Background: The light-cured resin-based pit and fissure sealants success and longevity are enhanced by sufficient curing. Multiple emission peak Light Emitting Diode Light Curing Units offer a wider range of wavelengths and different levels of irradiances to ensure sufficient curing.The irradiance is considered a main curing factor that can affect the material properties. Purpose: The aim of this study was to assess the effect of different settings of a multiwave LED LCU on the degree of conversion and microhardness of a pit and fissure sealant comparing the irradiance of 1000 mW/cm2 to 1400 mW/cm2 and 3200 mW/cm2 irradiances of the LCU using manufacturer’s guidelines for curing times at 2, 4 and, 6 mm distances. Methods: A multiwave LED light curing unit was evaluated on three different irradiance levels 1000 mW/cm2 (S), 1400 mW/cm2 (H), and 3200 mW/cm2 (X). A total of 90 samples made from the fissure sealant were fabricated and divided into eighteen groups (n=5/group). Samples were cured following manufacturer’s guidelines of curing times for each curing mode at 2, 4, or 6 mm distance between the light tip and top of samples. The DC was measured using (ATR-FTIR) spectroscopy. The KHN test was performed on five different locations of each specimen using a hardness tester (Leco LM247AT, MI, USA, software; Confident V 2.5.2). Results: The top DC for H-8 was significantly higher than S-10 at 2 and 4mm, H-20 DC was significantly lower than S-30 at only 2mm. The bottom DC for H-8 was significantly higher than S-10 at 2mm only, H-20 DC was significantly lower than S-30 at 4 and 6mm only. H-8 KHN at top surface was significantly lower than S-10 at 2mm only, H-20 was significantly lower than S-30 at 2 and 6mm only. H-8 KHN at bottom surface was significantly lower than S-10 at 4 and 6mm but significantly higher at 2mm. H-20 was significantly lower than S-30 at 2mm but significantly higher at 4 and 6mm. The top DC for X-3 was significantly lower than S-10 at all curing distances with no significant difference at all curing distances between X-9 and S-30. The bottom DC for X-3 was significantly higher than S-10 at all curing distances with no significant difference between X-9 and S-30. X-3 KHN at top surface was significantly lower than S-10s at all curing distances. X-9 was significantly lower than S-30 at 6mm only. X-3 KHN at bottom surface was significantly lower than S-10 at 2 and 4mm only with no significant difference at all curing distances between X-9 and S-30. Conclusions: Using a multiwave LED LCU to polymerize Delton Opaque resin-based fissure sealants will result in an optimal DC and KHN values for any irradiance level if the curing distance is kept at 4 mm or less and with at least two cycles of the shortest curing time recommended by the manufacturer. Using a multiwave LED LCU with 1000, 1400 or 3200 mW/cm2 irradiance levels with shortest curing times recommended resulted in unsatisfactory DC and KHN levels. LED LCU with high and extra high irradiance levels (1400 and 3200 mW/cm2) can result in high DC and KHN levels when used adequately. Xtra Power mode (3200 mW/cm2) used on shortest curing time (3 seconds) resulted in significantly lower mechanical properties and for that reason it is not recommended to be used.

L’industrie microélectronique est parmi les plus dynamiques qui soient. Pour demeurer concurrentiels, les fabricants doivent continuellement optimiser le temps de développement et de commercialisation de leurs nouveaux produits. Ces dernières décennies, un effort de recherche a été réalisé afin de caractériser et simuler par la méthode des éléments finis le comportement d’assemblages microélectroniques en fatigue. Une telle méthode, dont la précision serait démontrée, permettrait d’accélérer de façon significative les temps de développement, tout en réduisant les coûts et les risques. Le présent projet de recherche vise à mettre en oeuvre une nouvelle méthode de simulation par éléments finis du processus d’assemblage d’un module microélectronique à une carte, soit la formation d’un boîtier matriciel à billes par refusion. L’objectif est de vérifier s’il existe une corrélation empirique entre l’état des joints de soudure après l’assemblage et la durée de vie du produit soumis à un chargement thermique cyclique. La méthode développée pour simuler le procédé de fabrication inclura les phénomènes complexes en jeu, tels que la déformation non-linéaire des billes de soudure. La précision des résultats numériques sera démontrée avec des données expérimentales. Cet outil pourra être utilisé pour la résolution de problèmes importants relatifs à la fiabilité de composantes microélectroniques. Ce projet est effectué en partenariat avec IBM Canada situé à Bromont, le Fonds québécois de la recherche sur la nature et les technologies (FQRNT) et le Conseil de recherches en sciences naturelles et en génie du Canada (CRSNG).

