O balanço do fluoreto (F) dentro do corpo é modulado por sua ingestão, absorção e remoção, e os rins, responsáveis pela sua excreção do organismo, são particularmente vulneráveis à toxicidade do F. Os efeitos nefrotóxicos do F envolvem mudanças estruturais marcantes nos rins, além disso, estudos proteomicos têm mostrado grandes alterações no perfil de proteínas envolvidas em pontos chave na transdução de sinal. Estes efeitos podem influenciar negativamente no transporte iônico nos rins. A vista deste fato, o transporte iônico no canal de sódio epitelial (ENaC) é limitante para a taxa de reabsorção de sódio nos rins, sendo essencial para a manutenção do equilíbrio eletrolítico e homeostase do corpo. Assim, este trabalho objetivou investigar os efeitos do F, utilizando concentrações semelhantes às que podem ser encontradas no néfron durante a fluorose dentária, na viabilidade celular e expressão de transportadores de membrana (ENaC) em linhagem celular renal M-1. Para os ensaios de viabilidade das células da linhagem M-1 foi empregado os testes colorimétricos Cristal Violeta e MTT, utilizando as concentrações de tratamento com fluoreto de sódio (NaF) a 10, 40, 100, 200 e 400 M, durante períodos experimentais de 24, 48, 72 e 96 h. As mesmas concentrações e os mesmos tempos foram utilizados no tratamento com cloreto de sódio (NaCl), utilizado como controle na possível interferência de Na+ na modulação das células. Para a investigação da influência do F: 1) nos canais ENaC foi utilizada a técnica de imunofluorescência e 2) para a análise de expressão gênica das subunidades que formam o ENaC, foi utilizada a técnica RT-PCR. Em nossos resultados pudemos observar que as maiores concentrações tanto de NaF quanto de NaCl provocaram a diminuição da viabilidade celular para ambos os ensaios de viabilidade, no entanto, foi possível observar algumas diferenças na resposta do tratamento com NaF em comparação com NaCl, por meio do ensaio Cristal Violeta. Não foi observado diferenças nas imagens de imunofluorescêcia, mas outros aspectos morfológicos foram vistos nessas imagens, como o aparecimento de domes celular, sugerindo que até mesmo a maior concentração de F não foi capaz de inibir a proliferação celular. Nosso resultado mais significativo foi em relação à expressão das subunidades dos canais de ENaC, onde a concentração de 400 M foi capaz de diminuir bruscamente a expressão das três subunidades do ENaC, enquanto as concentrações de 100 e 200 M mostraram apresentar expressão igual e em alguns casos até maior que o grupo controle. Pudemos concluir que doses de F na ordem de micromolares podem modular a expressão das subunidades formadoras do ENaC, positivamente quando em baixas concentrações e negativamente quando em concentrações elevadas. / The balance of fluoride (F) within the body is modulated by its ingestion, absorption and removal, and the kidneys, responsible for their excretion of the organism, are particularly vulnerable to the toxicity of F. The nephrotoxic effects of F involve marked structural changes in the kidneys , in addition, proteomic studies have shown large changes in the profile of proteins involved in key points in signal transduction. These effects may negatively influence ion transport in the kidneys. In view of this fact, the ionic transport in the epithelial sodium channel (ENaC) is limiting to the rate of sodium reabsorption in the kidneys, being essential for the maintenance of the electrolyte balance and homeostasis of the body. Thus, the objective of this work was to investigate the effects of F, using concentrations similar to those found in the nephron during dental fluorosis, cell viability and expression of membrane transporters (ENaC) in renal cell line M-1. For the M-1 cell line viability assays, the Crystal Violet and MTT colorimetric assays were used, using the 10, 40, 100, 200 and 400 M sodium fluoride (NaF) treatment concentrations during experimental periods of 24, 48, 72 and 96 h. The same concentrations and the same times were used in the treatment with sodium chloride (NaCl), used as control in the possible interference of Na + in the modulation of the cells. For the investigation of the influence of F: 1) in the ENaC channels, the immunofluorescence technique was used and 2) for the analysis of gene expression of the subunits that form the ENaC, the RT-PCR technique was used. In our results it was observed that the higher concentrations of NaF and NaCl caused a decrease in cell viability for both viability assays, however, it was possible to observe some differences in NaF treatment response in comparison to NaCl, through test Crystal Violet. No differences were observed in immunofluorescence images, but other morphological aspects were seen in these images, such as the appearance of cellular \"domes\", suggesting that even the highest F concentration was not able to inhibit cell proliferation. Our most significant result was the expression of the subunits of the ENaC channels, where the concentration of 400 M was able to decrease expression of the three subunits of the ENaC, whereas the concentrations of 100 and 200 M showed equal expression and in some cases even higher than the control group. We can conclude that doses in the order of micromolar the F can modulate the expression of the ENaC forming subunits, positively when in low concentrations and negatively when in high concentrations.

