Este trabalho estuda a propagação da luz no esmalte e dentina humanos, através da transmitância direta e absorbância no intervalo de comprimento de onda de 200 a 3200nm, e através da transmitância total no intervalo de onda de 380 a 760nm. Foram utilizadas secções de 30 molares humanos íntegros, que foram seccionados nos sentidos VL (vestíbulo – Lingual), MD (mésio distal) e OC (ocluso cervical). As espessuras utilizadas foram de 0,5mm e 0,25mm. Foram agrupados 5 dentes para cada sentido para cada espessura. Esmalte e dentina estavam presentes de maneira simultânea na mesma amostra. A absorbância foi calculada, a partir dos espectros de transmitância direta, aplicando-se a Lei e Beer-Lambert. Os espectros de transmitância total foram obtidos no espectro visível, e comparados, em média, com os espectros de transmitância direta no mesmo intervalo, para obter a energia difusa das amostras. Os espectros UV (Ultravioleta), VIS (Visível) e IV (Infravermelho), foram tratados separadamente para cada tecido e espessura. No infravermelho foram identificados os picos de transmitância e absorbância para ambos os tecidos. Os valores de transmitância e absorbância para cada faixa espectral foram tratados pela ANOVA, e os grupos comparados pelo teste de intervalo de confiança (95%). Os resultados mostraram que, as propriedades ópticas do esmalte e dentina diferem no que diz respeito as 3 faixas espectrais testadas. Os resultados também mostram que as propriedades ópticas são dependentes da espessura e do sentido de seccionamento dos dentes. A pesar das diferenças apresentadas entre os espectros, as curvas espectrais mostraram um padrão semelhante para todas as amostras de dentina e de esmalte, independente da espessura. Este comportamento possibilitou a identificação de picos comuns nos espectros estudados. / This research studies the propagation of light in the human enamel and dentine, through direct transmittance and absorbance in the 200 to 3200nm wavelength interval, and through total transmittance in the 380 to 760nm wavelength interval. The study employed sections of 30 human integral molars, which were sectioned in the VL directions (vestibule – Lingual), MD (mesio distal), and OC (occlusion cervical). The thicknesses used were from 0.5mm to 0.25mm. Five teeth were grouped in each direction for each thickness. Enamel and dentine were simultaneously present in the same sample. Absorbance was calculated from the direct transmittance specters, applying the Beer-Lambert Law. Total transmittance specters were obtained in the visible specter, and compared, on average, with the Total transmittance specters in the same interval, to obtain the diffuse energy of the samples. UV (Ultraviolet), VIS (Visible), and IV (Infrared) specters, were treated separately for each tissue and thickness. In infrared, the transmittance and absorbance peaks were identified for both tissues. The transmittance and absorbance spectral range were treated by ANOVA, and the groups compared by the confidence interval test (95%). The results showed that the optical properties of the enamel and dentine differ with regard to the three tested spectral ranges. The results also showed that the optical properties are dependent on the thickness and the direction of the sectioning of the teeth. Despite the differences found between the specters, the special curves showed a similar pattern for all samples of dentine and enamel, independently of the thickness. This behavior allowed the identification of common peaks in the specters under study.

La pulpe dentaire est un tissu connectif innervé et vascularisé, contenu dans une structure minéralisée inextensible formée par l’émail, la dentine et le cément. Ce tissu assure l’homéostasie et la sensibilité de la dent. Il est sujet à des lésions sévères faisant suite à une carie ou à un traumatisme. La thérapeutique conventionnelle préconisée alors est le traitement endodontique, qui consiste en l’exérèse de la totalité du tissu pulpaire et le comblement de l’espace évidé par un matériau synthétique bioinerte. Malgré les résultats cliniques satisfaisants, cette thérapeutique induit une fragilisation de la dent et une plus grande susceptibilité aux infections, qui peuvent conduire à terme à la perte de la dent. En se basant sur la présence de cellules souches mésenchymateuses dans la pulpe dentaire, des stratégies de régénération alternatives au traitement endodontique traditionnel sont à l’étude, afin de permettre le maintien des fonctions de nutrition et de sensibilité de la pulpe, garantes de la pérennité de la dent sur l’arcade. Elles s’inscrivent dans deux approches: la régénération de novo, en cas de nécrose du tissu pulpaire et la régénération partielle, lorsque seul le tissu pulpaire endommagé est éliminé et régénéré. Nos travaux portent sur la faisabilité de cette dernière approche dans un modèle préclinique. En effet, dans la perspective d’un transfert vers la clinique humaine, des modèles chez le gros animal doivent être développés afin de tester la faisabilité et le succès de cette thérapie, dans des conditions proches de la clinique. Du fait de ses similitudes avec l’homme en termes d’anatomie et de physiologie, le miniporc représente un modèle de choix pour les études précliniques d’ingénierie pulpaire. L’objectif principal de cette étude est de tester la faisabilité de la régénération pulpaire partielle, en implantant des cellules pulpaires porcines (pDPCs) contenues des hydrogels injectables dans des défauts pulpaires artificiellement créés chez le miniporc. Au cours ce travail, différentes techniques d’imagerie d’évaluation du processus de régénération ont été développées. En particulier, un protocole