Analyse des interactions entre les processus d'oxydation et les mécanismes de déformation conduisant à un mode de propagation des fissures soit transgranulaire ductile, soit intergranulaire fragile, le dernier mode étant associé à une propagation beaucoup plus rapide des fissures. Proposition de différents modèles phénoménologiques permettant de relier le mode d'oxydation au mode de déformation, ainsi que le mode d'oxydation au mode de propagation des fissures.

Dans de nombreux assemblages de matériaux soumis à un chargement thermo-mécanique lors de l'élaboration ou en service, des contraintes résiduelles thermiques apparaissent, qui modifient les conditions d'amorçage des fissures. Si de plus l'un des composants a un comportement plastique, des déformations résiduelles plastiques peuvent à leur tour jouer un rôle. <br />En mécanique de la rupture fragile, une des difficultés majeures concerne la prédiction de l'amorçage de fissures en l'absence de défaut initial. Leguillon a proposé un critère d'amorçage combinant une condition énergétique de type Griffith et une condition de contrainte maximum. La mise en oeuvre du critère fait intervenir les développements asymptotiques raccordés et la théorie des singularités. La bonne corrélation du modèle avec des mesures expérimentales pour les matériaux homogènes isotropes sous chargement mécanique pur a conduit à envisager l'extension du critère afin de prendre en compte des contraintes résiduelles. <br />La comparaison du critère modifié avec des mesures expérimentales sur un assemblage aluminium/époxyde sous chargement thermo-mécanique se révèle satisfaisante quant à la prédiction de la rupture de l'interface entre les composants. Elle permet également de mettre en évidence, par inversion, une méthode d'identification des paramètres de rupture de cette interface. Le critère modifié est appliqué également à l'analyse de la décohésion tuile/structure dans les aiguilles formant le limiteur du tokamak Tore Supra. En effet, des contraintes résiduelles d'origine thermique et plastique apparaissent dans la partie métallique des tuiles de protection.

La plupart de l'énergie en France est d'origine nucléaire. Le bâtiment de réaction comporte une enceinte interne et une externe. L'enceinte interne est en béton précontraint, pour limiter le débit de fuite dans l'espace interne-ence inte. La précontrainte diminue au cours du temps à cause du fluage du béton. Il risque de se propager des fissures par une pression accidentelle interne. On pose alors deux problèmes de recherche : propagation de macrofissures dans une structure viscoélastique ; comportement effectif d'un matériau viscoélastique microfissuré. On développe tout d'abord un modèle viscoélastique de Burger pour le béton avec deux approches de calcul numérique et analytique. On traite ensuite le problème de fissure unique en développant thermodynamiquement la notion du taux de restitution d'énergie. Dans la troisième partie, on établit un modèle viscoélastique pour modéliser le comportement effectif des matériaux microfissurés dans le cas sans propagation. Le problème de propagation de microfisures est étudié ultérieurement par une approche numérique basée sur le "motif morphologique représentative". Ces études sont finalement appliquées pour traiter les problèmes de propagation de fissure et endommagement d'une enceinte de confinement sous l'application d'une pression accidentelle interne / Most of France's energy is nuclear. The reactor building comprises a internal and external containment. The internal containment is prestressed to limit the flow of leakage in the internal-external space. The prestress decreases during time by the creep of concrete. It may propagate the cracks by the accidental internal pressure. So we define two research problems : propagation of macrocracks in viscoelastic structure ; effective