Antimicrobial action, pH, and tissue dissolution capacity of 2,5% sodium hypochlorite gel and solution / Ação antimicrobiana, pH, e capacidade de dissolução tecidual de gel e solução de hipoclorito de sódio 2,5%

Objective: to evaluate antimicrobial action, pH, and tissue dissolution capacity of 2.5% sodium hypochlorite (NaOCl) gel and solution. Methods: The 2.5% NaOCl gel was produced from a colloidal base. The test groups included 2.5% NaOCl gel and solution and the control groups included gel base and distilled water. The antimicrobial activity was evaluated by the broth dilution technique against Enterococcus faecalis (ATCC 29212) at 15 and 30 seconds and at 1, 5, and 10 minutes. To evaluate tissue dissolution capacity, 30 pulp fragments of bovine incisors were weighed, 10 for each test group and 5 for each control group before and after exposure to the chemical auxiliaries. The final mass percentage of each fragment was calculated. The pH of the substances was measured in triplicate through a digital pH meter. Results: pH levels of 13.08 and 9.75 were observed for 2.5% NaOCl solution and gel, respectively. The antimicrobial action of 2.5% NaOCl was the same for both solution and gel, for all tested times. The 2.5% NaOCl solution group showed higher tissue dissolution capacity (Kruskal-Wallis and Student-Newman-Keuls tests P<0.0001). Conclusions: The type of medium, either solution or gel, containing 2.5% NaOCl did not influence the antimicrobial action at any of the tested times. However, 2.5% NaOCl gel did not present tissue dissolution capacity

Objetivo: avaliar a ação antimicrobiana, pH e capacidade de dissolução tecidual promovida por hipoclorito de sódio (NaOCl) 2,5%, nas formas líquida e gel. Métodos: O gel de NaOCl 2,5% foi produzido a partir de base coloidal. Os grupos testes foram NaOCl 2,5% gel e solução e os grupos controle incluíram a base gel e água destilada. A ação antimicrobiana foi avaliada por meio de método de diluição em caldo, frente a Enterococcus faecalis (ATCC 29212) após 15 e 30 segundos, e também a 1, 5 e 10 minutos. Para o teste de diluição tecidual, 35 fragmentos de polpa bovina (sendo 10 para cada grupo teste e 5 para o grupo controle) foram pesadas antes e após a exposição aos auxiliares químicos. O percentual de massa final de cada fragmento foi calculada. O pH dos auxiliares químicos foi medido em pHmetro digital, em triplicata. Resultados: Valores de pH iguais a 13,08 e 9,75 foram observados para solução e para o gel de NaOCl, respectivamente. A ação antimicrobiana do NaOCl foi a mesma para o gel e a solução, em todos os períodos testados. Maior capacidade de dissolução tecidual foi obtida no grupo onde se utilizou a solução de NaOCl 2,5% (Testes de Kruskal-Wallis e Student-Newman-Keuls, P<0,0001). Conclusões: A apresentação na forma de gel ou de líquido do NaOCl 2,5% não modificou a ação antimicrobiana em qualquer um dos períodos testados. Porém, o gel de NaOCl 2,5% não demonstrou capacidade de dissolução tecidual.

Avaliação da formação de smear layer no preparo químico mecânico realizado com solução ou gel de hipoclorito de sódio a 2, 5% / Evaluation of smear layer formation in mechanical chemical preparation performed with 2. 5% sodium hypochloride solution or gel

Introdução: a formação de smear layer durante o preparo dos canais radiculares com o uso de hipoclorito de sódio solução já foi amplamente estudada; entretanto, na apresentação em gel não existem relatos na literatura. Objetivo: avaliar, em MEV, a formação de smear layer durante o preparo endodôntico, utilizando o NaOCl nas formas líquida e gel, associado ou não ao EDTA. Métodos: sessenta raízes palatinas de molares superiores ou distais de inferiores, com comprimento radicular padronizado em 15 mm, foram utilizadas. As amostras foram divididas em quatro grupos controle com n = 5 cada (soro fisiológico ou base gel, associados ou não ao EDTA) e quatro grupos testes com n = 10 cada, de acordo com a substância irrigadora empregada durante o preparo (solução ou gel de NaOCl a 2,5%, associados ou não ao EDTA). Os canais foram modelados e posteriormente clivados para análise em MEV (ampliação de 2000x). Imagens de eletromicrografias foram obtidas nos terços cervical, médio e apical. A presença e as características da smear layer formadas foram categorizadas. As imagens foram analisadas por dois avaliadores, previamente, calibrados. Após a análise de concordância (Kappa = 0,806) dos escores, os dados foram tratados com o uso do teste Kruskall-Wallis, complementado pelo teste de Comparações Múltiplas SNK. O nível de significância foi de 5%. Resultados: a utilização do soro fisiológico e do NaOCl líquido, associados à irrigação final com EDTA, apresentou os melhores resultados de limpeza. Com o uso do NaOCl gel e da base gel, sem associação ao EDTA, houve uma maior quantidade de resíduos sobre as paredes dentinárias. Além disso, independentemente da substância irrigadora testada, pode-se observar que houve uma melhor capacidade de remoção da smear layer no terço cervical em relação ao apical. Conclusões: observou-se formação de smear layer após o preparo do canal radicular associado ao NaOCl líquido ou gel. A aplicação de EDTA promoveu a remoção da smear layer produzida durante o preparo do canal.

