Orientador: Livia Maria Andalo Tenuta / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-20T02:43:48Z (GMT). No. of bitstreams: 1 Cerezetti_RenataValvano_M.pdf: 3928150 bytes, checksum: 6b338ffbc7dd5c545ac34e60f55db427 (MD5) Previous issue date: 2012 / Resumo: O efeito anticárie da aplicação tópica profissional de fluoreto (ATPF) tem sido associado à formação do mineral tipo fluoreto de cálcio...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The anticaries effect of professional topical fluoride application (PTFA) has been associated with the formation of a calcium fluoride-like mineral...Note: The complete abstract is available with the full electronic document / Mestrado / Odontopediatria / Doutor em Odontologia

Ce manuscrit traite de la synthèse d'aldols mono- et difluorés à partir de précurseurs stables d'éthers d'énol silylés. En premier lieu, la synthèse et la réactivité de synthons de type RCF2Li sont abordées. Cette étude a notamment permis d'obtenir des alpha-trialkylsilylcarbinols stables par addition sur des acylsilanes. Ces composés nous sont apparus comme des précurseurs stables de fluoroénolates, capables de générer in situ ces nucléophiles après réarrangement de Brook et élimination d'un fluorure sous l'action d'une base. La deuxième partie de ce manuscrit traitera ainsi de deux méthodologies monotopes permettant d'aboutir à des aldols monofluorés comportant un centre tétrasubstitué fluoré directement à partir de ces précurseurs: soit en utilisant un équivalent de t-BuOK, soit avec une quantité catalytique de p-MeOPhONBu4 en présence d'une base relais. Dans un troisième temps, en se basant sur une séquence similaire, une synthèse monotope racémique d'aldols difluorés à partir du réactif de Ruppert-Prakash, d'acylsilanes et d'aldéhydes a été mise au point. Cette réaction étant catalysée par le TBAT, une version asymétrique organocatalysée a ensuite été explorée grâce à l'utilisation de paires d'ions chiraux coopératifs. / This manuscript deals with the synthesis of mono- and difluorinated aldols starting from stables precursors of silylated enol ethers. First, the synthesis and the reactivity of RCF2Li synthons has been investigated. A preparation of alpha-trialkylsilylcarbinols, which can be seen as fluoroenoxysilane precursors, has been developed. A sequence involving a Brook rearrangement followed by a fluoride elimination from these stable precursors has then been exploited in a second part to set up a one-pot preparation of monofluorinated aldols featuring a fluorinated tetrasubstituted center. Two methodologies were developped : one relying on the addition of a stoichiometric amount of t-BuOK and the second involving a catalytic amount of p-MeOPhONBu4 and a stoichiometric amount of a pro-base. Finally, a one-pot synthesis of difluorinated aldols starting from Ruppert-Prakash reagent, acylsilanes and aldehydes is described in a third part. This sequence, similar to the previous one, is catalyzed by TBAT and an asymmetric version relying on the use of chiral cooperative ion pairs has also been explored.

