AIDA-I (adhesin involved in diffuse adherence) est une importante adhésine autotransporteur exprimée par certaines souches de Escherichia. coli impliquée dans la colonisation des porcelets sevrés causant la diarrhée post-sevrage et la maladie de l’œdème. Une précédente étude de notre laboratoire a identifié l’apolipoprotéine AI (ApoAI) du sérum porcin, la protéine structurale des lipoprotéines à haute densité, comme récepteur cellulaire putatif de AIDA-I. L’interaction entre ces deux protéines doit être caractérisée. Ici, nous montrons par ELISA que AIDA-I purifiée est capable d’interagir avec l’ApoAI humaine, mais également avec les apolipoprotéines B et E2. L’ApoAI est rencontrée sous deux formes, soit libre ou associée aux lipides. Nous montrons que la forme libre n’interagit pas avec les bactéries AIDA-I+ mais s’associe spécifiquement à l’ApoAI membranaire de cellules épithéliales HEp-2. Afin d’étudier le rôle de l’ApoAI dans l’adhésion des bactéries, nous avons infecté des cellules HEp-2 en présence d’anticorps dirigés contre l’ApoAI, mais l’adhésion des bactéries AIDA I+ n’a jamais été réduite. De plus, l’induction de l’expression de l’ApoAI par fénofibrate et GW7647 chez les cellules Caco 2 polarisée et Hep G2, n’a pas permis l’augmentation de l’adhésion cellulaire des E. coli exprimant AIDA-I. Notre étude suggère davantage que l’interaction entre AIDA-I et ApoAI n’intervient pas dans les mécanismes d’adhésion cellulaire. / The adhesin involved in diffuse adherence (AIDA-I) is an important autotransporter adhesin expressed by some strains of Escherichia coli and is involved in the intestinal colonisation of weaned piglets, causing the postweaning diarrhea and the edema disease. A previous study from our laboratory identified the apolipoprotein AI (ApoAI) from porcine serum, the structural protein of high density lipoproteins, as a putative receptor of AIDA-I. The interaction between these two proteins must be characterized. Here, we show that purified AIDA-I, using an ELISA assay, is able to bind the human ApoAI and the apolipoprotein B and E2. The ApoAI is found under two forms, either free or bound to lipid. We show that the free form of ApoAI does not interact with AIDA-I+ bacteria but specifically interact with membrane bound ApoAI on Hep-2 epithelial cells. To study the role of ApoAI in the adhesion of bacteria, we infected Hep-2 cells preincubated with antibodies to ApoAI. The adhesion of AIDA-I+ bacteria to the cells couldn’t be reduced. Additionally, the induction of ApoAI synthesis using fenofibrate and GW7647 on polarized Caco-2 or Hep G2 cells did not increase the adhesion of AIDA-I+ bacteria. Our study suggests that the interaction between AIDA-I and ApoAI is not involved in the cellular adhesion of the bacteria.

