A ingestão excessiva de fluoreto por um longo período de tempo pode resultar em fluorose, que pode causar manifestações dentárias e esqueléticas. Danos metabólicos, funcionais e estruturais causados pela fluorose crônica tem sido relatados em vários tecidos. O objetivo deste estudo foi avaliar os efeitos do fluoreto administrado na água de beber, da administração de fluoreto na água de beber na defesa antioxidante de ratos. Quatro grupos de ratos wistar foram usados (n=10/grupo). Os animais receberam água de beber contendo 0 (controle), 5, 15 ou 50 ppm de fluoreto durante 60 dias. Eles foram eutanasiados e os tecidos (fígado, rins e coração) e plasma foram coletados e homogenizados. Superóxido dismutase (SOD), catalase (CAT), glutationa peroxidase (GPx), glutationa reduzida (GSH), substâncias antioxidantes totais (SAT), substâncias reativas ao ácido tiobarbitúrico (TBARS), hidroperóxido de lipídios (HL) e fluoreto foram análisadas. Dados foram analisados por ANOVA e teste de Tukey ou Kruskal-Wallis e teste de Dunn (p<0,05). Nos rins, SOD, GPx, GSH e SAT diminuiram e fluoreto e HL aumentaram significantivamente. No fígado, CAT e TBARS diminuiram, SOD, HL e SAT aumentaram significativamente. No coração, GPx aumentou significativamente. No plasma, SOD e HL diminuiram significativamente. Em resumo, esses resultados mostram que a administração crônica de fluoreto altera o sistema antioxidante de ratos. Nosso dados sugerem que a exposição em níveis elevados de fluoreto, a conversão do ânion superóxido em água nos rins parecem ocorrer principalmente através da SOD e CAT, com baixa participação do sistema glutationa, diferindo do que parece ocorrer no fígado. / Excessive fluoride intake over a long period of time could result in fluorosis, which can lead to dental and skeletal manifestations. Metabolic, functional and structural damages caused by chronic fluorosis have been reported in many tissues. The aim of this study was to evaluate the effect of fluoride, administered in drinking water, in the antioxidant defense of rats. Four groups of Wistar rats were included (n=10/group). The animals received drinking water containing 0 (control), 5, 15 or 50 ppm of fluoride during 60 days. They were euthanized and the tissues (liver, kidney and heart) and plasma were collected and homogenized. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), antioxidants, thiobarbituric acid reactive substances (TBARS), lipid hydroperoxide (LH), and fluoride were analyzed. Data were analyzed by ANOVA and Tukeys test or Kruskal-Wallis and Dunns tests (p<0.05). In the kidney SOD, GPx, GSH and SAT decreased and fluoride and LH increased significantly. In the liver, CAT and TBARS decreased and fluoride, SOD, LH and SAT increased significantly. In the heart, GPx increased significantly. In the plasma, SOD and LH decreased significantly. In summary, these results show that chronic fluoride administration alters the antioxidant system of the rats. Our data suggest that upon exposure to high levels of fluoride, the conversion of the superoxide anion to water in the kidney seems to occur mainly through the SOD and CAT, with a low participation of the glutathione system, differing from what seems to occur in the liver.

