O objetivo deste estudo clínico controlado de boca dividida foi avaliar longitudinalmente a progressão radiográfica de lesões de cárie em superfícies proximais de molares decíduos após o selamento com infiltrante resinoso em crianças de 3 a 8 anos. Foram incluídos neste estudo 16 pacientes que possuíam no mínimo duas lesões em superfície proximal de molares decíduos, com imagem radiográfica até o terço externo de dentina. As lesões foram alocadas de forma aleatória em dois grupos: teste (infiltrante resinoso) e controle (sem infiltrante). Os pacientes foram avaliados clinicamente quanto a presença de placa visível (IPV), sangramento gengival (ISG) e exame visual de cárie. Radiografias digitais interproximais foram realizadas em todos os pacientes, de ambas as lesões. Todos os pacientes receberam tratamento para a atividade de cárie que consistiu em aconselhamento dietético, instrução de higiene bucal incluindo fio dental e quatro aplicações tópicas de flúor. Ao final de 3 meses de acompanhamento os exames foram repetidos e as radiografias digitais foram comparadas utilizando a imagem original e dois filtros de tratamento de imagem a fim de observar presença ou ausência de progressão radiográfica das lesões dos grupos teste e controle. Em um total de 16 pacientes (64 radiografias digitais usando cada filtro) não foi observada diferença estatisticamente significante entre os grupos teste e controle (teste McNemar, p=1,00), apesar de ter sido observada uma tendência de progressão das lesões em ambos os grupos. Diferenças significativas (teste Wilcoxon, p=0,01) foram observadas entre IPV inicial (30,5 ±22,0) e final (14,0 ± 7,5) e entre ISG inicial (13,5 ±18,5) e final (2,8 ± 3,4). Não foi observada relação significante entre IPV, ISG e risco à carie com a progressão radiográfica das lesões (Teste Mann Whitney, p>0,05). Este estudo mostrou que não houve diferença significante na progressão de lesões de cárie em superfícies proximais seladas com infiltrante resinoso comparadas com tratamento placebo no período de tempo avaliado. / The prevalence of proximal caries lesions in primary molars is high in many countries. This split-mouth placebo-controlled randomized clinical trial aimed to assess the progression of early proximal caries lesions on primary molars after resin infiltration. Sixteen children aged 3 to 8 years old took part of this study. Participants had to have at least two proximal lesions radiographically extending to enamel or outer dentine. Visual examination was performed after tooth separation. Digital bitewing radiographs were taken, visual plaque (VPI) and gingival bleeding indexes (GBI) were recorded and visual examination of caries was performed (baseline assessments). Proximal lesions were randomly allocated to two groups: resin infiltration (test) and no infiltration (control). All patients received 4-week topical fluoride application, dietary counseling, toothbrushing and flossing instructions. After a 3 months follow-up period, baseline assessments of all patients were repeated and digital radiographs were taken. Original digital images and enhanced images, using two different filters, were compared aiming the observation of lesion progression in both test and control groups. Evaluation of digital radiographs of the 16 children (64 digital images for each filter) showed no statistical significant differences (McNemar test, p=1,00) when test and control groups were compared. However, a tendency of lesion progression could be observed in both groups. Significant differences (Wilcoxon t-test, p=0.01) were observed for VPI between baseline (30.5 ±22.0) and follow-up (14.0 ±7.5) and for GBI at baseline (13.5 ±18.5) and follow-up (2.8 ± 3.4). No significant relation between lesion progression and VPI, GBI and caries experience was observed (Mann Whitney Test, p>0.05). This study showed no significant differences in the progression of resin infiltrated proximal caries lesions compared to the placebo treatment in this follow-up period.

