Microbial leakage of MTA, Portland cement, Sealapex and zinc oxide-eugenol as root-end filling materials

Objective: The aim of this study was to compare the microbial leakage of mineral trioxide aggregate (MTA), Portland cement (PC), Sealapex and zinc oxide-eugenol (ZOE) as root-end filling materials.Study design: An in vitro microbial leakage test (MLT) with a split chamber was used in this study. A mixture of facultative bacteria and one yeast (S. aureus + E. faecalis + P. aeruginosa + B. subtilis + C. albicans) was placed in the upper chamber and it could only reach the lower chamber containing Brain Heart Infusion broth by way of leakage through the root-end filling. Microbial leakage was observed daily for 60 days. Sixty maxillary anterior human teeth were randomly assigned to different groups - MTA and PC (gray and white), Sealapex + zinc oxide and ZOE, control groups and subgroups to evaluate the influence of EDTA for smear layer removal. These materials were further evaluated by an agar diffusion test (ADT) to verify their antimicrobial efficacy. Data were analyzed statistically by Kruskal-Wallis and Mann-Whitney test.Results: In the MLT, Sealapex + zinc oxide and ZOE did not show evidence of microbial leakage over the 60-day experimental period. The other materials showed leakage from the 15th day. The presence of smear layer influenced microbial leakage. Microbial inhibition zones were not observed in all samples tested by ADT.Conclusion: Sealapex + zinc oxide and ZOE did not show microbial leakage over the experimental period, whereas it was verified within 15 to 45 days in MTA and Portland cement.

Structure, ferroelectric/magnetoelectric properties and leakage current density of (Bi0.85Nd0.15)FeO3 thin films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of dentine surface treatment on leakage of root fillings with a glass ionomer sealer.

The purpose of this study was to observe the quality of seal of the glass ionomer cement, Ketac-Endo, after treatment of the root canal wall. The root canals of 140 extracted human teeth were prepared biomechanically. The root canals were treated with either EDTA or received an intracanal dressing of calcium hydroxide or camphorated paramonochlorphenol. The root canals were filled by the lateral condensation technique with gutta-percha points and the sealer Ketac-Endo, or zinc oxide-eugenol cement or Sealapex. The teeth were placed into a 2% methylene blue dye solution inside a flask, which was attached to a vacuum pump. Leakage was measured linearly. Sealapex exhibited significantly less leakage than Ketac-Endo or zinc oxide-eugenol cement (P<0.01). The use of EDTA and intermediary dressings reduced significantly (P<0.01) the leakage observed with the zinc oxide-eugenol sealer and Ketac-Endo.

Apical leakage following root canal dressing with calcium hydroxide.

The purpose of this study was to analyse the apical leakage in teeth filled by the lateral condensation technique following medication with calcium hydroxide. One hundred and twenty extracted human teeth were biomechanically prepared by using exclusively reaming motion with files up to #40. Half of the teeth received a calcium hydroxide dressing for 3 days. The medication was removed by irrigation and reaming motion with files #40 up to #70. The teeth were divided in 6 experimental groups, according to the dimension of the utilized instrument. The root canals were filled and posteriorly the teeth were placed into a 2% methylene blue dye solution inside a flask, which was attached to a vacuum pump. Leakage was measured linearly, and the results showed significantly (p<0.01) less leakage in the experimental groups that received calcium hydroxide dressings than in the control groups. The results persisted even after the removal of 300 micrometers of dentin from the root canal dentinal walls.

Apical leakage after root canal filling with an experimental calcium hydroxide gutta-percha point

This study was an in vitro analysis of the apical seal of root canals filled with an experimental calcium hydroxide gutta-percha point. One hundred and ten recently extracted human permanent teeth with a single root were used. The root canals were biomechanically prepared, and some received a dressing of calcium hydroxide for 7 days. Root canals not dressed were filled by the lateral condensation technique with either regular gutta-percha or calcium hydroxide gutta-percha points. The dressed root canals were filled with the same sealers and regular gutta-percha points. The specimens were placed into a 2% methylene blue dye solution under vacuum, and the apical leakage was linearly evaluated. The experimental groups with calcium hydroxide dressing and the one with calcium hydroxide gutta-percha points exhibited significantly (p < 0.05) less leakage than the groups filled with regular gutta-percha points. The results obtained indicated that calcium hydroxide guttapercha points produced an improvement in the apical sealing quality of the root canal filling. Copyright © 1996 by The American Association of Endodontists.

