Thèses sur le sujet « Microflora orale »

A saúde bucal, na maioria dos municípios brasileiros, constitui ainda um grande desafio aos princípios do Sistema Único de Saúde, principalmente no que se refere à universalização, à eqüidade do atendimento e alto custo envolvido na terapia restauradora. A procura pela descoberta de novos compostos metabólicos com atividade antibacteriana para a prevenção de doenças bucais e talvez com menores impactos a saúde e financeiros, seria muito importante para obtenção de um meio efetivo de controle da formação de um biofilme patogênico e da cárie dental. O objetivo deste trabalho é estudar a viabilidade biotecnológica do uso de venenos nativos de diferentes serpentes quanto à capacidade de inibir o crescimento de Streptococcus mutans, principal agente envolvido na cárie dental. Nossos resultados mostraram que os venenos das serpentes Bothrops moojeni e Bothrops jararacussu inibiram o crescimento de Streptococcus mutans e o componente responsável pela inibição parece ser a peróxido de hidrogênio. Apesar de ainda não totalmente conclusivos, os ensaios já realizados, permitem afirmar que venenos de serpentes são ferramentas importantes na inibição do crescimento de patógenos, especificamente daqueles envolvidos nas doenças cariogênicas.
The oral health at the most of Brazilian municipalities is still a big challenge to the principles of the Brazilian Health Unique System (SUS), particularly with regard to the globalization, the equity of care and high cost involved in restorative therapy. The demand for discovery of new natural products with antibacterial activity in order to prevent dental diseases and perhaps with fewer health and financial impacts, would be very important to achieve an effective means to control the formation of a pathogenic biofilm and dental caries. The objective of this work is to study the feasibility of the use of different snakes crude venom in inhibiting the growth of Streptococcus mutans, the principal agent involved in dental caries. Our results showed that Bothrops moojeni and Bothrops jararacussu venoms were able to inhibit the growth of Streptococcus mutans and the component responsible for that inhibition appears to be the hydrogen peroxide. Though still not fully conclusive, the tests already carried out, show that snake venoms are important tools to inhibit the growth of pathogens, specifically those involved in caries diseases. MOSCA, R.C., 2008 7 SUMÁRIO 1. INTRODUÇÃO................................................................................................

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Mes études ont pour but d'examiner les altérations métaboliques et comportementales dans des modèles de souris axéniques. Nous avons démontré que les souris axéniques présentent une augmentation de préférence et d'acceptation des solutions sucrées. Cette augmentation est corrélée à des changements des niveaux d'expression des récepteurs du goût sucré au niveau de l'épithélium lingual et la muqueuse intestinale; T1R2, T1R3, et le transporteur de glucose SGLT-1. De plus, elles ont une préférence pour des fortes concentrations de saccharose comparées aux souris normales. Cet effet est associé à une augmentation des niveaux d'expression de T1R3 et SGLT-1 dans l'intestin. Nous avons étudié si cette augmentation de consommation de sucre était similaire à celle de acide gras, étayé les effets d'une consommation des lipides sur les niveaux d'expression des récepteurs des acides gras "CD36" au niveau de l'épithélium lingual et la muqueuse intestinale ainsi que les niveaux d'expression et de sécrétion des peptides intestinales à vocation satiétogène chez les souris axéniques comparées aux souris normales. En effet, nous avons démontré que les souris axéniques affichent une consommation accrue et une préférence pour les acides gras à des fortes et faibles concentrations respectivement. Ces changements étaient associés à une diminution des niveaux d'expression des détecteurs gustatifs de gras (GPRs), des faibles taux d'expression et de sécrétion des peptides intestinales, une augmentation d'expression du récepteur des acides gras au niveau de l'épithélium lingual et une augmentation des taux circulants des acides gras. Ces modifications peuvent constituer des mécanismes d'adaptation à l'état énergétique appauvri des souris axéniques. Nous avons essayé de savoir si ces altérations étaient présentes chez le rat dépourvu axénique. En effet, nous avons constaté que les rats axéniques présentent un niveau similaire ou élevé de la masse grasse, avec une diminution de la lipogenèse et une augmentation de l'adipogenèse expliquant l'hyperphagie du tissu adipeux. En résumé, nous avons démontré que l'absence du microbiote intestinal chez la souris conduit à une augmentation de l'apport énergétique en augmentant la consommation de sucres et de gras. Ces effets sont associés à des altérations orales et post-orales des niveaux d'expressions des détecteurs gustatifs tandis que le microbiote intestinal du rat F344 ne joue pas un rôle central dans l'adiposité