Nous avons développé de nouveaux accès pour la construction de molécules comportant les motifs Csp3-CF3 et Csp3-SCF3. Deux réactions de transfert d'hydrure sur des composés trifluorométhylés par catalyse avec des métaux de transition ont été réalisées : 1) l'isomérisation catalytique d'alcools allyliques trifluorométhylés par des complexes de fer (II); 2) le transfert d'hydrogéne énantiosélectif de céto-imines trifluorométhylées par des complexes chiraux de ruthénium en utilisant l'isopropanol comme source d'hydrure pour obtenir des amines trifluorométhylées optiquement actives avec de hauts rendements et de hautes énantiosélectivités. La trifluorométhylthiolation allylique nucléophile de dérivés de Morita-Baylis-Hillman a été étudiée. L'accès régio- et stéréosélectif aux produits SCF3 thermodynamiques a été réalisé par la combinaison de S8/CF3SiMe3/KF/DMF avec de bons rendements. Le produit cinétique a été obtenu en utilisant le réactif de Zard. / We have developed new accesses for the construction of molecules featuring Csp3-CF3 and Csp3-SCF3 motifs. Two atom-economical hydride transfer reactions of trifluoromethylated compounds by transition-metal catalysis were realized: 1) the isomerization of trifluoromethylated allylic alcohols by iron (II) complexes; 2) the enantioselective transfer hydrogenation of trifluoromethylated ketimines by a chiral complex of ruthenium and isopropanol as hydride source for the preparation of optically pure trifluoromethylated amines in high yields and high enantioselectivities. The nucleophilic allylic trifluoromethylthiolation of Morita-Baylis-Hillman derivatives was investigated. The regio- and stereoselective access to thermodynamic trifluoromethylthiolated products has been achieved by combination of S8/KFfMe3SiCF3/DMF in good yields. The kinetic trifluoromethylthiolated products were obtained by using Zard's trifluoromethylthiolating reagent.

L’hexafluorure d’uranium, de formule chimique UF 6 , est un composé clé du cycle du combustible car il est utilisé pour l’étape d’enrichissement isotopique. Toutefois, des impuretés présentes et mélangées à l’UF 6 sont à éliminer afin de garantir un uranium de pureté nucléaire. Dans ce manuscrit, les réactions chimiques entre les polluants et les filtres chimiques retenus pour la purification sont étudiées. Par ailleurs, l’étude de la réactivité en milieu liquide est réalisée afin de se rapprocher des conditions industrielles. Une voie de recyclage des filtres chimiques est également investiguée afin de réutiliser les adsorbants sur plusieurs cycles de purification. L’ensemble des performances (taux de sorption des polluants, décontamination lors du recyclage) sont évaluées avant la mise au point du pilote à l’échelle industrielle. / Uranium hexafluoride, which chemical formula is UF 6 , is a key compound of nuclear fuel cycle due to its use during isotopic enrichment process. Nethertheless, pollutants melted with UF 6 have to be removed in order to ensure a nuclear purity fuel. In this manuscript, the reactions occurring between pollutants and chemical filters selected for this application are studied. Then, the reactivity in liquid UF 6 is also examined with the aim of being close to the industrial process. The regeneration of adsorbents is investigated so that chemical filter can be used for several purification cycles. The performances (sorption rate of pollutants, purifying during recycling step) are evaluated before simulations at industrial scale.

Il a été montré que l’addition de fluor en petite quantité sur la surface de nanotubes de carbone mono et multiparois engendre des radicaux à long temps de vie, caractérisés ici par RPE. Ce phénomène a pu être mis à profit pour initier la polymérisation du styrène, de l’acide acrylique ou encore de l’aniline. Les chaînes polymères formées apparaissent alors greffées à la surface des tubes. Il a été observé qu’un tel greffage facilite grandement la mise en suspension des nanotubes dans des solvants organiques. Ce travail s’est également attaché à exalter la complémentarité entre nouveaux matériaux fluorés et techniques avancées de mise en œuvre. Pour la première fois, l’incorporation de nanocarbones fluorés de différentes dimensionnalités (noirs de carbone, nanotubes, nanofibres, nanodisques) dans une matrice polymère électrofilée de polyvinylpyrrolidone a été réalisée. Les tissus nanocomposites microfibreux ainsi obtenus ont ensuite fait l’objet de traitements de re-fluoration en conditions douces, afin d’augmenter leur taux de fluor final et d’en modifier la texture. Les caractérisations par microscopie à balayage, RMN du solide et XPS ont permis d’établir que l’enrichissement en fluor de la matrice polymère et la structure multi échelle spectaculaire résultant du traitement de post-fluoration réalisé permettent d’induire la propriété de superhydrophobicité, mise en évidence par la mesure d’angles de contact avec l’eau supérieurs à 150°. / It has been shown that the addition of a small amount of fluorine to the surface of single and multi-walled carbon nanotubes generates long life-time radicals, here studied by EPR. The latter phenomenon can be usefully harnessed to initiate the polymerization of styrene, acrylic acid or still aniline. The polymeric chains thus formed appear to be grafted to the tubes surface. It has been observed that such a grafting process highly increases the dispersibility of tubes in some organic solvents. This work also focused on illustrating how advanced processing techniques may complement the assets of novel fluorinated materials. Hence, the inclusion of fluorinated nanocarbons with varied dimensionalities (carbon black, nanotubes, nanofibers, nanodisks) into an electrospun polyvinylpyrrolidone polymer matrix has been achieved for the first time. The nanocomposite-based microfibrous membranes thus obtained have been reacted with gaseous fluorine in mild conditions, in order to increase their final fluorine content and modify their texture. Characterizations performed using scanning electron microscopy, solid state NMR and XPS have shown that both the fluorination of the polymer matrix and quite spectacular multiscale structure resulting from etching by fluorine induce superhydrophobicity, evidenced through contact angles of the membranes with water exceeding 150°.