An active leakage-injection scheme applied to low-voltage SRAMs

An active leakage-injection scheme (ALIS) for low-voltage (LV) high-density (HD) SRAMs is presented. By means of a feedback loop comprising a servo-amplifier and a common-drain MOSFET, a current matching the respective bit-line leakage is injected onto the line during precharge and sensing, preventing the respective capacitances from erroneous discharges. The technique is able to handle leakages up to hundreds of μA at high operating temperatures. Since no additional timing is required, read-out operations are performed at no speed penalty. A simplified 256×1bit array was designed in accordance with a 0.35 CMOS process and 1.2V-supply. A range of PSPICE simulation attests the efficacy of ALIS. With an extra power consumption of 242 μW, a 200 μA-leakage @125°C, corresponding to 13.6 times the cell current, is compensated.

In vitro evaluation of marginal leakage in bonded restorations, with mechanical or chemical-mechanical (Carisolv) removal of carious tissue

This study carried out an in vitro evaluation and comparison of the occurrence of marginal leakage in bonded restorations using mechanical or chemical-mechanical (Carisolv) removal of carious tissue. For that purpose, 40 extracted decayed human molars were divided into 4 groups: GI (burs + Prime & Bond NT + TPH), GII (Carisolv + Prime & Bond NT + TPH), GIII (burs + SBMP + Z100) and GIV (Carisolv + SBMP + Z100). After accomplishment of the restorations and thermal cycling, the teeth were exposed to dye, sectioned and qualitatively evaluated. The results demonstrated that the system of removal of carious tissue did not influence the results of microleakage at any of the cavity margins. At dentinal margins, use of the Prime & Bond NT + TPH restorative system allowed the occurrence of less microleakage than the SBMP + Z100 system.

The effect of endodontic materials on the optical density of dyes used in marginal leakage studies

The aim of this study was to determine the effect of the exposure of different endodontic materials to different dye solutions by evaluating the optical density of the dye solutions. Seventy-five plastic tubes were filled with one of the following materials: AH Plus, Sealapex, Portland cement, MTA (Angelus and Pro Root) and fifteen control plastic tubes were not. Each specimen of material and control was immersed in a container with 1 ml of each dye solution. A 0.1 ml-dye solution aliquote was removed before immersion and after 12, 24, 48 and 72 hours of each specimen immersion to record its optical density (OD) in a spectrophotometer. Statistical analysis was performed with ANOVA and Tukey tests (5%). No significant difference was found among any of the solution OD values for AH Plus cement. Portland cement promoted different OD values after 12 hours of immersion. MTA-Angelus cement presented different OD values only for 2% rhodamine B and the MTA-Pro Root cement presented different OD values in all 2% rhodamine B samples. Sealapex cement promoted a reduction in the India Ink OD values. Dye evaluation through OD seems to be an interesting method to select the best dye solution to use in a given marginal leakage study.

Resilience as protagonism: interpersonal relationships, cultural practices, and personal agency among working adolescents in Brazil

A visual methods study was conducted with 16 at-risk youth living in a mid-sized Brazilian city. In this study, we focus on data obtained from four of those youth who were working adolescents, aged 13-15, and identify contextually specific protective processes associated with resilience. Through a reciprocal process of collaborative research that included observation, photo elicitation, video recording of a 'day in the life' of each youth, and semi-structured interviews, youth and researchers co-constructed an understanding of adaptive coping in a particularly challenging social environment. By employing techniques from grounded theory to analyze the data, we identified a pattern of protagonism among these youth that enabled them to maintain well-being despite exploitation as working children. This conceptualization of protagonism as a protective process has implications for human service workers who intervene to improve the living conditions of working children. © 2013 Taylor & Francis.