Le transfert horizontal participe à l'évolution rapide des génomes bactériens. Les éléments intégratifs et conjugatifs (ICE) sont des îlots génomiques capables de se transférer par conjugaison vers une bactérie receveuse. Streptococcus agalactiae est une bactérie pathogène opportuniste qui est à l'origine de problèmes sanitaires et économiques majeurs. Des études ont révélé la présence de nombreux ICE chez cette espèce, notamment à l'extrémité 3' d?un gène codant un ARNtLys. La fonctionnalité de l'ICE intégré à ce locus chez la souche 515 de S. agalactiae a été démontrée. Les fonctions véhiculées par ICE_515_tRNALys et pouvant conférer un avantage adaptatif ont été caractérisées et leur transfert vers d'autres espèces a été évalué. Les résultats ont montré que l'ICE confère à S. agalactiae des propriétés d'adhésion à l'hôte et de formation de biofilm et pourrait être impliqué dans l'agrégation cellulaire. Un antigène I/II codé par l'ICE est impliqué dans des phénotypes d'adhésion. De plus, un nouveau facteur co-hémolytique de type CAMP, codé par l'ICE et qui pourrait être impliqué dans la virulence et la survie des souches, a été caractérisé. La fonctionnalité de ces facteurs de virulence chez des espèces bactériennes pathogènes et non pathogènes a été établie. Les travaux ont également révélé la prévalence et la dynamique évolutive des ICE appartenant à la famille d'ICE_515_tRNALys et des fonctions adaptatives codées par ces éléments chez plusieurs espèces de streptocoques. En conclusion, les ICE de la famille d'ICE_515_tRNALys représentent des vecteurs de traits phénotypiques importants pour la virulence et la survie chez les streptocoques / Horizontal gene transfer is a rapid mechanism of evolution. Integrative and conjugative elements (ICEs) are genomic islands which can transfer by conjugation to recipient bacteria. Streptococcus agalactiae is a human and animal opportunistic pathogen that is responsible for major health and economic problems. Studies revealed the presence of numerous ICEs in S. agalactiae, in particular at the 3' end of a tRNALys encoding gene. The functionality of the element present in strain S. agalactiae 515 was demonstrated and was thus chosen as a model for this study. This work focused on the characterization of adaptive and virulence functions encoded by ICE_515_tRNALys and their transfer to other species. Results indicated that this ICE confers adhesion properties to host, increases biofilm formation and may be involved in cell aggregation. A new protein belonging to the antigens I/II family is involved in fibronectin binding and contributes to the biofilm phenotype. In addition, a new co-hemolytic CAMP factor encoded by ICE_515_tRNALys, which could be involved in virulence and bacterial survival, was identified and characterized. These virulence factors are functional in other bacterial species. This work also revealed the prevalence and evolutionary dynamics of ICE belonging to the family of ICE_515_tRNALys and adaptive functions encoded by these elements in several species of streptococci. In conclusion, ICEs of the ICE_515_tRNALys family represent vectors of phenotypic features important for virulence and survival in streptococci

O desenvolvimento e aprimoramento de novas tecnologias para prevenção/controle da doença cárie têm ocorrido nos últimos anos, destacando-se a utilização dos lasers na Odontologia. Estudos revelam o potencial dos lasers de alta potência para o aumento da resistência ácida do esmalte dental. Porém, ainda se questiona se as possíveis alterações morfológicas na superfície do esmalte, resultante da interação dos lasers com o tecido mineralizado, podem promover o aumento da aderência bacteriana e, conseqüentemente, aumentar o risco de desenvolvimento de lesões de cárie. O objetivo deste estudo in vitro foi avaliar a aderência bacteriana à superfície de esmalte dental irradiado por diferentes lasers de alta potência com parâmetros para prevenção de cárie, correlacionando com a rugosidade superficial do substrato, além da avaliação da perda mineral do substrato dental. Sessenta amostras de esmalte dental humano (4 X 4 mm) foram distribuídas aleatoriamente em 6 grupos (n=10): G1 controle negativo (sem tratamento); G2 - controle positivo (flúor); G3 Laser de Er:YAG; G4 Laser de Er,Cr:YSGG; G5 Laser de Nd:YAG e G6 Laser de CO2. A avaliação da rugosidade superficial foi realizada através da técnica OCT, seguida do ensaio de aderência bacteriana que foi realizada utilizando-se o Streptococcus mutans como organismo do teste. A análise de perda mineral foi realizada pelo ensaio de microdureza Knoop. Os resultados foram avaliados pelo testes de ANOVA e Tukey (=5%). Concluiu-se que não houve correlação entre o tratamento de superfície e a adesão de Streptococcus mutans. As superfícies de esmalte tratadas com flúor ou laser de CO2 apresentaram os menores valores de rugosidade enquanto o laser de Er:YAG os maiores valores. O grupo flúor apresentou menor taxa de formação de biofilme, enquanto Controle e Er:YAG as maiores. Além do mais, verificou-se que todos os tratamentos de superfície mostraram-se efetivos, sendo os tratamentos com flúor fosfato acidulado e laser de CO2 os mais efetivos na prevenção de cárie e redução da perda