O objetivo deste estudo foi comparar a concentração de flúor do biofilme dental de indivíduos residenteste em áreas com água fluoretada (AF) ou sal fluoretado (SF) e determinar o efeito do dentifrício fluoretado na concentração de flúor [F] do biofilme dental destes indivíduos. Dezesseis indivíduos resendentes em Montevidéu (SF) e dezesseis indivíduos residentes em Porto Alegre (AF) participaram deste estudo randomizado, cruzado e duplo-cego. Profilaxia dental e raspagem supragengivel foram realizaras antes de cada fase experimental. Durante as fases experimentais (14 dias/cada), os indivíduos escovaram os dentes, 2x/dia, com dentifrício fluoretado (DF) ou dentifrício não-fluoretado (DNF). As amostras de biofilme dental foram coletadas 8 horas após a última escovação. As análises de [F] no biofilme dental foram realizadas com um íon epecífico e as leituras foram convertidas em μgF¯/g de biofilme. Equações de estimativas generalizadas foram aplicadas para analisar a variância de medidas repetidas e as diferenças em cada desfecho. Uma maior [F] no biofilme foi observada na área com SF(2.69±0.10 IC 2.48–2.89) em comparação a área com AF (2.44±0.06 IC 2.32-2.57) quando do uso regular de DNF (p = 0.047). Entretanto, não houve diferença significativa na [F] no biofilme entre as áreas com SF (2.60±0.12 IC 2.37-2.83) e AF (2.81±0.10 CI 2.62-3.01) quando do uso de FD (p = 0.153). Adicionalmente, não foi observada diferença siginifcativa na [F] do biofilme quando DF e DNF foram usados nas áreas com SF (p = 0.294) e AF (p = 0.320). A maior [F] no biofilme observada na área com SF, sob uso regular DNF, pode não ter significância clínica, uma vez que ela desapareceu quando o DF foi usado. / The aim of this study was to compare the fluoride concentration in dental biofilm of subjects living in fluoridated- salt (FS) or water (FW) areas and to determine the effect of fluoride dentifrice on the fluoride concentration [F] in dental biofilm of these subjects. Sixteen individuals residing in Montevideo (FS) and sixteen individuals living in Porto Alegre (FW) participated in this randomized, double-blind, crossover study. Dental prophylaxis and scaling were performed prior to each experimental phase. During the experimental phases (14d/each) subjects brushed their teeth, 2x/day, with fluoridated dentifrice (FD) or non-fluoridated fluoride (NFD). Dental biofilm samples were collected 8 hours after the last toothbrushing. Analyses were performed with a fluoride ion-specific electrode and the reading was transformed into μgF¯/g biofilm. Generalized estimating equations were used to analyze the variance for repeated measures and the differences in each outcome. Higher biofilm [F] was found in FS (2.69±0.10 CI 2.48–2.89) compared to FW (2.44±0.06 CI 2.32-2.57) areas under regular use of NFD (p = 0.047). However, no significant differences were found on dental biofilm [F] between FW (2.60±0.12 CI 2.37-2.83) and FS (2.81±0.10 CI 2.62-3.01) areas under FD use (p = 0.153). Furthermore, no significant difference was observed in the biofilm [F] when FD or NFD were used in the FS (p = 0.294) and FW (p = 0.320) areas. The higher dental biofilm [F] was found in FS areas under NFD use may not have clinical significance once it disappeared when FD was used.

Karies muss nicht zwangsweise durch invasives Bohren und anschließendes Restaurieren des Zahns behandelt werden. Beginnenden Entmineralisierungen der Zahnhartsubstanz kann heutzutage in verschiedener Weise substanz¬schonend entgegengewirkt werden. Ziel der vorliegenden In-vitro-Studie war es das Remineralisationspotential diverser neuartiger, zahnärztlicher Fluoridlacke auf initialen Schmelzläsionen zu untersuchen. Hierfür wurden aus gesunden, bovinen Zähnen Probenblöcke (n= 276) hergestellt und zufällig in zwölf Versuchsgruppen eingeteilt. Nach dem Erzeugen einer künstlichen Schmelzkaries durch 21-tägiges Lagern der Proben in einer Demineralisationslösung, wurden den Herstellerangaben folgend verschiedene Fluoridlacke appliziert: a) Natriumfluorid (Duraphat, 22.600 ppm F), b) Natriumfluorid in Kombination mit Kalziumfluorid (Biophat, 45.200 ppm F-), c) Natriumfluorid in Kombination mit Trikalziumphosphat (Clinpro White Varnish Mint, 22.600 ppm F-), d) Natriumfluorid in Kombination mit Casein Phospho¬peptid - amorphem Kalziumphosphat (MI Varnish, 22.600 ppm F-) und e) Silber-Diamin-Fluorid (Cariestop 30%, 