behavior of microcracked viscoelastic material. Firstly, we develop a Burger viscoelastic model of concrete with two approaches: numerical and analytical. Then we solve the problem of single cracks in developing thermodynamically the concept of energy release rate. In the third part we develop a viscoelastic model to study the effective behavior of microcracked materials in the case without propagation. The problem of propagation of microcracks is then studied by a numerical approach based on the "representative pattern morphology". These studies are finally applied to solve the problems of crack propagation and damage of containment under accidental internal pressure

Les différents processus de dégradation des structures de génie civil induisent une micro, puis macro- fissuration du béton. Celle-ci génère alors une réduction des propriétés mécaniques de l'ouvrage et, à terme, sa perte d'étanchéité. Il est donc nécessaire de fournir des informations quant à la présence et à la taille de fissures pour procéder aux réparations nécessaires et conserver l'intégrité de l'ouvrage. Dans un premier temps, le contrôle du béton ainsi que la morphologie de la fissure réelle sont présentés. La notion de contacts entre ses lèvres est introduite pour définir la problématique de sa caractérisation. La bibliographie montre que les méthodes acoustiques standards ne sont pas adaptées à la caractérisation d'une fissure dans le béton. Deux pistes sont alors identifiées : les ultrasons diffus et l'acoustique non linéaire. Nous présentons dans un second temps la caractérisation de la fissure par analyse du transport de l'énergie suivant une équation de diffusion. Les paramètres associés (diffusivité et dissipation) sont déterminés expérimentalement sur des éprouvettes fissurées sur différentes profondeurs. Nous introduisons et définissons le temps d'arrivée du maximum de l'énergie (ATME) qui s'avère être le paramètre le plus sensible à la partie ouverte d'une fissure. Son évolution au regard des incertitudes de mesure ne permet toutefois pas de caractériser totalement la partie fermée. Une simulation numérique en différences finies est réalisée. Elle met en évidence le rôle des contacts au sein de la partie fermée de la fissure et confirme les observations expérimentales. / The various processes of deterioration of the building structures lead to a micro and macro-cracking of the concrete. Consequently, the mechanical properties of the structure are reduced and, eventually, the building is no longer airtight. It is therefore necessary to supply information regarding the presence and size of cracks to carry out the necessary repairs and keep the integrity of the structure. First, the control of concrete as well as the morphology of the actual crack are presented. The notion of contacts between its lips is introduced to define the problem of its characterization. The bibliography shows that the standard acoustic methods are not adapted for characterizing of a crack in concrete. Two tracks are then identified: the diffuse ultrasound and the nonlinear acoustics. Subsequently, we present the characterization of the crack by analyzing the transport of the energy with a diffusion equation. The associated parameters (diffusivity and dissipation) are experimentally determined on test tubes cracked at different depths. We introduce and define the arrival time of the maximum energy (ATME), which turns out to be the most sensitive parameter to the open part of a crack. Its evolution with regard to the measurement uncertainties does not allow a full characterization of the closed part. A digital modeling in finite differences is performed. It highlights the role of the contacts within the closed part of the crack and confirms the experimental observations. Then, we present the nonlinear acoustics and the associated methods applied to concrete.