The present studies examine intestinal, metabolic, and behavioral alterations in germ-free (GF) animals. The first set of experiments examine preference and acceptance for sweet solutions, sucrose and saccharin, in GF C57Bl/6J mice with associated changes in expression of lingual and intestinal nutrient-sensing sweet taste receptors, T1R2 and T1R3, and the glucose transporter, SGLT1. It demonstrates that GF mice consumed more of the highest concentration of sucrose relative to NORM controls, with an increased expression of intestinal T1R3 and SGLT1. The second set of studies examine if findings of increased sucrose intake extend to fat, and whether the GF mice display alterations in lingual and intestinal fat sensors as well as intestinal satiety peptides. We found that GF mice display increased intake and preference of fat at high and low concentrations, respectively. Additionally GF mice display decreased fatty-acid GPRs and satiety peptides in the intestine, decreased circulating gut peptide levels, increased lingual fat detecting receptors, and increased markers of fatty-acid metabolism, all of which are adaptive effects to the chronically depleted energy state of the GF mice. The final succession of experiments was to determine if the GF state, with its associated decreases in adiposity and chronic fasting state in mice, is present in the GF rat model. Interestingly, we found that GF rats display similar or increased levels of body adiposity, with decreased markers of liver lipogenesis, yet increased lipogenesis in adipose tissue associated with adipocyte hypertrophy. Overall, these data demonstrate that absence of gut microbiota in mice leads to increased energy consumption of sugars and fats associated with alterations in oral and intestinal nutrient sensors while the gut microbiota in the F344 does not play a pivotal role in adiposity

The emergence of antibiotic-resistant bacteria has become a major threat to public health. The increased use of antibiotics has selected for the dissemination of antibiotic resistance genes between organisms from different species and different genera. There is a large body of evidence that the indigenous microbiota can act as a reservoir of antibiotic-resistant bacteria. However little is known about the molecular basis for this in bacteria from the oral cavity. Therefore the aim of this work was to determine the prevalence of antibiotic-resistant bacteria and antibiotic resistance genes in the cultivable oral microbiota. Saliva and plaque samples were taken from each of 60 healthy adults who had not taken any antibiotics during the previous three months. Each sample was plated onto antibiotic-containing media to quantitate and identify antibiotic-resistant strains. All of the individuals harboured bacteria resistant to erythromycin, gentamicin, vancomycin and tetracycline. Only 4 individuals (7%) did not have any cultivable bacteria resistant to amoxycillin. Oral bacteria resistant to gentamicin were the most commonly isolated (constituting 23% of total cultivable oral bacteria) followed by erythromycin (18% of the total viable count), vancomycin (16% of the total viable count), tetracycline (10% of the total viable count) and amoxycillin (4% of the total viable count). Multiply-resistant bacteria were found with 55% of tetracycline-resistant isolates being resistant also to erythromycin and 6% resistant also to both amoxycillin and erythromycin. The most prevalent genes encoding tetracycline and erythromycin resistance were tet(M), tet(W), tet(0), and mef and erm(B) respectively. In some cases, tet(M) and ermB were contained within a Tn/5 5-like conjugative transposon and could be co-tranferred to Enterococcus faecalis. Finally the nature of the genetic support for one of the tet(W) genes, was determined and found to be flanked by two transposases belonging to two different families of insertion sequences (IS30 and IS256). This element was highly unstable in E. coli. This study showed that antibiotic-resistant bacteria and antibiotic resistance genes are present in the oral microbiota and that oral bacteria are likely to play an important role in the evolution and dissemination of antibiotic resistance genes.