de volume mineral. / The development and improvement of new technologies for prevention/control of dental caries has increased in the last years, specially the use of lasers in Dentistry. Studies show the potential of high power lasers to enhance the dental enamel acid resistance. However, it is still questioned if the morphological changes on the enamel surface, as a result of laser irradiation, can increase the surface bacterial adhesion and as a result, increase the risk for development of dental caries. The main objective of this in vitro study was to evaluate bacterial adhesion to enamel surface previously irradiated by different high power lasers using parameters for caries prevention, correlating with surface roughness after treatments, and besides that, the evaluation of dental substrate mineral loss. Sixty specimens of dental enamel (4 x 4 mm) were randomly distributed in 6 groups (n=10): G1 - negative control (no surface treatment); G2 - positive control (fluoride); G3 - Er:YAG laser; G4 - Er,Cr:YSGG laser; G5 - Nd:YAG laser and G6 - CO2 laser. The surface roughness test was developed using the OCT method, followed by the evaluation of bacterial adhesion that was performed using Streptococcus mutans as the tested microorganism. The evaluation of mineral loss was done by Knoop microhardness test. The results were evaluated by means of ANOVA and Tukey tests (=5%). It was concluded that there is no correlation between surface treatment and adhesion of Streptococcus mutans. The enamel surfaces treated with fluoride or CO2 laser showed the lesser roughness values, while Er:YAG laser the higher values. The fluoride group showed the lesser biofilm formation tax, while Control and Er:YAG the higher ones. Besides that, it was verified that all the surface treatments were effective, and the treatments with fluoride and CO2 laser the most effective on caries prevention and mineral loss reduction.

De multiples micro-organismes ont la capacité de catalyser l’oxydation électrochimique de matières organiques en s’organisant en biofilm à la surface d’anodes. Ce processus est à la base de procédés électro-microbiens très innovants tels que les piles à combustible microbiennes ou les électrolyseurs microbiens. L’interface biofilm/électrode a été l’objet de nombreuses étudesdont les conclusions restent difficiles à démêler en partie du fait de la diversité des paramètres interfaciaux mis en jeu. L’objet de ce travail de thèse est d’exploiter les technologies microsystèmes pour focaliser l’impact de la topographie de surface des électrodes sur le développement du biofilm et sur ses performances électro-catalytiques. La formation de biofilmsélectroactifs de Geobacter sulfurreducens a été étudiée sur des électrodes d’or présentant des topographies bien contrôlées, sous la forme de rugosité, porosité, réseau de piliers, à des échellesallant du nanomètre à quelques centaines de micromètres. La présence de microrugosité a permis d’accroitre les densités de courant d’un facteur 8 par rapport à une surface lisse et son effet a étéquantifié à l’aide du paramètre Sa. Nous avons tenté de distinguer les effets des différentes échelles de rugosité sur le développement du biofilm et la vitesse des transferts électroniques.L’intérêt de la microporosité a été discuté. L’accroissement de surface active par la présence de micro-piliers s’est avéré très efficace et une approche théorique a donné des clés de compréhension et d’optimisation. Les connaissances acquises dans les conditions de culture pure ont finalement été confrontées avec la mise en oeuvre de biofilms multi-espèces issus d’un inoculum complexe provenant de sédiments marins. / Many microorganisms have the ability to catalyze the electrochemical oxidation of organic matterby self-organizing into biofilm on the surface of anodes. This process is the basis of highlyinnovative electro-microbial processes such as microbial fuel cells or microbial electrolysis cells.The biofilm/electrode interface has been the subject of numerous studies whose conclusionsremain difficult to disentangle partly because of the diversity of the interfacial parameters involved.The purpose of this thesis work is to exploit microsystem technologies to focus the impact ofelectrode surface topography on biofilm development and electro-catalytic performance. Theformation of electroactive biofilms of Geobacter sulfurreducens was studied on gold electrodespresenting well-controlled topographies, in the form of roughness, porosity, pillar networks, atscales ranging from nanometer to a few hundred micrometers. The presence of micro-roughnessincreased the current densities by a factor of 8 compared to a smooth surface and its effect wasquantified using the Sa parameter. We have tried to distinguish the effects of different roughnessscales on biofilm development and electron transfer rates. The suitability of micro-porosity wasdiscussed. The increase of active surface area by the presence of micro-pillars has proved veryeffective and a theoretical approach has given keys to understanding and optimization. Theknowledge acquired under pure culture conditions was finally confronted with the use of multispeciesbiofilms formed from a complex inoculum coming from marine sediments.