Fluorine gas is produced industrially by electrolysing hydrogen fluoride in a potassium acid fluoride electrolyte. Fluorine is produced at the carbon anode, while hydrogen is produced at the mild-steel cathode. The fluorine produced has a wide range of uses, most notably in the nuclear industry where it is used to separate 235U and 238U. The South African Nuclear Energy Corporation (Necsa) is a producer of fluorine and requested an investigation into the hydrodynamics of their electrolysis cells as part of a larger national initiative to beneficiate more of South Africa’s large fluorspar deposits. Due to the extremely corrosive and toxic environment inside a typical fluorine electrolysis reactor, the fluid dynamics in the reactor are not understood well enough. The harsh conditions make detailed experimental investigation of the reactors extremely dangerous. The objective of this project is to construct a model that can accurately predict the physical processes involved in the production of fluorine gas. The results of the simulation will be compared to experimental results from tests done on a lab-scale reactor. A good correlation between reality and the simulacrum would mean engineers and designers can interrogate the inner operation of said reactors safely, effortlessly and economically. This contribution reports a time-dependent simulation of a fluorine-producing electrolysis reactor. COMSOL Multiphysics was used as a tool to construct a two dimensional model where the charge-, heat-, mass- and momentum transfer were fully coupled in one transient simulation. COMSOL is a finite element analysis software package. It enables the user to specify the dimensions of his/her investigation and specify a set of partial differential equations, boundary conditions and starting values. These equations can be coupled to ensure that the complex interaction between the various physical phenomena can be taken into account - an absolute necessity in a model as complex as this one. Results produced include a set of time dependent graphics where the charge-, heat-, mass- and momentum transfer inside the reactor and their development can be visualized clearly. The average liquid velocity in the reactor was also simulated and it was found that this value stabilises after around 90 s. The results of each transfer module are also shown at 100 s, where it is assumed that the simulation has achieved a quasi-steady state. The reactor, on which the model is based, is currently under construction and will be operated under the same conditions as specified in the model. The reactor, constructed of stainless steel, has a transparent side window through which both electrodes can clearly be seen. Thus the bubble formation and flow in the reactor can be studied effectively. Temperature will be measured with a set of thermocouples imbedded in PTFE throughout the reactor. The electric field will similarly be measured using electric induction probes. / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted

Orientador: Lívia Maria Andaló Tenuta / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T14:38:08Z (GMT). No. of bitstreams: 1 Kusano_SandroCarvalho_M.pdf: 956275 bytes, checksum: f7babc0a1138faa960f02a6d9ca0a048 (MD5) Previous issue date: 2011 / Resumo: O Fluoreto (F) interfere com o desenvolvimento de cárie dental quando presente no meio bucal, reduzindo a desmineralização e ativando a remineralização da estrutura dental. Embora ambos os mecanismos estejam envolvidos na redução da perda mineral na presença de F, não foi encontrado nenhum estudo in situ que avaliasse a importância relativa de cada um deles na inibição do desenvolvimento de cárie. Desta forma, foi realizado um estudo in situ, cruzado e cego, com o objetivo de avaliar o efeito do momento de uso do dentifrício fluoretado, i.e., antes ou após desafios desmineralizantes diários (para simular efeito na redução da desmineralização ou ativação