Effect of Denture Cleansers on the Cobalt-Chromium Alloy Surface: A Simulated Period of 5 Years' Use.

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 ( null 12 x 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 1/2, 1, 2, 3, 4, and 5 years, by laser confocal microscope (Sa, mu m) and profilometer (Ra, mu m). 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 (alpha = 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 1/2, 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 1/2 (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 mu m, are clinically acceptable. Thus, all solutions can be used safely in removable partial denture cleaning for a period of 5 years.