d’angiographie tridimensionnelle in- pour la visualisation du réseau vasculaire pulpaire a été mise au point. Par ailleurs, en utilisant des paramètres morphométriques spécifiques, initialement développés pour caractériser l’os, une analyse tridimentionnelle par micro-CT des tissus minéralisés de réparation a été élaborée. En appliquant un “split mouth model”, les hydrogels injectables ensemencés ou non par des pDPCs ont été implantés dans des molaires et des prémolaires, après amputation de la pulpe camérale. À 21 jours après la chirurgie, les analyses d’imagerie, d’histologie et d’immunologie ont mis en évidence, qu’indépendamment de la présence des pDPCs, l’implantation des hydrogels a induit la formation d’un pont d’ostéodentine. La caractérisation morphométrique tridimensionnelle a montré que la microarchitecture de ce pont différait largement de la dentine native. De plus, en présence des pDPCs, le processus de réparation était modifié, avec une moins bonne étanchéité du pont. Au cours de ce travail, une technique de suivi non invasive de la régénération a tenté d’être mise au point. Une angiographie tridimensionnelle par soustraction a été réalisée avant et après la procédure de régénération pulpaire partielle. Si les angiographies ont révélé l’entière vascularisation des mâchoires et des dents à croissance continue, l’apport vasculaire des dents matures traitées, du fait de son faible flux, n’a pas pu être mis en évidence. L’absence de régénération partielle de la pulpe dans les conditions testées souligne l’importance des modèles précliniques pour identifier les facteurs promouvant un environnement favorable à la régénération, dans la perspective d’un transfert vers la clinique humaine. / The dental pulp is a connective tissue, which is highly innervated and vascularized, encapsulated in a mineralized inextensible structure formed by enamel, dentin and cementum, ensuring the homeostasis and sensibility of the tooth. The pulp is often damaged by caries and trauma, resulting in infection or necrosis. In such situations, the routine clinical treatment is a root canal therapy, which consists in the elimination of the affected tissue and filling of the endodontic canal system with bioinert synthetic materials. In spite of satisfactory clinical outcomes, none of the original functions is restored and the lack of sensitivity as well as natural defence may lead to tooth fracture and reinfection. Cell-based pulp regeneration could provide a valid alternative to traditional endodontic treatment of damaged teeth. This strategy focuses, in fact, on the preservation of the healthy pulp tissue and the regeneration of the damaged one, by combining stem cells, scaffolds and growth factors. In case of trauma or carious lesion, as the pulp inflammatory reaction is compartmentalized in first instance, such conservative approach could be indicated. Regarding non-rodent animal model, to our knowledge, only Iohara et al. (2009) reported the achievement of partial pulp regeneration in canine tooth by implantation of subfractions of autologous pulp cells; however, in the perspective of a transfer to the human clinic, larger animal models should be developed to test the feasibility and the success of the therapy mimicking the clinical conditions of pulpotomy. Due to dental anatomical and physiological similarities with human, the minipig constitutes a model of choice for preclinical pulp engineering studies. The aim of this study was to develop a preclinical model of partial dental pulp regeneration in minipig, by implanting a pulp construct, made by self-assembling nano-peptide injectable hydrogel and porcine minipig dental pulp cells (pDPCs), in artificially created pulp defects. Secondarily, in the context of this preclinical model, two different techniques of analysis of the regeneration process have been developed. In particular, an in vivo 3D subtraction angiography has been set for the visualization of dental pulp vascular network. Indeed, further developments of this modality open promising perspectives of its application for the morphometric characterization of angiogenesis process in newly formed dental tissues and bone defects. Moreover, using specific morphometric parameters, initially developed to characterize bone, a micro-CT morphometric analysis of the mineralized reparative tissues, obtained by the partial pulp regeneration protocol, has been elaborated. By split mouth model, pulp constructs made with self-assembling injectable nano-peptide hydrogel with and without porcine dental pulp cells (pDPCs) were implanted, after pulp chamber amputation in premolars and molars. At day 21 after surgery, three-dimensional morphometric characterization, Masson’s trichrome and immunolabeled for DSP and BSP were performed on treated teeth. 3D subtraction angiographies have been performed before and after partial pulp regeneration procedure. Regardless of the presence of pDPCs, the implantation of pulp construct induces the formation of an osteodentin bridge, whose microarchitecture sensibly differs from the native dentin. Furthermore, the presence of pDPCs in the construct slightly impairs this reparative process. The latter was led the remaining pulp cells, instead of the pDPCs in the scaffold. Angiographies could show entire vascularization of jaws and continuously growing teeth but blood supply of treated mature permanent teeth could not be displayed. The failure of partial pulp regeneration cell based strategy, in these near-real clinical conditions, highlights the importance of preclinical models, to identify the factors promoting a favourable regenerative environment, in the perspective of a transfer to the human clinics.