Este estudo foi realizado a fim de avaliar a microdureza da dentina radicular adjacente a materiais restauradores contendo fluoretos após desafios erosivos. Foi utilizado um delineamento crossover de duas fases de 4 dias consecutivos cada. Cento e doze fragmentos de dentina bovina foram obtidos, nos quais foi confeccionada uma cavidade padronizada no centro de cada um. Estas cavidades foram restauradas aleatoriamente com cimento de ionômero de vidro (Ketac-fil) ou resina composta (Filtek Z-250). Em seguida, os fragmentos restaurados foram distribuídos aleatoriamente entre os 14 voluntários, montados em aparelhos, cada um com 4 espécimes restaurados com o mesmo material. A partir do segundo dia, metade do aparelho, com dois espécimes, foi imersa em refrigerante de limão por 90 s, quatro vezes por dia, fora da boca por 3 dias. Após um intervalo de 3 dias, fragmentos restaurados com o material ainda não utilizado foram montados no aparelho e foi iniciada a segunda fase do experimento. Após os desafios erosivos, foram realizadas as medidas da microdureza da dentina adjacente às restaurações. Independente do material empregado, os espécimes erodidos apresentaram menores valores de microdureza (p<0.0001). Com relação aos materiais restauradores, foi verificado que a dentina, nas condições deste estudo, apresentou maiores valores de microdureza quando restaurada com cimento de ionômero de vidro (p<0.0001). Sendo assim, podemos concluir que o cimento de ionômero de vidro diminui a progressão da erosão da dentina radicular adjacente à restauração. / This study sought to evaluate the microhardness of root dentine adjacent to fluoride-containing restorative materials after erosive challenge. A cross-over study was performed in two phases of 4 consecutive days each. One hundred and twelve bovine root dentine slabs were obtained, and standardized box-shaped cavities were prepared at center of each specimen. The prepared cavities were randomly restored with glass-ionomer cement or composite resin. The slabs were randomly assigned among 14 volunteers, which wore intraoral palatal device containing 4 restored root dentin slabs. Starting on the second day, half of the palatal acrylic devices were immersed extraorally in a lemonade-like carbonated soft drink for 90 seconds, four times daily for 3 days. After 3-day wash-out, dentine slabs restored with the alternative material were placed into palatal appliance and the volunteers started the second phase of this study. After erosive challenges, microhardness measurements were performed. Regardless of the restorative material employed, eroded specimens demonstrated lower microhardness value (p<0.0001). At any given dentine condition examined in this study, dentine restored with glass-ionomer cement showed higher microhardness values (p<0.0001). It may be concluded that the glass-ionomer cement decreases the progression of root dentine erosion at restoration margin.

