exposures to fluoride in water to a similar degree to blinded, subjective clinical scoring. There was significant agreement between the two methods (ICC 0.65 Spearman's rho). However, confounding factors for QLF were found. The aim of the second project was to assess the use of blinded and objective methods for assessing caries and fluorosis in fluoridated Newcastle and non-fluoridated Manchester in northern England. This study involved clinical and intra-oral photographic caries examinations using ICDAS, together with standardized photography and QLF imaging for fluorosis examinations. The results in Newcastle and Manchester suggested that there were significantly lower levels of caries in the fluoridated population compared to the non-fluoridated population. For early caries (Newcastle mean DMFT 2.94[clinical]/2.51[photo], Manchester mean DMFT 4.48 [clinical]/3.44[photo]) and caries into dentine (Newcastle Mean DMFT 0.65[clinical]/0.58[photo], Manchester mean DMFT 1.07 [clinical]/0.98 [photo]). This was reflected as an increase in caries as the level of deprivation increased (confirmed through intra-oral photographic scoring). The reduction in caries levels was associated with increased levels of fluorosis in Newcastle. The prevalence of fluorosis from photographic scores in fluoridated Newcastle was 55%, in non-fluoridated Manchester it was 27%. In Newcastle, 48% of subjects had TF scores of 1 or 2 and 7.1% of subjects had TF scores of 3 or greater. QLF showed significant associations with the clinical scores for fluorosis (ICC 0.405 Kendall's tau) and suggested a fluorosis prevalence for TF 3 or greater of 19% in Newcastle and 10% in Manchester. The integration of technologies such as intra-oral photographs for blind caries scoring and QLF for the detection and objective quantification of fluorosis may still prove to be useful adjunctive tools when used alongside clinical indices. The data derived from the methodologies under investigation suggest a benefit in caries reduction from community water fluoridation and this may help to reduce inequalities in oral health by reducing the social gradient between deprivation and caries.

Magister Scientiae Dentium - MSc(Dent) / High caries burden coupled with a lack of water and salt fluoridation make it imperative that toothpastes marketed to the South African consumer demonstrate adequate caries inhibition. It is generally accepted that an effective toothpaste contain between 1000ppm and 1500ppm total fluoride (TF) and that of this at least 1000ppm F should be in free available form. Studies conducted in other countries have demonstrated that toothpastes often do not conform to this regulation, indicating the need for quality assessments to be undertaken. Objectives: This study therefore aimed to determine total and free available (potentially bioavailable) fluoride concentrations in 28 adult, fluoridated toothpastes marketed to the South Africa consumer. Labeling practices were also assessed. Materials & Methods: Convenience samples were purchased from a major pharmaceutical and food retailer located in each of the five metropolitan areas of South Africa. Information detailed on the packaging was evaluated for compliance with national standards. Total and bioavailable fluoride concentrations were determined potentiometrically, in quadruplicate, following acid hydrolysis of the samples using a Combination Fluoride Ion Selective Electrode, calibrated with standards containing 0.0625ppm F to 6.25ppm F. Results: Although TF content on analysis was found to be statistically significantly lower than manufacturer declaration (1.2x10-7; p≤0.05), 78.6% still contained adequate free, available F levels. Relative mean available fluoride content for toothpastes formulated with a calcium-based abrasive was 85,5% as opposed to 98.7% for those containing silica. Partial alignment with national labeling statutes was observed for all toothpastes. Conclusion: Most commercially available toothpastes are adequately formulated to provide anticariogenic activity, but consumers should be advised against the use of products containing calcium. Improvements to national standards and stricter regulation of labeling practices are required.

Inelastic neutron scattering measurements by Okazaki, Tuberfield, and Stevenson (1964) of the antiferromagnetic spin wave energy, spectrum in manganese fluoride crystal at low temperatures, agree with the results predicted by a dispersion relation introduced without proof in their paper. In this thesis the question is considered in detail to what extent this dispersion relation is justified. The interaction between the manganese ions is described by the Heisenberg exchange Hamiltonian. Following Holstein and Primakoff's formalism the spin deviation operators are introduced and the part of the Hamiltonian ℋ[superscript B] containing all the terms up to those bilinear in the spin deviation operators is diagonalised by means of the Anderson transformation. A correction is next obtained by retaining the diagonal part of those terms which are quadrilinear in the spin deviation operators. Under certain conditions it is shown that ℋ[superscript B] together with the correction term give rise to, a dispersion relation which is identical with that used by Okazaki et al. (1964). Finally the validity of the approximations is also discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-24T10:28:13Z (GMT). No. of bitstreams: 1 Silva_AmandaFalcaoda_D.pdf: 1562450 bytes, checksum: f94a4f323b0604892bc95caf3aec4e5a (MD5) Previous issue date: 2014 / Resumo: Há clara evidência da importância da água fluoretada como um meio coletivo de uso de fluoreto (F), responsável pelo decréscimo na incidência de cárie dental. Entretanto, ainda se discute a respeito de seu mecanismo de ação, quer seja relacionado ao aumento da concentração de F na saliva pelo contato com a água fluoretada, quer seja pelo retorno do íon à cavidade bucal, após sua absorção, pela secreção salivar. Além disso, não apenas a ingestão de água fluoretada, mas também de alimentos com ela preparados, tem potencial anticárie, porém desconhece-se se há diferença entre ambas as formas de utilização na capacidade de elevar a concentração salivar de F. Assim, o objetivo deste trabalho foi avaliar a biodisponibilidade de F proveniente da ingestão de água ou de alimentos preparados com água fluoretada. O estudo foi in vivo (n=20), cruzado, duplo cego, e realizado em 4 fases experimentais, nas quais os voluntários ingeriram: água não fluoretada (< 0,01 µg F/mL), água fluoretada (1 µg F/mL), refeição preparada com água não fluoretada ou refeição preparada com água fluoretada. A refeição foi composta por arroz, feijão, carne, vagem, cenoura, suco e gelatina, e o tempo para ingestão foi padronizado em 15 minutos. A dose de F ingerida foi baseada no peso corporal para atingir 0,8 µg F/kg peso corporal, quando da ingestão água ou da refeição preparada com água não fluoretada (dose correspondente ao F residual presente nos alimentos), e 12 µg F /Kg de peso corporal, quando da ingestão de água ou refeição preparada com água fluoretada. Imediatamente antes e 5, 10, 15, 30, 45, 60, 120 e 180 minutos após a ingestão, amostras de sangue e saliva não estimulada foram coletadas para determinação da concentração de F. As amostras de sangue (de 1 a 10 µL) foram obtidas por punção digital e a concentração de F foi determinada no plasma sanguíneo por eletrodo íon-específico, adaptado para microanálise. Na saliva, a concentração de F foi determinada após microdifusão facilitada com hexametildisiloxano. A biodisponibilidade de F foi estimada a partir da área sob a curva (ASC) das concentrações plasmática e salivar de F em função do tempo. Os grupos foram comparados utilizando análise de variância, seguida de teste de Tukey. Significativo aumento na ASC da concentração de F no plasma e saliva foi observado quando da ingestão de água e da refeição preparada com água fluoretada em comparação com os grupos controles (p<0,05), sem diferença entre as formas de utilização (p>0,05). Conclui-se que tanto a ingestão de água quanto de alimento fluoretado aumentam a biodisponibilidade de F no plasma e na saliva e podem contribuir para seu benefício anticárie / Abstract: There is clear evidence of the importance of fluoridated water as a public measure of fluoride (F) use, being responsible for the decrease in dental caries incidence. Nevertheless, its mechanism of action, whether related to the increase in salivary F concentration by the immediate contact with fluoridated water or by the return of the ion to the oral cavity by salivary secretion after its absorption, is still under discussion. Moreover, not only the ingestion of fluoridated water, but also of food cooked with it, has anticaries potential, but it is unknown whether there