35.400 ppm F-). Zwei Gruppen erfuhren zur Kontrolle keine Behandlung mit einem Lack. Um eine realitätsgetreue Umgebungssituation ähnlich der Mundhöhle zu simulieren, lagerten die Proben 28 Tage in einem pH-Wechselbad (6x120 Min Demineralisation/Tag). Zweimal täglich sorgten in verdünnter fluoridhaltiger Zahnpasta (14500 ppm F-, bzw. 5000 ppm F- Zahnpasta) getränkte Bürsten für die Reinigung der Schmelzoberflächen für je 10 Sekunden. Alle Proben wurden nach der 21-tägigen Demineralisationsphase, sowie nach der Lackbehandlung fotografiert und hinsichtlich der Läsionstiefe und des Mineralverlustes analysiert. Hierfür wurde die Technik der Transversalen Mikroradiographie zur Hilfe genommen. Alle angewandten Fluoridlacke führten zu einem signifikant geringeren Mineralverlust, sowie einem geringeren Fortschreiten der Läsionstiefe nach pH-cycling im Vergleich zur Negativkontrolle N1/N5 ohne Lackbehandlung (p≤0,043; außer NaF5, CPP5, SDF5). Unter den gewählten Versuchsbedingungen wurde jedoch alleinig durch die Behandlung mit Natriumfluorid in Kombination mit Kalziumfluorid (CaF1/CaF5) eine Remineralisation der künstlichen Schmelzkaries erzielt. Ein signifikanter Unterschied zwischen der Verwendung von 5.000 ppm F- Zahnpasta zu 1.450 ppm F- Zahn¬pasta hin¬sichtlich einer Verbesserung der Remineralisationsparameter konnte nur bei den Negativ¬kontrollgruppen festgestellt werden. Hochfluoridhaltige Zahnpasta in Kombination mit zahnärztlichen Lacken erzeugte hingegen keinen zusätzlichen Effekt im Vergleich zu normalfluoridhaltiger Zahnpasta in Kombination mit zahnärztlichen Lacken.:Inhaltsverzeichnis Abkürzungsverzeichnis IV 1 Einleitung 1 2 Literaturübersicht 3 2.1 Zahnschmelz 3 2.1.1 Aufbau und Eigenschaften 3 2.1.2 Rinderzahnschmelz als Ersatzmaterial für In-vitro-Versuche 6 2.2 Karies 7 2.2.1 Grundzüge der Kariesätiologie 8 2.2.2 Demineralisation und Remineralisation 9 2.3 Fluoride 12 2.3.1 Wirkungsweisen 12 2.3.2 Fluoridierungsmaßnahmen 13 3 Zielsetzung 21 4 Material und Methoden 23 4.1 Stichprobenumfangsplanung 23 4.2 Probenherstellung 23 4.3 Erzeugen einer künstlichen Kariesläsion 26 4.4 Erstellen von Dünnschliffen 28 4.5 Kolorimetrische Analyse 30 4.5.1 Fotoaufnahmen der Probe 30 4.5.2 Farbanalyse 32 4.5.3 Gruppeneinteilung 32 4.6 Probenbehandlung 33 4.7 pH-cycling 35 4.8 Analysen 37 4.8.1 Transversale Mikroradiographische Analyse 37 4.8.2 Kolorimetrische Analyse 38 4.9 Digitalisierung und Auswertung der Aufnahmen 38 4.9.1 Statistische Auswertung 40 5 Ergebnisse 42 5.1 Validierung des Stichprobenumfangs 42 5.2 TMR-Analyse - Ergebnisse des Mineralgehalts 43 5.2.1 ΔZDT 43 5.2.2 ΔZST 45 5.3 TMR-Analyse - Ergebnisse der Läsionstiefe 47 5.3.1 LDDT 47 5.3.2 LDST 48 5.4 Kolorimetrische Analyse 49 5.5 Graphische Auswertung des Läsionsverlaufs 51 6 Diskussion 54 6.1 Diskussion des In-vitro-Modells 54 6.2 Diskussion der Ergebnisse 56 7 Zusammenfassung 64 8 Summary 66 9 Verzeichnisse I 9.1 Abbildungsverzeichnis I 9.2 Tabellenverzeichnis II 9.3 Diagrammverzeichnis II 9.4 Literaturverzeichnis III 10 Erklärung über die eigenständige Abfassung der Arbeit IX 11 Lebenslauf X 12 Danksagung XI / The treatment of caries does not necessarily require invasive measures. Initial demineralization of the tooth substance can also be counteracted in various ways without sacrificing further substance losses. The aim of this study was to compare the caries preventive effect of different fluoride varnishes on sound enamel, as well as on artificial enamel caries-like lesions. For this purpose, bovine enamel specimens (n = 276) with one sound surface [ST] and one artificial caries lesion [DT] were prepared and randomly allocated to twelve groups. The interventions before pH-cycling were: application of a varnish containing NaF (Duraphat, 22.600 ppm F-, NaF1/NaF5), NaF plus calcium fluoride (Biophat, 45.200 ppm F-, CaF1/CaF5), NaF plus tricalcium phosphate (Clinpro White Varnish Mint, 22.600 ppm F-, TCP1/TCP5), NaF plus CPP-ACP (MI Varnish, 22.600 ppm F-, CPP1/CPP5) and silver diamine fluoride (Cariestop 30%, 35.400 ppm F-, SDF1/SDF5). One group got no intervention. During the pH-cycling (28 days, 6x120 min demineralization/day) the half of the specimens of every group were brushed (10 s; 2x/d) with either 1.450 ppm F- or 5.000 ppm F- dentifrice slurry. The differences in view of the mineral loss, lesion depth and the color gradient between the two states after