O íon fluoreto (F) provém do elemento flúor. Sua absorção é inversamente relacionada ao pH e ocorre rapidamente no estômago e posteriormente no intestino delgado. Após sua absorção, o F é distribuído pelos tecidos através da corrente sanguínea e armazenado nos tecidos calcificados e moles. Sua excreção acontece por via renal. Trata-se de um elemento relevante em termos de Saúde Pública, devido às suas propriedades de prevenir ou reverter lesões cariosas em indivíduos de todas as idades. No entanto, sua ingestão excessiva é capaz de afetar o metabolismo ósseo e desenvolvimento do esmalte dentário. Estudos sugerem que o F pode interferir em vias metabólicas, inibindo a ação de diversas enzimas. Entretanto, a literatura é conflitante em relação aos seus efeitos na homeostasia da glicose, o que poderia, talvez, ser explicado pela diferença genética entre as linhagens utilizadas. Sabe-se que camundongos da linhagem A/J são extremamente sensíveis aos efeitos do F, enquanto que os camundongos da linhagem 129P3/J são altamente resistentes ao tratamento com esse íon. Por este motivo, foi investigado se esses animais que sabidamente apresentam uma expressão proteica diferencial em função do F devido ao seu background genético apresentam também respostas diferentes em parâmetros bioquímicos (glicemia jejum, insulinemia, índice de resistência à insulina [HOMA2-IR] e teste de tolerância à insulina) e imunológicos (TNF-&alpha;). Após aprovação da Comissão de ética, 156 animais (78 da linhagem A/J e 78 da linhagem 129P3/J) foram divididos em 3 grupos para cada linhagem, e tratados por um período de 42 dias com doses de 0, 15 ou 50 ppm de F na água e ração com baixo teor de F. Após o término do tratamento, os camundongos foram eutanasiados para a obtenção de amostras de sangue. Os dados foram analisados por ANOVA a 2 critérios e testes de Tukey e Sidak para comparações individuais (p<0,05). Para a glicemia, os animais A/J que receberam água sem F e com a dose de 15 ppm F tiveram glicemia significativamente mais alta que os animais 129P3/J que receberam o mesmo tratamento. Para as dosagens de insulina no plasma, houve diferença significativa apenas entre os camundongos A/J 0 ppm F e 50 ppm F, sendo mais baixa a insulinemia para os animais tratados. O índice HOMA2-IR mostrou diferença significativa somente entre os animais da linhagem A/J, sendo que o grupo que recebeu água contendo 50 ppm F apresentou valores menores quando comparado para os grupos 0 ppm F e 15 ppm F. Quanto ao TNF-&alpha;, não foi observada diferença significativa entre as linhagens e entre os tratamentos. Entretanto, houve uma tendência para seu aumento nos grupos tratados com água contendo 15 ppm F nas duas linhagens. Para o teste de tolerância à insulina, também não foram observadas diferenças significativas entre as linhagens, nem entre os tratamentos. Levando em consideração os resultados, percebe-se que as diferentes concentrações de F alteram os resultados para os parâmetros analisados, e, as linhagens respondem diferentemente a essas alterações. No entanto, é necessário que se analisem outras variáveis para que esse assunto seja melhor elucidado. / Fluoride (F) comes from the element fluorine. Its absorption is inversely related to the pH and occurs quickly in the stomach and later in the small intestine. After absorption, F is distributed to the tissues through the bloodstream and stored in calcified and soft tissues. Excretion occurs via the kidneys. It is an important element in terms of public health, due to its properties to prevent or reverse caries in individuals of all ages. However, its excessive intake can affect bone metabolism and the development of tooth enamel. Studies suggest that F can interfere with metabolic pathways, by inhibiting the action of several enzymes. However, there is contradiction in the literature regarding its effects on glucose homeostasis, which could possibly be explained by genetic differences between the strains used. A/J mice are extremely sensitive to the effects of F, whereas 129P3/J mice are highly resistant to treatment with this ion. For this reason, it was investigated whether these animals which are known to exhibit differential protein expression upon exposure to F due to their genetic background also exhibit distinct responses in biochemical (fasting glucose, insulin, insulin resistance index [HOMA2-IR] and insulin tolerance test) and immune (TNF-&alpha;) parameters. After approval by the Ethics Committee, 156 animals (78 of A/J strain and 78 of 129P3/J strain) were obtained, divided into 3 groups for each strain and treated for a period of 42 days with 0, 15 or 50 ppm F in the drinking water. They received low-F diet. After treatment, the mice were euthanized and blood samples were obtained. Data were analyzed by 2-way ANOVA and Tukey and Sidak tests for individual comparisons (p<0.05). For blood glucose analysis, A/J mice treated with water containing no F containing 15 ppm F had significantly higher levels of glucose than 129P3/J animals receiving the same treatment. For plasma insulin, there was significant difference only between A/J mice treated with no F and 50 ppm F, with lower values for the treated animals. HOMA2-IR index showed a significant difference only between A/J animals, where the group received water containing 50 ppm F had lower values when compared to those receiving water containing no F or 15 ppm F. Regarding TNF-&alpha;, no significant differences were observed between the strains or among the treatments. However, there was a trend towards an increase in the groups treated with water containing 15 ppm F for both strains. For insulin tolerance test, also no significant differences between the strains or among treatments were observed. The results suggest that the different F concentrations alter the results of the parameters analyzed, and the strains respond differently to these changes. However, it is necessary to analyze other variables in order to better elucidate these findings.