Toxoplasma gondii infection in susceptible C57BL/6 mice induces a strong Th1 immune response causing intense inflammation and lesions in ileum in response to microbial antigens and if controlled causes death of animals. The Th1 immune response is similar to that in patients with inflammatory bowel disease (IBD) such as Crohn\'s disease (CD) and ulcerative colitis (UC). Therefore find alternative treatments that have adjuvant effect of conventional treatments are of great interest. The use of probiotics is increasing due to several benefits found in inflammatory diseases. To verify the effects of probiotics Lactobacillus casei Shirota, Lactobacillus acidophilus and Lactococcus lactis NCDO 2118 in C57BL/6 mice, we treat one day before and 7 days after oral infection with 30 cysts of the ME-49 strain. We found that L. casei- and L. acidophilus-treatment mice decreased intestinal parasitism reducing the pathology in small intestine of C57BL/6 mice and prevent death. In addition, the microbiological culture of organs shows L. casei- and L. acidophilus-treatment mice prevent bacterial translocation from the intestinal lumen to organs such as liver, spleen, lung and blood, moreover the microbiological analysis of feces showed that there were fewer gram negative bacteria species in feces of probiotic treated mice. The NAG, MPO and EPO assay that are characteristic of macrophages, and eosinophils neutrophils respectively showed that there was a decrease in the activity of enzymes MPO and NAG and a small increase in activity and EPO. Finally, the qPCR analysis revealed that treatment with L. acidophilus decreased IFN-γ and TNF-α mRNA induced by infection with T. gondii and L.casei treatment increased the expression of Foxp3 and IL-10. Our results demonstrate the ability of probiotics to control the inflammation response and reduce mortality caused by ileitis. However, further studies are needed to find out what the precise mechanisms that probiotics L. casei and L. acidophilus modulate the host immune response.
A infecção por Toxoplasma gondii em camundongos susceptíveis C57BL/6 com 30 cistos da cepa ME-49 induz uma forte resposta do sistema imune do tipo Th1 causando uma intensa inflamação com lesão no íleo em resposta a antígenos da microbiota e se não for controlada causa a morte dos animais. Essa resposta é semelhante à encontrada em pacientes com doenças inflamatórias intestinais (IBD) como a doença de Crohn (CD) e colite ulcerativa (UC). Portanto encontrar tratamentos alternativos que tenham efeito adjuvante aos tratamentos convencionais é de grande interesse. O uso de probióticos em produtos fermentados vem aumentando devido aos vários benefícios encontrados em pacientes com doenças inflamatórias que utilizam esses produtos. Com o objetivo de investigar o efeito da administração dos probióticos Lactobacillus casei Shirota, Lactobacillus acidophilus e Lactococcus lactis NCDO 2118 no intestino delgado, tratamos camundongos C57BL/6 um dia antes e 7 dias depois da infecção oral com 30 cistos da cepa ME-49 de T. gondii. O tratamento com L. casei ou L. acidophilus diminuiu o parasitismo intestinal, reduziu a patologia associada ao intestino delgado e evitou a morte dos animais. Além disso, a cultura microbiológica dos órgãos revelou que L. casei e L. acidophilus foi capaz de impedir a translocação de bactérias do lúmen intestinal para órgãos como fígado, baço, pulmão e também para o sangue. O cultivo microbiológico das fezes mostrou que houve menos espécies de bactérias gram negativas encontradas nas fezes dos animais tratados com probióticos. A análise das enzimas NAG, MPO e EPO que são características de macrófagos, neutr´filos e eosinófilos, respectivamente mostrou que houve diminuição na atividade das enzimas MPO e NAG e um pequeno aumento na atividade e EPO. Por último, a análise em qPCR revelou que o tratamento com L. acidophilus diminuiu a expressão de IFN-γ e TNF-α induzido pela infecção por T. gondii e o tratamento com L.casei aumentou a expressão de Foxp3 e IL-10. Esses resultados demonstram a capacidade dos probióticos em controlar a resposta inflamação e reduzir a mortalidade causada pela ileíte. Contudo, serão necessários mais estudos para descobrir quais os mecanismos precisos que os probióticos L. casei e L. acidophilus utilizam para modular a resposta imune em favor do hospedeiro.
