Effect of Intracoronal bleaching agents on dentin microhardness

The purpose of this in vitro study was to compare the effect of intracoronal bleaching agents associated or unassociated with chlorhexidine gel on dentin microhardness. Sixty human maxillary incisor crowns were divided into six groups, and bleaching agents were sealed into the pulp chambers as follows: sodium perborate + water (SPW), sodium perborate + 2% chlorhexidine gel (SP + CHX), sodium perborate + 30% hydrogen peroxide solution (SP + HP), 37% carbamide peroxide gel (CP), 37% carbamide peroxide gel + 2% chlorhexidine gel (CP + CHX), and water (W). After the bleaching procedure, microhardness testing was carried out on the dentin surface at three different levels: inner, middle, and outer dentin. The greatest reduction in microhardness was observed for the SP + HP group. No differences were observed between the SPW and SP + CHX group. The 2% chlorhexidine gel did not adversely affect dentin microhardness when associated with the tested bleaching agents. CHX might be considered as an antimicrobial vehicle during intracoronal bleaching.33446046

Ex vivo antimicrobial activity of several bleaching agents used during the walking bleach technique

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)To investigate ex vivo the antimicrobial activity of a paste of sodium perborate associated with various vehicles comparing it with 37% carbamide peroxide and 35% hydrogen peroxide. The antimicrobial activity of these agents was evaluated against three microorganisms: Enterococcus faecalis, Streptococcus mutans and Candida albicans. One millilitre of each tested substance was placed on the bottom of wells of 24-well cell culture plates. Six wells were used for each time period and group. Two millilitres of the microbial suspension was ultrasonically mixed for 10 s with the bleaching pastes and placed in contact with them for 10, 30, 45 s; 1, 3, 5, 10, 20, 30 min; and 1 and 2 h. After each period of time, 1 mL from each well was transferred to tubes containing 2 mL of freshly prepared brain heart infusion agar + neutralizers. Agar plates were inoculated in appropriate gaseous conditions. Data were analysed statistically by the Kruskal-Wallis test with the level of significance set at P < 0.05. In all groups containing chlorhexidine (groups 3, 5 and 7), the antimicrobial activity of the bleaching paste was significantly increased when compared with groups with other kinds of vehicle (groups 1, 2, 4, 6 and 8). For all tested groups, the most resistant microorganism was E. faecalis. Chlorhexidine when used as a vehicle for sodium perborate enhanced its antimicrobial activity.411210541058Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES [BEX: 0173/05-3

Incorporação das ciências sociais na produção de conhecimentos sobre trabalho e saúde Incorporation of the social sciences in the production of knowledge about work and health

Este artigo apresenta uma revisão bibliográfica sobre a influência das ciências sociais para a superação de concepções reducionistas de relação trabalho-saúde, nas duas últimas décadas. Trata-se de um tipo de diagnóstico da produção científica, no qual destacam-se: as contribuições para a caracterização da saúde do trabalhador, como campo de conhecimento e de intervenção, e para a análise da política e das práticas das instituições públicas; as abordagens compreensivas e as questões de gênero. Efetuou-se um levantamento de artigos de periódicos indexados e de dissertações e teses de pós-graduação. Foram consultados: o banco de dissertações e teses da Coordenação de Aperfeiçoamento do Ensino Superior e do Instituto Brasileiro de Informação em Ciência e Tecnologia; a Biblioteca Virtual em Saúde da Biblioteca Regional de Medicina e o site do Scientific Electronic Library On-line. Constatou-se a predominância de estudos sobre temáticas específicas e determinadas categorias de trabalhadores, em contraposição a tentativas de abordagens totalizadoras. Apesar dos notáveis avanços em termos de conhecimento, existe carência significativa de investigações sobre segmentos da população trabalhadora que apresentam maior vulnerabilidade social.<br>This article presents a bibliographical revision on the influence of the social sciences to overcome the reducing conceptions of relationship work-health, in the last two decades. It is a type of diagnosis of the scientific production, in which outstanding aspects are: the contributions for the characterization of the worker’s health, as knowledge field and of intervention, and for the analysis of the politics and of the practices of the public institutions; the comprehensive approaches and gender questions. It was conducted an assessment of indexed journals and masters degree dissertations and doctoral thesis. It was consulted: the bank of dissertations and thesis organized by the Coordination of Improvement of the Higher Education and for the Brazilian Institute of Information in Science and Technology; the Virtual Library in Health of the Regional Library of Medicine and Scientific Electronic site On-line Library. It was verified the predominance of studies on specific themes and certain categories of workers, in opposition to attempts of totalizing approaches. In spite of the outstanding progresses in knowledge terms and of enlargement of study objects, significant lack of investigations exists on segments of the working population that present larger social vulnerability

A two-level evolutionary algorithm for solving the petrol station replenishment problem with periodicity constraints and service choice

This paper addresses the petrol station replenishment problem with periodicity constraints and introduces the frequency service choice as a decision variable. We present a mathematical optimization model for the problem and we develop first a simple heuristic method that is able to handle the complexity of the problem and then two metaheuristic approaches based on a novel two-level evolutionary algorithm. The first level deals with the periodicity and frequency selection of the visits to the petrol stations. The second level of evolution assigns the stations to the tank-trucks such that the total traveled distance is minimized. The effectiveness of the proposed approaches has been tested by means of a comprehensive experimental study by using first a set of randomly generated test cases and then a real-life problem. © 2018, Springer Science+Business Media, LLC, part of Springer Nature