This study analysed the effect of frequency of intake and amount of fluoride in milk on the remineralisation of artificial enamel and dentine caries lesions in situ. Predemineralised bovine enamel and dentine slabs were randomly allocated to 5 in situ phases. Twenty-three subjects wore removable appliances with 2 enamel and 2 dentine slabs for 7 days each phase (separated by a 7-day washout period), following a crossover double-blind protocol. In each phase, treatment was performed with milk containing 2.5 ppm fluoride (F) everyday (T1), 2.5 ppm F every other day (T2), 5.0 ppm F every day (T3), 5.0 ppm F every other day (T4) or no treatment (control; T5). The subjects were instructed to immerse the appliance in 100 ml of milk for 5 minutes and then drank 200 ml of the respective milk. The enamel alterations were quantified by surface hardness (%SHR) and transversal microradiography (TMR, Z) and dentine by TMR only. Data were analysed by repeated-measures ANOVA/Tukey´s tests (p<0.05). For enamel, the highest %SHR was found for groups treated with fluoridated milk every day compared to control, without significant differences between T1 and T3. All groups showed positive values of Z, except for T4; significant differences were seen between T1/T3 and T4. For dentine, the only group that presented remineralisation was T2. Fluoridated milk every day seems to have better remineralising effect on enamel than its use every other day, but no dose-response effect was seen. Dentine, however, does not seem to benefit from every day use of fluoridated milk. / O presente estudo teve como objetivo analisar o efeito do leite fluoretado com concentrações e frequências diferentes na remineralização de lesões de cárie de esmalte e dentina produzidas artificialmente in situ. Blocos de esmalte e dentina bovino previamente desmineralizados foram distribuídos aleatoriamente em cinco grupos. Vinte e três indivíduos usaram aparelhos removíveis contendo 2 blocos de esmalte e 2 blocos de dentina por 7 dias em cada fase (separadas por um período de washout de 7 dias), seguindo um protocolo duplo-cego, cruzado. Em cada fase, o tratamento realizado foi com leite contendo 2,5 ppm de flúor (F), todos os dias (T1), 2,5 ppm de F em dias alternados (T2), 5,0 ppm F todos os dias (T3), 5,0 ppm F em dias alternados (T4) ou sem tratamento (T5). Os sujeitos foram instruídos a mergulhar o aparelho em 100 ml de leite por 5 minutos e, em seguida, beberam 200 ml do mesmo leite. As alterações no esmalte foram quantificadas por dureza superficial e microradiografia transversal (TMR), e dentina apenas por microradiografia transversal. Os dados foram analisados por medidas repetidas ANOVA / Tukey (p <0,05). Para o esmalte, o mais alto valor de porcentagem de recuperação de dureza superficial foi encontrado para os grupos tratados com leite fluoretado todos os dias em relação ao controle, sem diferenças significativas entre T1 e T3. Todos os grupos apresentaram valores positivos de Z, com exceção de T4; foram observadas diferenças significativas entre T1/T3 e T4. Para a dentina, o único grupo que apresentou remineralização foi T2. O leite fluoretado todos os dias parece ter melhor efeito remineralizante sobre o esmalte do que seu uso em dias intercalados, mas nenhum efeito dose-resposta foi visto. A dentina, no entanto, não parece se beneficiar do uso diário de leite fluoretado.

Made available in DSpace on 2017-07-24T19:22:29Z (GMT). No. of bitstreams: 1 Luis Alfonso Arana.pdf: 2635884 bytes, checksum: d4307fc168407477c95f82f579d9612f (MD5) Previous issue date: 2013-06-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This study was evaluated clinically and laboratorially the effects of the application of two types of bleaching agents, Tréswhite Ortho (TWO) and Trés white Supreme (TWS) in patients with fixal orthodontic appliance. In the laboratorial study 50 healthy human teeth were used. For the microhardness, roughness and AFM tests, 60 enamel fragments, obtained from the crowns of 20 molars were divided depending on the treatment TWO and TWS (n=10). For each test it was performed a baseline measurement and a one week after treatment measurement. For the permeability test 30 healthy human premolars were used, divided into three groups: TWO, TWS and CTRL (SA). The variability of the pH of TWO and TWS was analyzed. For the clinical study 40 patients with fixal orthodontic appliance were recruited and divided into two groups TWO and TWS (n=20) , for each patient a color measurement was performed before the treatment and one week after the treatment; for the evaluation of sensitivity the patients received orientation in order to fill a NRS101 form before, during and after the treatment. After these tests, the normality of the obtained results was analyzed by using Kolmogorov Smirnov and Shapiro-Wilk tests. In the laboratorial assessment, there was a significant reduction on the microhardness values when compared with the initial measurements; for the roughness test there was a significant decrease on the (Ra) values when compared with the initial values for the TWO group, for the TWS group non significant alterations were observed; on the permeability test the TWS group obtained higher values of the mg/mL concentration when compared to TWO, which presented higher values than CTRL group. The pH values of both groups were statistically different with tendency to alkalinity and acidity for the groups TWO and TWS respectively. On the clinical study there was a significant decrease of tooth color values for both groups when compared with the initial values, and showed non-significant differences between groups when compared to each other; for dental sensitivity, when each of the evaluated days were compared to day 0, there was a significant increase for both groups, however, non-significant statistical differences were also found. It was concluded that the tested products on the laboratorial assessment can modify the superficial properties of the enamel, and have the capacity of permeabilizing the dentin-enamel complex until reaching the pulp chamber, also showing variability on the pH values due to the time of application, clinically, both products showed treatment effectiveness and a increase of tooth sensitivity. / Este estudo avaliou laboratorial e clinicamente dois agentes clareadores (Treswhite Ortho (TWO) e Tres white Supreme (TWS)) em pacientes com aparelho ortodôntico fixo. No estudo laboratorial, foram utilizados 50 dentes humanos hígidos. Para os testes de microdureza, rugosidade e AFM foram utilizados 60 fragmentos de esmalte, obtidos a partir das coroas de 20 molares hígidos; divididos segundo o tratamento, TWO e TWS (n=10). Para cada teste, foram realizadas mensurações de linha base e uma semana após o tratamento; sendo para o teste de permeabilidade utilizados 30 pré-molares