O fluoreto (F) é amplamente empregado na Odontologia para o controle da cárie dentária. Entretanto apesar de suas propriedades terapêuticas, também pode oferecer riscos ao organismo se aplicado ou consumido de maneira indiscriminada ou inadequada. São encontrados estudos em humanos associando o consumo excessivo de F com intolerância à glicose. Estudos com animais submetidos a doses agudas ou crônicas altas de F revelam alterações na cascata de sinalização insulínica. Entretanto, seu efeito quando administrado em doses crônicas associadas àquelas equivalentes em humanos que recebam níveis ótimos de F através da água artificialmente fluoretada ou níveis aumentados através da água naturalmente fluoretada, ou ainda quando administrado a animais com diabetes já instalada, nunca foi testado. O presente trabalho teve por objetivo avaliar, em ratos normais ou com diabetes já instalada, expostos cronicamente a doses de F na água de beber que simulam a ingestão de F pela água natural e artificialmente fluoretada, parâmetros relacionados à interferência do F na resistência à insulina. Para tanto, foram utilizados inicialmente 214 ratos Wistar, com 60 dias de idade. Dentre estes, foi induzido diabetes em 133 animais por injeção intraperitoneal de estreptozotocina (50 mg/Kg peso corporal), sendo que 111 animais tiveram diabetes confirmado e foram aleatoriamente alocados a 3 grupos, diferindo em relação à concentração de F na água de beber (0, 10 ou 50 ppm), com a qual foram tratados por 22 dias. Oitenta e um animais não diabéticos foram também aleatoriamente alocados a estes 3 grupos. Decorrido o período experimental, os animais foram eutanasiados e foram avaliados: fluoremia, glicemia, insulinemia, concentração de F no fígado, a velocidade de desaparecimento da glicose sanguínea após estímulo insulínico (KITT), a resistência à insulina (HOMA2-IR), sensibilidade à insulina (%S) e função das células &#x3B2; pancreáticas (%B) e grau de fosforilação em tirosina do substrato do receptor de insulina pp185 (IRS-1/IRS-2) após estímulo insulínico, em tecidos muscular e hepático (Western blotting). As análises laboratoriais revelaram que: 1) houve dose-resposta para as concentrações de F no plasma e no fígado, sendo as concentrações maiores nos animais diabéticos comparados aos não diabéticos; 2) a glicemia não foi alterada mediante exposição ao F, tanto para animais não diabéticos quanto para animais diabéticos, embora estes tenham apresentado glicemias significativamente mais altas que aqueles; 3) os animais diabéticos apresentaram uma insulinemia significativamente menor quando comparados aos não diabéticos e o tratamento com F não afetou a insulinemia nos animais não diabéticos, mas a reduziu nos diabéticos, sem efeito dose-resposta; 4) a KITT foi significativamente menor nos animais diabéticos comparados aos não diabéticos (controle e tratados com 10 ppm F); 5) independentemente do tratamento com F, a %B nos animais diabéticos foi significativamente menor que aquela observada para os não diabéticos; 6) o índice HOMA2-IR e a %S não apresentaram diferenças significativas nem para os tratamentos com F nem para os animais diabéticos e não diabéticos, sendo que para aqueles foi observada uma tendência de aumento nos grupos tratados com F, especialmente para o grupo de 10 ppm F; 7) não houve alteração significativa no grau de fosforilação em tirosina da pp185 em função do tratamento com F. / Fluoride (F) is broadly used in Dentistry for caries control. However, despite its therapeutic properties, when used in excess, toxic signs and symptoms may occur. Studies conducted with humans have reported association between excessive F intake and glucose intolerance. Studies conducted with animals submitted to acute or high chronic doses of F have revealed alterations in the insulin signaling pathway. However, its effect when administered in chronic doses that simulate those present in the artificially or naturally fluoridated water ingested by humans, or when ingested by diabtetic animals, was not evaluated before. The present study aimed to evaluate in normoglycemic or diabetic rats chronically exposed to water containing F levels that simulate those present in the artificially or naturally fluoridated water, parameters related to the interference of F in the insulin resistance. For this purpose, 214 60-dayold Wistar rats were initially employed. Among these, diabetes was induced in 133 animals through intraperitoneal injection of streptozotocin (50 mg/Kg body weight).From these, 111 diabetic animals were randomly allocated to 3 groups that differed according to the F concentration on the water (0, 10 or 50 ppm) that was drank for 22 days. Eight-one non-diabetc animals were allocated to the same groups. After the experimental period, animals were euthanized and the following parameters were evaluated: fluoremia, glucemia, insulinemia, F concentration in