Chitosan: antimicrobial action upon staphylococci after impregnation onto cotton fabric.

BACKGROUND: High levels of viable Staphylococcus aureus, which are often found on inflamed skin surfaces, are usually associated with atopic dermatitis. Textiles, owing to their high specific surface area and intrinsic hydrophilicity, retain moisture while also providing excellent environmental conditions for microbial growth and proliferation. Recently, a number of chemicals have been added to textiles, so as to confer antimicrobial activity. AIMS: To evaluate the antimicrobial action of chitosan upon selected skin staphylococci. METHODS AND RESULTS: We isolated staphylococci from normal skin of 24 volunteers and studied their survival upon contact with chitosan-impregnated cotton fabric. Low and high molecular weight chitosans were used at two concentrations; all four did effectively reduce the growth of some staphylococci (namely Staph. aureus), by up to 5 log cycles, thus unfolding a potential towards control and even prevention of related skin disorders. CONCLUSION: Our data suggest an effective, but selective antibacterial action of chitosans towards skin bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The possibility to use a natural biopolymer incorporated in a textile to alleviate and even treat some of the symptoms associated with this skin condition may raise an alternative to existing medical treatments. The selectivity observed prevents full elimination of bacteria from the skin surface, which is an advantage.

Análise comparativa da formaçäo do "zip" apical em canais curvos e atresiados produzidos "in vitro" por duas técnicas de instrumentaçäo / Comparative analysis of the formation of the apical zip in thin and curved canals by means of two instrumentation techniques

O objetivo do presente estudo foi avaliar a formaçäo do "zip" apical em canais curvos e atresiados produzido por duas técnicas de instrumentaçäo. Para tanto, 50 canais simulados em resina "epoxi" foram confeccionados a uma curvatura de 40º e divididos em dois grupos de 25 canais cada um. O primeiro grupo foi preparado pela Técnica Convencional e o segundo pela Técnica Escalonada. Depois de feitos os reparos, os canais foram avaliados por dois observadores. Diante dos resultados obtidos, chegou-se às seguintes conclusöes: a) a Técnica Convencional produziu zip apical em maior número do que a Técnica Escalonada; b) a Técnica Escalonada proporcionou maior segurança no preparo, tendo obtido, na maioria dos casos, uma forma cônica afunilada contínua, com o desgaste sendo menor no ápice e maior no orifício de entrada do canal