are differences between these two ways in respect to the ability to elevate salivary F concentration. Thus, the aim of this study was to evaluate the F bioavailability from drinking water or foods prepared with fluoridated water. The study was in vivo (n = 20), crossover, double blind, conducted in 4 experimental phases, in which volunteers ingested: non-fluoridated water (< 0.01 µg F / ml), fluoridated water (1 µg F / ml), meal prepared with non-fluoridated water and meal prepared with fluoridated water. The meal consisted of rice, beans, meat, beans, carrot, juice and gelatin, and the time for intake was standardized in 15 minutes. The dose of ingested F was based on body weight to achieve 0.8 µg F/kg body weight, considering the intake of the water or meal prepared with non-fluoridated water (corresponding to the residual F dose present in foods), and 12 µg F/kg of body weight, considering the intake of water or food prepared with fluoridated water. Immediately before and 5, 10, 15, 30, 45, 60, 120 and 180 minutes after ingestion, unstimulated saliva and blood samples were collected to determine the F concentration. Blood samples (1 to 10 µL) were obtained from finger draws and F concentration in blood plasma was determined by ion-specific electrode, adapted for microanalysis. In saliva, the F concentration was determined after microdiffusion with hexamethyldisiloxane. The F bioavailability was estimated from the area under the curve (AUC) of plasma and salivary F concentrations as a function of time. Groups were compared using analysis of variance followed by Tukey test. Significant increase in the AUC of plasma F and saliva concentrations were observed when both water and meal prepared with fluoridated water were compared to control groups (p<0.05), with no difference between the forms of use (p>0.05). We conclude that both the intake of fluoridated water or foods prepared with it increase the F bioavailability in plasma and saliva and can have anticaries potential / Doutorado / Cariologia / Doutora em Odontologia

Thesis (Ph. D. (Chemistry)) -- University of Limpopo, 2019 / This work presents the synthesis, characterisation and application of poly(vinylidene fluoride-co-hexafluropropylene) (PVDF-HFP) membrane prepared using a phaseinversion method. PVDF-HFP was blended with either functionalised multi-walled carbon nanotubes (MWCNTs), poly-amidoamine (PAMAM) dendrimeric MWCNTs or silver (Ag) nanoparticles and their combinations. Nanocomposite blends such as MWCNTs/PVDF-HFP, PAMAM-MWCNTs/PVDF-HFP, Ag-MWCNTs/PVDF-HFP and Ag-PAMAM-MWCNTs/PVDF-HFP were synthesised successfully. A variety of PVDF-HFP composite membranes prepared were characterised by X-ray powder diffraction (XRD), fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and contact angle. The fMWCNTs, Ag-MWCNTs, PAMAM-MWCNTs and Ag-PAMAMMWCNTs nanocomposites were further characterised by Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). FTIR spectra of PAMAMMWCNTs confirmed the formation of functional groups such as COOH, NCO, NH2 and PAMAM dendrimer. XRD analysis demonstrated that the crystallite sizes of the silver nanoparticles were larger (8.4 nm) than those of Ag-MWCNTs (7.8 nm) and Ag-PAMAM/MWCNTs (6.4 nm) nanocomposites. These findings were further confirmed by TEM analysis which showed Ag nanoparticles, Ag-MWCNTs and Ag-PAMAM/MWCNTs having diameters of silver particles between 9 to 20 nm, 5 to 10 nm and 4 to 8 nm respectively. The reduced Ag particle sizes was due to the complexation of MWCNTs and PAMAMMWCNTs with Ag metal ions, which correlates with an enhanced surface area in the nanocomposite membranes, leading to good filtration and antibacterial properties. TGA studies demonstrated that the thermal stability of PVDF-HFP composite membrane was greatly enhanced by the addition of PAMAM-MWCNTs. However, the composite membranes consisting of both Ag nanoparticles and MWCNTs on PVDFHFP did not improve the structural stability of PVDF-HFP. All composite membranes have shown stability up to 400 oC. The contact angle, porosity, swellability and water content measurements of the composite membranes were improved showing enhanced hydrophilicity due to addition of MWCNTs, PAMAM-MWCNTs and/or Ag nanoparticles. The scanning electron microscopy (SEM) images have depicted the formation of microporous structure, with few MWCNTs on the surface strongly interacting with PVDF-HFP as demonstrated by TGA, XRD and FTIR data. SEM cross-sections of PVDF-HFP composite membranes showed a mixture of fingure-like microvoids with a membrane diameter of approximately 180 μm. The BET data showed an improved surface area, pore volume and pore sizes of PVDF-HFP composite membranes when blended with fMWCNTs and PAMAM. These membranes also showed high fouling resistance, good desalination and high Cd(II) ions rejections during permeability studies. E. coli filtration studies indicated that 2.5 wt.