the liver, velocity of disappearance of blood glucose (KITT), insulin resistance (HOMA2-IR), insulin sensitivity (%S), function of &#x3B2; pancreatic cells (%B), degree of insulin receptor substrate tyrosine phosphorylation state (pp 185, IRS-1/IRS-2) - after insulin stimulus in liver and muscle (Western blotting). Laboratory analyses revealed: 1) doseresponse for plasma and liver F concentrations that were higher in the diabetic animals compared to those non-diabetic; 2) glucemia was not altered upon exposure to F, both for non-diabetic and diabetic animals, despite the latter presented higher values compared to the first; 3) diabetic animals had significantly lower insulinemia when compared to non-diabetic animals; treatment with F did not affect insulinemia in non-diabetic animals, mas reduced this parameter in diabetic animals, without dose-response; 4) KITT was significantly lower in diabetic animals compared to non-diabetic animals (control and treated with water containing 10 ppm F); 5) Regardless treatment with F, %B in diabetic animals was significantly lower than the same parameter in non-diabetic animals; 6) HOMA2-IR and %S did not present significant differences in function of treatment with F or condition (diabetes or not); for the diabetic animals these parameters were slightly increased in the groups treated with F (specially 10 ppm F); 7) the status of phosphorylation of pp185 did not change upon treatment with F.

A incidência de lesões dentais não cariosas vem aumentando nos últimos anos, entre outros fatores devido a mudanças de hábitos alimentares da população, assim como ao aumento na freqüência de indivíduos que apresentam distúrbios gastro-esofágicos ou doenças como bulimia. Esse estudo teve como objetivo avaliar se o laser de CO2 associado ou não ao flúor poderia prevenir a erosão ácida causada por ácido cítrico em esmalte. 10 voluntários participaram desse estudo in situ e cruzado, onde 4 tratamentos foram testados: G1 controle, sem tratamento; G2 irradiação com laser de CO2 através dos parâmetros: 0.3J/cm2-5s-226Hz; G3 aplicação tópica de flúor (1.25% - 3 minutos); G4 aplicação tópica de flúor + laser de CO2). Durante cada tratamento os voluntários utilizaram durante o dia e noite, exceto durante as refeições e higiene bucal, dispositivo palatino removível contando amostras de esmalte bovino esterilizadas. A desmineralização das amostras foi realizada através da imersão do dispositivo palatino contendo as amostras em 80 ml de ácido cítrico (0.05M pH 2.3) durante 20 minutos 2 vezes ao dia (entre 6:00 e 9:00 horas a primeira imersão e entre 18:00 e 21:00 horas na segunda imersão). Durante toda a pesquisa a higiene bucal foi realizada pelos voluntários com pasta dentifrícia sem flúor e sem o dispositivo palatino in situ. Antes e durante os tratamentos o intervalo de 7 dias foi mantido. Duas amostras foram coletadas do dispositivo palatino de cada voluntário nos dias 1, 3 e 5 (n=20/dia/tratamento). A perda de estrutura foi medida utilizando-se um perfilômetro digital. Mensurações da quantidade de flúor através da técnica de biópsia e espectroscopia de fluorescência de Raios-X por energia dispersiva (EDX) e análises morfológicas foram realizadas nos grupos nos dias 1, 3 e 5. Nos testes realizados in vitro, os mesmos tratamentos foram realizados durante os mesmos tempos, no entanto, ao invés das amostras estarem presas ao dispositivo palatino na cavidade bucal dos voluntários, as mesmas foram armazenadas em água deionizada em temperatura ambiente (n=12/dia/tratamento). Os resultados mostraram que os grupos laser e flúor + laser apresentaram uma redução significante (p<0.05) na perda de estrutura de esmalte em todos os tempos tanto no modelo in situ quanto in vitro. O grupo flúor apresentou uma redução significativa apenas no modelo in vitro (p<0.05). A análise por EDX mostrou que o grupo flúor + laser apresentou um aumento significativo quantidade de flúor comparado aos outros grupos, assim como as mensurações de flúor através da técnica de biópsia revelaram que apenas no dia 1 os grupos flúor + laser e flúor apresentaram uma quantidade significativa de flúor (p<0.05). A irradiação com laser de CO2 com os parâmetros de baixa fluência (0.3J/cm2, 5s e 226Hz), associada ou não ao flúor, deixou a superfície de esmalte mais resistente a erosão do causada por ácido cítrico tanto in situ quanto in vitro. / Dental erosion is increasing as consequence of changing habits from the population, as well as increase of prevalence gastric reflux or vomiting. The possibility of making dental enamel more resistance to erosion is the objective of this study. 