humanos hígidos, divididos em três grupos: TWO, TWS e CTRL (SA). A variação do pH dos produtos TWO e TWS foi analisada. No estudo clínico, foram recrutados 40 pacientes com aparelhos ortodônticos fixos, divididos em dois grupos, TWO e TWS (n=20). Em cada paciente foi realizado um registro de cor antes do tratamento e uma semana após o mesmo; para avaliar a sensibilidade dental os pacientes foram orientados a preencher um formulário NRS101, antes e durante o tratamento. Após os testes, a normalidade dos dados obtidos foi analisada empregando-se o teste de Kolmogorov Smirnov e Shapiro-Wilk. No estudo laboratorial, a microdureza sofreu uma diminuição significativa em relação aos valores finais comparados com os valores iniciai; para o teste de rugosidade, houve uma diminuição significativa nos valores de (Ra) iniciais e finais para o grupo TWO. O grupo TWS não sofreu alterações significativas; no teste de permeabilidade, o grupo TWS obteve valores de mg/mL significativamente maiores ao grupo TWO, que foi significativamente maior ao grupo CTRL. Os valores de pH de ambos os grupos foram estatisticamente diferentes com tendências a alcalinização e acidificação para os grupos TWO e TWS respectivamente. No estudo clínico houve uma diminuição significativa da cor, para ambos os grupos, em relação aos valores iniciais sem diferença significativa entre os grupos; para a sensibilidade ao comparar cada um dos dias testados com o dia 0 encontrou-se um aumento significativo para ambos os grupos porém, sem diferença estatística entre os mesmos. Concluiu-se que os produtos testados num modelo de estudo laboratorial podem alterar as propriedades superficiais do esmalte; tem a capacidade de permeabilizar o complexo dentinaesmalte até atingir a câmara pulpar e apresentam variação nos valores de pH, conforme o tempo de aplicação. No estudo clínico ambos os produtos demonstraram efetividade de tratamento e aumento na sensibilidade dentária.

Este trabalho estudou os efeitos de algumas soluções irrigadoras sobre a microdureza dentinária e capacidade de remoção da smear layer. As soluções testadas foram: soro fisiológico, hipoclorito de sódio a 2,5%, EDTA a 15% em pH 7,3, EDTA a 15% em pH 9,0, ácido etileno diamino di-succínico (EDDS), Smear Clear® e BioPure MTAD®. Para o estudo de microdureza, 70 fragmentos de dentina medindo 5x5 mm foram obtidos do terço médio de hemissecções radiculares de incisivos bovinos, sendo separados aleatoriamente em sete grupos. A microdureza Knoop inicial da dentina foi aferida por meio de microdurômetro acionado com uma carga de 25 g por 15 s. As amostras eram então tratadas pela imersão nas soluções experimentais por um minuto, após o qual tinham a sua microdureza mensurada. Após mais quatro minutos de imersão nas soluções testadas, os valores de microdureza eram novamente registrados. Os valores de microdureza iniciais e após cada imersão nas soluções testadas foram então submetidos à análise estatística (two-way ANOVA). Para a avaliação da capacidade de remoção da smear layer, 35 raízes de incisivos bovinos foram separadas aleatoriamente em sete grupos e instrumentadas pela técnica step-back. Cada grupo recebeu um tipo de solução irrigadora experimental, ficando estas em contato com as paredes dentinárias por 5 minutos. Os espécimes foram cisalhados e observados ao microscópio eletrônico de varredura com um aumento de 350 vezes para avaliação da remoção da smear layer. Fotomicrografias do terço médio do canal radicular foram obtidas e, por meio de uma grade de integração, foi contabilizado o percentual de áreas contendo smear layer. Os resultados da análise da microdureza dentinária indicaram que, com exceção do soro fisiológico, todas as soluções testadas causaram uma redução significativa desta propriedade. Hipoclorito de sódio a 2,5%, EDDS e Smear Clear® apresentaram resultados semelhantes, causando diminuição da microdureza menos acentuada do que o BioPure MTAD® ou as soluções de EDTA em pH 7,3 ou 9,0. Para a análise de remoção da smear layer, as soluções de EDTA em pH 7,3 ou 9,0, o Smear Clear® e o BioPure MTAD® mostraram resultados semelhantes. O EDDS mostrou semelhanças estatísticas tanto com o hipoclorito de sódio como com as outras soluções quelantes testadas, ocupando uma posição intermediária na capacidade de remoção da smear layer. Pode-se concluir que o EDTA em pHs 7,3 ou 9,0 são estatisticamente semelhantes, bem como o BioPure MTAD®. Enquanto o Smear Clear® é capaz de remover a smear layer sem diminuir a microdureza dentinária, o EDDS reduz moderadamente a microdureza dentinária, porém é deficiente na limpeza das paredes do canal radicular. / This study evaluated the effects of some irrigating solutions on dentine microhardness and smear layer removal. The tested solutions were: saline, 2.5% sodium hypochlorite, 15% EDTA in pH 7.3, 15% EDTA in pH 9.0, ethylene diamine dissuccinic acid (EDDS); Smear Clear® and BioPure MTAD®. For the microhardness study, 70 5x5 mm dentine stubs obtained from the middle third of root hemisections were randomly divided in seven groups. The initial Knoop Hardness Values of the samples were assessed by a microhardness tester with a 25 g load, for 15 s. The samples were then immersed on tested solutions for one minute, after which the KHN values were again measured. One more evaluation of microhardness was performed after four more minutes of treatment with the tested solutions. Results were then submitted to statistical analysis (two-way ANOVA). For the smear layer removal study, 35 bovine incisor roots were randomly assigned to seven groups, according to the irrigating solution, and instrumented following the step-back technique. The irrigating solution was left for 5 minutes in the canals after instrumentation, and then washed with distilled water. Samples were then split and observed under the SEM with 350x magnification. Photomicrographs were obtained from the middle third of the root canal and evaluated for the percentage of remaining smear layer. Results of the microhardness tests showed that all solutions yeld to a hardness reduction of dentine, except saline solution. Sodium hypochlorite, EDDS and Smear Clear presented similar results, with mild reduction of microhardness, while MTAD or EDTA solutions presented severe microhardness alterations. Regarding smear layer removal, EDTA solutions, Smear Clear® and BioPure MTAD® presented similar results, with clean root canal walls and no visible débris. EDDS was more effective than saline solution or sodium hypochlorite, but less effective than the other chelating solutions. It can be concluded that EDTA at pH 7.3 or 9.0 are statistically similar, as well as BioPure MTAD®. While Smear Clear® is able to remove smear layer without reducing dentine microhardness, EDDS does reduce it moderately, but without properly cleaning the root canal walls.

