Disinfection Strategies for Poly(methyl methacrylate): Method Sequence, Solution Concentration, and Intraoral Temperature on Antimicrobial Activity

This study aimed to evaluate the antimicrobial effectiveness of different disinfection protocols for dentures by combining methods, varying intervention sequences, sodium hypochlorite (NaOCl) concentrations (0.1% and 0.25%), and post-exposure to intraoral temperature. The heat-polymerized poly(methylmethacrylate) (PMMA) was divided into groups (n = 15): control (C, distilled water immersion), B (brushing), I0.1% and I0.25% (isolated NaOCl immersion), B + I0.1% and B + I0.25% (brushing followed by immersion), I + B0.1% and I + B0.25% (immersion followed by brushing), and B + I0.1% + T and B + I0.25% + T (brushing, NaOCl immersion, and overnight exposure to 35 °C ± 2 °C). The post-disinfection exposure to intraoral temperature simulated the denture use during sleeping time. Quantitative evaluation was performed by colony-forming unit (CFU/mL) counting of <i>C. albicans</i> and qualitative analysis by scanning electron microscopy (SEM) images. Data were processed by one-way ANOVA with Tukey's post-hoc test to compare different protocols at the same concentration and among groups (α ≤ 0.05). Applying 0.25% NaOCl in associated protocols, the intervention sequence was no different (B + I and I + B) and caused the lowest <i>C. albicans</i> counts. The 0.1% NaOCl lost part of its action when the immersion method started the protocols. B + I0.25%, I0.25% + B, and B + I0.1% had similar antimicrobial efficacy, but the intraoral temperature (B + I + T) reduced the efficacy of these protocols, regardless of NaOCl concentration. Residual biofilm recolonization was also detected in SEM images. In conclusion, all the combinations between mechanical and chemical methods using 0.25% NaOCl were the most effective against <i>C. albicans</i>. The antimicrobial efficacy of NaOCl at 0.1% changes depending on the intervention sequence. The intraoral temperature influenced the <i>C. albicans</i> recolonization after the disinfection protocols.