Eficácia da ação antimicrobiana de soluções químicas - hipoclorito alcalino e mamona (Ricinus communis) - frente a micro-organismos específicos

Abstract

SALLES, M.M. Efficacy of antimicrobial action of chemical solutions – alkaline hypochlorite and castor oil (Ricinus communis) – against specific microorganisms. Ribeirao Preto, 2013. 175p. Dissertation (Master’s Degree in Oral Rehabilitation). Ribeirao Preto School of Dentistry, University of Sao Paulo, Brazil. ABSTRACT The objective of this study was to evaluate, through laboratory and clinical study, the efficacy of alkaline hypochlorite solutions (0.25% and 0.5%) and 10% castor oil solution (Ricinus communis) about the antimicrobial action against specific microorganisms, by counting the number of Colony Forming Units (CFU). In the laboratory study, 360 denture base acrylic resin specimens (Lucitone 550) were obtained from square metal matrix (10 mm x 2 mm), which were sterilized with microwave (650W, for 6 minutes), contaminated with Staphylococcus aureus,The objective of this study was to evaluate, through laboratory and clinical study, the efficacy of alkaline hypochlorite solutions (0.25% and 0.5%) and 10% castor oil solution (Ricinus communis) about the antimicrobial action against specific microorganisms, by counting the number of Colony Forming Units (CFU). In the laboratory study, 360 denture base acrylic resin specimens (Lucitone 550) were obtained from square metal matrix (10 mm x 2 mm), which were sterilized with microwave (650W, for 6 minutes), contaminated with Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Bacillus subtilis, Escherichia coli, Streptococcus mutans, Enterococcus faecalis and Candida glabrata and immersed (20 minutes) in the hygiene solutions (n = 10): Group A 0.25% Sodium Hypochlorite; Group B 0.5% Sodium hypochlorite; Group C – 10% Castor oil solution; Group D (Positive Control) saline and Group E (Negative Control) no contamination and immersed in saline (n = 5). The specimens were washed in saline solution and immersed in liquid culture medium (Letheen), from which were obtained serial dilutions (10 to 10) and seeded into specific solid media. After incubation at 37o C for 24 hours, the colonies were counted and the values of CFU/mL calculated. In the clinical study, 64 complete denture wearers were instructed to brush their dentures (Bitufo ® brush and liquid neutral soap) three times a day and to soak them (20 minutes), once a day, in the solutions: Solution 1 – 0.25% Sodium Hypochlorite; Solution 2 0.5% Sodium hypochlorite; Solution 3 – 10% Castor oil and Solution 4 saline (control). According to a randomized sequence, each solution was used for 7 days, with a period of wash out between them. The evaluation of the antimicrobial action was performed before the use of the products (Baseline) and after 7 days using each solution, by counting the Colony Forming Units (CFU) of Streptococcus mutans, Candida spp. and gram negative. For collection the biofilm, each upper complete denture was placed in a Petri dish, the internal surface was brushed with saline solution for 2 minutes and the suspension was transferred to a test tube. After decimal dilutions (10 to 10), aliquots of 50 uL were seeded inside Petri dishes containing Mitis Salivarius Agar Base, Candida Chromagar ® and Mac Conkey Agar for the detection of Streptococcus mutans, Candida spp. or gram negative, respectively. After incubation at 37° C (in microaerophilic conditions for 48-72 hours for mutans and aerobiosis for 48 hours for Candida spp. and gram negative), in accordance with characteristic morphology, the number of characteristic colonies was counted and the number of CFU/mL calculated. Data were processed following transformation into the formula log10 (CFU +1) and statistically analyzed using the Student t test (α = 0.05) for laboratory analysis, and Friedman test (α = 0.05), for clinical analysis. The results showed that, in the laboratory study, sodium hypochlorite (0.25% and 0.5%) eliminated completely all microorganisms. The Castor oil solution eliminated B. subtilis, had no effect on E. faecalis and showed moderate antimicrobial activity against other strains, with a significant reduction (p < 0.05) in the number of CFU compared with group D (positive control). In the clinical study, there was significant difference between the solutions (P < 0.001), and 0.5% sodium hypochlorite had effective action on all evaluated microorganisms (Candida spp., S. mutans and gram negative); 0.25% sodium hypochlorite had effective action on S. mutans and moderate on Candida spp. and gram negative, and the castor oil solution had effective action on S. mutans and moderate against Candida spp. The Candida species most often isolated was C. albicans, followed by the species C. tropicalis and C. glabrata. It was concluded that the solution of 0.5% sodium hypochlorite was the most effective presenting antimicrobial action on both biofilms (in vitro and in vivo), followed by 0.25% sodium hypochlorite solution that showed antimicrobial activity on biofilms in vitro and on S. mutans (biofilm in vivo). The 10% castor oil was less effective, with antimicrobial action on Bacillus subtilis (biofilm in vitro) and S. mutans (biofilm in vivo).