Na literatura não existe consenso em relação à quantidade de dentina cariada que deve ser removida durante o preparo cavitário. Desta forma, este estudo teve como objetivo comparar os microorganismos remanescentes após a remoção total de tecido cariado e selamento e a remoção parcial de tecido cariado e selamento. Molares permanentes com lesões de cárie primárias ativas localizadas no terço médio da dentina e apresentando polpa vital foram divididos aleatoriamente em dois grupos: grupo teste - remoção parcial de tecido cariado (n=18), ou grupo de controle - remoção total de tecido cariado (tratamento restaurador convencional) (n=18). Os desfechos analisados foram a quantificação microbiana e a freqüência de isolamento microbiano. Amostras de dentina foram obtidas com duas brocas de baixa rotação estéreis n º 4, após a remoção da cárie e após 3 meses de proteção com cimento de hidróxido de cálcio e selamento das cavidades com cimento de ionômero de vidro. As amostras foram armazenadas em um recipiente estéril contendo 1,2 ml de RTF e submetidas a diluições decimais. Análises microbiológicas foram realizadas para Streptococcus spp., estreptococos do grupo mutans, Lactobacillus spp. e contagem total de anaeróbios.Antes do selamento, uma maior contagem de microrganismos foi detectada no grupo teste, em comparação ao grupo controle. No grupo de teste, uma redução significativa foi encontrada, após o selamento, na contagem de anaeróbios totais, Streptococcus spp. e Lactobacillus spp. Após 3 meses de selamento, não foi detectada diferença no crescimento microbiano entre os grupos para qualquer um dos microrganismos estudados. Portanto, a semelhança observada entre a infecção microbiana após a escavação convencional e remoção parcial de tecido cariado sugere que não há necessidade de realizar a remoção total do tecido cariado baseada em critérios clínicos convencionais de dureza. / In the literature there is no consensus on the amount of carious dentin to be removed during the cavity preparation. Thus, this study aimed to compare the remaining microorganisms after complete caries removal and sealing to partial caries removal and sealing. Permanent molars with active primary carious lesions located in the middle third of dentin and vital pulp were randomly divided into two groups of 18: test group - partial caries removal, or control group – complete caries removal (conventional restorative treatment). The outcomes analyzed were microbial quantification and frequency of microbial isolation. Dentin samples were obtained with two sterile n° 4 round burs after caries removal and after 3 months of protection with calcium hydroxide cement and sealing of the cavities with glass ionomer cement. The samples were stored in a sterile container with 1.2 ml of RTF and submitted to decimal dilutions. Microbiological analyses were performed to the Streptococcus spp., Mutans streptococci, Lactobacillus spp. and total anaerobes counts. Before sealing, a higher microorganism counts were detected in the test group compared to the control group. In the test group, significant reduction was found after sealing in the total anaerobes count, Streptococcus spp. and Lactobacillus spp. After 3 months of sealing, no difference was detected in microbial growth between groups for any of the microorganisms studied. Therefore, the observed similarity between the microbial infection after conventional excavation and partial caries removal suggests that there is no need to perform complete caries removal based on conventional clinical criteria of hardness.