L’objectif de cette étude est de caractériser expérimentalement la propagation de fissures de fatigue affectée par l’hydrogène (Hydrogen-Affected Fatigue Crack Growth, HAFCG) dans diverses conditions et de clarifier le mécanisme impliqué en se concentrant sur la plasticité en pointe de fissures. Pour cet objectif, dans une première étape, l’influence de l’hydrogène sur la déformation plastique a été étudiée à l’aide d’essais de traction effectués sur un fer commercialement pur, le fer Armco, sous hydrogène gazeux. Les résultats ont montré que l’effet de l’hydrogène sur la propagation des fissures après apparition de la striction est plus important que celui sur la déformation plastique uniforme. Le HAFCG a ensuite été étudié au moyen d’essais de fissuration pour diverses valeurs de l’amplitude de facteur d’intensité de contrainte ΔK, de pression d’hydrogène (PH2 = 3,5 et 35 MPa) et de fréquence de chargement (f = 0,02 - 20 Hz). Il a été révélé que les vitesses de propagation dans un régime à ΔK élevé étaient fortement augmentées par l'hydrogène, jusqu'à 50 fois plus élevé que celles dans l'air. Le mode de rupture est une rupture intergranulaire fragile dans un régime de propagation à faible ΔK, alors qu’on observe une rupture transgranulaire de type quasi-clivage dans un régime à ΔK élevé. La valeur de ΔKtr (valeur de ΔK déclenchant l'augmentation de la vitesse de fissuration) diminue en augmentant la pression PH2. En outre, la vitesse augmente en diminuant la fréquence f. Une fois que la fréquence devient inférieure à une valeur critique, la vitesse de fissuration diminue considérablement jusqu'au même niveau que celle sous azote. La plasticité en pointe de fissure a été analysée à plusieurs échelles par microscopie optique, par mesure de déplacement hors plan et par microscopie électronique à balayage par transmission de la structure de dislocation située immédiatement sous la surface de rupture (FIB/STEM). Aucune modification claire de la zone plastique monotone en pointe de fissure sous hydrogène n’a été observée, alors qu’une réduction drastique de la plasticité cyclique associée à l'augmentation de la vitesse a été identifiée. Sur la base des observations expérimentales, des modèles de mécanisme de fissuration intergranulaire induit par l'hydrogène impliquant la coalescence des micro-vides le long de joints de grain et de mécanisme de fissuration transgranulaire induit par l'hydrogène impliquant un clivage cyclique dû à la réduction de la plasticité en pointe de fissure ont été proposés. Trois critères caractéristiques de fissuration assistée par hydrogène (ΔKtr, gradient d'hydrogène (PH2 × f)1/2 et limite supérieure de vitesse de fissuration) ont été établis. Ces critères devraient être utiles pour améliorer la conception en fatigue et la fiabilité des équipements exposés à l'hydrogène gazeux. / The objective of this study is to experimentally characterize Hydrogen-Affected Fatigue Crack Growth (HAFCG) behavior under various conditions and clarify the mechanism by focusing on crack tip plasticity. For this objective, as a first step, the influence of hydrogen on plastic deformation has been investigated by means of tensile tests in a commercially pure iron, Armco iron, under gaseous hydrogen. The results of the tests pointed out that the hydrogen effect on crack propagation is more important than that on uniform plastic deformation. Then, the HAFCG was investigated by means of FCG tests under various conditions of crack tip stress intensity ΔK, hydrogen gas pressure (PH2 = 3.5 and 35 MPa) and loading frequency (f = 0.02 – 20 Hz). It has been revealed that the FCGRs in a high ΔK regime were highly enhanced by hydrogen up to 50 times higher than the one in air. The fracture mode was a brittle intergranular fracture in a low ΔK regime, while it is a brittle transgranular quasi-cleavage one in a high ΔK regime. The value of ΔKtr (value of ΔK triggering the FCGR enhancement) decreases by increasing the pressure PH2. Besides, the FCGR enhancement increases by decreasing the frequency f. Once f becomes lower than a critical value, the HAFCG rate significantly decreases down to the same level as in nitrogen., The crack tip plasticity was analyzed in a multiscale approach by means of optical microscopy, out-of-plane displacement measurement, and scanning transmission electron microscopy of dislocation structure immediately beneath the fracture surface (FIB/STEM). As a result, no clear modification of monotonic crack tip plasticity by hydrogen was observed, while a drastic reduction of cyclic crack tip plasticity associated with the FCGR enhancement was identified. Based on the experimental evidences, models of the hydrogen-induced intergranular FCG mechanism involving microvoid coalescence along grain boundary and the hydrogen-induced transgranular FCG mechanism involving cyclic cleavage due to crack tip plasticity reduction have been proposed. Three characteristic criteria of HAFCG (ΔKtr, hydrogen gradient (PH2 × f)1/2 and upper limit of FCGR) have been established. These criteria are expected to be useful for improving fatigue design and reliability of hydrogen-related equipment.