initial demineralization and after pH-cycling were investigated by a transversal microradiograph and a colorimetric analysis. The treatments of all varnishes showed a significantly lower increase in mineral loss and lesion depth after pH-cycling in comparison to the negative control without an intervention (p ≤ 0.043; except NaF5, CPP5, SDF5). However under the conditions chosen, only NaF + CaF could remineralize artificial enamel caries-like lesions. A significant difference between the use of 5.000 ppm F- toothpaste and 1.450 ppm F- toothpaste in terms of an enhanced remineralization could only be observed in groups N1/N5. The applications of a varnish in combination with the highly fluoridated toothpaste did not result in a significant difference in comparison to a varnish in combination with normal fluoridated toothpaste.:Inhaltsverzeichnis Abkürzungsverzeichnis IV 1 Einleitung 1 2 Literaturübersicht 3 2.1 Zahnschmelz 3 2.1.1 Aufbau und Eigenschaften 3 2.1.2 Rinderzahnschmelz als Ersatzmaterial für In-vitro-Versuche 6 2.2 Karies 7 2.2.1 Grundzüge der Kariesätiologie 8 2.2.2 Demineralisation und Remineralisation 9 2.3 Fluoride 12 2.3.1 Wirkungsweisen 12 2.3.2 Fluoridierungsmaßnahmen 13 3 Zielsetzung 21 4 Material und Methoden 23 4.1 Stichprobenumfangsplanung 23 4.2 Probenherstellung 23 4.3 Erzeugen einer künstlichen Kariesläsion 26 4.4 Erstellen von Dünnschliffen 28 4.5 Kolorimetrische Analyse 30 4.5.1 Fotoaufnahmen der Probe 30 4.5.2 Farbanalyse 32 4.5.3 Gruppeneinteilung 32 4.6 Probenbehandlung 33 4.7 pH-cycling 35 4.8 Analysen 37 4.8.1 Transversale Mikroradiographische Analyse 37 4.8.2 Kolorimetrische Analyse 38 4.9 Digitalisierung und Auswertung der Aufnahmen 38 4.9.1 Statistische Auswertung 40 5 Ergebnisse 42 5.1 Validierung des Stichprobenumfangs 42 5.2 TMR-Analyse - Ergebnisse des Mineralgehalts 43 5.2.1 ΔZDT 43 5.2.2 ΔZST 45 5.3 TMR-Analyse - Ergebnisse der Läsionstiefe 47 5.3.1 LDDT 47 5.3.2 LDST 48 5.4 Kolorimetrische Analyse 49 5.5 Graphische Auswertung des Läsionsverlaufs 51 6 Diskussion 54 6.1 Diskussion des In-vitro-Modells 54 6.2 Diskussion der Ergebnisse 56 7 Zusammenfassung 64 8 Summary 66 9 Verzeichnisse I 9.1 Abbildungsverzeichnis I 9.2 Tabellenverzeichnis II 9.3 Diagrammverzeichnis II 9.4 Literaturverzeichnis III 10 Erklärung über die eigenständige Abfassung der Arbeit IX 11 Lebenslauf X 12 Danksagung XI

Orientador: Sandra Helena Penha de Oliveira / Banca: Marília Afonso Rabelo Buzalaf / Banca: Carlos Ferreira dos Santos / Resumo: O declínio mundial da cárie dentária é atribuído ao uso abrangente do flúor. Embora esse elemento seja capaz de proteger os dentes, seu uso excessivo pode levar a uma ação citotóxica causando a inibição do crescimento celular, da síntese de proteínas e até mesmo a morte celular. O primeiro objetivo deste estudo foi investigar a concentração ideal do NaF (NaF) capaz de ativar os fibroblastos gengivais de camundongos sem induzir morte celular. Observou-se que, nesses fibroblastos, a concentração de 40 μg F/mL induziu morte celular de 62,6 %. Na concentração de 20 μg F/mL a morte celular foi de apenas 22,1%. Com base nesses resultados, optou-se por utilizar a concentração de 20 μg F/mL como dose máxima para investigar os mecanismos envolvidos na ativação dos fibroblastos gengivais. Dessa forma, avaliou-se a capacidade do NaF induzir a expressão de MMP-2 e MMP-9 pelos fibroblastos gengivais de camundongos na presença ou ausência de LPS, assim como a produção da quimiocina CCL-3/MIP-1α e óxido nítrico. Avaliou-se também a participação das vias de sinalização intracelular p44/42, p38, PI3K e NF-кB envolvidas durante essa ativação, por meio da utilização dos respectivos inibidores PD98059 (50 μM), SB202190 (10 μM), LY294002 (30 μM) e dexametasona (10 μM). Observou-se que o NaF foi capaz de estimular os fibroblastos gengivais a expressarem MMP-9, mas não MMP-2, na concentração de 20 μg F/mL com pico máximo 6 horas após, retornando aos níveis normais 24 horas após. A produção da quimiocina CCL3/MIP-1α pelos fibroblastos estimulados pelo NaF também foi observada com a concentração de 20 μg F/mL com pico máximo 6 horas após estímulo. Na presença de LPS, observou-se uma potenciação da expressão de MMP-9 e produção de CCL3/MIP-1α na concentração de 20 μg F/mL, 6 horas após. / Abstract: The worldwide decline of the dental caries is attributed to the widespread use of fluoride. Although this