% Ag-MWCNTs/PVDF-HFP and 1.8 wt.% Ag-PAMAM-MWCNTs/PVDF-HFP composite membranes displayed good microbial load reduction (100%) and excellent antibacterial properties as evidenced by the bacterial growth on the edges of the membranes. The microbial, physicochemical and chemical analysis of surface water samples from Sekhukhune area showed that the water was contaminated with Enterobacteriaeceae, E. coli, total coliform with high turbidity and total suspended solids above the South African national standard (SANS 241) water guidelines. After filtration with 1.8 wt.% Ag-MWCNTs/PVDF-HFP composite membrane, turbidity was reduced to 4 Nephelometric turbidity units (NTU), total suspended solids to 1 mg/L while Enterobacteriaeceae, E. coli and total coliform were undetectable and complied with SANS 241 limits. Chromium concentration levels were reduced from 0.194 to 0.0138 mg/L, after filtration with 1.8 wt.% Ag-PAMAM-MWCNTs/PVDF-HFP composite membrane also within acceptable SANS 241 limits. Adsorption studies of all composite membranes demonstrated that the adsorption processes of Cd(II) ions was well conformed to Freundlich model (R2 = 0.999), which suggests that the sorption process met heterogeneous adsorption. However, for Cr(VI) ions studies, the adsorption process was conformed to both Langmuir (R2 = 0.999) and Freundlich (R2 = 0.998) model which suggest that that the adsorption process meet both monolayer and heterogeneous adsorption. The maximum adsorption capacity fitted by Langmuir isotherm was 166.7 and 9.72 mg/g for Cd(II) ions (at optimum pH 6.5) and Cr(VI) ions (at optimum pH 2.5) respectively, using 1 wt.% PAMAM-MWCNTs/PVDF-HFP composite membrane. The adsorption capacities of Cd(II) ions were higher than those of Cr(VI) ions, which is thought to be due to the properties of the composite membrane material. According to the thermodynamic parameters, the Cd(II) and Cr(VI) ions adsorption process was spontaneous and endothermic. Reusability studies showed that PVDF-HFP composite membranes can be reused at least 4 times with an adsorption loss of only 5% for 1 wt.% PAMAMMWCNTs/PVDF-HFP composite membrane, confirmed by TGA and ICP-OES analysis. The 1 wt.% PAMAM-MWCNTs-PVDF-HFP composite membrane exhibited a higher selectivity towards Cd(II) over Cu(II), Zn(II) and Ni(II) in binary and quaternary metal adsorption studies.

Excess fluoride in groundwater used for drinking can pose serious health hazards, especially in poor, rural areas of the developing world lacking water treatment. The World Health Organization recommends a maximum fluoride contaminant level of 1.5 mg/L in drinking water [1]. Over 200 million people in low- and middle-income countries currently drink groundwater over that limit [2]. Current field detection of fluoride typically uses HACH kits, with several groups developing smartphone based alternatives [3]. These methods are based on colorimetry. The HACH kit is limiting because appropriate training is required, results are sensitive to competing ion contamination and chlorine, the glassware must be clean, and repetition is needed to ensure reliability [4]. The use of a smartphone for in-field detection of fluoride is promising and takes a strong step towards quick, easy, reliable, and portable fluoride detection. Our research takes the concept of a portable device one step further by using a fundamentally different, and simpler, mode of detection. We have demonstrated the use of optical fibers as an alternative, non-colourimetric fluoride detection method. The tip of a single mode optical fiber is coated with a thin film of Al and is immersed in an aqueous fluoride solution. The reaction between fluoride and the Al coating changes internal reflection proportional to fluoride concentration which is measured by a photodetector as an output voltage. We made great steps in optimizing the methods, materials, and code required for this sensor. Additionally, we built a device to allow approximate standardization of Al thickness as a function of the distance from the target and time of sputtering. We established the best practical thickness of Al coating, improved repeatability between sputter deposition events, and implemented an optical switch into the experimental set-up. / Graduate / 2021-07-28

No description available.

