In vitro antifungal action of different substances over microwaved-cured acrylic resins

OBJECTIVE: The presence of Candida albicans on the surfaces of denture-base acrylic resins is strongly related to the development of oral stomatitis. This study evaluated the antifungal action of different agents over microwave-cured acrylic resin without polishing specimens previously contaminated with Candida albicans. MATERIAL AND METHODS: Sixty specimens were immersed in BHI broth previously inoculated with the yeast and stored for 3 h at 37ºC. They were divided into 5 experimental groups (n=10): G1: 2 percent chlorhexidine solution (10 min); G2: 0.5 percent sodium hypochlorite (10 min); G3: modified sodium hypochlorite (10 min); G4: effervescent agent (5 min); G5: hydrogen peroxide 10v (30 min). The specimens of the control group 1 (C1) were not disinfected. Ten additional specimens of the control group 2 (C2) were not infected with the yeast, aiming to check the asepsis during the experiment. The disinfection agents were neutralized and the acrylic resin specimens were immersed in BHI Broth for 24 h. Culture media turbidity was evaluated spectrophotometrically according to the transmittance degree, i.e. the higher the transmittance the stronger the antimicrobial action. Statistical analysis was performed (Kruskal-Wallis Test, p<0.05). RESULTS: The results, represented by the medians, were: G1 = 40; G2 = 100; G3 = 100; G4 = 90; G5 = 100; C1 = 40; C2 = 100. CONCLUSIONS: This in vitro study suggested that sodium hypochlorite-based substances and hydrogen peroxide are more efficient disinfectants against C. albicans than 2 percent chlorhexidine solution and the effervescent agent.

Influência da imersão em água na porosidade de resina acrílica polimerizada por energia de microondas / Influence of water immersion on porosity of acrylic resin polymerized by microwave energy

Objetivo: Foi propósito deste trabalho avaliar se a imersão em água poderia alterar o grau de porosidade interna da resina acrílica processada em microondas. Metodologia: Foram confeccionados 50 corpos-de-prova (20x20x5mm) utilizando-se as resinas acrílicas incolores Vipi Cril® e Vipi Wave®. A polimerização do Grupo 1 (G1) foi obtida pela técnica convencional em banho de água quente (12h a 74ºC) e os grupos experimentais (G2, G3, G4 e G5) foram polimerizados por energia de microondas (ciclo de 20min a 180W, mais 5min a 540W). Os corpos-de-prova dos grupos G2 e G4 foram polimerizados imersos em água, enquanto que a polimerização dos grupos G3 e G5 ocorreu sem imersão. Todos os corpos-de-prova de resina acrílica incolor foram submetidos à avaliação visual a olho nu por um único observador calibrado, que atribuiu valores de 0 a 3 em uma escala crescente de porosidade. Resultados: Todos os corpos-de-prova receberam escore 0. A resina convencional (líquido Vipi Cril®) processada por energia de microondas não resultou em porosidade visível a olho nu. Conclusão: Os resultados permitiram concluir que não houve alteração na porosidade da resina polimerizada por energia de microondas, com ou sem imersão da mufla em água.

Purpose: The purpose of this investigation was to evaluate if immersion in water during polymerization would affect the porosity of acrylic resins polymerized by microwave energy. Methods: Fifty specimens (20x20x5mm) were fabricated with two types of colorless acrylic resin (Vipi Cril® and Vipi Wave®). Group 1 (G1) specimens were polymerized by conventional hot water bath (12h at 74ºC), and the experimental groups (G2, G3, G4 and G5) were polymerized by microwave energy (cycle of 20min at 180W, plus 5min at 540W). Groups G2 and G4 were immersed in water during the polymerization cycle in a microwave oven, and G3 and G5 were polymerized without water immersion. Specimens were subjected to visual evaluation without magnification by one calibrated observer, using a score system of porosity with values ranging from 0 to 3 in ascending order. Results: All specimens scored zero. The conventional resin (Vipi Cril liquid®) could be processed by microwave energy resulting no visible porosity. Conclusion: The results showed that immersion in water during microwave polymerization did not influence acrylic resin porosity.