10 volunteers participated in the in situ study, in a crossover design with 4 treatments (G1 control, no treatment; G2 CO2 laser irradiation; 0.3J/cm2-5s-226Hz; G3 topical fluoride treatment 1.25% - 3 min; G4 - CO2 laser + fluoride treatment). For each treatment the volunteers used palatal appliances containing fixed sterilized bovine enamel samples during day and night except for meals. For erosive demineralization the mouth appliances were immersed extra-orally in 80ml of 0.05M citric acid (pH 2.3) for 20 minutes twice daily. Individual oral hygiene was performed with fluoride-free products and without the appliance in situ. Before and between the treatment periods, a 1 week wash out period was included. Two samples were collected from the appliances for analysis on days 1, 3 and 5 (n=20/day/treatment). Surface loss was measured by digital profilometer. Additional fluoride measures, morphological analyses and EDX analyses were performed. For the in vitro model all the procedures were repeated, but instead of maintaining the samples in oral cavity, they were maintained for the same time in deionized water (n=12/day/treatment) and the surface loss was analyzed by digital profilometer. The results showed that the groups laser and fluoride + laser presented significant lower surface loss in all times both in situ and in vitro models. Fluoride presented significant surface loss only in the in vitro model. The EDX analysis, showed that fluoride + laser group presented significant more fluoride than the others groups, and the fluoride measurements of the samples showed that only in the first day the groups fluoride and fluoride + laser presented significant more fluoride that the other groups. CO2 laser irradiation at 0.3J/cm2 (5s, 226Hz) associated or not with fluoride decreases enamel erosive surface loss caused by citric acid, in situ and in vitro.

Purpose: The purpose of this study is to evaluate the effectiveness of MI Paste Plus™ in increasing remineralization and improving the esthetic appearance of white spot lesions in patients who have been treated with fixed orthodontic appliances. Material and Methods: A total of twelve subject participants aged twelve to twenty years were selected in this pilot study. The six treatment group subjects were treated with MI Paste PlusTM every three weeks in-office (4 applications) and via invisible retainer every night for a total of 12 weeks. The in-office application consisted of a 1 minute 35% phosphoric acid and a 5 minute MI Paste PlusTM contact time. At home, the subjects went about their routine oral hygiene practices, but added MI Paste PlusTM to their invisible retainer before bedtime which was worn throughout the night. Photographs and quantitative light-induced fluorescence (QLF) were used to calculate white spot lesion area and ∆F values respectively. Results: A significant difference was found in the control group for the area of the white spot lesion in antimere teeth #6 and #11. When analyzing the white spot lesion area in the treatment group, significant differences were found in tooth #6, antimere teeth #6 and #11, antimere teeth #8 and #9, as well as all teeth. ∆F values for all teeth in both the control and treatment groups were significant. Conclusion: In-office and at home treatment with MI Paste Plus™ showed a statistically significant reduction in photographic lesion area when compared to controls. Both MI Paste Plus™ and a fluoride toothpaste will provide some remineralization of white spot lesions.

The tea plant, Camellia sinensis, is a fluoride (F) accumulator. Upon brewing, tea releases large amounts of F. Excessive amounts of F can cause dental fluorosis (DF) and skeletal fluorosis (SF). This study aims to determine the F levels in 4 brands of green tea and 4 brands of black tea. F was measured using an ion selective electrode (ISE) in 3 analyses: i) standard tea infusion, ii) infusion over time with spectrophotometric determination, and iii) microwave digestion. By considering the existing literature and the results of this study, the health risk associated with consuming these 8 brands of tea is evaluated. In accordance with the literature, black tea infusions have significantly higher F than green tea infusions (p < 0.01). As the brew with the significantly highest F concentration (4.07 mg L-1 ), Tetley was chosen to demonstrate the relationship between infusion time and F concentration. As expected, both F concentration and absorbance increase with infusion time. The microwave digestion results are less conclusive. There is no significant difference between the dry mass of F (mg kg-1 ) in green and black tea. Across all samples, approximately 10-31% of the total F is released after 2 minutes of infusion. These results suggest that chronic tea consumption could cause DF and SF. A cup of Tetley tea contains 0.81 mg of F. Only 7.4 or 2.2 cups of Tetley tea would need to be consumed by an adult or child, respectively, to exceed the daily upper limit at which symptoms of SF can arise. Considering the multiple other dietary fluoride sources and the increased susceptibility of children, F in tea should be more closely monitored.