The aim of this study was to evaluate the efficacy of an infiltrant (Icon, DMG, Germany) in molars and premolar´s lesions in patients attended to Dental Faculties in Santa Maria and Porto Alegre, each having two or more proximal lesions extending until the outer third of dentin. This was a split-mouth randomized doubleblind trial: the lesions were randomly allocated into two treatment groups; in the test group, lesions were infiltrated (Icon application) and the control group received a placebo treatment. All participants were assessed by visible plaque, papillary bleeding, salivary flow rate, dietary habits, DMFT. Fluoridation oral hygiene, dietary instructions and gel topical applications were given to all patients. After 12 months, radiographic lesion progression was evaluated using two different methods: (1) radiographs were read in pairs, (2) using subtraction radiography of digitized images. A total of 13 pairs of lesions finished the study. No difference in caries development was noted between the groups when read in pairs (p=1,0) and subtraction radiography (p=0,25). The baseline and final VPI were 24,13 ± 18,86 and 7,07 ± 4,45 (p=0,024) and the baseline and final SI were 18,38 ± 16,07 and 14,68 ± 2,62 (p=0,057). In conclusion, the use of a low viscosity resin on the treatment of proximal lesions is unnecessary when the patient adhere the non operative treatment of dental caries. / O objetivo deste estudo foi avaliar a eficácia de um infiltrante resinoso (Icon, DMG, Hamburgo, Alemanha) em lesões proximais de molares permanentes e prémolares de pacientes que freqüentavam os ambulatórios do Curso de Odontologia da UFSM e UFRGS. O delineamento deste estudo foi um ensaio clínico randomizado controlado duplo cego de boca dividida. Para tanto, selecionou-se radiograficamente 31 pacientes que possuíssem, pelo menos, duas lesões de cárie com imagem radiolúcida até terço externo de dentina com semelhante grau de desmineralização. As lesões foram divididas de forma aleatória por um software de computador em dois grupos: teste (aplicação do Icon conforme fabricante) e controle (placebo). Todos os pacientes foram avaliados quanto à presença de placa visível, sangramento gengival, CPO-S, diário alimentar e secreção salivar. Os pacientes receberam tratamento da atividade cariogênica individualizado que compreendia: instruções de higiene oral, aplicações tópicas de flúor, orientação dietética. Ao final de doze meses, as radiografias inicial e final foram comparadas pela técnica da subtração radiográfica e visual lado a lado a fim de se verificar a possível progressão das lesões. Em um total de 13 pares de lesões avaliadas, não houve diferença estatisticamente significante entre os grupos na avaliação lado a lado (p=1,0) e subtração radiográfica (p=0,25). O IPV inicial e final foram 24,13 ±18,86 e 7,07±4,45 (p=0,024) e o ISG inicial e final foram de 18,38 ± 16,07 e 14,68 ± 2,62(p=0,057). O estudo demonstra que o uso de infiltrantes resinosos se torna desnecessário ao tratamento de lesões proximais quando existe a adesão dos pacientes ao tratamento não invasivo de cárie dentária.

O objetivo deste estudo clínico controlado de boca dividida foi avaliar longitudinalmente a progressão radiográfica de lesões de cárie em superfícies proximais de molares decíduos após o selamento com infiltrante resinoso em crianças de 3 a 8 anos. Foram incluídos neste estudo 16 pacientes que possuíam no mínimo duas lesões em superfície proximal de molares decíduos, com imagem radiográfica até o terço externo de dentina. As lesões foram alocadas de forma aleatória em dois grupos: teste (infiltrante resinoso) e controle (sem infiltrante). Os pacientes foram avaliados clinicamente quanto a presença de placa visível (IPV), sangramento gengival (ISG) e exame visual de cárie. Radiografias digitais interproximais foram realizadas em todos os pacientes, de ambas as lesões. Todos os pacientes receberam tratamento para a atividade de cárie que consistiu em aconselhamento dietético, instrução de higiene bucal incluindo fio dental e quatro aplicações tópicas de flúor. Ao final de 3 meses de acompanhamento os exames foram repetidos e as radiografias digitais foram comparadas utilizando a imagem original e dois filtros de tratamento de imagem a fim de observar presença ou ausência de progressão radiográfica das lesões dos grupos teste e controle. Em um total de 16 pacientes (64 radiografias digitais usando cada filtro) não foi observada diferença estatisticamente significante entre os grupos teste e controle (teste McNemar, p=1,00), apesar de ter sido observada uma tendência de progressão das lesões em ambos os grupos. Diferenças significativas (teste Wilcoxon, p=0,01) foram observadas entre IPV inicial (30,5 ±22,0) e final (14,0 ± 7,5) e entre ISG inicial (13,5 ±18,5) e final (2,8 ± 3,4). Não foi observada relação significante entre IPV, ISG e risco à carie com a progressão radiográfica das lesões (Teste Mann Whitney, p>0,05). Este estudo mostrou que não houve diferença significante na progressão de lesões de cárie em superfícies proximais seladas com infiltrante resinoso comparadas com tratamento placebo no período de tempo avaliado. / The prevalence of proximal caries lesions in primary molars is high in many countries. This split-mouth placebo-controlled randomized clinical trial aimed to assess the progression of early proximal caries lesions on primary molars after resin infiltration. Sixteen children aged 3 to 8 years old took part of this study. Participants had to have at least two proximal lesions radiographically