da remineralização, respectivamente), na perda mineral do esmalte e dentina radicular. Doze voluntários utilizaram dispositivos intrabucais palatinos contendo 3 blocos de esmalte e 3 de dentina radicular hígidos e com dureza de superfície previamente determinada, durante 3 fases de 14 dias cada. Os blocos foram fixados 1 mm abaixo do nível do dispositivo e cobertos por uma tela plástica para favorecer o acúmulo de biofilme dental, e foram expostos à sacarose 20% 8x/dia. Os voluntários realizaram os seguintes tratamentos: G1 - dentifrício placebo (nãofluoretado) três vezes/dia (grupo controle); G2 - dentifrício fluoretado pela manhã (7:00), antes dos desafios desmineralizantes diários, e dentifrício não-fluoretado nas escovações seguintes; e G3 - dentifrício fluoretado à noite (entre 20:00 e 21:00), após os desafios desmineralizantes, e dentifrício não-fluoretado nas duas escovações anteriores. A desmineralização do esmalte e dentina radicular foi avaliada pela porcentagem de perda de dureza de superfície (%PDS). Também foi avaliada a concentração de fluoreto incorporado aos blocos dentais (fluorapatita). Os resultados de %PDS dos tratamentos com dentifrício fluoretado diferiram do grupo controle (p<0,05), tanto para o esmalte (G1=72,0%±20,8; G2=41,6%±21,5; G3=30,0%±15,8) quanto para a dentina (G1=76,5%±9,3; G2=61,8%±11,8; G3=48,4±19,1), sendo que na dentina, a %PDS foi menor (p<0,05) no grupo tratado com dentifrício fluoretado após os desafios desmineralizantes. A concentração de F nos blocos de esmalte não diferiu entre os grupos tratados com dentifrício fluoretado (p>0,05), no entanto, foi significativamente maior no grupo tratado com dentifrício fluoretado após os desafios desmineralizantes, quando comparado ao grupo controle (p<0,05). Nos blocos de dentina, os grupos tratados com dentifrício fluoretado apresentaram concentrações significativamente maiores quando comparados ao grupo controle (p<0,05), entretanto não diferiram entre si (p>0,05). Os resultados do presente estudo sugerem que o dentifrício fluoretado é mais eficaz na redução da cárie através da ativação da remineralização do esmalte e dentina radicular, do que pela inibição da sua desmineralização / Abstract: Fluoride (F) interferes with dental caries development when present in oral environment, reducing dental demineralization and enhancing its remineralization. Although both mechanisms are related to the reduction of mineral loss in the presence of F, no experimental study which evaluated the relative importance of each mechanism on the inhibition of development of dental caries was found. Thus, this in situ, crossover and blind study was performed to evaluate the effect of the period of F dentifrice use, i.e., either before or after daily cariogenic challenges (to simulate either the effect on the reduction of demineralization or on the enhancement of remineralization, respectively), on enamel and root dentin remineralization. Twelve volunteers wore palatal appliances containing three sound enamel slabs and three sound root dentin slabs, with surface hardness previously determined, during three phases of 14 days each. Dental slabs were fixed 1 mm underneath the level of the appliance and covered by a plastic mesh to allow dental biofilm accumulation, and exposed to sucrose 20% 8x/day. The volunteers performed the following treatments: G1 - placebo toothpaste (non-fluoride) three times/day (control group); G2 - fluoride toothpaste in the morning (7:00), before cariogenic challenges, and non-fluoride toothpaste in the next two toothbrushings; and G3- fluoride toothpaste at night (between 20:00 and 21:00), after cariogenic challenges, and non-fluoride toothpaste in the previous two toothbrushings. Enamel-dentin demineralization was evaluated by percentage of surface hardness loss (%SHL). F uptake by enamel and dentin was also determined (as fluorapatite). %SHL data in groups treated with fluoride toothpaste differ from control group (p<0.05), for both enamel (G1=72.0%±20.8; G2=41.6%±21.5; G3=30.0%±15.8) and dentin (G1=76.5%±9.3; G2=61.8%±11.8; G3=48.4±19.1). For dentin, %SHL was lower (p<0.05) in the group using fluoride toothpaste after cariogenic challenges. F concentration in enamel slabs did not differ between groups using fluoride toothpaste (p>0.05), however, it was significantly higher in the group treated with fluoride toothpaste after cariogenic challenges compared to control group (p<0.05). For dentin slabs, groups using fluoride toothpaste showed significantly higher F concentration compared to control group (p<0.05), but no difference was observed between each other (p>0.05). The findings of this study suggest that F from toothpaste is more effective to reduce caries by enhancing enamel-dentine remineralization than by reducing their demineralization / Mestrado / Cariologia / Mestre em Odontologia

Orientador: Luís Roberto Marcondes Martins / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T14:18:22Z (GMT). No. of bitstreams: 1 Santos-Caldeira_MilenaMariaPierre_M.pdf: 1500767 bytes, checksum: 7089c23fae597d1c4940deba6843ad02 (MD5) Previous issue date: 2011 / Resumo: A presente pesquisa objetivou avaliar in situ o potencial anticariogênico de cimento de ionômero de vidro convencional na prevenção da desmineralização de esmalte e dentina, sozinho ou sob ação de dentifrício fluoretado. Foi realizado um estudo cego, cruzado, de indução de cárie, em blocos dentais obtidos a partir de terceiros molares humanos hígidos, pelo acúmulo de biofilme e exposição à sacarose, conduzido em 2 fases clínicas de 14 dias cada. O estudo foi fatorial 2 x 2 cruzado sendo: (1) Tratamento em 2 níveis, bloco dental com restauração de cimento de ionômero de vidro convencional (GI) e bloco dental hígido (ST); (2) Dentifrício em 2 níveis, fluoretado (FD) e não fluoretado (NF). Foi avaliado o efeito dos fatores nas variáveis de resposta: área de perda de dureza (?S) (quantitativamente) e microscopia de luz polarizada (qualitativamente), considerando esmalte e dentina individualmente. Os grupos experimentais foram obtidos pela associação dos fatores em estudo e atribuídos aos voluntários. Os voluntários utilizaram dispositivo intraoral com 2 blocos dentais referentes a cada tratamento, alternando, aleatoriamente, o tipo de dentifrício em cada fase. Os voluntários (n=7) foram considerados unidades experimentais para todas variáveis em estudo. Sobre as amostras no dispositivo intraoral foi acumulado biofilme dental e induzido alto desafio cariogênico pela exposição à solução de sacarose 20% sobre o biofilme 8x/dia, com os dispositivos fora da cavidade bucal. Após cada fase experimental foi avaliada, por microdureza longitudinal, a área de perda de dureza por ?S, em esmalte e dentina, e as amostras foram analisadas sob microscopia de luz polarizada quanto à desmineralização. Após análise estatística (ANOVA com arranjo fatorial dos níveis dos fatores, e Teste de Tukey), não foi encontrada interação dos fatores avaliados (p>0,05). Foi observada menor desmineralização em esmalte e dentina após o uso de FD do que NF (p<0,05). Quanto à comparação entre GI e ST, maior desmineralização para ST foi encontrada em esmalte (p<0,01), contudo não foram encontradas diferenças entre GI e ST para o substrato dentinário (p>0,05). A microscopia por polarização revelou maior porcentagem de sinais de desmineralização para ST+NF (64,28%) e GI+NF (50%), e menor porcentagem de desmineralização aparente para GI+FD (28,57%) seguido por ST+FD (42,85%). Concluiu-se que a presença de dentifrício fluoretado proporcionou menores áreas de desmineralização, proveu efeito anticárie sob todas condições estudadas, e, que a associação do cimento de ionômero de vidro convencional ao dentifrício fluoretado levou à menor porcentagem de desmineralização aparente nas imagens de microscopia de luz polarizada. Independente de dentifrício, restaurações