element is capable of protecting the teeth, its excessive use, can lead to a cytotoxic action, causing an inhibition of the cell growth, of the protein synthesis and even the cellular death. Based on these results, we have chosen to use a concentration of 20 μ g F/mL as maximum concentration to investigate the mechanisms involved in the activation of the gingival fibroblasts. It was observed that, on those fibroblasts, the concentration of 40 μg F/mL has resulted in a death cellular index of 62.6%. In the concentration of 20 μg F/mL the cellular death was of 22.1% only. Based on these results, the concentration of 20 μg F/mL has been chosen as maximum concentration to investigate the mechanisms involved in the activation of the gingival fibroblasts. Later, the ability of NaF to induce the expression of MMP-2 and MMP-9 in gingival fibroblasts of mice in the presence or absence of LPS has been assessed, as well as the production of chemokine CCL-3/MIP-1a and nitric oxide. It also evaluated the participation of intracellular signaling pathways p44/42, p38, PI3K e NF-kB involved in this activation, through inhibitors PD98059 (50 μM), SB202190 (10 μM), LY294002 (30 μM) e dexamethasone (10 μM). It was observed that the NaF was capable to stimulate the gingival fibroblasts to express MMP-9, at the concentration of 20 μgF/mL with maximum peak 6 hours after, returning to normal levels 24 hours after. The expression of MMP-2 was not observed. The production of chemokine CCL3/MIP-1α was also observed with the concentration of 20 μgF/mL with maximum peak 6 hours after the stimulation. In the presence of LPS, it was observed an intensification in the expression of MMP-9 and also in the production of CCL3/MIP-1α at the concentration of 20 μgF/mL, 6 hours later. / Mestre

Text in Afrikaans / Die tydruimtelike variasie in die fluoriedinhoud vannatuurlike drinkwater en in die voorkoms van tandfluorose, die verband tussen hierdie veranderlikes asook hulle kovariasie is op 'n hoe resolusievlak in geselekteerde endemiese gebiede ondersoek. Die drie studiegebiede verskil grootliks van mekaar wat sommige fisies- en menslik-geografiese kenmerke betref, maar ondergrondse water was oral die belangrikste bron van drinkwater. Ioonspesifieke analise en laboratoriumtegnieke is gebruik om die fluoriedinhoud van die drinkwater uit 517 bronne te bepaal. Die tande van 3 068 kinders is klinies en fotografies ondersoek. Die erkende Tooth Fluorosis Index en die indeks van Dean is gebruik om die voorkoms van fluorose te beskryf. Grafiese tegnieke, beskrywende statistieke en nieparametriese analise van variansietoetse is gebruik om die voorkoms en tydruimtelike variasiepatrone van die sleutelveranderlikes in elke studiegebied, asook die verskillende ruimtelike eenhede binne die studiegebiede, te beskryf. Die verband tussen die sleutelveranderlikes asook hul intra- en interareale kovariasie is ontleed. Daar is gevind dat die fluoriedinhoud van die ondergrondse water in die Pilanesberg- en Hammanskraal-studiegebied relatief hoog tot hoog is en die in die Vrystaat-studiegebied relatief laag. Ruimtelike veranderlikheid met groot verskille oor klein afstande kenmerk die fluoriedinhoud van ondergrondse water ongeag die gesteentes waaruit dit onttrek word. Middelwaardes bied ontoereikende beskrywings van die fluoriedgehalte van die drinkwater. Die skep van nuwe drinkwaterbronne veroorsaak langtermynvariasie in die fluoriedinhoud van die beskikbare drinkwater. Fluoroseprevalensie in die studiegebiede bet van 62% tot 87% gewissel, met meer ernstige aantasting in die Pilanesberg- en Hammanskraal-gebied as in die Suid-Vrystaat. Beduidende intra-areale ruimtelike variasie is 'n wesenlike kenmerk van die voorkoms van fluorose in al drie studiegebiede. In alle gevalle het die variasiepatroon in die fluoriedinhoud van die drinkwater die in die voorkoms van fluorose slegs gedeeltelik verklaar. Sporadiese en/of periodieke kortstondige blootstelling aan hoe fluoriedkonsentrasies lei tot emstige aantasting ten spyte van die gereelde gebruik van water met 'n laefluoriedinhoud. Ligte fluorose ontwikkel geredelik in assosiasie met <0,5 mgF-/l en matige fluorose in assossiasie met 0,5-0,7 mgF-/l, die optimum konsentrasieinterval vir fluoridasie in Suid-Afrika. / The spatiotemporal variation in the fluoride content of natural drinking water and the occurrence of dental fluorosis, the relation