Mestre em Imunologia e Parasitologia Aplicadas

L’écosystème buccal est un environnement complexe dans lequel cohabitent plus de 700 espèces de bactéries différentes. Un déséquilibre au sein de ce biofilm est à l’origine des principales maladies de la cavité buccale : les maladies carieuses et parodontales.Pendant plusieurs années, l’étude de l’écosystème buccal s’est faite par une approche réductionniste : les microbiologistes étudiaient les espèces bactériennes individuellement. Cette stratégie a permis d’examiner et de comprendre tous les différents composants de cet écosystème, sans pour autant pouvoir appliquer les conclusions de ces études au biofilm buccal dans son ensemble. En effet, les bactéries ne se comportent pas de la même façon lorsqu’elles sont à l’état planctonique, ou lorsqu’elles sont organisées en biofilm.La flore microbienne buccale est reconnue comme étant l’une des plus complexes dans le corps humain. La multitude d’espèces en présence complique l’étude de ce biofilm. En effet, sa reproduction in vitro est rendue difficile par la complexité des relations entre chacune des espèces. De plus, son recueil, et ses décomptes qualitatif et quantitatif restent très délicats.Dans la littérature sont décrits plusieurs modèles de biofilm.Les modèles pluri-espèces dynamiques in vitro ont l’avantage de se rapprocher des conditions retrouvées in vivo, permettant un certain flux de milieu, le contrôle de paramètres tels que le pH et la température, ainsi que l’élimination des déchets produits.Cependant, ces modèles restent très onéreux et difficiles de mise en place, ce qui complique l’étude du biofilm buccal. Egalement, l’identification des bactéries mises en présence reste un sujet d’étude délicat : en effet, les méthodes traditionnelles de culture montrent des limites, et ne permettent pas une analyse quantitative des résultats, essentielle à la compréhension des phénomènes mis en jeu dans cet écosystème.Le but de notre travail ici est la mise en place de modèle de biofilm pluri-espèces dynamique, fiable et reproductible, facile à mettre en place et moins onéreux que ceux décrits dans la littérature. Ce modèle de biofilm doit permettre l’étude de l’influence de variations de conditions environnementales sur ce dernier, ainsi que celle de candidats probiotiques ayant déjà prouvé leur efficacité sur des supports in vitro statiques. Enfin, toujours dans une optique de simplification, les différentes méthodes d’identification des biofilms formés sont comparées (méthodes de culture traditionnelle, PCR conventionnelle, spectrométrie de masse MALDI-TOF, et qPCR), afin d’établir un protocole d’identification reproductible permettant une analyse qualitative et quantitative des résultats
The oral ecosystem presents a great complexity since it can harbor more than 700 different bacterial species. Most of them are organized in a biofilm on both the dental and the mucosal surfaces. Studying this complex environment is of utmost importance because a rupture in its stability can lead to the preeminence of pathogenic microorganisms, causing dental decay, gingivitis and periodontitis.For many years, the study of the oral ecosystem was conducted throught a reductionist approach: microbiologists studies bacterial strains individually. This strategy allowed the understanding of all different components of this ecosystem, but lacked the transposition of its conclusions to the study of a whole complex oral biofilm. As a matter of fact, bacteria don’t behave the same way in a planktonic state or when they are organized in a biofilm.The oral microflora is known to be one of the most complex floras hosted by the human body. The multitude of strains hardens its study. Indeed, its in vitro reproduction is made as complex as the different interactions occurring between each strain. Moreover, harvesting and quantitative and qualitative analysis of such biofilms remain very delicate procedures.Several biofilm models have been described in the literature. In vitro dynamic multispecies models share the same asset: to closely mimic in vivo conditions. They allow a medium flow, and parametrical controls such as pH, temperature; and waste removal. However, those models are very expensive and difficult to master. Also, bacterial identification is still a tough matter : traditional culture methods have shown their limits, and don’t allow a quantitative analysis, which is essential to understand the phenomenons occurring in this ecosystem.The aim of our work was to set up a dynamic multispecies oral biofilm, both reliable and reproducible, easy to set up and less expensive than those previously described in the literature. This model shall allow the study of environmental conditions variations and the efficiency of probiotic candidates that already showed their efficacy on static supports.Lastly, we compared different biofilm identification methods, traditional culture, conventional PCR, MALDI-TOF mass spectrometry, and quantitative PCR, in order to establish a reproducible identification protocol allowing both quantitative and qualitative analysis

Les maladies parodontales, mondialement répandues se caractérisent par une dysbiose favorisant l’émergence de pathogènes, détruisant le tissu parodontal appelé parodonte par des processus inflammatoires chroniques. L’objectif de cette thèse est donc d’élaborer de nouvelles stratégies et d’utiliser de nouvelles techniques d’études pour étudier les potentiels acteurs dans l’apparition des maladies parodontales. Une bibliographie exhaustive sur les maladies parodontales a permis la publication d’une revue mettant en évidence les dernières connaissances sur l'association entre la parodontite et la composition du microbiome, ainsi que les stratégies de diagnostic et les techniques de traitement récents. Dans une seconde étude, un protocole de culture, un nouvel outil d’identification par la réaction de polymérisation en chaine (q-PCR) et un système de typage Multi-Locus Sequence Typing (MLST) basé sur le génome ont été créés pour étudier l’implication du protiste Trichomonas tenax dans la survenue de la parodontite. Dans un autre travail, la combinaison de deux approches d’analyses, culturomique (reposant sur la multiplication des conditions de culture utilisée) et métagénomique a permis de mettre en évidence des espèces, des genres et des familles spécifiques chez les patients atteints de parodontites, de même que des bactéries dites « protectrices » présentent en majorité chez des contrôles ainsi que la détection d’une nouvelle espèce.Accessoirement, les nouvelles espèces bactériennes isolées par la technique de culturomique ont été étudiée par une approche taxonogénomique