de ionômero de vidro apresentaram efeito anticárie em esmalte / Abstract: The aim of this study was to assess in situ anticaries potential of conventional glass ionomer cement (GIC) to prevent enamel and dentine demineralization either alone or in combination with a fluoride (F) regimen. A randomized, blind, crossover design for caries induction was carried out in 2 phases of 14 days each. This study was a 2 x 2 cross-over factorial design as follows: (1) Material Treatment at 2 levels, dental slabs restored with glass ionomer cement (GI) and sound tooth slabs (ST); and (2) Dentifrice at 2 levels, F dentifrice (FD) and non-F dentifrice (NF). The effect of the factors on the response variables was evaluated: hardness loss area (?S) (quantitative assessment) and light polarized microscopy (qualitative), concerning enamel and dentine, individually. The experimental groups obtained from the association of those factors were assigned to the volunteers. In each experimental phase, volunteers used a palatal device loaded with two dental slabs from each treatment group, using FD or NF depending on the experimental phase. Volunteers (n=07) were considered experimental units for all variables being studied. Biofilm was allowed to accumulate on the slabs, and a high cariogenic challenge was provided by exposing the biofilm/slab sets to a 20 % sucrose solution 8 times/day extra-orally. After each experimental phase was evaluated the integrated area of hardness loss as a function of lesion depth (?S) in enamel and dentine by cross-sectional microhardness, and demineralization was observed by light polarized microscopy. After statistical analysis (ANOVA and Tukey test), for both dental substrates no significant interaction between the factors was found (p>0.05). Also, for enamel and dentin FD provided lower demineralization than NF (p<0.05). For material treatment, higher enamel demineralization was found for ST compared to GI (p<0.01), but no differences were found between GI and ST in dentin substrate (p>0.05). By PLM was observed that the largest percentage of apparent demineralization occurred in NF+ST group (64.28%) and GI+NF (50%), and lowest apparent demineralization percentage occurred in GI+FD (28.57%) followed by ST+FD (42.85%). In concluded, fluoride dentifrice showed lower demineralization areas, and anticaries effect of FD was proven under all conditions studied. And, the association of conventional glass ionomer cement with fluoride dentifrice led to a lower percentage of apparent demineralization lesions in images of polarized light microscopy. Independent of dentifrice, glass-ionomer restorations showed anticaries effect on enamel / Mestrado / Dentística / Mestre em Clínica Odontológica

Orientador: Luis Alexandre Maffei Sartini Paulillo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-27T08:06:16Z (GMT). No. of bitstreams: 1 Barbosa_IsabelFerreira_M.pdf: 17100621 bytes, checksum: 989f3c819b4db9c4a6cb6fec6d487a59 (MD5) Previous issue date: 2015 / Resumo: O objetivo neste estudo, duplo cego de "boca-dividida", foi avaliar, clinicamente, o efeito de dois agentes dessensibilizantes utilizados previamente à aplicação de um gel clareador, a base de peróxido de hidrogênio a 35%, com relação a sensibilidade dental, e se os mesmos interferem na efetividade do clareamento. Para isso foram consideradas duas hipóteses: os géis dessensilizantes iriam reduzir a sensibilidade decorrente do clareamento; os géis dessensibilizantes não iriam influenciar a eficácia do clareamento. Foram utilizados dois agentes dessensibilizantes com diferentes mecanismos de ação, o Flúor Neutro 2% (Flugel, DFL) (FN) que atua através do bloqueio dos canalículos dentinários enquanto o Nitrato de Potássio 5% com Fluoreto de Sódio 2% (Desensibilize KF 2%, FGM) (NP) que atua na transmissão nervosa e no bloqueio. Foram selecionados 30 pacientes, os quais receberam os quatro tratamentos, dois dessensibilizantes e