extending to enamel or outer dentine. Visual examination was performed after tooth separation. Digital bitewing radiographs were taken, visual plaque (VPI) and gingival bleeding indexes (GBI) were recorded and visual examination of caries was performed (baseline assessments). Proximal lesions were randomly allocated to two groups: resin infiltration (test) and no infiltration (control). All patients received 4-week topical fluoride application, dietary counseling, toothbrushing and flossing instructions. After a 3 months follow-up period, baseline assessments of all patients were repeated and digital radiographs were taken. Original digital images and enhanced images, using two different filters, were compared aiming the observation of lesion progression in both test and control groups. Evaluation of digital radiographs of the 16 children (64 digital images for each filter) showed no statistical significant differences (McNemar test, p=1,00) when test and control groups were compared. However, a tendency of lesion progression could be observed in both groups. Significant differences (Wilcoxon t-test, p=0.01) were observed for VPI between baseline (30.5 ±22.0) and follow-up (14.0 ±7.5) and for GBI at baseline (13.5 ±18.5) and follow-up (2.8 ± 3.4). No significant relation between lesion progression and VPI, GBI and caries experience was observed (Mann Whitney Test, p>0.05). This study showed no significant differences in the progression of resin infiltrated proximal caries lesions compared to the placebo treatment in this follow-up period.

O objetivo deste estudo clínico controlado de boca dividida foi avaliar longitudinalmente a progressão radiográfica de lesões de cárie em superfícies proximais de molares decíduos após o selamento com infiltrante resinoso em crianças de 3 a 8 anos. Foram incluídos neste estudo 16 pacientes que possuíam no mínimo duas lesões em superfície proximal de molares decíduos, com imagem radiográfica até o terço externo de dentina. As lesões foram alocadas de forma aleatória em dois grupos: teste (infiltrante resinoso) e controle (sem infiltrante). Os pacientes foram avaliados clinicamente quanto a presença de placa visível (IPV), sangramento gengival (ISG) e exame visual de cárie. Radiografias digitais interproximais foram realizadas em todos os pacientes, de ambas as lesões. Todos os pacientes receberam tratamento para a atividade de cárie que consistiu em aconselhamento dietético, instrução de higiene bucal incluindo fio dental e quatro aplicações tópicas de flúor. Ao final de 3 meses de acompanhamento os exames foram repetidos e as radiografias digitais foram comparadas utilizando a imagem original e dois filtros de tratamento de imagem a fim de observar presença ou ausência de progressão radiográfica das lesões dos grupos teste e controle. Em um total de 16 pacientes (64 radiografias digitais usando cada filtro) não foi observada diferença estatisticamente significante entre os grupos teste e controle (teste McNemar, p=1,00), apesar de ter sido observada uma tendência de progressão das lesões em ambos os grupos. Diferenças significativas (teste Wilcoxon, p=0,01) foram observadas entre IPV inicial (30,5 ±22,0) e final (14,0 ± 7,5) e entre ISG inicial (13,5 ±18,5) e final (2,8 ± 3,4). Não foi observada relação significante entre IPV, ISG e risco à carie com a progressão radiográfica das lesões (Teste Mann Whitney, p>0,05). Este estudo mostrou que não houve diferença significante na progressão de lesões de cárie em superfícies proximais seladas com infiltrante resinoso comparadas com tratamento placebo no período de tempo avaliado. / The prevalence of proximal caries lesions in primary molars is high in many countries. This split-mouth placebo-controlled randomized clinical trial aimed to assess the progression of early proximal caries lesions on primary molars after resin infiltration. Sixteen children aged 3 to 8 years old took part of this study. Participants had to have at least two proximal lesions radiographically extending to enamel or outer dentine. Visual examination was performed after tooth separation. Digital bitewing radiographs were taken, visual plaque (VPI) and gingival bleeding indexes (GBI) were recorded and visual examination of caries was performed (baseline assessments). Proximal lesions were randomly allocated to two groups: resin infiltration (test) and no infiltration (control). All patients received 4-week topical fluoride application, dietary counseling, toothbrushing and flossing instructions. After a 3 months follow-up period, baseline assessments of all patients were repeated and digital radiographs were taken. Original digital images and enhanced images, using two different filters, were compared aiming the observation of lesion progression in both test and control groups. Evaluation of digital radiographs of the 16 children (64 digital images for each filter) showed no statistical significant differences (McNemar test, p=1,00) when test and control groups were compared. However, a tendency of lesion progression could be observed in both groups. Significant differences (Wilcoxon t-test, p=0.01) were observed for VPI between baseline (30.5 ±22.0) and follow-up (14.0 ±7.5) and for GBI at baseline (13.5 ±18.5) and follow-up (2.8 ± 3.4). No significant relation between lesion progression and VPI, GBI and caries experience was observed (Mann Whitney Test, p>0.05). This study showed no significant differences in the progression of resin infiltrated proximal caries lesions compared to the placebo treatment in this follow-up period.

