Microbial Adhesion to a Nanoceramic Coated PMMA After the Use of Antimicrobial Denture Cleaner

Objectives: The aim of this study is to assess surface roughness and microbial colonization of nanoceramic coated PMMA after long-term exposure to denture cleaner. Methods: Seventy-two PMMA samples (5mm x 5mm x1mm) were fabricated and serially polished to P4000 grit. Forty-eight samples were subjected to Atomic Layer Deposition (ALD), and received either a nano-thin coating of TiO2 (N=24) or a mixed TiO2/ZrO2 coating (N=24). Surface roughness was tested for the different coatings. Samples were then soaked in Polident denture cleaner 180 times for 30 minutes and washed three times with deionized water between each soaking period. Control samples were exposed only to deionized water. All samples were sterilized and roughness testing was completed a second time. The samples were then coated with artificial saliva for 30 minutes, and exposed to C. albicans or S. mutans respectively for 6 hours. Adherent cells were rinsed off with PBS and sonication. Serial dilutions were prepared and C. albicans was plated on SDB agar and S. mutans was placed on BHI agar and both were incubated. The CFU’s were counted and converted to the logarithmic scale. Results: Results showed significantly less C. albicans and S. mutans attachment to both TiO2 coated PMMA and TiO2/ZrO2 coated PMMA than to the uncoated PMMA when samples were soaked in water. After soaking in Polident cleaner, the uncoated PMMA had significantly less viable C. albicans cells than coated samples, and TiO2/ZrO2 coated PMMA had significantly less C. albicans attachment than TiO2 coated samples. There was no significant difference in attachment of S. mutans between the uncoated PMMA or the TiO2 coated or the TiO2/ZrO2 coated PMMA after soaking in Polident cleaner. Conclusions: This study revealed that either TiO2 or TiO2/ZrO2 coating help limit PMMA surface roughening after long-term soaking of in chemical denture cleaner. Results suggest that PMMA coated with either TiO2 or TiO2/ZrO2 may be helpful in reducing the adhesion of S. mutans and C. albicans when there is no use of chemical denture cleaner. It was also suggested that TiO2/ZrO2 coating may be more efficacious at inhibiting microbial attachment. Further studies are needed that assess biofilm on nanoceramic coated PMMA after use with chemical denture cleaner.