A busca por uma terapia não-cirúrgica para o tratamento da fissura anal crônica resulta de que a esfincterotomia, a despeito de eficaz para a cura da fissura anal, pode levar a graus variáveis de incontinência fecal. Poucos estudos comparativos contemplando o emprego de bloqueadores de canais de cálcio podem ser identificados. Associadamente, a evidência científica acerca da eficácia do cloreto de betanecol para o tratamento da fissura anal crônica é pouco robusta na literatura mundial e nula em nosso meio. O objetivo do presente estudo foi analisar comparativamente os resultados de eficácia, segurança e recidiva associados ao emprego de duas modalidades de tratamento farmacológico tópico: o cloridrato de diltiazem e o cloreto de betanecol. Trata-se de estudo retrospectivo e uni-institucional. Entre janeiro de 2001 e abril de 2005 foram avaliados os prontuários médicos relativos a 332 pacientes com diagnóstico de fissura anal crônica. Dos 332 pacientes cujos prontuários médicos foram revisados, 30 pacientes submetidos a tratamento com diltiazem gel 2% (grupo D) e 30 submetidos a tratamento com betanecol gel 0,1% (grupo B) foram selecionados. Uma vez indicado o tratamento clínico da fissura anal crônica, este tinha duração de oito semanas para os grupos D e B. Todos os pacientes eram orientados para realizar a aplicação tópica do gel contendo o princípio ativo após higiene local e na freqüência de duas vezes ao dia. Os pacientes eram entrevistados após uma e oito semanas do início do tratamento. Sucesso do tratamento no presente estudo foi definido como a ausência de sintomas ao final do tratamento com ou sem a cicatrização da fissura anal. A recidiva foi definida no presente estudo como a presença de sintomas após ter sido diagnosticado sucesso do tratamento. Com relação ao sexo, no grupo D haviam 13 (43,3%) pacientes do sexo masculino e no grupo B, 11 (36,7%) p=0,598 . Com relação à idade, a mediana no grupo D foi de 36 (19-76) anos e no grupo B foi de 39 (20-75) anos p=0,937. No que se refere à duração dos sintomas conforme o grupo de estudo, o grupo D apresentou mediana de 11 (2 82) meses e o grupo B, de 12 (2 276) meses - p=0,958. Com relação à distribuição da casuística conforme a localização da fissura anal, no grupo D, ela estava localizada na região posterior em 22 (73,4%) pacientes; na região anterior, em seis (20%); em posição lateral, em um (3,3%) caso; e havia uma fissura anterior e outra posterior em outro (3,3%) caso. No grupo B, havia 17 (56,7%) pacientes com fissura posterior e 13 (43,3%) com fissura na localização anterior p=0,899. No que se refere à distribuição da casuística conforme a presença de sintomas e cicatrização da fissura analisadas sete dias após o início do tratamento, no grupo D foram observados seis (35,3%) pacientes com sintomas; no grupo B, esses eram 11 (68,8%) p=0,055. No que se refere à cicatrização da fissura anal após sete dias de tratamento, no grupo D foram observados três (17,6%) pacientes com fissura cicatrizada; no grupo B foram identificados quatro (25%) pacientes p=0,688. Ao final de dois meses de tratamento, nos grupos D e B, 11 (36,7%) pacientes ainda apresentavam sintomas enquanto 19 (63,3%) pacientes se encontravam sem sintomas. Com relação à cicatrização da fissura ao final do tratamento, no grupo D, 16 (53,3%) pacientes evoluíram com cicatrização e no grupo B, 15 (50%) pacientes apresentaram cicatrização p=0,796. Ao final do tratamento, ambos os grupos apresentavam 19 (63,3%) pacientes com sucesso. Com relação à necessidade de tratamento cirúrgico durante o tempo de acompanhamento do estudo, no grupo D, nove (30%) pacientes foram operados e no grupo B, 11 (36,7%) pacientes foram submetidos a tratamento cirúrgico p=0,584. Com relação à ocorrência de complicações associadas ao tratamento, três (10%) dos pacientes no grupo D apresentaram complicações. No grupo B, complicações ocorreram em somente um caso (3,3%) p=0,612. A recidiva sintomática ocorreu em 4 (21%) de 19 pacientes submetidos ao tratamento com sucesso com o emprego do diltiazem e foi a mesma (21%) para os pacientes tratados por betanecol. A mediana do intervalo de tempo (meses) até o diagnóstico da recidiva no grupo D foi de 16 (10-24) meses. No grupo B, o intervalo médio até o diagnóstico de recidiva foi de 7,5 (2-15) meses