Ce travail de thèse fait partie d’un effort pour le développement des biomarqueurs, actuellement largement inexistants, pour une meilleure classification, pour une détermination plus précise du pronostic, et pour la prédiction de la réponse au traitement des tumeurs gliales malignes de l’enfant (épendymomes et gliomes de haut grade). Dans certains cas, ces biomarqueurs peuvent aussi devenir des cibles thérapeutiques.Dans ces études, nous avons pu montrer que la surexpression fréquente des marqueurs neuronaux distingue les épendymomes supratentoriels des formes infratentorielles. Parmi les épendymomes supratentoriels, une forte expression de neurofilament 70 (NF) est corrélée avec une meilleure survie sans récidive. La tenascine C (TNC) est surexprimée dans les épendymomes infratentoriels. Une étude de collaboration européenne multi-institutionnelle a été mise en place, permettant d’analyser une cohorte pédiatrique de 250 patients atteints d’un épendymome, et de démontrer la forte immunoexpression de TNC comme un marqueur robuste, associé a des survies globale et sans récidive plus péjoratives, particulièrement parmi les enfants âgés de moins de trois ans. Ceci a été validé dans une cohorte indépendante. Des immunomarquages pour NF et TNC pourraient être utilisés en clinique pour aider à déterminer le pronostic des épendymomes chez l’enfant.Une analyse des marqueurs pour la prédiction de la réponse à une thérapie ciblée anti-EGFR (erlotinib) a été réalisée par imunnohistochimie et FISH. La perte fréquente de PTEN dans les gliomes infiltrants du tronc cérébrale et la confirmation des caractéristiques des certains sous groupes (avec une forte expression de EGFR ou avec une différentiation oligodendrogliale) nous a permis de dessiner le protocole pour la prochaine étude de phase III pour cette maladie dans le cadre d’un futur essai thérapeutique de phase I/II. Nous rapportons par ailleurs des mutations du gène PI3KCA dans certains gliomes infiltrants du tronc cérébral, qui comme la perte d’expression de PTEN pourrait entrainer une activation de la voie mTOR qui devient donc une cible thérapeutique majeure théorique dans cette maladie. Des études ultérieures seront nécessaires pour définir le rôle de l’interaction entre la perte de PTEN, la surexpression de EGFR, la différentiation oligodendrogliale, les mutations de PI3KCA et d’autres altérations récemment décrites, (gains et amplifications de PDGFRA/MET mutations de TP53) et leur relation avec le devenir des patients sous traitement ciblé et les thérapies ciblées les plus intéressantes dans cette maladie uniformément fatale.Ce travail de thèse nous a permis d’explorer le rôle de la pathologie moléculaire dans la prise en charge des épendymomes et gliomas de haut grade chez l’enfant. / Biomarkers for the classification, clinical management and prognosis of pediatric brain tumors (ependymoma and high grade glioma, (HGG)) are lacking. To address this, biomarkers were developed and explored in view of classification, prognostication, target identification and prediction of the efficacy of treatment for patients with such tumors.We show that overexpression of neuronal markers distinguishes supratentorial from infratentorial ependymoma, and among the former higher immunoexpression of neurofilament 70 (NEFL) is correlated with better progression free survival (PFS). Tenascin-C (TNC) is significantly overexpressed in infratentorial ependymoma. A multi-institutional European ependymoma collaboration group was established and analyses were performed in a pediatric cohort of 250 patients, where immunohistochemistry (IHC) for TNC showed to be a robust marker of poor overall survival (OS) and PFS, particularly among children under 3 years, this being further validated in an independent cohort. Techniques and scoring performed in different laboratories were highly reproducible. IHC for NEFL and TNC could be used for prognostication of pediatric ependymoma.The analysis of putative predictive markers for the response to targeted therapies in pediatric HGG in the setting of a clinical trial with the anti-EGFR agent erlotinib was performed by IHC and fluorescent in situ hybridization. The frequent loss of PTEN in diffuse intrinsic pontine glioma (DIPG) and the confirmation of the biological singularity of the certain subgroups (expressing EGFR, displaying oligodendroglial differentiation) which seem to be associated with better response to erlotinib have helped our group to establish the design of the next Phase III protocol for this disease at our institution. We report mutations in PI3KCA constituting the first identification of oncogene mutations in some DIPG, which further highlight their biological heterogeneity. Further studies are needed to define the interaction between PTEN loss, EGFR overexpression, oligodendroglial differentiation, PI3KCA mutations and other recent findings such as PDGFRA/MET gains/amplification and TP53 mutations in these heterogeneous lesions and their relationship to the outcome of patients under new targeted therapies for this largely fatal disease.This thesis has allowed us to explore the molecular pathology in the context of biology and clinical setting of pediatric brain tumors.