dois placebos, divididos, aleatoriamente, por quadrante. O gel dessensibilizante NP e seu respectivo placebo foram aplicados durante 10 minutos em uma arcada enquanto o gel de FN e seu respectivo placebo foram aplicados por 4 minutos na outra arcada, com o cuidado para que a substância em gel permanecesse nos dentes de cada quadrante. Os dessensibilizantes foram utilizados no inicio de cada sessão, previamente à aplicação do peróxido de hidrogênio 35%. Para o clareamento foram realizadas 3 sessões clinicas, com intervalo de 7 dias entre as mesmas, havendo 3 aplicações do gel clareador por 15 minutos, totalizando 45min por sessão. Os pacientes utilizaram escala analógica de dor de 0-4 para relatarem a sensibilidade, sendo 0 = nenhuma dor, 1 = correspondente a uma dor leve, 2 = moderada, 3 = considerável e 4 = dor intensa. Antes do início de cada sessão, a cor foi registrada de forma objetiva com a utilização de espectrofotômetro (Easyshade, Vident), com o auxilio de uma matriz de silicone para que a medida da cor fosse feita sempre na mesma posição. A variação de cor (?E) foi submetida a ANOVA casual e teste de Tukey (p<0,05). A sensibilidade dental foi avaliada através de ANOVA em esquema fatorial (4x6), sendo que os fatores estudados foram dessensibilizantes e tempo. Dois pacientes desistiram após a primeira sessão de clareamento devido a grande intensidade de dor, e não foram considerados para análise estatística. A alteração de cor após a terceira semana de clareamento apresentou diferença significativa em relação a cor obtida na primeira semana. A intensidade de dor foi estatisticamente significante para os fatores tempo e dessensibilizante, mas não para a interação entre os mesmos. O NP apresentou redução da intensidade de dor quando comparado ao seu placebo, porém a aplicação de FN não diferiu do seu placebo. Com relação ao tempo, a intensidade de dor foi menor durante o clareamento do que nas semanas entre os tratamentos. Pôde-se concluir que a utilização do dessensibilizante a base de nitrato de potássio a 5% e fluoreto de sódio a 2%, aplicado previamente ao clareamento, reduziu a intensidade da sensibilidade dolorosa durante a aplicação do gel clareador, sem alterar a efetividade do clareamento / Abstract: This double blind split-mouth study clinically evaluated the effect of desensitizing agents previously to in-office dental bleaching, evaluating pain intensity and if the desensitizing agents influence the effectiveness of tooth whitening. For this, two following hypotheses were postulated: the desensitizing agent will reduce the soreness resulting from tooth whitening and the desensitizing agent will have no influence on the effectiveness of tooth whitening. The desensitizing agents utilize two mechanisms. Neutral Fluoride 2% (FN) (Flugel, DFL) act obliterate the dentin tubules, and the Potassium Nitrate with 2% sodium fluoride (NP) (Desensibilize KF 2%, FGM) act by blockage of pulp enervation reduction nociceptor sensorial excitability. In total, 30 volunteers were evaluated, and witch one received the four groups of studying, two desensitizing agents and two placebo, randomly distributed between the quadrant. The desensitizing agent corresponding to each group was applied (NP and Placebo I for 10 minutes; FN and Placebo II for 4 minutes) in each arch, with carefully for each substance remained in their quadrant. The desensitizing agents was applied before the bleaching procedure with hydrogen peroxide 35%. Tree sessions was performed for the bleaching, with one week interval between sessions. The gel remained in contact with the teeth for 15 minutes, and was performed three times at each session result in in 45 minutes per session. To evaluate dental sensitivity it was utilizing a numerical scale with intensity scores that ranged from 0 to 4 (0 = no sensitivity, 1 = light sensitivity, 2 = moderate sensitivity, 3 = considerable sensitivity and 4 = intense sensitivity). The