between these variables as well as their covariation were investigated at a high resolution level in selected endemic areas. Groundwater was the most important source of drinking water in all three study areas, but they differed markedly in respect of some physical and human geographical characteristics. Ion specific analysis and laboratory techniques were used to determine the fluoride content of the water from 517 sources. The teeth of 3 068 children were examined clinically and photographically. The fluorosis was scored according to the Tooth Fluorosis Index and Dean's classification. Graphical techniques, descriptive statistics and nonparametric analysis of variance were used to describe the occurrence and variation patterns of the key variables in the different spatial units is each study area. The relation between the variables as well as their intra and interareal covariation were analysed. The fluoride content of the groundwater in the Pilanesberg and Hammanskraal areas was relatively high to high; in the southern Free State it was relatively low. Spatial variability and significant differences over small distances typify the fluoride content of the groundwater, irrespective of the aquifer. Central statistics inadequately describe the fluoride quality of the natural drinking water. The development of new water sources causes long term variation in the fluoride content of the available drinking water. Fluorosis prevalence varied form 62% to 87%, with more severe fluorosis in Pilanesberg and Hammanskraal than in the southern Free State. Significant intra-areal spatial variation is an attribute of fluorosis in all three study areas. In all cases the variation pattern in the fluoride content of the drinking water partly explained the spatial pattern in the occurrence of fluorosis. Sporadic and/or periodic brief exposure to high fluoride concentrations leads to severe fluorosis despite regul~ usage of water with a low fluoride content. Mild fluorosis readily develops in association with <0,5 mgF-1~ and medium fluorosis in association with 0,5-0,7 mgF-/l, the optimum concentration interval for fluoridation in South Africa. / Geography / D. Phil. (Geografie)

Fluoride naturally occurs in some ground and surface waters at high concentrations all around the world. Due to increasing health concerns about over-exposure to fluoride in drinking water, the United States Environmental Protection Agency (USEPA) has begun to review fluoride as a drinking water contaminant. Should the USEPA decide to lower the fluoride maximum contaminant limit (MCL), many water systems in addition to those already struggling to meet the fluoride MCL will require defluoridation as part of their drinking water treatment process. Alum coagulation was investigated as a defluoridation treatment strategy in this research project. Surface and blended (ground/surface) drinking water sources with high fluoride concentrations pose a unique challenge to defluoridation by alum coagulation because of the presence of both natural organic matter (NOM) and fluoride. Defluoridation of synthetic and natural waters using jar tests elucidated interactions of fluoride, NOM, and aluminum during alum coagulation. Alum coagulation was able to remove 80% of fluoride from natural waters with a 500 mg/L alum dose; however, 50% fluoride removal was observed to be possible with an alum dose of 150-170 mg/L. The optimum pH for fluoride removal in synthetic and natural waters was observed to be approximately 6.5 and was found to be an important factor in determining the overall performance of alum coagulation. The presence of fluoride during alum coagulation was found to reduce the removal of three low molecular weight (LMW) organics, acting as surrogates for NOM, to different extents depending on their functionality. The presence of LMW organic acids in synthetic waters did not impact the removal of fluoride; however, increasing NOM concentrations in the natural waters likely accounted for decreasing fluoride removals observed in the natural waters. Additional jar tests with natural waters revealed that pH adjustment was unnecessary for defluoridation of high pH and high alkalinity waters and that an enhanced precipitation effect occurred at low alum doses when no pH adjustment was made during alum coagulation. The enhanced precipitation effect caused comparable or enhanced removals of fluoride and NOM to be observed despite system pH values being higher than the optimal defluoridation pH of 6.5. Lower aluminum residuals were also observed as part of the enhanced precipitation effect, suggesting that when precipitation begins under high pH conditions, fluoride interference does not occur and therefore promotes more precipitate formation with greater available surface area for adsorption. However, as precipitation occurs, pH drops, and fluoride increasingly interacts with the aluminum precipitate resulting in greater overall fluoride removals. / text