La dentine est l’un des principaux éléments constitutifs de la dent humaine. Elle montre une structure hiérarchique. A l’échelle microscopique, la dentine est composée de tubules (porosité naturelle du tissu), de dentine péritubulaire et de dentine intertubulaire.L’organisation de ces structures détermine fortement ses propriétés mécaniques. La connaissance de sa structure, de ses propriétés mécaniques et de ses déformations dues aux variations de l’environnement extérieur peuvent être utiles afin d’améliorer les protocoles de restauration de la dentine. Dans ce travail, quatre techniques d’observation (µCT, microscope optique, ESEM et microscope confocal) ont été explorées et comparées. En particulier, la microscopie confocale a été utilisée afin de visualiser en 3D le réseau poreux dentinaire. Comparée à l’observation 2D, elle permet d’obtenir des informations supplémentaires. Par example, les tubules montrent des structures en arbre plus complexes près de l’email que la forme en Y déduite des observations 2D. Ces résultats peuvent également nous fournir des données d’entréespour une modélisation réaliste prenant en compte la structure poreuse complexe à l’intérieur de la dentine humaine.Par la suite, un test de compression associé à la correlation d’images numérique a été mis en place avec un système qui permet de commander simultanément l’humidité et la température de l’environnement. Grâce à ce dispositif, le module d’élasticité de la dentine humaine a été mesuré (16.7GPa avec un écart-type de 5.1GPa), et le coefficient de Poisson a été estimé à 0.31. Le comportement de dilatation de la dentine humaine avec l’humidité relative a été étudié. La spectroscopie par résonance ultrasonore (RUS) a été utilisée et ses résultats comparés au test de compression mécanique. À échelle microscopique, les propriétés mécaniquesde la dentine péritubulaire et de la dentine intertubulaire ont été caractérisées par nanoindentation. Les deux méthodes utilisées (méthode dynamique CSM et méthode de déchargement statique) indiquent les mêmes tendances en matière de module d’Young pour les deux composantes de la dentine. La dentine péritubulaire a un module d’élasticité plus élevé (26.7GPa avec un écart type de 3.1GPa) que la dentine intertubulaire (16.2GPa avec un écart type de 5.5GPa). De plus, le comportement en fluage de la dentine a été étudié par nanoindentation. Il se trouve qu’un modèle de Maxwell-Voigt à quatre éléments peut être utilisé pour évaluer le comportement en fluage de la dentine.Pour résumer, une étude morphologique et mécanique du tissu dentinaire a été effectuée. De nouvelles techniques, par example, la microscopie confocale ont été utilisées et ont montré leur utilité dans le but de donner un nouvel éclairage sur le tissu dentinaire. Les protocoles d’essais mécaniques qui ont été mis en place à différentes échelles permettront de mieux comprendre la relation structure-propriété en utilisant les outils d’observation validés dans ce travail. / Human dentin is one of the main components of human tooth. It shows a hierarchicalstructure from a multi-scale point of view. Generally speaking, dentin can be seen as a hard biomaterial consisting in 3 phases: the porous phase made of tubules, the inclusion phase made of peritubular dentin and the matrix phase made of intertubular dentin. These hierarchical structures strongly determine its mechanical properties. The knowledge of its structure, its mechanical property and its deformation behavior due to the variation of the external environment may be useful to improve the dentin restoration process. In this work, four observation techniques (µCT, optical microscope, ESEM and confocal microscope) have been used and compared. Particularly, confocal microscopy is proposed to allow 3D visualization of the complex dentin porous network. Compared with usual 2D observation tool, it may provide new information. For example, near the DEJ, tubules show a more complex treestructure than the Y-shaped deduced from 2D observations. These findings may also allow to achieve more realistic modeling considering the complex porous structure inside human dentin.Later on, compression test associated with DIC was carried out within an integrated system which can control simultaneously the humidity and the temperature of the environment. Using this system, the elastic modulus of human dentin was measured to be 16.7GPa with a standard deviation of 5.1GPa. And the Poisson’s ratio was found to be 0.31. The dilatation behavior of human dentin due to relative humidity was also explored. Furthermore, resonant ultrasound spectroscopy was performed in order to compare the results with these mechanical testing. At the micro-scale, the mechanical properties of peritubular dentin and intertubular dentin werecharacterized by nanoindentation. The two methods used in this work (dynamic CSM method and the static unload method) present the same trends of elastic moduli for the two components. Peritubular dentin has a higher elastic modulus (26.7GPa with a standard deviation of 3.1GPa) than intertubular dentin(16.2GPa with a standard deviation of 5.5GPa). Besides, the creep behavior of dentin was assessed by nanoindentation. Four elements Maxwell-Voigt model can be used to model dentin’s creep behavior.To sum up, a morphological and mechanical study of the dentinal tissue has been performed. New techniques, such as confocal microscopy have been used and showed their usefulness in order to give new insight into the dentinal tissue. The mechanical testing protocols that have been set up at different scales will enable to better understand the structure-property relationship by using them associated with the observation tools validated in this work.

