The various solutions tested did not have any deleterious effects on the Co-Cr alloy surface. Steradent, however, presented the smallest ionic release.

Purpose To compare the effect of solutions of effervescent tablets (ET), cetylpyridinium chloride (CPC), and experimental solutions of Ricinus communis on the surface of cobalt‐chromium (Co‐Cr) alloys. Materials and Methods Fifty‐five specimens of Co‐Cr were prepared by the lost‐wax casting method using circular patterns (∅12 × 3 mm). The specimens were randomly divided into 5 groups: deionized water (control); 2% R. communis; 10% R. communis; ET, and CPC. The surface roughness of specimens (n = 10) was evaluated before immersion (baseline), and at simulated times of ½, 1, 2, 3, 4, and 5 years, by laser confocal microscope (Sa, μm) and profilometer (Ra, μm). The surface topography and chemical composition (n = 1) was qualitatively analyzed with scanning electron microscopy (SEM), and energy dispersive X‐ray spectrometry (EDS). Data were subjected to Kruskal–Wallis followed by Dunn tests, and Friedman followed by Wilcoxon tests (α = 0.05). Results For Sa, there was no difference for the solution factor. For the time factor a significant difference was found with 2% R. communis solution among baseline and ½, 2, 3, and 5 years (p < 0.001) and with 10% R. communis solution between 1 and 2 years (p = 0.007), with decreasing roughness over time. For Ra, cetylpyridinium chloride exhibited less roughness than 10% R. communis solution in ½ (p = 0.048) and 5 years (p = 0.013). In the SEM and EDS analysis the solutions did not present deleterious effects or changes in the chemical composition on the surfaces. Conclusions Although a significant difference was found for the roughness, the results, below 0.2 μm, are clinically acceptable. Thus, all solutions can be used safely in removable partial denture cleaning for a period of 5 years.

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ObjectiveTo evaluate the anti‐biofilm action of chitosan, nanoparticulate chitosan, and denture cleanser Nitradine™ against biofilms comprising Candida albicans, Candida glabrata, Staphylococcus aureus, and Streptococcus mutans.BackgroundBiofilm removal from removable partial dentures (RPD) is important for success in prosthetic rehabilitation.Materials and MethodsThe anti‐biofilm action of the experimental chitosan‐based solutions and Nitradine™ was evaluated on acrylic resin and cobalt‐chromium alloy through assessing cell viability, cell metabolism, residual aggregated biofilm, and extracellular polymeric substance and biofilm morphology.ResultsOnly chitosan reduced the viability of C. albicans on cobalt‐chromium alloy surface, by 98% (a 1.7 log10 reduction in cfu). Chitosan‐based solutions neither promoted substantial alteration of the metabolic activity of the four‐species biofilm nor reduced the amount of the aggregated biofilm. After immersion in chitosan and nanoparticulate chitosan, viable microorganisms and extracellular polymeric substances distributed over the entire specimens' surfaces were observed. Nitradine™ reduced the viability and metabolic activity of biofilm grown on both surfaces, but it did not remove all aggregated biofilm and extracellular polymeric substances. After immersion in Nitradine™, approximately 35% of the specimens' surfaces remained covered by aggregated biofilm, mainly composed of dead cells.ConclusionAlthough chitosan and Nitradine™ promoted changes in the viability of microorganisms, neither solution completely removed the four‐species biofilm from the Co–Cr and acrylic resin surfaces. Thus, isolated use of hygiene solutions is not indicated for biofilm control on RPDs; this requires complementary mechanical removal.

Paulo (FORP-USP) e ao Programa de Pós-Graduação em Odontologia (Área de concentração: Reabilitação Oral) pela oportunidade de cursar a pós-graduação e pelos conhecimentos adquiridos.