Study on the vulnerability and resilience of Caribbean Small Island Developing States (SIDS)

Caribbean Small Island Developing States are considered to be particularly vulnerable to external shocks that stem from changes in climate and the increase in frequency and magnitude of natural disasters. Quantification of the extent of vulnerability of these islands may be measured by the use of several indices including the Economic Vulnerability Index (EcVI), the Disaster Deficit Index (DDI), the Environmental Vulnerability Index (EVI) and the Social Vulnerability Index (SVI). The capacity to build resilience may be measured by the Economic Resilience Index (ERI). Of importance in the measurement of vulnerability and resilience is the impact on women and children. In order to reduce vulnerability and promote resilience, Caribbean SIDS are urged to develop adaptation strategies. Such strategies include the conduct of indepth studies on natural environmental impacts specifically in terms of biophysical and socio economic impacts. It is also necessary to review best practices in terms of preparedness, resilience building and climate change adaptation in other countries such as Cuba. Addressing vulnerability and building resilience requires appropriate information and data and priority should be given to addressing data gaps. It would also be expedient to classify vulnerability and resilience as regional public goods wherein one country’s benefit does not compromise another country’s ability to benefit. Finally, it is important to acknowledge that vulnerability is, in part, is a function of gender so that indicators need to be disaggregated to reflect the country-specific gendered socioeconomic situation.

An assessment of social vulnerability and resilience in poverty reduction strategy papers (PRSPS/I-PRSPS) of selected Caribbean SIDS

The study undertakes a review of the Poverty Reduction Strategy Papers (PRSPs), and Interim Poverty Reduction Strategy Papers (I-PRSPs) of four selected Caribbean SIDS from the Eastern Caribbean. The countries had participated in the Poverty Reduction Strategy initiative formulated by the World Bank. The country papers reviewed were the Commonwealth of Dominica, Grenada, Saint Lucia and St. Vincent and the Grenadines. The review assesses and provides a comparative analysis of the general awareness of the notions of vulnerability and the inclusion and use of strategies that address the reduction of vulnerability and the strengthening of resilience by the countries reviewed. It also explores how vulnerability reduction strategies were applied to differing groups, as elaborated through the PRSPs.

Leakage detection in water pipe networks using electromechanical impedance (EMI) based technique

The electromechanical impedance (EMI) technique has been successfully used in structural health monitoring (SHM) systems on a wide variety of structures. The basic concept of this technique is to monitor the structural integrity by exciting and sensing a piezoelectric transducer, usually a lead zirconate titanate (PZT) wafer bonded to the structure to be monitored and excited in a suitable frequency range. Because of the piezoelectric effect, there is a relationship between the mechanical impedance of the host structure, which is directly related to its integrity, and the electrical impedance of the PZT transducer, obtained by a ratio between the excitation and the sensing signals.This work presents a study on damage (leaks) detection using EMI based method. Tests were carried out in a rig water system built in a Hydraulic Laboratory for different leaks conditions in a metallic pipeline. Also, it was evaluated the influence of the PZT position bonded to the pipeline. The results show that leaks can effectively be detected using common metrics for damage detection such as RMSD and CCDM. Further, it was observed that the position of the PZT bonded to the pipes is an important variable and has to be controlled.

Subtle leakage of a Majorana mode into a quantum dot

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Critical discourses on resilience: exploring alternatives strategies used by young people at-risk

The concept of resilience is often situated in a dominant discourse that reflects medical and developmentalist epistemology, in Western models, with the ideology of white people, and middle class hegemonic norms. Behavior that falls outside of the normal, or what is socially acceptable, is associated with riskiness and tacitly if not explicitly labeled as pathological, and then, not resilient. However, the context of social injustice of many young people at-risk can have drastic effects on them. When we offer institutions such as schools that do not understand their needs, they may refuse our services and some of them may engage in antisocial activities, since they are looking for personal validation, pathways to recognize themselves, and places and organizations that contribute to the building of their social identity. This paper analyses how the denial of support and resources for the wellbeing of young people can lead them to situations that are socially unacceptable, such as sexual exploitation and drug trafficking. The main argument is that these activities, in the absence of conventional mechanisms, may bring some benefit to the subjects. Benefits may be in material conditions, though strongly marked by issues of social inequality; or subjective, in gaining relationships with people outside the normative places and institutions for young people. Unconventional circumstances produce unconventional attitudes that are expressed in alternative forms of resilience.