O uso de materiais resinosos sobre o tecido dentário é uma alternativa para a prevenção da progressão da erosão, contudo existem poucas informações sobre o efeito da infiltração resinosa na lesão de erosão. O objetivo deste estudo foi avaliar o efeito dos materiais resinosos sobre (sem remoção de excesso) e supostamente dentro (com remoção de excesso) do esmalte previamente erodido, submetido a desafio erosivo subsequente. Os blocos de esmalte bovino foram imersos em HCl 0,01 M, pH 2,3 durante 30 segundos para a formação de lesão inicial de erosão. Em seguida, os blocos foram divididos aleatoriamente e tratados de acordo com 8 grupos (n=12): Cc e Cs- controle sem tratamento, Hc e Hs- selante de fossas e fissuras (Helioseal Clear®), Ac e As- adesivo autocondicionante (Adhese®), Ic e Is- infiltrante (Icon®); sendo c- com remoção de excesso e s- sem remoção de excesso do material. Os materiais foram aplicados de acordo com as recomendações dos fabricantes. Nos grupos com remoção de excesso, após a aplicação dos materiais houve a remoção de seu excesso da superfície de esmalte com um cotonete, anteriormente a fotopolimerização. Após o tratamento, todos os espécimes foram submetidos à ciclagem erosiva, por meio da imersão em ácido clorídrico (0,01M; pH 2,3) por 2 minutos, seguida da imersão em saliva artificial por 120 minutos, 4 vezes ao dia, durante 5 dias. A espessura de material e o desgaste dentário foram analisados por meio da perfilometria e os resultados submetidos ao teste ANOVA a dois critérios e teste de Tukey (p<0,05). Na análise do desgaste dentário após o desafio erosivo, os grupos sem remoção de excesso (Hs, As, Is) se comportaram de forma semelhante (p>0,05), constatando-se a presença de material sobre o esmalte prevenindo a perda da estrutura dentária. Os grupos nos quais o excesso de material sobre o esmalte foi removido (Hc, Ac, Ic) resultaram em perda de esmalte após a aplicação. Além disso, esses grupos (Hc, Ac, Ic) não foram capazes de proteger o esmalte contra a erosão, uma vez que após o desafio erosivo o desgaste do esmalte destes grupos foi semelhante ao grupo controle. Com base nos resultados do presente estudo, conclui-se que os materiais resinosos são capazes de proteger o esmalte contra a erosão dentária somente quando estão presentes sobre a superfície dentária, formando uma barreira mecânica. / The use of resin-based materials over the dental tissue is an alternative for erosion progression prevention, however there is little information regarding the effect of resin infiltration into erosive lesion. The aim of this study was to evaluate the effect of resin-based materials over (without excess removal) and into (with excess removal) previously eroded enamel, subjected to erosive challenge. Bovine enamel blocks were immersed in HCl 0.01 M, pH 2.3 for 30 seconds for the formation of softened erosion lesion. Then the blocks were random divided and treated according to 8 groups (n=12): Cc and Cs- control without treatment, Hc and Hs- fissure resin sealant (Helioseal Clear®), Ac and As- self-etch adhesive (Adhese®), Ic and Isinfiltrant (Icon®); being c- with excess removal and s- without excess removal of the material. The materials were applied according to manufacture instructions. The groups with excess received the same materials, however before light curing the excess of material over enamel was gently removed with a cotton roll. After treatment, the blocks were immersed in HCl for 2 min, followed by immersion in artificial saliva for 120 min, 4 times per day, during 5 days (erosive cycling). Enamel wear and material thickness were analyzed using profilometry and the results submitted to two-way ANOVA and Tukeys test (p<0.05). Groups Hs, As, Is, resulted in the formation of a layer of material over enamel, being effective in inhibiting erosion progression. Groups in which the material over enamel was removed (Hc, Ac, Ic), resulted in enamel loss after application. In addition, they (Hc, Ac, Ic) were not able to protect enamel, since after the erosive challenge enamel wear of these groups was similar to control. Based on the results of this study, resin-based materials are able to protect enamel against erosion only when they are present over enamel, forming a mechanical barrier.