Bacterial adhesion is the first step of biofilm formation and in the focus of research interest since several decades. Biofilms cause many problems, sometimes dramatic, for example in health, food packing or waste water purification. Despite of high interest, bacterial adhesion process is only poorly understood yet. In this work, bacterial adhesion was investigated on well-organized and structured model surfaces with various chemistries at molecular scale. For that purpose a characterization methodology was developed to sufficiently analyze monolayers on silicon wafers, and controlled mixed monolayers surfaces with different densities of NH 2 backfilled with CH3 were developed and optimized. These controlled surfaces with different densities of 0 % NH2 up to 100% NH2 were eventually used as tool to study bacterial adhesion in batch and real time conditions. The results demonstrate a significant impact on bacterial adhesion of weak difference in the surface chemistry at molecular scale. In the batch experiments, two so-called "plateaus" zones were determined, in which bacterial adhesion is not significantly different despite the change of the amine concentration on the surface. On the contrary, one transition zone exists between the "plateaus" in which a slight chunge.in the amine concentration leads to a significant increase / decrease of the bacterial adhesion. The same trend of bacteria behavior was observed for different bacterial strains.

AIDA-I (adhesin involved in diffuse adherence) est une importante adhésine autotransporteur exprimée par certaines souches de Escherichia. coli impliquée dans la colonisation des porcelets sevrés causant la diarrhée post-sevrage et la maladie de l’œdème. Une précédente étude de notre laboratoire a identifié l’apolipoprotéine AI (ApoAI) du sérum porcin, la protéine structurale des lipoprotéines à haute densité, comme récepteur cellulaire putatif de AIDA-I. L’interaction entre ces deux protéines doit être caractérisée. Ici, nous montrons par ELISA que AIDA-I purifiée est capable d’interagir avec l’ApoAI humaine, mais également avec les apolipoprotéines B et E2. L’ApoAI est rencontrée sous deux formes, soit libre ou associée aux lipides. Nous montrons que la forme libre n’interagit pas avec les bactéries AIDA-I+ mais s’associe spécifiquement à l’ApoAI membranaire de cellules épithéliales HEp-2. Afin d’étudier le rôle de l’ApoAI dans l’adhésion des bactéries, nous avons infecté des cellules HEp-2 en présence d’anticorps dirigés contre l’ApoAI, mais l’adhésion des bactéries AIDA I+ n’a jamais été réduite. De plus, l’induction de l’expression de l’ApoAI par fénofibrate et GW7647 chez les cellules Caco 2 polarisée et Hep G2, n’a pas permis l’augmentation de l’adhésion cellulaire des E. coli exprimant AIDA-I. Notre étude suggère davantage que l’interaction entre AIDA-I et ApoAI n’intervient pas dans les mécanismes d’adhésion cellulaire. / The adhesin involved in diffuse adherence (AIDA-I) is an important autotransporter adhesin expressed by some strains of Escherichia coli and is involved in the intestinal colonisation of weaned piglets, causing the postweaning diarrhea and the edema disease. A previous study from our laboratory identified the apolipoprotein AI (ApoAI) from porcine serum, the structural protein of high density lipoproteins, as a putative receptor of AIDA-I. The interaction between these two proteins must be characterized. Here, we show that purified AIDA-I, using an ELISA assay, is able to bind the human ApoAI and the apolipoprotein B and E2. The ApoAI is found under two forms, either free or bound to lipid. We show that the free form of ApoAI does not interact with AIDA-I+ bacteria but specifically interact with membrane bound ApoAI on Hep-2 epithelial cells. To study the role of ApoAI in the adhesion of bacteria, we infected Hep-2 cells preincubated with antibodies to ApoAI. The adhesion of AIDA-I+ bacteria to the cells couldn’t be reduced. Additionally, the induction of ApoAI synthesis using fenofibrate and GW7647 on polarized Caco-2 or Hep G2 cells did not increase the adhesion of AIDA-I+ bacteria. Our study suggests that the interaction between AIDA-I and ApoAI is not involved in the cellular adhesion of the bacteria.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2007. / Härtill 4 uppsatser.