p=0,147. As conclusões do presente estudo sobre o emprego do diltiazem e do betanecol tópicos para o tratamento clínico da fissura anal foram: 1. é possível que o emprego do diltiazem no tratamento clínico da fissura anal esteja associado a resposta clínica mais precoce; 2. ao final do tratamento clínico de mesma duração, diltiazem e betanecol são igualmente eficazes; 3. diltiazem e betanecol têm perfil de utilização seguro e estão ambos associados a baixa ocorrência de complicações e efeitos colaterais; 4. a ocorrência de recidiva após sucesso do tratamento clínico parece similar; entretanto, o diltiazem pode estar associado a maior sustentação da resposta clínica de sucesso. / Surgical treatment of chronic anal fissure is effective but is associated to some risk of fecal continence impairment in the early or late postoperative period. Few clinical trials comprising calcium channel blockers are available. Moreover, solid scientific evidence regarding bethanechol use for chronic anal fissure is lacking. The present study aims to comparatively analyze safe and effectiveness of two topical pharmacological agents for treatment of chronic anal fissure: diltiazem and bethanechol. This was a retrospective study and was performed in a single institution. Between January 2001 and April 2005, the medical records of 332 patients with chronic anal fissure were reviewed. Of these patients, it was possible to evaluate outcomes of thirty patients treated with diltiazem 2% gel (group D) which were compared to thirty patients who underwent clinical management with bethanechol 0.1% gel (group B). The treatment duration was 8 weeks. All patients in both groups were asked to apply a small gel amount to the anus twice a day, and they were interviewed after seven days and at the end of the treatment (8 weeks). Treatment success was defined as symptoms absence associated or not to fissure healing. Recurrence was defined as symptom recurrence after successful treatment. There were 13 (43.3%) men in group D and 11 (36.7%) in group D p=0.598. Median age was 36 (19-76) for patients in group D, and 39 (20-75) in group B p=0.937. Regarding symptoms duration, its median value in group D was 11 (2-82) months, and 12 (2-276) in group B p=0.958. The anal fissure had the following location in group D: posterior in 22 (73.4%) patients; anterior in six (20%) patients, lateral in one (3.3%) patient, and there was an anterior and a posterior fissure in another (3.3%) case; in group B, it was located in the posterior wall in 17 (56.7%) patients, and in the anterior wall in 13 (43.3%) p=0.899. Seven days after the beginning of treatment, in group D, six (35.3%) were still symptomatic; in group B, 11 (68.8%) were symptomatic p=0.055. Regarding healing of the fissures after seven days, in group D it occurred in three (17.6%) cases, and in group B, it was observed in 4 (25%) cases p=0.688. At the completion of treatment (8 weeks), in both groups, 11 (36.7%) patients were still symptomatic. Regarding fissure healing at the end of treatment, it occurred for 16 (53.3%) patients in group D, and for 15 (50%) patients in group B - p=0.796. Success at treatment completion was the same for both grous: 19 (63.3%) patients. In group D, 9 (30%) patients were operated on while in group B, 11 (36.7%) required surgery p=0.584. In group D, 3 (10%) patients had treatment-related complications; in group B, they occurred in only one (3.3%) patient p=0.612. Symptomatic recurrence was observed in 4 (21%) out of 19 patients with successful initial treatment in group D. Recurrence was the same after successful treatment with bethanechol. Mean time interval to recurrence diagnosis in group D was 16 (10-24) months; this interval was 7.5 (2-15) in group B p=0.147. The conclusions of the present study regarding medical management of chronic anal fissure with diltiazem and bethanechol are the following: 1. there is evidence to suggest that topical diltiazem treatment is associated to an earlier clinical response; 2. after eightweek topical treatment, diltiazem and bethanechol are equally efficient; 3. both are safe and associated to a low complication rate; 4. recurrence rates after successful treatment seem to be similar although clinical success may be more lasting after diltiazem treatment.