O uso de materiais resinosos sobre o tecido dentário é uma alternativa para a prevenção da progressão da erosão, contudo existem poucas informações sobre o efeito da infiltração resinosa na lesão de erosão. O objetivo deste estudo foi avaliar o efeito dos materiais resinosos sobre (sem remoção de excesso) e supostamente dentro (com remoção de excesso) do esmalte previamente erodido, submetido a desafio erosivo subsequente. Os blocos de esmalte bovino foram imersos em HCl 0,01 M, pH 2,3 durante 30 segundos para a formação de lesão inicial de erosão. Em seguida, os blocos foram divididos aleatoriamente e tratados de acordo com 8 grupos (n=12): Cc e Cs- controle sem tratamento, Hc e Hs- selante de fossas e fissuras (Helioseal Clear®), Ac e As- adesivo autocondicionante (Adhese®), Ic e Is- infiltrante (Icon®); sendo c- com remoção de excesso e s- sem remoção de excesso do material. Os materiais foram aplicados de acordo com as recomendações dos fabricantes. Nos grupos com remoção de excesso, após a aplicação dos materiais houve a remoção de seu excesso da superfície de esmalte com um cotonete, anteriormente a fotopolimerização. Após o tratamento, todos os espécimes foram submetidos à ciclagem erosiva, por meio da imersão em ácido clorídrico (0,01M; pH 2,3) por 2 minutos, seguida da imersão em saliva artificial por 120 minutos, 4 vezes ao dia, durante 5 dias. A espessura de material e o desgaste dentário foram analisados por meio da perfilometria e os resultados submetidos ao teste ANOVA a dois critérios e teste de Tukey (p<0,05). Na análise do desgaste dentário após o desafio erosivo, os grupos sem remoção de excesso (Hs, As, Is) se comportaram de forma semelhante (p>0,05), constatando-se a presença de material sobre o esmalte prevenindo a perda da estrutura dentária. Os grupos nos quais o excesso de material sobre o esmalte foi removido (Hc, Ac, Ic) resultaram em perda de esmalte após a aplicação. Além disso, esses grupos (Hc, Ac, Ic) não foram capazes de proteger o esmalte contra a erosão, uma vez que após o desafio erosivo o desgaste do esmalte destes grupos foi semelhante ao grupo controle. Com base nos resultados do presente estudo, conclui-se que os materiais resinosos são capazes de proteger o esmalte contra a erosão dentária somente quando estão presentes sobre a superfície dentária, formando uma barreira mecânica. / The use of resin-based materials over the dental tissue is an alternative for erosion progression prevention, however there is little information regarding the effect of resin infiltration into erosive lesion. The aim of this study was to evaluate the effect of resin-based materials over (without excess removal) and into (with excess removal) previously eroded enamel, subjected to erosive challenge. Bovine enamel blocks were immersed in HCl 0.01 M, pH 2.3 for 30 seconds for the formation of softened erosion lesion. Then the blocks were random divided and treated according to 8 groups (n=12): Cc and Cs- control without treatment, Hc and Hs- fissure resin sealant (Helioseal Clear®), Ac and As- self-etch adhesive (Adhese®), Ic and Isinfiltrant (Icon®); being c- with excess removal and s- without excess removal of the material. The materials were applied according to manufacture instructions. The groups with excess received the same materials, however before light curing the excess of material over enamel was gently removed with a cotton roll. After treatment, the blocks were immersed in HCl for 2 min, followed by immersion in artificial saliva for 120 min, 4 times per day, during 5 days (erosive cycling). Enamel wear and material thickness were analyzed using profilometry and the results submitted to two-way ANOVA and Tukeys test (p<0.05). Groups Hs, As, Is, resulted in the formation of a layer of material over enamel, being effective in inhibiting erosion progression. Groups in which the material over enamel was removed (Hc, Ac, Ic), resulted in enamel loss after application. In addition, they (Hc, Ac, Ic) were not able to protect enamel, since after the erosive challenge enamel wear of these groups was similar to control. Based on the results of this study, resin-based materials are able to protect enamel against erosion only when they are present over enamel, forming a mechanical barrier.