These PhD projects represent secondary analyses of data from the ongoing Iowa Fluoride Study (IFS)/Iowa Bone Development Study (IBDS). The aim of this dissertation was to explore the associations between period-specific and cumulative fluoride intakes from birth to age 17, and from birth to age 19 years and bone measures of participants. Also, this dissertation looked into the associations between the clinical presence of dental fluorosis and bone outcomes. Participants have been participating in the IBDS that grew out of the IFS, which is a longitudinal investigation of dietary and non-dietary fluoride exposures, dental fluorosis and dental caries. IFS participants were recruited during 1992-95 from 8 hospital postpartum wards in Iowa, and detailed questionnaires were sent every 1.5-6 months. Data on intakes from water, other beverages, selected foods, dietary fluoride supplements and dentifrice were collected from the questionnaires, and, in combination with water and beverage fluoride levels, combined fluoride was estimated. For the first dissertation project, the association between fluoride intake and peripheral quantitative computed tomography (pQCT)-derived bone outcomes at age 17 were assessed. Participants underwent pQCT of the radius and tibia (XCT-2000) at age 17 years. pQCT results of trabecular bone mineral density (BMD) and bone mineral content (BMC), cortical BMD and BMC, and compression and torsion strength were related to fluoride intake through bivariate and multivariable analyses, adjusting for height, weight, years since peak height velocity, average daily time spent in moderate-to-vigorous intensity physical activity, daily calcium intake, and daily protein intake. P-values < 0.01 were considered statistically significant rather than p< 0.05 due to multiple hypothesis tests. The mean daily fluoride intake estimated by area-under-the-curve (AUC) from birth to 17 years was 0.79 mg (SD = 0.32) for males and 0.70 mg (SD = 0.25) for females. Spearman correlation coefficients between daily fluoride intake and pQCT bone measures were weak (for females r= -0.01 to 0.15 for radius bone outcomes and -0.001 to 0.23 for tibia bone outcomes; for males r= 0.03 to 0.24 for radius bone outcomes and -0.008 to 0.27 for tibia bone outcomes). In sex-specific linear regression analyses for females, partially-adjusted for height, weight, and years since peak height velocity, statistically significant negative associations were detected between all radial bone outcomes and period-specific fluoride intake from 0-8.5 years. Significant positive associations were detected for females between period-specific fluoride intakes from 14-17 years and all tibia bone outcomes, and between period-specific fluoride intakes from 14-17 years and all radius and tibia bone outcomes for males. In the fully-adjusted models, which also included physical activity, protein intake and calcium intake, statistically suggestive negative associations were detected for females during the early fluoride intake period from 0 to 8.5 years and radial cortical bone content and torsion bone strength. A statistically suggestive positive association was found between period-specific fluoride intake from 8.5 to 14 years and torsion bone strength (pSSI) (p< 0.05) for females. For males, statistically significant positive associations were detected between fluoride intake for the period from 14 to 17 years and cortical content and torsion strength (pSSI) at the 0.01 level. The second project examined the associations between period-specific and cumulative fluoride intakes from birth to age 19 years and MDCT-derived bone outcomes at age 19. Age 19 MDCT-derived trabecular and cortical bone micro-architecture scans were acquired at the University of Iowa Comprehensive Lung Imaging Center. MDCT results of the trabecular (volumetric bone mineral density (vBMD), transpose bone mineral density (tBMD), plate trabecula bone mineral density (pBMD), plate width (TS-PW), trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), trabecular network area (Tb.NA)) and cortical (cortical bone porosity (Cb.Poro), cortical thickness (Cb.Th)) bone were related to fluoride intake through bivariate and multivariable analyses, adjusting for height, weight, years since peak height velocity, average daily time spent in moderate-to-vigorous intensity physical activity, Healthy Eating Index (HEI) score, calcium intake and protein intake. P-values < 0.01 were considered statistically significant rather than p< 0.05 due to multiple hypothesis tests. The mean daily fluoride intake estimated by area-under-the-curve (AUC) from birth to 19 years was 0.81 mg (SD = 0.33) for males and 0.69 mg (SD = 0.27) for females. Spearman correlation coefficients between daily fluoride intake and MDCT bone measures were weak (for females r= -0.001 to 0.20 for trabecular bone outcomes and -0.01 to 0.02 for cortical bone outcomes; for males r= -0.003 to 0.16 for trabecular bone outcomes and -0.09 to -0.02 for cortical bone