O objetivo deste estudo foi avaliar, in vitro, quantitativamente e qualitativamente, a estabilidade de um híbrido experimental em duas concentrações diferentes (concentrado e diluído) aplicado sobre a simulação de uma dentina sensível. Dentes molares humanos foram selecionados e tiveram suas coroas seccionadas abaixo do sulco oclusal de forma a obter espécimes de discos de dentina que foram planificados e polidos até atingirem a espessura de 1,0 milímetro. Os espécimes foram divididos em 4 grupos (n=9) de acordo com os tratamentos de superfície propostos: saliva artificial (SAL), adesivo dentinário autocondicionante (AD), híbrido experimental concentrado (TC) e híbrido experimental diluído na proporção de 1:3 (TD). Dois métodos foram empregados para avaliar a estabilidade: condutância hidráulica (permeabilidade dentinária) e microscopia eletrônica de varredura. Foi realizada a leitura da permeabilidade dentinária em 6 tempos experimentais: Mínima (sem tratamento), Máxima (com túbulos abertos), Tratamento (após aplicação dos respectivos tratamentos), Erosão (após 5 minutos de imersão em ácido cítrico 0,05M pH 3,8), Escovação (após escovação de 3900 ciclos) e Erosão Pós (repetição da erosão após o processo de escovação). A microscopia eletrônica de varredura foi realizada em espécimes de dentina com área central de aplicação dos tratamentos e tecido natural nas laterais para evidenciar as características da película aplicada. As leituras foram feitas após a aplicação dos tratamentos, após a erosão, após a escovação e após a erosão pós escovação, para todos os 4 tratamentos propostos. O teste de análise de variância (ANOVA) de Medidas Repetidas com 2 fatores de variação foi aplicado juntamente com o teste de comparações múltiplas pareadas (Tukey). Para permeabilidade dentinária todos os tratamentos reduziram a condutância hidráulica (Lp) em relação à Máxima. TC e TD apresentaram os menores valores (24% e 15%) respectivamente. O TD continuou apresentando valores semelhantes estatisticamente após a Erosão (36%), sendo estatisticamente semelhante ao TC (55%).. No tempo Escovação o TD apresentou Lp estatisticamente semelhante aos tempos Tratamento e Erosão. Todos os grupos apresentaram-se estatisticamente semelhantes entre os tratamentos nos tempos Escovação e Erosão Pós. A análise das MEVs evidencia túbulos dentinários com conteúdo no seu interior nos grupos TC e TD, mantendo-se durante todos os tempos experimentais. O AD apresentou uma película evidente, que começou a se destacar e exibir falhas a partir do tempo Erosão. Conclui-se que o TD apresentou o melhor comportamento sendo capaz de diminuir a permeabilidade dentinária, formando uma película fina, transparente, imperceptível, capaz de vedar (totalmente ou parcialmente) e penetrar dentro dos túbulos dentinários, resistindo aos desafios erosivos e abrasivos. / The aim of this study was to evaluate, in vitro, quantitatively and qualitatively, the stability of an experimental hybrid with two different concentrations (concentrated and diluted) applied at a simulation of a sensitive dentin. Human molar teeth were selected and their crowns were sectioned below the occlusal groove in order to obtain specimens of dentine disks that were ground flat and polished to achieve a thickness of 1.0 millimeter. The specimens were divided into 4 groups (n = 9) in accordance with proposed surface treatments: Artificial saliva (SAL) dentinal self-etching adhesive (AD), concentrated experimental hybrid (TC) and experimental hybrid diluted in the ratio 1: 3 (TD). Two methods were used to assess the stability: hydraulic conductance (dentin permeability) and scanning electron microscopy. The dentin permeability in 6 experimental times was carried out: Minimum (no treatment), Maximum (with open tubules), treatment (after application of their treatments), erosion (after 5 minutes of immersion in citric acid 0.05M pH 3, 8), brushing (brushing after 3900 cycles) and Post erosion (erosion was repeated after brushing). The scanning electron microscopy was performed on dentin specimens with a central area of application of treatments and natural tissues on the sides to show the film characteristics applied. Readings were made after application of treatments, after erosion, after brushing and after erosion after brushing, for all 4 treatments proposed. The analysis of variance (ANOVA) for repeated measures with two variation factors was applied with the multiple comparisons paired test (Tukey). For dentin all treatments reduced hydraulic conductance (Lp) in relation to Maximum. TC and TD showed the lowest values (24% and 15%) respectively. The TD continued to show statistically similar values after erosion (36%), being statistically similar to TC (55%). In brushing time the TD Lp was statistically similar to Treatment and erosion times. All groups were statistically similar between treatments in brushing and Post Erosion times. The analysis of SEM shows dentinal tubules with content inside on the TC and TD groups, remaining during all experimental period. AD presented a clear film, which began to stand out and show failure from erosion time. It follows that the TD had better behavior being able to decrease permeability of dentin by forming a thin film transparent, imperceptible, capable of sealing (fully or partially) and penetrate within the dentine tubules, resisting the erosive and abrasive challenges.

O presente estudo avaliou ex vivo a capacidade de infiltração do hipoclorito de sódio em diferentes concentrações nos canalículos dentinários. 40 incisivos centrais superiores tiveram suas coroas seccionadas, e passaram pelo preparo biomecânico pela técnica Crown-Down, inundação com EDTA 17% por 3 minutos e irrigação final com água destilada. Após o preparo biomecânico os espécimes foram secos externamente com toalha de papel absorvente e internamente por meio de cones de papel. Permaneceram no dessecador a vácuo por 120 minutos e imersos em uma solução de sulfato de cobre, durante 15 minutos sob vácuo com o objetivo de remover o ar do interior do canal radicular e consequentemente permitir maior penetração da solução citada e mantida por mais 75 minutos à pressão ambiente. Posteriormente os espécimes foram removidos da solução e secas com papel toalha e cones de papel absorvente. Foram então imersos na solução de ácido rubeânico sob vácuo por 15 minutos e mantido por mais 225 minutos à pressão ambiente. Os espécimes foram aleatoriamente divididos em 4 grupos de acordo com a solução irrigante a ser utilizada: GRUPO 1 (n=10) - Água destilada; GRUPO 2 (n=10) - Hipoclorito de Sódio 1%; GRUPO 3 (n=10) - Hipoclorito de Sódio 2,5%; GRUPO 4(n=10) - Hipoclorito de Sódio 5,25%. Nesta fase os espécimes foram irrigados com 2 ml a cada 2 minutos por 30 minutos com a solução irrigante de acordo com seu grupo, terminando com irrigação abundante com água destilada. Após a irrigação, foram obtidos slices de 1,0 mm de espessura por meio da máquina de corte de tecido duro IsoMet® 1000. As amostras foram polidas e por meio de microscópio digital ligado a um computador obteve-se as imagens dos slices, que foram mensuradas por um software AxioVision 4.8. Em seguida, calculou-se as áreas de dentina da região descolorida pela solução irrigante. Os resultados mostraram que no G1 não houve descoloração da dentina. Para as soluções de hipoclorito, os resultados mostraram que a concentração da solução interferiu no poder de descoloração em profundidade dentinária.Quando analisados os resultados estatisticamente, houve diferença entre a área de penetração da solução a 1% e a 5,25%, já a solução a 2,5% apresentou valores intermediários.Podendo pertencer tanto aos grupos do hipoclorito a 1% como a 5,25%. / The aim of this study was to evaluate in ex vivo the capacity of different concentrations of sodium hypochlorite to infiltrate in the root canal dentinal tubules. 