The purpose of this study was to investigate the effects of a fluoride releasing orthodontic primer on demineralization adjacent to brackets. Twenty-two patients were recruited for this study. One premolar was randomly chosen as the experimental tooth, the contralateral tooth was the control. Teeth were visually analyzed for white spot lesions (WSLs). Knoop microhardness was used to determine hardness. Visual examination results showed no significant difference in the number of WSLs observed between Opal Seal and Transbond XT over the duration of this study. Solid conclusions could not be drawn from the results of microhardness testing. Therefore, it cannot be concluded that there is a difference in enamel hardness between Opal Seal and Transbond XT. However, prior to 90 days, teeth showed a significant difference in WSLs. Suggesting a protective effect of Opal Seal that diminished with time. Future studies are necessary to determine the clinical performance of this product.

Purpose: The purpose of this study was to asses fluoride varnish use by dental practitioners in Virginia. Methods: Using a cross sectional survey design, all dentists in Virginia who are members of the Virginia Dental Association (VDA) were sent an online survey about usage and knowledge of fluoride varnish. Results: The majority of the respondents were general dentists (79%) followed by pediatric dentists (12%). Fluoride varnish use increased with year of graduation from dental school. Dentists who thought fluoride varnish was more effective and less time consuming use it more than other topical fluorides. Dentists who thought their patients prefer fluoride varnish use it more than other topical fluorides.Conclusion: The majority of dentists are not aware of the advantages of fluoride varnish. However, those who are, choose to use it as opposed to foams and gels. Recent graduates, with more exposure to fluoride varnish, use it more frequently.

The theoretical work presented in this thesis is concerned with the highest possible oxidation states of the 5d transition metal row. Based on a validation study of several DFT functionals against accurate coupled-cluster CCSD(T) methods we will present calculations on a series of new high oxidation state HgIV species. Quantum-chemical calculations have also been applied to various fluoro complexes of gold in oxidation states +V through +VII to evaluate the previously claimed existence of AuF7. The calculations indicate clearly that the oxidation state (+V), e.g., in [AuF5]2, remains the highest well-established gold oxidation state. Further calculations on iridium in oxidation state (+VII) show that IrF7 and IrOF5 are viable synthetic targets, whereas higher oxidation states of iridium appear to be unlikely. Structures and stabilities of several osmium fluorides and oxyfluorides were also studied in this thesis. It is shown that homoleptic fluorides all the way up to OsF8 may exist. Combining the results of the most accurate quantum-chemical predictions of this thesis and of the most reliable experimental studies, we observe a revised trend of the highest oxidation states of the 5d transition metal row. From lanthanum (+III) to osmium (+VIII), there is a linear increase of the highest oxidation states with increasing atomic number. Thereafter, we observe a linear descent from osmium (+VIII) to mercury (+IV). We will also present a short outlook to the transition metals of the 3d and 4d row and their highest reachable oxidation states. / In der vorliegenden theoretischen Arbeit wurden mittels quantenchemischer Methoden die höchsten Oxidationsstufen der späten Übergangselemente untersucht. Um eine adäquate Beschreibung dieser Systeme zu gewährleisten, wurde zuerst eine Validierungsstudie verschiedener Dichtefunktionale, die mit hochgenauen