Biofilm Formation of Respiratory Pathogens on Vanillin-Incorporated Denture Base Resin

Abstract

The adherence of microorganisms to denture base materials and the consequent formation of biofilms on these surfaces are contributing factors to biofilm-related oral and systemic diseases. Aspiration pneumonia is a potentially life-threatening respiratory infection associated with the entry of foreign materials into the bronchi. Vanillin-incorporated polymethyl methacrylate (PMMA) resin has been developed for the use in dentistry and demonstrated to have antimicrobial activity. Objective: To evaluate antimicrobial property of vanillin-incorporated PMMA denture base resin on biofilm formation of respiratory pathogens. Materials and methods: The heat polymerized PMMA denture base resin samples (Siam Cement Group, Thailand) were prepared according to the percentage of vanillin incorporation (0%, 0.1% and 0.5% vanillin). Another group of commercial resin samples without vanillin (Triplex®, Ivoclar Vivadent, USA) was prepared in the same manner. All samples were coated with sterile unstimulated saliva collected from three healthy adult volunteers at 37 °C for 60 min. The respiratory pathogenic bacteria used in this study were Staphylococcus aureus ATCC 5638, Streptococcus pneumoniae ATCC 49619, and Pseudomonas aeruginosa ATCC 27853. They were prepared to a concentration of approximately 107 colony forming unit (CFU)/mL. The bacterial biofilm formation was done in 96-well plate and incubated at 37°C for 24-48 h. The amount of biofilm was quantified by Cell Counting Kit WST-8 (Dojindo Molecular Technologies, USA) at 420 nm. All tests were performed in triplicate on three separate occasions. One-way ANOVA and Turkey’s test were used for the statistical analysis. Results: The vanillin-incorporated resin groups (0.1% and 0.5% vanillin) had a significant reduction of S. aureus and P. aeruginosa biofilm mass compared with resins without vanillin (0% vanillin and commercial resin groups). No significant difference was observed in the S. pneumonia biofilm formation. Up to 80% and 33% reductions of biofilm mass were demonstrated on P. aeruginosa and S. aureus, respectively. Conclusion: The incorporation of vanillin to denture base PMMA resin could significantly inhibit biofilm formation of respiratory pathogens. Using this PMMA resin, denture base materials with antimicrobial property can be applied to reduce a risk of respiratory infection in denture wearing patients.