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Le gliome infiltrant du tronc cérébral est une tumeur rare, non opérable et inéluctablement fatale. En raison du manque de ressource biologique disponible, aucun progrès dans la compréhension de la biologie de ces tumeurs n’a été fait jusqu’à ces dernières années, laissant la radiothérapie pour seul traitement efficace, et seulement transitoirement. Enfin, grâce à la mise en place de collecte d’échantillons de gliomes infiltrant du tronc cérébral au diagnostic ou à l’autopsie, un nombre sans précédent d’analyses biologiques et génomiques a pu être mené et améliorer la connaissance de ces tumeurs. Si ces études ont montré que ces gliomes pédiatriques étaient bien différents de ceux de l’adulte, elles ont aussi fait apparaître la présence d’anomalies génétiques récurrentes spécifiques de ces tumeurs sous-tentorielles. Ainsi le Platelet-Derived Growth Factor Receptor Alpha (PDGFRα) est apparu comme cible prédominante dans ces tumeurs compte tenu des nombreuses anomalies génétiques constatées. La recherche d’un médicament efficace pouvant inhiber cette voie nous a conduit à évaluer l’effet du dasatinib qui est un inhibiteur multi-ciblé. Nous en rapportons ici l’efficacité in vitro sur de nouvelles lignées cellulaires de gliomes infiltrants du tronc cérébral établies à partir de biopsies stéréotaxiques réalisées au diagnostic. Sachant néanmoins que les thérapies ciblées restent peu efficaces en clinique quand elles sont utilisées seules, nous mettons en évidence l’intérêt de combiner le dasatinib avec un inhibiteur de MET, 2ème oncogène fréquemment amplifié dans ces tumeurs. D’autre part, une stratégie originale de criblage médicamenteux a été mise en œuvre. Celle-ci a permis de définir de manière fonctionnelle de nouveaux médicaments potentiellement efficaces dans les gliomes infiltrants du tronc cérébral, incluant les inhibiteurs d’Histone deacetylases (HDAC), les inhibiteurs des Cyclin-Dependent Kinases (CDK) ou encore les inhibiteurs du protéasome. Enfin par la technique de séquençage génome-entier, de nouvelles anomalies génétiques jamais rencontrées dans aucun autre cancer ont été détectées. Parmi celles-ci se trouvent des mutations d’histone H3K27M dont la fréquence élevée (80%) suggère leur rôle fondamental dans la genèse de ces tumeurs. Des mutations activatrices d’ACVR1/ALK2 ont été également mises en évidence. Celles-ci représentent désormais de nouvelles cibles à explorer.Ce travail de thèse rapporte la recherche de nouvelles cibles thérapeutiques d’une part, via une approche exploratoire par criblage médicamenteux et recherche d’anomalies génétiques par séquençage « génome-entier », et d’autre part, via une approche de validation préclinique sur le plan des thérapies ciblées de type inhibiteurs de tyrosine-kinases. / Diffuse Intrinsic Pontine Glioma (DIPG) is a rare, unresectable and universally fatal tumor. Due to the lack of available material, no improvements have been made in the knowledge of the biology of this tumor until recent years, leaving radiotherapy as the only efficient treatment, and only transiently. Recently, the effort engaged for collecting samples in this disease at the diagnosis or at the autopsy resulted in an unprecedented number of analyses consequently improving our knowledge in DIPG. Those studies bring evidences for their differences with adult gliomas, but also with other pediatric supratentorial glioma showing specific genomic alterations. Thus, Platelet-Derived Growth Factor Receptor Alpha (PDGFRα) appeared to be one of the major target given its frequent aberrations found in those tumors. Investigating an effective drug to inhibit this pathway led us to evaluate the effect of dasatinib, which is known as a multi-targeted inhibitor. We report here the in vitro efficacy of dasatinib on new cell lines of DIPG developed from stereotaxic biopsy at diagnosis. Because therapies are largely inefficient in the clinic when they are used as a monotherapy, we bring out our interest on combining dasatinib with an inhibitor of MET, which is the 2nd most common amplified oncogene in these tumors.Additionally, an innovative strategy of pharmacological screening has been successfully tested. New drugs, potentially efficient in DIPG, have been fonctionnaly-defined, including Histone deacetylase inhibitors (HDACi), Cyclin-Dependent Kinases inhibitors (CDKi) and proteasome inhibitors as well.Finally, by using whole genome sequencing (WGS), we have been able to discover new genetic abnormalities, never encountered before in other cancers. Among those, mutations of histone H3K27M with a high frequency of 80% were found, suggesting that they have a fundamental role in tumors genesis. Moreover, ACVR1/ALK2 activating mutations have been identified as well. And this gene now represents a new target to explore. This work reports the research of new therapeutic targets through an exploratory approach using drug screening and WGS on the one hand, and on the other hand through a preclinical validation approach in terms of targeted therapies with tyrosine-kinases inhibitors.