coupled-cluster CCSD(T) Berechnungen verglichen wurden, durchgeführt. Das zugrundeliegende Referenzsystem war Quecksilber in der Oxidationsstufe +IV (HgF4, HgCl4, HgH4). Es wurden Strukturoptimierungen von Minima und Übergangszuständen, Atomisierungsenergien sowie die entsprechenden Zerfallsreaktionen für die Systeme betrachtet. Basierend auf diesen Ergebnissen konnten weitere HgIV Systeme mit sogenannten „Weakly Coordinating Anions“ wie z.B. [OTeF5]-, [AsF6]-, [Sb2F11]- usw. unter Verwendung von Dichtefunktionalmethoden untersucht werden. Die beiden Verbindungen Hg[OTeF5]4 und Hg[AsF6]4 scheinen dabei die Oxidationsstufe +IV am besten zu stabilisieren. Quantenchemische Methoden wurden ebenfalls zur Berechnung von Fluorkomplexen des Goldes in den Oxidationsstufen von +V bis +VII verwendet. Dabei wurde insbesondere überprüft, ob das angeblich experimentell gefundene AuF7 tatsächlich existiert. Es konnte gezeigt werden, dass eine Existenz von AuF7 unter den in der Literatur angegebenen Bedingungen sehr wahrscheinlich ausgeschlossen werden kann. Diese Instabilität wird ebenfalls für das quantenchemisch untersuchte AuF6 beobachtet. Somit bleibt die Oxidationsstufe +V in [AuF5]2 die höchste erreichbare Oxidationsstufe für Gold. Basierend auf coupled-cluster CCSD(T) Berechnungen konnten die Verbindungen des Iridiums in der Oxidationsstufe +VII (IrF7, IrOF5) als thermochemisch stabil vorhergesagt werden, wohingegen die höheren Iridiumverbindungen des IrVIII und IrIX sehr unwahrscheinlich sind. Außerdem wurden Strukturen und Stabilitäten verschiedener Osmiumfluoride und Oxyfluoride in dieser Arbeit diskutiert. Es konnte gezeigt werden, dass ausgehend von OsF6 auch die höheren Verbindungen OsF7 und OsF8 experimentell zugänglich sein sollten. Kombiniert man die in dieser Arbeit vorhergesagten Verbindungen in ihren höchsten Oxidationsstufen mit den verlässlichsten experimentellen Untersuchungen, so beobachtet man einen revidierten Trend der höchsten Oxidationsstufen der 5d-Übergangsmetallreihe: Direkt proportional zur Ordnungszahl steigen die höchsten Oxidationszahlen zunächst linear an, von Os (+VIII) bis hin zu Hg (+IV) kann ein linearer Abfall beobachtet werden. Abschließend werden in dieser Arbeit die höchsten Oxidationsstufen der 3d und 4d Übergangsmetalle in einer kurzen Übersicht vorgestellt.

A ingestão de dietas com níveis elevados de flúor interfere na mineralização óssea e, conseqüentemente, poderá influenciar nas propriedades mecânicas dos ossos. Este trabalho teve como objetivo estudar e avaliar algumas propriedades mecânicas de fêmures de coelhos submetidos a dietas com diferentes concentrações de flúor, mediante ensaios mecânicos de flexão em três pontos. Foram utilizados os fêmures de 40 coelhos machos, albinos, da raça Nova Zelândia com 1 mês de idade. Durante 40 dias os animais, divididos em 5 grupos, receberam dietas contendo diferentes concentrações de flúor. As propriedades mecânicas da deformação proporcional e resiliência, apresentaram diferença estatisticamente significante. Houve redução nos valores para rigidez, tensão máxima, carga máxima, mas sem diferença estatisticamente significante, para os grupos com maior concentração de flúor. Diante destas considerações e dos achados neste trabalho, fica evidente a necessidade de mais investigações para caracterizar a relação entre o flúor e as propriedades mecânicas. / High levels of fluoride ingestion may interfere with bone mineralization and, therefore, cause modification in the bone mechanical properties. In this investigation we studied the relationship between some mechanical properties of the rabbit femur and different concentration of fluoride in the diets. It was performed the three bending test in forty femurs obtained from New Zealand white rabbits that had been fed with diet with different fluoride concentration during 40 days since they were one month old. The animals were divided into 5 different groups according to the fluoride concentration in diets. The resilience and proportional deformation were higher for the group with the highest fluoride ingestion and there was no difference among the other groups. Rigidity, ultimate load and tension were lower as fluoride concentration increased but with no statistical difference. It was concluded that more investigation is necessary to establish the relationship of the mechanical properties with fluoride intake.