Introduction: the formation of smear layer during the preparation of root canals with the use of sodium hypochlorite solution has been widely studied; however, in the gel presentation there aren't reports in the literature. Objective: to evaluate, in SEM, the formation of smear layer during endodontic preparation, using NaOCl in liquid and gel forms, associated or not with EDTA. Methods: sixty palatal roots of maxillary molars or distal roots of lower molars, with a root length of 15 mm, were used. The samples were divided into four control groups with n = 5 each (saline or gel base, associated or not with EDTA) and four test groups (n = 10 each) according to the irrigation substance used during the preparation (2.5% NaOCl solution or gel, associated or not with EDTA). The root canals were instrumented and later split for SEM analysis (2000x magnification). Electromicrographic images were obtained from the cervical, middle and apical thirds. The presence and characteristics of the smear layer formed were categorized. The images were analyzed by two previously calibrated evaluators. After the Kappa analysis (0.806), the data were treated using the Kruskall-Wallis test, complemented by the SNK Multiple Comparison Test. The level of significance was 5%. Results: the use of saline and liquid NaOCl, associated with final rinsing with EDTA, showed the best cleaning results. With the use of NaOCl gel and gel base, with no EDTA association, there was a greater amount of residues on the dentin surfaces. In addition, despite the irrigation substance tested, it can be observed that there was a better capacity of removal of the smear layer in the cervical third in relation to the apical. Conclusion: root canal instrumentation associated with NaOCl solution or gel EDTA produced smear layer. Smear layer was removed with the use of EDTA as a final flushing.

Finding Home: Landmark Ambiguity in Human Navigation.

Memories of places often include landmark cues, i.e., information provided by the spatial arrangement of distinct objects with respect to the target location. To study how humans combine landmark information for navigation, we conducted two experiments: To this end, participants were either provided with auditory landmarks while walking in a large sports hall or with visual landmarks while walking on a virtual-reality treadmill setup. We found that participants cannot reliably locate their home position due to ambiguities in the spatial arrangement when only one or two uniform landmarks provide cues with respect to the target. With three visual landmarks that look alike, the task is solved without ambiguity, while audio landmarks need to play three unique sounds for a similar performance. This reduction in ambiguity through integration of landmark information from 1, 2, and 3 landmarks is well modeled using a probabilistic approach based on maximum likelihood estimation. Unlike any deterministic model of human navigation (based e.g., on distance or angle information), this probabilistic model predicted both the precision and accuracy of the human homing performance. To further examine how landmark cues are integrated we introduced systematic conflicts in the visual landmark configuration between training of the home position and tests of the homing performance. The participants integrated the spatial information from each landmark near-optimally to reduce spatial variability. When the conflict becomes big, this integration breaks down and precision is sacrificed for accuracy. That is, participants return again closer to the home position, because they start ignoring the deviant third landmark. Relying on two instead of three landmarks, however, goes along with responses that are scattered over a larger area, thus leading to higher variability. To model the breakdown of integration with increasing conflict, the probabilistic model based on a simple Gaussian distribution used for Experiment 1 needed a slide extension in from of a mixture of Gaussians. All parameters for the Mixture Model were fixed based on the homing performance in the baseline condition which contained a single landmark. from the 1-Landmark Condition. This way we found that the Mixture Model could predict the integration performance and its breakdown with no additional free parameters. Overall these data suggest that humans use similar optimal probabilistic strategies in visual and auditory navigation, integrating landmark information to improve homing precision and balance homing precision with homing accuracy.

The role of oxidative stress in the pathophysiology of gestational diabetes mellitus.

Normal human pregnancy is considered a state of enhanced oxidative stress. In pregnancy, it plays important roles in embryo development, implantation, placental development and function, fetal development, and labor. However, pathologic pregnancies, including gestational diabetes mellitus (GDM), are associated with a heightened level of oxidative stress, owing to both overproduction of free radicals and/or a defect in the antioxidant defenses. This has important implications on the mother, placental function, and fetal well-being. Animal models of diabetes have confirmed the important role of oxidative stress in the etiology of congenital malformations; the relative immaturity of the antioxidant system facilitates the exposure of embryos and fetuses to the damaging effects of oxidative stress. Of note, there are only a few clinical studies evaluating the potential beneficial effects of antioxidants in GDM. Thus, whether or not increased antioxidant intake can reduce the complications of GDM in both mother and fetus needs to be explored. This review provides an overview and updated data on our current understanding of the complications associated with oxidative changes in GDM.