Este estudo procurou verificar o efeito de dois selantes no tratamento de lesões cariosas não cavitadas em dentina, no que diz respeito à progressão da cárie na superfície oclusal de molares permanentes, em adolescentes com idades entre 11 e 15 anos. A amostra do estudo constituiu-se de 28 dentes: 14 selados com selante resinoso (Fluroshield®, Denstply), no grupo Gres, e 14 selados com selante ionomérico (RIVA Protect®, SDI), no grupo Gciv. A avaliação dos desfechos se deu por meio da análise dos exames radiográficos inicial e após 12 meses de acompanhamento; através de dois métodos: avaliação radiográfica qualitativa e quantitativa. A análise qualitativa foi realizada por um único examinador devidamente calibrado (Kappa = 0,837) com o uso de negatoscópio em sala escura e lupa de aumento 10x, e considerou como sucesso do tratamento a regressão ou paralisação da lesão; e insucesso, a evolução da lesão cariosa. A análise quantitativa se deu por meio da comparação entre os coeficientes de densidade radiográfica obtidos através do software DIGORA®, observando aumento (sucesso) ou diminuição (insucesso) dos coeficientes de densidade. Após a avaliação qualitativa, observou-se sucesso do tratamento em 64,3% dos casos (n=9) do grupo Gciv e 85,7% (n=12) do grupo Gres, sem diferença estatística entre os grupos (p=0,39). A avaliação quantitativa mostrou que no Gres foi observado um aumento significante dos coeficientes de densidade (p=0,003) e no Gciv se observou uma estabilidade dos coeficientes após 12 meses (p=0,49). Desta forma, pode-se concluir que, nas condições deste estudo, o uso de selantes de sulcos e fóssulas mostrou-se eficaz no tratamento de lesões cariosas. / This study examined the effect of two sealants in the treatment of non-cavitated occlusal carious lesions, regarding to the progression or arresting of the lesions in permanent molars in adolescents 11 to 15 years age. The sample consisted of 28 teeth: 14 sealed with resin-based sealant (Fluroshield®, Denstply), Gres group, and 14 sealed with glass ionomer sealant (RIVA Protect®, SDI), Gciv group. Caries progression was monitored by radiographic examination, using two methods: qualitative and quantitative trough radiographic evaluation. Qualitative analysis was performed by a single calibrated examiner (Kappa = 0.837) using light box in a darkened room and 10x magnifying glass, and considered as success treatment the regression or interruption of the injury caries, and failure treatment, the evolution of the lesion carious. Quantitative analysis occurred by comparing the radiographic density coefficient obtained through software DIGORA®, observing increased (success) or decreased (failure) of the coefficients. After the qualitative evaluation, it was observed success of treatment in 64.3% (n = 9) of Gciv group and 85.7% (n = 12) on Gres group, with no statistical difference between the them (p=0,39). The quantitative analysis showed in Gres group a significant increase in the density coefficient (p = 0.003) and in the Gciv group the stability of coefficients after 12 months (p = 0.49). It can be concluded that under the conditions of this study, the use of sealants proved to be effective in the treatment of occlusal carious lesions.