Thesis (Ph.D. in Pharmacology) -- University of Colorado Denver, 2007. / Typescript. Includes bibliographical references (leaves 203-212; 260-261). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;

Made available in DSpace on 2016-06-02T19:02:44Z (GMT). No. of bitstreams: 1 6426.pdf: 2868015 bytes, checksum: e3bf13cc85e7606dc2d0f7dbb387ebaa (MD5) Previous issue date: 2014-11-24 / Financiadora de Estudos e Projetos / The evaluation of new materials and biomaterials modified with silver nanoparticles is a line of research that has been gaining strength in various knowledge areas including dentistry. Even considering international scientific publications, however, there are still few studies evaluating dental restoration materials that are modified with silver nanoparticles. Proposal: this study aimed to compare a photopolymerizable composite resin modified with an antimicrobial silver nanoparticle additive (an experimental resin), with the photopolymerizable composite resin in its unmodified form (a commercially available dental restoration material), by evaluating the in vitro antibacterial properties and also some of the primary physical properties of the resin. Methodology: composite resin disks were made for three experimental groups: unmodified resin (control group) and modified resin with different silver nanoparticle concentrations: 0.3% and 0.6% wt (groups 1 and 2). The antibacterial activity on the surface of the samples was evaluated by in vitro growth of of Streptococcus mutans and Lactobacillus acidophilus biofilms in a 20% sucrose medium, which is followed by counting the viable cells from the biofilms through serial dilutions after three incubation periods - 1, 4 and 7 days (n = 9). Optical transmittance was tested to measure the percentage of transmittance in the samples (n = 9). The surface roughness was evaluated using Atomic Force Microscopy (n = 9). The colour of the samples and the colour difference between the groups was measured in a colorimetry test according to the CIELab system. The presence of silver in the nanoparticle additive was analysed using X-Ray Fluorescence Spectroscopy. The quality of the dispersion and distribution of silver on the samples was analysed using Transmission Microscopy. The liberation of silver in artificial saliva was also evaluated in vitro after three incubation periods (60, 120 and 210 days) with agitation of the samples, using the Inductively Coupled Plasma Optical Emission Spectroscopy technique. Results: for the three incubation times, the number of viable cells was statistically lower in groups 1 and 2 than in the control group (p < 0.05), and groups 1 and 2 were not statistically different (p > 0.05) for the two bacterial species (ANOVA Two way/Tukey). There was no significant difference in optical transmittance between group 1 and the control (p > 0.05), and group 2 had a lower transmittance value than the other groups (p < 0.05) (ANOVA/Tukey). The analysis of the values of the arithmetic roughness, which was obtained using the NanoScope software, showed that there was no significant difference in surface roughness between the three groups (p > 0.05) (ANOVA/Tukey). From the measurements of the colours, the total colour difference (&#916;E) between all of the groups was higher than 1 (the minimum value that represents a colour alteration perceptible to human vision) and lower than 3,3 (critical &#916;E). The presence of silver in the nanoparticle additive was confirmed in the X-Ray Fluorescence test. Microscopic analysis showed good distribution of silver for groups 1 and 2 (with silver in the four quadrants of the regions analysed). The dispersion was better for group 1 than for group 2 (which showed a higher number of particle clusters). After the three incubation times, silver was not detected in the artificial saliva for the three groups or; if it was present, the concentration was below the limit of detection for this technique (< 0.02 mg/L). Conclusions: the antibacterial property on the surfaces of the experimental resins was verified for the two cariogenic bacteria considered. Furthermore, the addition of