<p> The optical absorption in manganese fluoride has been studied in the range of 30 to 300 cm^-1 with emphasis placed on the possible multiple magnon absorptions (other than two-magnon) and an induced single magnon absorption. It is shown that theoretically one can expect four-magnon processes by expanding the Heisenberg spin hamiltonian to higher orders in the creation and annihilation operators introduced by the Holstein-Primakoff transformation. However, neither an induced one magnon nor four magnon process was observed. The absorptions which were seen in the spectra were attributed to phonon processes.</p> / Thesis / Master of Science (MSc)

Indiana University-Purdue University Indianapolis (IUPUI) / Background: The importance of fluoride in the prevention of dental caries has been well documented in the literature, as it inhibits demineralization of the tooth structure and enhances remineralization. One of the major public health policies to prevent caries is to provide the population with an adequate amount of fluoride through community water fluoridation. Nowadays many people drink bottled water instead of tap water due to its easy access, convenience, and low cost. Besides fluoride, other minerals present in tap and bottled water, such as calcium and magnesium, are also important in decreasing dental caries prevalence. However, our knowledge of the role of bottled water in caries prevention and especially when combined with fluoride toothpaste usage is still poor. Objectives: The aim of this in-vitro study was to evaluate the effects of some bottled waters on fluoride toothpaste efficacy in enhancing caries lesion remineralization. Methodology: Early caries lesions were created in bovine enamel specimens and stratified into treatment groups based on Vickers surface microhardness (VHN). The present study followed a two (fluoride and fluoride-free toothpaste) by five (four bottled waters and tap water) factorial design. The treatment groups were bottled water with the following attributes: a) 309.9 ppm Ca/1.20 ppm F; b) 118.4 ppm Ca/0.16 ppm F; c) 1.00 ppm Ca/1.01 ppm F; d) 0.1 ppm Ca/0.04 ppm F, and tap water (48.7 ppm Ca/0.7 ppm F). The five water groups were paired either with 1100 ppm fluoride or fluoride-free toothpaste, yielding 10 groups. Specimens were pH-cycled for 10 days with the daily regimen comprised of twice daily toothpaste slurry, with four exposures to water in between. VHN was measured, again, and the difference calculated (ΔVHN). Data were analyzed using two-way ANOVA at a 5-percent significance level. Results: The two-way interaction between water and toothpaste was significant (p < 0.001). All groups except fluoride-free toothpaste/bottled water with 0.1 ppm Ca/0.04 ppm F (p = 0.411) had significant increases in VHN after pH cycling (p ≤ 0.023). Fluoridated toothpaste resulted in a higher rate of remineralization compared to fluoridefree toothpaste (all p < 0.001). Bottled water with 1.20 ppm F/309.9 ppm Ca exhibited the greatest extent of remineralization within fluoride toothpaste groups (p < 0.001) and higher remineralization than lower fluoride water in fluoride-free toothpaste groups (p ≤ 0.006). Within the fluoridated toothpaste group, tap water exhibited significantly less remineralization compared to all bottled waters (all p < 0.001). Conclusion: Within the limitation of this study, bottled water with higher fluoride and calcium concentrations might improve fluoridated toothpaste efficacy by enhancing remineralization of early enamel caries-like lesions.

AbstractObjective: The purpose of the study is to investigate how fluoride content in saliva depends on different fluoride mouth rinses: 1450 ppm, 910 ppm, 225 ppm and to compare a new 1450 ppm fluoride mouth rinse with the other concentrations. Material and method: The study included 17 subjects which rinsed with three different mouth rinses, A (225 ppm), B (1450 ppm) and C (910 ppm) at three different times. They rinsed for 1 minute and then spat out all content in a container. After different intervals they passively transferred their saliva into a given container for 1 minute. The samples were sealed and stored in a freezer until the time of analyzing. After the trial, the samples were taken out of the freezer and were reheated. They were mixed with TISAB III and measured with an ion specific electrode. The group’s values were compared by analyzing the results using Tukey’s test.Results: A visible difference between the three mouth rinses were detected, however, only the difference between mouth rinse A and B were deemed statistically significant at all time points. A statistical significant difference between mouth rinse B and C were found at the time point of 45 minutes. Conclusion: There is a statistical significant difference between the new, high fluoride containing mouth rinse B and mouth rinse A, but there is not enough data in the study to see a statistically significant difference between mouth rinse B and C, or A and C. Further studies need to be made.