Methods: Fifteen volunteers, who have been wearing upper and lower dentures for 2 years were instructed to clean their dentures daily by immersing in a 0.5% NaOCl solution for 3 minutes. The experimental time was 30 days and data were collected before and after this period. For microbiological analysis, dentures were rubbed with sterile cotton swab and it was sonicated in PBS. After, 20µL of this solution was plated on SDA and blood agar and incubated for 48h at 37°C, and the number of colony-forming units (cfu/mL) was counted. Color stability of upper base acrylic resin, was assessed with a portable colorimeter. The color changes (ΔE) values of each denture were calculated using the CIEL*a*b* colorimetric system, expressed in NBS units. Surface roughness was assessed on 2 rectangular specimens (4x4x2 mm) made of heat-polymerized acrylic resin, which were glued to the buccal surface of each lower denture. The surface roughness was measured, using a profilometer, at baseline and after the cleansing treatment. Data were submitted to Student’ t-test (α=0.05).
Results: Before the treatment with NaOCl, 10 volunteers presented Candida spp. in their dentures, but after 30 days only 3. A significant reduction of the total number of microorganisms was also noticed after the soaking period (p<0.001). The ΔE values demonstrated “trace” or “slight” changes for 13 dentures. “Noticeable” color change was noted for 2 dentures. Surface roughness showed significant difference after immersion period (p<0.001).
Conclusion: Sodium hypochlorite was effective in reducing microorganisms; however this substance increased the surface roughness of dentures. Color changes exhibited for all dentures can be considered clinically acceptable.
Keywords: Color, Denture, Disinfection/sterilization and Surfaces