Les fossés agricoles sont des lieux préférentiels d’écoulement des pesticides à l’échelle du bassin versant depuis les parcelles agricoles vers les masses d’eau avales de surface et souterraines. Du fait de leur capacité de rétention ils sont réputés pouvoir exercer un pouvoir tampon pour limiter la dispersion des pesticides dans l’environnement. Les opérations d’entretien des fossés sont identifiées comme un moyen d’améliorer ce pouvoir tampon. Cependant, la connaissance du pouvoir tampon des fossés en fonction de leurs caractéristiques et de leur entretien est très limitée. L’objectif de ce travail est ainsi de quantifier l’impact des principales pratiques d’entretien sur l’évolution du pouvoir tampon d’une gamme de fossés infiltrants.La démarche suivie repose sur i) une caractérisation expérimentale de l’effet des principales pratiques d’entretien sur l’évolution des propriétés des fossés, ii) une analyse de l’influence de ces propriétés sur deux processus clé modulant la rétention des herbicides : la sorption et l’infiltration, iii) une exploration numérique, conçue sur la base des expérimentations, de l’effet de chaque pratique sur l’évolution annuelle du pouvoir tampon des fossés. Le dispositif expérimental a combiné des observations in situ à l’échelle du fossé élémentaire sur 3 bassins versants et des expérimentations au laboratoire et a concerné l’étude du comportement de 3 herbicides, glyphosate, diuron et isoproturon.Les résultats de ce travail ont mis en évidence que les opérations de brûlis, fauche et désherbage chimique améliorent le pouvoir tampon des fossés par rapport à un fossé non-entretenu alors que le curage le détériore. Ils ont aussi permis d’améliorer notre connaissance des propriétés et de la variabilité des matériaux formant les fossés, de proposer un nouvel indicateur de la capacité de rétention des fossés et d’évaluer des approches de modélisation de la rétention des pesticides par un bief de fossé infiltrant. / By linking cropped fields to downstream groundwater and surface water bodies, farm ditches constitute preferential pathways for pesticide dispersal at the catchment scale. But thanks to their pesticide retention capacity ditches are known for buffering pesticide non-point source pollutions. Ditch management operations were identified as mean to improve ditch buffering capacities. However, little is known about how pesticide retention capacities of ditches vary as a function of ditch properties and management. Accordingly, the objective of this work is to quantify how pesticide retention capacity in a range of infiltrating ditches evolves subsequently to the main management operations.The methodology relies on i) an experimental characterization of the main management operation effects on the evolution of ditch properties, ii) an analysis of how these properties influence two key processes regulating herbicides retention: sorption and infiltration, iii) a numerical exploration, based on the previously mentioned experimentations, of each operation effects on the yearly evolution of pesticide retention capacity of ditches. The experimental design combined in situ observations at the reach scale on 3 catchments as well as laboratory experimentations and concerned the behavior of 3 herbicides, glyphosate, diuron and isoproturon.The results of this works highlighted the fact that burning, mowing and chemical weeding operations increase pesticide retention capacities of the ditches as compared to an unmanaged ditch while dredging deteriorates it. They also allowed us to improve our knowledge on ditch materials properties and variability, to propose a new indicator of ditch retention capacity and to evaluate different modelling approaches of pesticide retention by infiltrating ditches.