color evaluation was performed by an objective analysis utilizing a spectrophotometer (Easyshade, Vivadent) and was made before witch session, with a silicon guide to evaluate the color at different times at the same place. The color variation (?E) were submitted to an analysis of one way variance (ANOVA) and the Tukey test (p<0,05). Pain intensity was submitted to a two-way ANOVA analysis (time and desensitizing agent). Two of the patients discontinued treatment due to hypersensitivity, and they aren¿t including in the statistical analises. The desensitizing products used before the treatment did not influence the final treatment efficacy. The diference of colors ate the third week was significantly different from que diference colors obtained ate the fish week of bleaching. For painful sensations during the treatments a significant difference for desensitizing agent and time was demonstrated, but the interaction of the two factors was not significant. The Tukey test indicated differences between NP and the Placebo I, but there was no significant difference between neutral FN and the placebo II. The pain intensity was lower with the use of the gel during the bleaching compared to the days after treatment, regardless of the desensitizing agent being used. It can be concluded that 5% potassium nitrate with sodium fluoride 2%, applied before in-office bleaching can reduced sensitivity intensity and the use of desensitizing gel prior to bleaching does not alter the effectiveness of whitening / Mestrado / Dentística / Mestra em Clínica Odontológica

Les composés fluorés ont montré une importance croissante dans le développement d'agents pharmaceutiques en raison des propriétés exceptionnelles de l'atome de fluor. Dans cette thèse, nous nous sommes concentrés sur la synthèse des composés énantiopurs contenant de l'azote.A partir de l'aldimine trifluorométhylée, une réaction d’aza-Baylis-Hillman asymétrique a été réalisée et a permis d’obtenir un nouvel acide (R)-α-méthylène-β-CF3-β-aminé avec un bon rendement et une excellente diastéréosélectivité. Puis, en utilisant une réaction d’allylation dans les conditions de Barbier, de nouveaux acides aminés trifluorométhylés cycliques à cinq ou six chaînons ont été obtenus avec de bons rendements et d’excellents diastéréosélectivités. En particulier des acides γ et β-aminés, comme la CF3-β-proline, qui est très intéressante dans la synthèse peptidique.Enfin, grâce à l'addition d'éther de vinyle sur l’aldimine trifluorométhylée, différentes amines trifluorométhylées ont été obtenues. Parmi ces composés, les amino-alcools CF3 qui sont très utiles pour la conception de médicaments et dans la synthèse asymétrique, et les amines cycliques trifluorométhylées qui peuvent servir de bon substrat pour synthétiser des composés CF3-cycliques plus fonctionnalisés. / Fluorinated compounds have shown a growing importance in the development of pharmaceutical agents owing to the outstanding properties of the fluorine atom. In this thesis, we focused on the synthesis of enantiopure trifluoromethyl nitrogen-containing compounds.Starting from the trifluoromethyl aldimine, firstly, an asymmetric aza-Baylis–Hillman reaction was realized with high reaction rates, and diastereoselectivities, and the previously unknown enantiomerically pure (R)-α-methylene β-CF3 β-amino acid was obtained in good yield. Then, through aza-Barbier reaction, the five-membered and six-membered trifluoromethyl cyclic amino acids were obtained, including β-amino acid and γ-amino acid, especially CF3-β-proline, which is very interesting in the further peptide synthesis.Finally, through the addition of vinyl ether to imine, different novel trifluoromethylated amines were afforded. Among these compounds, CF3-amino alcohols are very useful in drug design and asymmetric synthesis, and enantiopure CF3-cyclic amine is a very good substrate to synthesize more functionalized CF3-cyclic compounds.