40 maxillary central incisors had theyre crowns sectioned and were submitted into a mechanical preparation by Crown-down technique followed by a 3 min. irrigation with 17% EDTA and for final irrigation with distilled water. After mechanical preparation the specimens were externally dried with an absorbent paper towel and internally with absorbent paper cones. They remained in a vacuum desiccator for 120 minutes and after that, they were immediately immersed in a container with copper sulfate solution for 15 minutes also in vaccum for the purpose of removing the air from the root canal and consequently increase the cuprum solution penetration. Then, they were kept for more 75 minutes in an ambient pressure. The specimens were removed from the solution and dried with absorbent paper towel and cones and immersed in a rubeanic acid solution, in vacuum, for 15 minutes in an ambient pressure for 225 minutes. The specimens were randomly divided in 4 groups, according to the used irrigant solution: Group 1(n=10) - distilled water; Group 2(n=10) sodium hypochlorite 1%; Group 3 (n=10) sodium hipochlorite 2,5% and Group 4 (n=10) sodium hypochlorite 5,25%. In this phase the specimens were irrigated with 2 ml in each 2 minutes for 30 minutes with the irrigation solution in accordance with they\'re group, and finalized with an abundance of destilled water. After the irrigation, 1.0 mm slices of the thickness were obtained by means of an hard tissue specimen cutting machine Isomet® . The samples were polished and, with the help of a digital microscope, which was connected to a computer, the sections of the speciments were obtained, and later measured by a software - AxioVision 4.8. Then the areas of the specimens who were discolored by the irrigant solution were calculated. The results showed that in G1 showed no discoloration of the dentin. For the groups who used hypochlorite solutions, the results showed that the concentration of the solution could interfere with the discoloration of the dentine in depth. When analized, the results, there was a statistically significant difference between the area of penetration of a 1% solution (G2) and 5.25% solution (G4), however the 2.5% (G3) presented intermediate values, which can represent either the 1% hypochlorite group as the 5,25% hypochlorite.

Dans cette thèse, le problème de l'infiltration de bio-adhésifs résineux dans la dentine a été abordé par le biais de deux études, expérimentale et numérique. L'originalité de ces travaux réside dans le fait que l'échelle à laquelle nous nous sommes placés est nanoscopique. En effet, c'est l'infiltration d'un réseau de fibres de collagène de diamètre de l'ordre de 80nm qui pilote l'adhésion des composites résineux à la dentine. Une étude MEB a été menée pour confirmer et compléter la connaissance actuelle du milieu poreux. Cependant un paramètre manque dans la perspective d'une modélisation géométrique du réseau : la porosité n'est pas connue. Une étude complémentaire du substrat par porosimétrie à intrusion de mercure a donc été menée. La porosité volumique de la dentine déminéralisée est estimée à 55%. Deux tailles de pores sont révélées : la première correspond aux tubules et canalicules (autour de 1micron) et la seconde aux espaces interfibrillaires (autour de 50nm) jamais encore caractérisés de manière volumique. Cette étude permet aussi une investigation méthodologique. La lyophilisation, technique de séchage peu utilisée en odontologie, est évaluée et comparée à la technique de séchage utilisant l'HMDS. La lyophilisation semble être une technique de séchage fiable et convient parfaitement aux essais de porosimétrie. La modélisation géométrique du réseau fibreux est ensuite réalisée : les fibres sont considérées comme des zones à viscosité élevée. Cette modélisation est validée par comparaison des écoulements entre une fibre modélisée implicitement et une autre modélisée plus classiquement. L'orientation des fibres n'étant pas connue quantitativement, il a été choisi de construire trois types de réseau, le plus proche de la réalité (à la vue des images MEB) étant le réseau où les fibres sont disposées aléatoirement. Sa perméabilité a été estimée et validée par comparaison avec différentes études de réseaux fibreux ou non. Enfin, l'avancée du front est abordée de manière dynamique. Les équations d'avancée du front sont mises en place. Les équations de Navier Stokes sont couplées avec une méthode level set : l'interface correspondant au front d'infiltration n'est pas maillé (tout comme les fibres) mais correspond à une isovaleur d'une certaine fonction. Un attention particulière est portée aux conditions aux limites au niveau de la ligne triple et par le biais d'un terme ajouté à la formulation variationnelle, l'angle de contact est fixé. Ici, la principale difficulté est la prise ne compte des fibres qui ont été définies de manière implicite. Cette fois, les fibres sont uniquement le lieu de l'application de la condition aux limites fixant l'angle de contact et ne sont plus des zones de viscosité élevée car cela bloquerait le front. Le problème est résolu pour différentes géométries de réseaux fibreux. Tout d'abord, l'influence de certains paramètres sur des réseaux simples est sondée puis l'infiltration du modèle géométrique complet (réseau fibreux et tubules) est réalisée. Une conclusion cruciale pour les praticiens est mis en avant : augmenter le temps d'infiltration de la résine n'améliore pas l'infiltration. La simulation d'un essai de porosimétrie permet de distinguer deux tailles de pores distinctes et nécessite un ajustement car un décalage en pression par rapport à la courbe expérimentale est observée. L'outil construit permet une approche pédagogique de l'essai de porosimétrie et, après ajustement, pourra permettre la validation de diverses géométries.