Influência do preparo cavitário apical e do tipo de material retrobturador pela análise da infiltraçäo marginal / Influence of apical preparation and retrofilling material on dye marginal leakage

O objetivo deste trabalho foi avaliar o preparo cavitário apical com ultra-som sobre a infiltraçäo marginal por corante empregando três materiais retrobturadores. Foram utilizados 72 dentes unirradiculados humanos extraídos, divididos em seis grupos de 12. Os dentes receberam apicectomia, preparo cavitário com ultra-som ou brocas convencionais e retrobturaçäo com cimento de ionômero de vidro (Grupos 1 e 4), Super EBA (Grupos 2 e 5) e Sealapex associado ao óxido de zinco (Grupos 3 e 6). Os espécimes foram imersos em corante durante 48 horas a 37ºC, e as infiltraçöes ocorridas foram avaliadas com o auxílio de um estereomicroscópio. Pôde-se concluir que os métodos de preparo cavitário apical (com ultra-som ou brocas) näo influenciaram os resultados da infiltraçäo marginal apresentada pelos três materiais retrobturadores. Os materiais retrobturadores influenciaram os valores da infiltraçäo marginal. Os melhores resultados em termos de infiltraçäo foram obtidos com o cimento de ionômero de vidro e Super EBA

A comparative evaluation of open loop and closed loop drug administration strategies in the treatment of AIDS

In recent years, many researchers in the field of biomedical sciences have made successful use of mathematical models to study, in a quatitative way, a multitude of phenomena such as those found in disease dynamics, control of physiological systems, optimization of drug therapy, economics of the preventive medicine and many other applications. The availability of good dynamic models have been providing means for simulation and design of novel control strategies in the context of biological events. This work concerns a particular model related to HIV infection dynamics which is used to allow a comparative evaluation of schemes for treatment of AIDS patients. The mathematical model adopted in this work was proposed by Nowak & Bangham, 1996 and describes the dynamics of viral concentration in terms of interaction with CD4 cells and the cytotoxic T lymphocytes, which are responsible for the defense of the organism. Two conceptually distinct techniques for drug therapy are analyzed: Open Loop Treatment, where a priori fixed dosage is prescribed and Closed Loop Treatment, where the doses are adjusted according to results obtained by laboratory analysis. Simulation results show that the Closed Loop Scheme can achieve improved quality of the treatment in terms of reduction in the viral load and quatity of administered drugs, but with the inconvenience related to the necessity of frequent and periodic laboratory analysis.