Os objetivos deste trabalho foram avaliar e comparar por 24 meses, a retencao e as caracteristicas superficiais de dois diferentes materiais seladores, Helioseal Clear e Helioseal F ambos da Ivoclar Vivadente, AG - Schaan, Liechtenstein. Participaram desse estudo, 50 criancas de 6 a 8 anos de idade, com no minimo dois primeiros molares permanentes higidos e historia de carie, num total de 153 dentes divididos em dois grupos: GHC(Helioseal Clear) e GHF (Helioseal F). O selamento foi realizado sob isolamento relativo para todos os grupos, após profilaxia previa com jato de bicarbonato (Profident Dabi-Atlante) e agua e, condicionamento com gel de acido fosforico a 34% por 15 segundos. Apos 6, 12, 18 e 24 meses, a avaliacao clinica foi realizada por dois examinadores calibrados. Avaliou-se a retencao e a incidencia de carie nas 5 areas oclusais: OM, OC, OD, OV e OL (DEERY et al.) e; as caracterisiticas superficiais e a retencao considerando a superficie oclusal com o um todo (criterio modificado de RYGE &SNYDER).Nao houve diferenca estatisticamente significante atraves do teste exato de Fisher na taxa de sucesso (p=0,496 a 1,0) ou para a incidencia de carie (p=0,472 a 1,0) entre as areas avaliadas quando comparado o GHC com GHF durante todo o período estudado. Considerando todas as areas juntas e os grupos separados ou, os dois grupos juntos mas as areas separadas, nao houve diferenca estatisticamente significante, respectivamente, pelo teste de Fisher (p=0,170 a 0,534) e do Qui- Quadrado (p=0,058 a p=0,909), quanto ao sucesso na retencao em nenhum periodo. Quanto a analise da superficie oclusal toda quanto a retencao, esta foi maior e estatisticamente significante para o GHC aos 12m (p=0,0345) e 24m (0,0076). Em relacao as caracteristicas superficiais, o GHC so nao apresentou superioridade quanto a descoloracao superficial, durante o periodo estudado. Para as demais caracteristicas, os resultados do teste de Mann-Whitney foram altamente significantes em diferentes periodos (p= 00000 a 0,0421). A frequencia de bolhas nas superficies seladas, determinada pelo teste do Qui-quadrado, foi maior e significante (p=0,000:12 e 18 meses a p=0,002: 6 e 24 meses) no GHF. Portanto, pode-se concluir que quanto a retencao e caracteristicas superficiais, na superfície oclusal toda, o selante Helioseal Clear apresentou melhor desempenho. / The objectives of this study were evaluated and compared for 24 months, the retention and surface characteristic of two different sealing materials, and Helioseal F Clear Helioseal both of Ivoclar Vivadent, AG - Schaan, Liechtenstein. 50 children from 6 to 8 years of age with at least with two sound first permanent molars and caries of history, total of 153 teeth, were divided into 2 groups: GHC (Helioseal Clear) and GHF (Helioseal F). The sealing was done with ruber dam for all groups, after prophylaxis with air-polishing jet (Profident --Dabi Atlante) and water, and acidetching with 34 % phosphoric acid 34% for 15 seconds. After 6, 12, 18 and 24 months, clinical evaluation was evaluated by two calibrated examiners. To evaluate the retention and the incidence of occlusal caries in 5 areas: OM, OC, OD, and OV OL (DEERY et al.). And, the surface characteristics and retention considering the all occlusal surface (modified criterion RYGE & SNYDER ). There was no statistically significant by Fisher\'s exact test in the rate of success (p = 0,496 to 1.0) or the incidence of caries (p = 0,472 to 1.0) between the areas assessed when compared with the GHC GHF throughout the study period. Considering all areas and groups together or separated, the two groups together but separate areas, there was no statistically significant difference, respectively, by Fisher\'s test (p = 0170 to 0534) and Chi-Square (p = 0,058 to 0,909), about the success in holding in any period. The analysis of the entire occlusal surface on retention, it was higher and statistically significant for the GHC to 12m (p = 0.0345) and 24m (0.0076). In relation to surface characteristics, the GHC showed superiority not only on the superficial discoloration over the period studied. For other characteristics, the results of the Mann-Whitney test were highly significant in different periods (p = 00000 to 0.0421). The frequency of bubbles in the sealed surfaces, as determined by Chi-Square was higher e statistically significant difference (p = 0,000:12 and 18 months p = 0,002: 6 and 24 months) in GHF. Therefore,the retention and surface characteristic in the all occlusal surface, the Helioseal Clear sealant showed better performance