Ação microbicida do ozônio sobre tecidos hospitalares / Antimicrobial action of ozone on hospital fabrics

Lavanderias hospitalares lavam e desinfetam tecidos contaminados consumindo grandes quantidades de água, energia e produtos químicos. Sua água de efluxo contém medicamentos, produtos químicos e grande carga microbiológica. No presente trabalho foi realizada análise microbiológica em Columbia Ágar acrescido de sangue de amostras de tecido hospitalar e de um tecido novo submetido à lavagem sob a ação antimicrobiana do ozônio (12 g/h). Os resultados mostraram grande quantidade de micro-organismos na água antes da aplicação do ozônio. Após a aplicação do ozônio houve redução gradativa da carga microbiana nos tecidos, entretanto não houve completa eliminação de fungos e leveduras após o processo de lavagem completo. Os resultados evidenciam a viabilidade do uso do ozônio como agente desinfectante nos tecidos processados em lavanderias.

AFM characterization of bovine enamel and dentine after acid-etching.

Teeth are constituted mainly of hydroxyapatite molecules (Ca(10)(PO(4))(6)(OH)(2)), grouped in different microstructural arrangements, depending on the dental layer considered (enamel or dentine). In the present work, these dental microstructural arrangements were characterized by atomic force microscopy. Enamel and dentine samples were cut from freshly extracted bovine incisor teeth. After metallographic polishing, the dental surfaces were etched with lactic acid (113.8 mmol/L, pH 3.3). Three etching times were tested: 1, 3 and 5 min. Atomic force micrographs showed that 1 min of etching time was effective to remove the smear layer, polishing debris and scratches, and display the characteristics of interest for both enamel and dentine. Although the bovine dental enamel rod cross-section presented keyhole-like shape, its measured dimensions (8.8 microm of major axis and 3.7 microm of minor axis) exhibited an insignificant discrepancy from human prisms diameters. Bovine dentinal tubules displayed larger mean diameters (4.0 microm) and a lower density (approximately 17,100 tubules/mm(2)) than human dentine, suggesting that the use of bovine dentine as a substitute for human dentine in resin adhesion investigations should be reconsidered. Apatite nanoparticles presented a mean radius (22-23 nm) considerably smaller than that of human teeth.

High-speed cavity preparation techniques with different water flows.

STATEMENT OF PROBLEM: Cavity and tooth preparations generate heat because the use of rotary cutting instruments on dental tissues creates friction. Dental pulps cannot survive temperature increases greater than 5.5 degrees C. PURPOSE: This study evaluated the efficiency of 3 different water flows for 2 different tooth preparation techniques to determine which are safe for use. MATERIAL AND METHODS: Thermocouples were placed in the pulpal chambers of 30 bovine teeth, and 1 of 2 tooth preparation techniques was used: a low-load intermittent tooth preparation technique or a high-load tooth preparation technique without intervals. Water flows of 0, 30, and 45 mL/min were associated with each technique, for a total of 6 different groups. The results were analyzed with a 2-factor analysis of variance (P<.05). RESULTS: Temperature increases with the high-load technique were 16.40 degrees C without cooling (group I), 11.68 degrees C with 30 mL/min air-water spray cooling (group III), and 9.96 degrees C with 45 mL/min cooling (group V). With the low-load tooth preparation technique, a 9.54 degrees C increase resulted with no cooling (group II), a 1.56 degrees C increase with 30 mL/min air-water spray cooling (group IV), and a 0.04 degrees C decrease with 45 mL/min cooling (group VI). The low-load technique was associated with more ideal temperature changes. CONCLUSION: The results of this study confirm the necessity of using a low-load technique and water coolants during cavity and tooth preparation procedures.

Esterilizaçäo de limas endodônticas com plasma de oxigênio / Sterilization of endodontic files with oxygen plasma

No presente trabalho, analisou-se a eficácia de uma nova técnica de esterilizaçäo de instrumental odontológico. Limas endodônticas contaminadas com Escherichia coli, Pseudomonas aeruginosa e Staphylococcus aureus foram esterilizadas em plasma de oxigênio formado através de uma descarga elétrica contínua de 75 mA. Os resultados demonstraram efetiva eliminaçäo dos microrganismos testados, utilizando-se um processo a baixas temperaturas e em tempos menores que os preconizados para processos convencionais (forno de Pasteur e autoclave). Microrganismos gram-negativos foram destruídos em 1 minuto de exposiçäo e gram-positivos em 10 minutos