silver did not cause negative alterations to the resin modified with the lower concentration of nanoparticles, which makes the continuation of this study possible and valuable. / A avaliação de novos materiais e biomateriais modificados com nanopartículas de prata é uma linha de pesquisa que vem ganhando força em várias áreas do conhecimento, inclusive na área odontológica. Porém, mesmo considerando a publicação científica internacional, ainda há poucas pesquisas que avaliam materiais restauradores dentários modificados desta forma. Proposição: o propósito deste estudo foi comparar a resina composta fotopolimerizável modificada com um aditivo antimicrobiano nanoparticulado de prata (uma resina experimental), com a resina composta fotopolimerizável em sua forma não modificada, um material restaurador dentário disponível comercialmente, avaliando a propriedade antibacteriana, in vitro, e também algumas de suas principais propriedades físicas. Metodologia: foram confeccionados discos de resina composta para 3 grupos experimentais: resina não modificada (grupo controle), e resina modificada com diferentes concentrações de nanopartículas de prata, 0,3 e 0,6% (grupos 1 e 2). A atividade antibacteriana na superfície das amostras foi avaliada pelo crescimento in vitro de biofilme de Streptococcus mutans e Lactobacillus acidophilus em meio de cultura contendo 20% de sacarose, seguido de contagem de células viáveis provenientes dos biofilmes após 3 períodos de incubação, 1, 4 e 7 dias, através de diluições seriadas (n=9). Um ensaio de transmitância óptica foi realizado para medir a porcentagem de transmitância das amostras (n=9). A rugosidade superficial foi avaliada por Microscopia de Força Atômica (n=9). A cor das amostras e a diferença de cor entre os grupos foi medida em um ensaio de colorimetria considerando o sistema CIELab. A presença de prata no aditivo nanoparticulado foi analisada por meio da Espectrometria de Fluorescência de Raios X. A qualidade da dispersão e distribuição da prata nas amostras foi analisada através da Microscopia de Transmissão. Foi também avaliada a liberação de prata em saliva artificial, in vitro, após 3 períodos de incubação das amostras, sob agitação, 60, 120 e 210 dias, através da técnica de Espectrometria de Emissão Óptica por Plasma Acoplado Indutivamente. Resultados: para os 3 tempos de incubação, o número de células viáveis foi estatisticamente mais baixo nos grupos 1 e 2 do que no grupo controle (p < 0,05), e os grupos 1 e 2 não mostraram entre si diferença estatisticamente significante (p > 0,05), para as 2 espécies bacterianas (ANOVA Two way/Tukey). Não houve diferença significante na transmitância óptica entre o grupo 1 e o controle (p > 0,05), já o grupo 2 apresentou um valor de transmitância menor que os demais grupos (p < 0,05) (ANOVA/Tukey). A análise dos valores de rugosidade aritmética, obtidos através do software NanoScope, mostrou que não houve diferença significante na rugosidade superficial entre os 3 grupos (p > 0,05) (ANOVA/Tukey). A partir das medições de cores, a diferença total de cor (&#916;E) entre todos os grupos foi superior a 1 (valor mínimo que representa uma alteração de cor perceptível à visão humana) e inferior a 3,3 (&#916;E crítico). A presença de prata no aditivo nanoparticulado foi confirmada no ensaio de Fluorescência de Raios X. A análise microscópica demonstrou boa distribuição de prata para o grupo 1 e 2 (com prata nos 4 quadrantes das regiões analisadas), e a dispersão foi melhor para o grupo 1 do que para o grupo 2 (que apresentou maior número de aglomerados de partículas). Após os 3 tempos de incubação, não foi detectada a presença de prata na saliva artificial, para os 3 grupos, sendo que, se presente, ela encontrava-se em uma concentração abaixo do limite de detecção da técnica (< 0,02 mg/L). Conclusões: a propriedade antibacteriana foi verificada nas superfícies das resinas experimentais para as duas espécies bacterianas cariogênicas consideradas, e a adição de prata não provocou alterações negativas na resina modificada com a menor concentração de nanopartículas, o que viabiliza a continuidade do estudo.