Globally widespread periodontal diseases are characterized by dysbiosis that promotes the emergence of pathogens, destroying periodontal tissue called periodontal disease by chronic inflammatory processes. The goal of this thesis is to develop new strategies and use new study techniques to study the potential actors in the onset of periodontal diseases.An exhaustive bibliography on periodontal diseases has enabled the publication of a review highlighting the latest knowledge on the association between periodontitis and microbiome composition, as well as diagnostic strategies and recent treatment techniques.In a second study, a culture protocol, a new chain polymerization reaction identification tool (q-PCR) and a genome-based Multi-Locus Sequence Typing (MLST) typing system were created to study the involvement of protist Trichomonas tenax in the occurrence of periodontitis.In another work, the combination of two approaches of analysis, culturomic (based on the multiplication of the conditions of cultivation used) and metagenomics made it possible to highlight specific species, genera and families in the patients with periodontitis, as so-called "protective" bacteria present mostly in controls as well as the detection of a new species.Incidentally, the new bacterial species isolated by the technique of culturomics were studied by a taxonogenomic approach

Introdução: A saúde oral é parte da saúde geral, bem-estar e qualidade de vida. Deste modo, o conhecimento da prevalência da cárie dentária na população infantil leva-nos a adotar, cada vez mais, um conjunto de medidas de prevenção, permitindo o controlo, não só dos fatores etiológicos da doença, mas também a diminuição da sua incidência. O conhecimento da microflora oral e a exploração do potencial alcalinizante de algumas bactérias orais, são uma estratégia promissora no que diz respeito à prevenção da cárie dentária. Objetivos: Este estudo visa avaliar, os comportamentos e o estado de saúde oral das crianças participantes. Estudar a associação entre o estado de saúde oral das crianças e a presença de Streptococcus mutans; Streptococcus gordonii e Streptococcus salivarius. Métodos: Foi realizado um estudo epidemiológico observacional transversal com 189 crianças dos 6 aos 10 anos de idade. Foi aplicado um questionário aos pais/encarregados de educação sobre os comportamentos de higiene oral das crianças participantes no estudo. Realizou-se uma observação intraoral que nos permitiu determinar o índice de cpo-d e o CPO-D. Por fim, realizou-se a recolha e análise molecular de biofilme oral das crianças participantes. Resultados: Das crianças participantes 70 (36,8%) apresentam cpo-d de 0, com cpo-d entre 1-3 temos 84 (44,2%), e superior a 3 temos 35 (18,4%). Relativamente ao índice de CPO-D de 0 temos 136 (71,6%) crianças, entre 1-3 temos 47 (24,7%) e superior a 3 temos 7 (3,7%). Este estudo permitiu ainda demonstrar, que crianças que apresentam o dente da recolha cariado revelam a presença de Streptococcus mutans em 80% das vezes. Por sua vez, das crianças que não apresentavam o dente da recolha cariado, foram encontrados Streptococcus gordonii e Streptococcus salivarius numa percentagem de 85,7% para ambas as bactérias. Conclusões: Este estudo estabelece uma relação entre ausência de cárie e a presença de Streptococcus gordonii e Streptococcus salivarius.
Introduction: Oral health is part of overall health, wellbeing and quality of life. Thus, knowledge of the prevalence of dental caries in children leads us to adopt increasingly a set of preventive measures allowing control not only of the etiological factors of the disease, but also to decrease its incidence. Knowledge of oral microflora and exploitation of alkalizing potential of some oral bacteria are a promising strategy with regard to the prevention of dental caries. Objectives: This study aims to evaluate the behavior and oral health status of children participating by studying the association between oral health status of children and the presence of Streptococcus mutans; Streptococcus gordonii and Streptococcus salivarius. Methods: An observational cross-sectional epidemiological study was conducted with 189 children 6 to 10 years old. A questionnaire was given to parents / guardians regarding oral hygiene behaviors of participating children. We conducted an intraoral observation to determine the rate of dmtf/DMTF. Finally, the collection and molecular analysis of oral biofilm was done. Results: From the 70 participating children (36.8%) have dmtf 0, with dmtf between 1-3 have 84 (44.2%), and 35 have more than 3 (18.4%). Relating to DMFT index of 0 we have 136 (71.6%), children aged 1-3 have 47 (24.7%) and greater than 3 have 6 (3.7%). This study also demonstrated that children who have the decayed teeth are colonized by Streptococcus mutans 80% of the time. In turn, 85.7% of the children who did not have decayed teeth, were colonized by Streptococcus gordonii and Streptococcus salivarius. Conclusions: This study establishes a relationship between the absence of caries and colonization by Streptococcus gordonii and Streptococcus salivarius.

Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz
Objetivos: Este estudo tem como objetivo principal compreender se existe alguma associação entre a microflora de doentes portadores de próteses totais acrílicas mucosuportadas e portadores de próteses totais acrílicas implantosuportadas. Procurou-se então avaliar a prevalência, grau de colonização e distribuição das espécies bacterianas presentes em duas localizações distintas (rebordo alveolar e sulco) de próteses totais implantosuportadas e comparar com o rebordo das próteses totais mucosuportadas recorrendo a um estudo prévio. Materiais e Métodos: Foram observados e avaliados 30 indivíduos portadores de próteses totais implantosuportadas, de ambos os sexos, na Clínica Universitária do Instituto Superior de Ciências da Saúde Egas Moniz, Centro Médico Dentário de Mafra e Clínica de Reabilitação Oral Avançada. Todos os participantes foram informados dos propósitos do estudo e após seu consentimento foram efetuados inquéritos, observações clínicas e recolhas recorrendo a zaragatoas e cones estéreis. Os resultados obtidos foram analisados em Excel e SPSS. Resultados: Das 60 amostras recolhidas (30 do sulco e 30 do rebordo) as principais espécies bacterianas isoladas foram cocos Gram positivos como Staphylococcus epidermidis, seguida de Staphylococcus aureus e Streptococcus oralis e bacilos Gram negativos como Pseudomonas fluorescens, Enterobactérias, Proteus, Klebsiella oxytoca e Morganella morganii. Conclusões: A localização das PTIS (superior/inferior), os fatores de risco e a presença de sinais inflamatórios por si só não estão diretamente relacionados com o crescimento ou tipo de bactérias. O tipo de prótese (PTMS/PTIS) só parece influenciar a presença de Streptococcus mutans e Streptococcus salivarius e a presença de bactérias patogénicas aparenta ser possível em implantes saudáveis.

Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz
Introdução: A perimplantite é uma doença inflamatória crónica, caracterizada pela perda de suporte ósseo nos implantes afectados, daí que conhecer a reacção do hospedeiro à ação dos microrganismos externos é fundamental para o entendimento da natureza multifactorial daqueles processos inflamatórios. Dentes artificiais implantosuportados podem ser fixados a implantes por parafusos ou ser cimentados a pilares, a escolha do tipo de conexão é importante pela impacto na interface implante/osso. Objetivos: Analisar a flora microbiana e resposta do sistema imunológico de doentes reabilitados com implantes com coroas aparafusadas e com coroas cimentadas, compreender de que forma as coroas aparafusadas a implantes e as coroas cimentadas podem ter influência sobre a flora periimplantar e quantidade de IgA na saliva. Materiais e Métodos: A 91 doentes com coroas aparafusadas a implantes A e cimentadas GC, após o preenchimento de um inquérito de caracterização geral e do consentimento informado, assinado pelo doente foi recolhida saliva e amostras microbiológicas do sulco periimplantar. Procedeu-se ao exame laboratorial para identificação dos microrganismos e das IgA, os dados foram trabalhados com recurso ao SPSS Resultados: Foram identificadas espécies diferentes em cada grupo, no grupo C: Citrobacter braakii, Enterobacter cloacae, no grupo A: Streptococcus Oralis, Pseudomonas aeruginosa, Lactococcus lactis spp cremoris, Streptococcus mitis, Streptococcus salivarius, Serratia odorífera, Streptococcus bovis I, Klebsiella oxytoca; e uma média de IgA de 434,3700 μg/mL no grupo C e 353,1775 μg/mL no grupo A Conclusão: Embora os resultados não sejam estatisticamente significativos, nas coroas aparafusadas foram encontradas a maioria dos microrganismos potencialmente patogénicos, por outro lado nas coroas Cimentadas uma maior quantificação de IgA.