outcomes). In sex-specific partially-adjusted regression analysis adjusted for height, weight, and years since peak height velocity, no statistically significant associations were found for females or males. In the fully-adjusted models, which also included physical activity, HEI score, and protein and calcium intakes, no statistically significant associations were found for either females or males. The third project explored the associations between dental fluorosis score at age 8 and DXA-derived bone outcomes at age 5. DXA bone assessments of the whole body, proximal femur (hip), and lumbar spine were performed at The University of Iowa in the Clinical Research Center (Hologic QDR-2000 DXA unit). The dental fluorosis score was defined as the proportion of zones with definitive or severe fluorosis per person. In the unadjusted associations between bone outcomes and dental fluorosis score, no statistically significant associations were detected for females at the 0.05 level. For males, a statistically significant negative association was found between hip BMD and dental fluorosis score. Sex-specific partial correlation coefficients were estimated between DXA-derived bone outcomes and dental fluorosis score adjusted for height, weight, physical activity, calcium intake and fluoride intake. No statistically significant associations were found for females. For males, a statistically significant negative association was detected between dental fluorosis score and hip BMD. The findings of this dissertation show that life-long intakes from combined sources for adolescents and young adults living in fluoridated areas in the United States were weakly associated with bone measures at age 17 and 19. Furthermore, it was shown that bone outcomes can’t be predicted by the score of dental fluorosis. Fluoride is a mineral that plays an important role in the mineralization of bone and teeth, as well as in dental caries prevention. Numerous professional health organizations endorse the adjusted fluoridation of public water supplies for caries prevention. Results from this dissertation will also help in supporting additional efforts to promote water fluoridation and expand its use, as this dissertation’s outcomes did not demonstrate adverse outcomes related to bone.

The purpose of this research was to determine whether or not canning fruit using fluoridated water made a difference in the fluoride contents of the juice and the pulp. Four cities in Utah were chosen. Two cities were fluoridated (Brigham City and Helper) and two cities were not fluoridated (North Ogden and Price). Three homes were chosen within each city, and three jars of canned fruit (one jar each of apricots, cherries, and peaches) were selected from each home. The fruit samples were freeze-dried, and then the fluoride was measured with a fluoride ion electrode. A difference was found in the fluoride level of the juice and the pulp when canning using fluoridated water. However, this difference was not statistically significant and did not greatly contribute to the overall dietary fluoride intake.

The relationship between the fluoride content of the enamel and dentine of deciduous teeth and the number of tooth lesions/mouth was compared to fluoride treatment in Logan , Brigham City, Helper and Milford, Utah. Bone measurement data was obtained on the second metacarpal bones of the mother s of the participating children from the same communities except Brigham City. The fluoride treatment in the communities were as follows: Logan has no fluoride added to the domestic water supply but some children received fluoride treatment through tablets, drops, etc. Milford has water which naturally contains 0 . 8 ppm fluoride , Helper and Brigham City have 1 ppm fluoride added to their water ,supplies. The results showed that significantly less (P > 0.05) fluoride existed in the dentine of teeth originating from Logan children without fluoride treatment than the dentine from fluoride treated children in Logan and Brigham City. The fluoride content of the enamel showed a tendency to be increased with increasing amount of fluoride exposure. The fluoride content of the enamel and dentine from non fluoride treated Logan children was considerably less than from fluoride treated Logan children and from Brigham City children. Logan children who had received fluoride treatments had significantly (P > 0.05) fewer dental lesions/mouth compared to the nontreated Logan children. The fluoride exposed Milford and Helper children had a greater frequency of dental lesions/mouth than even nonfluoride treated Logan children . This might be explained by the socioeconomic differences existing between Logan in comparison to Helper and Milford. Midshaft bone measurements were taken on x-rays of the second metacarpal of women (average age 35.7) residing ten or more years in the respective community. When measuring cortical thickness, cortical area, medullary area, and per cent cortical area, no significant differences could be shown.