O desenvolvimento e aprimoramento de novas tecnologias para prevenção/controle da doença cárie têm ocorrido nos últimos anos, destacando-se a utilização dos lasers na Odontologia. Estudos revelam o potencial dos lasers de alta potência para o aumento da resistência ácida do esmalte dental. Porém, ainda se questiona se as possíveis alterações morfológicas na superfície do esmalte, resultante da interação dos lasers com o tecido mineralizado, podem promover o aumento da aderência bacteriana e, conseqüentemente, aumentar o risco de desenvolvimento de lesões de cárie. O objetivo deste estudo in vitro foi avaliar a aderência bacteriana à superfície de esmalte dental irradiado por diferentes lasers de alta potência com parâmetros para prevenção de cárie, correlacionando com a rugosidade superficial do substrato, além da avaliação da perda mineral do substrato dental. Sessenta amostras de esmalte dental humano (4 X 4 mm) foram distribuídas aleatoriamente em 6 grupos (n=10): G1 controle negativo (sem tratamento); G2 - controle positivo (flúor); G3 Laser de Er:YAG; G4 Laser de Er,Cr:YSGG; G5 Laser de Nd:YAG e G6 Laser de CO2. A avaliação da rugosidade superficial foi realizada através da técnica OCT, seguida do ensaio de aderência bacteriana que foi realizada utilizando-se o Streptococcus mutans como organismo do teste. A análise de perda mineral foi realizada pelo ensaio de microdureza Knoop. Os resultados foram avaliados pelo testes de ANOVA e Tukey (=5%). Concluiu-se que não houve correlação entre o tratamento de superfície e a adesão de Streptococcus mutans. As superfícies de esmalte tratadas com flúor ou laser de CO2 apresentaram os menores valores de rugosidade enquanto o laser de Er:YAG os maiores valores. O grupo flúor apresentou menor taxa de formação de biofilme, enquanto Controle e Er:YAG as maiores. Além do mais, verificou-se que todos os tratamentos de superfície mostraram-se efetivos, sendo os tratamentos com flúor fosfato acidulado e laser de CO2 os mais efetivos na prevenção de cárie e redução da perda de volume mineral. / The development and improvement of new technologies for prevention/control of dental caries has increased in the last years, specially the use of lasers in Dentistry. Studies show the potential of high power lasers to enhance the dental enamel acid resistance. However, it is still questioned if the morphological changes on the enamel surface, as a result of laser irradiation, can increase the surface bacterial adhesion and as a result, increase the risk for development of dental caries. The main objective of this in vitro study was to evaluate bacterial adhesion to enamel surface previously irradiated by different high power lasers using parameters for caries prevention, correlating with surface roughness after treatments, and besides that, the evaluation of dental substrate mineral loss. Sixty specimens of dental enamel (4 x 4 mm) were randomly distributed in 6 groups (n=10): G1 - negative control (no surface treatment); G2 - positive control (fluoride); G3 - Er:YAG laser; G4 - Er,Cr:YSGG laser; G5 - Nd:YAG laser and G6 - CO2 laser. The surface roughness test was developed using the OCT method, followed by the evaluation of bacterial adhesion that was performed using Streptococcus mutans as the tested microorganism. The evaluation of mineral loss was done by Knoop microhardness test. The results were evaluated by means of ANOVA and Tukey tests (=5%). It was concluded that there is no correlation between surface treatment and adhesion of Streptococcus mutans. The enamel surfaces treated with fluoride or CO2 laser showed the lesser roughness values, while Er:YAG laser the higher values. The fluoride group showed the lesser biofilm formation tax, while Control and Er:YAG the higher ones. Besides that, it was verified that all the surface treatments were effective, and the treatments with fluoride and CO2 laser the most effective on caries prevention and mineral loss reduction.