In vitro antiseptic properties of an ammonium compound combined with denture base acrylic resin.

BACKGROUND Denture base acrylic resin is easily colonised by oral endogenous bacteria and Candida spp., and eventually by extra-oral species such as Staphylococcus spp., Pseudomonadaceae or members of Enterobacteriaceae. This microbial reservoir can be responsive for denture related stomatitis and aspiration pneumonia, a life-threatening infection especially in geriatric patients. However, the oral and denture hygiene of dependent elderly individuals is extremely poor. OBJECTIVE This in vitro study aimed to determine the per cent of a quaternary ammonium compound heat-polymerised in acrylic resin necessary to obtain denture base displaying antiseptic properties. DESIGN Acrylic resin discs containing 2-50% ammonium polymer (Poly 202063A; 0% control) were soaked in artificial saliva for 4 weeks. Resin discs were incubated for 24 hours with Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa [37 degrees C, brain-heart infusion (BHI) broth and phosphate-buffered saline (PBS) buffer] and Candida albicans (30 degrees C, Schaedler broth), in 15 ml (168 discs) and 600 microl (168 discs) of inoculum. Microbial growth was verified at t 0 hours and t 24 hours. Data were recorded as the mean of three colony forming unit (CFU) numerations. The borderline of antimicrobial effect was determined at 0.1% viable cells. RESULTS In 600 microl of PBS inoculum, resin specimens had a bactericidal effect (E. coli and S. aureus: 2%; P. aeruginosa: 10%) and a fungicidal effect (C. albicans: 50%). Long-term stability and toxicity in vivo studies are now required. CONCLUSION A 2% quaternary ammonium compound polymerised with a denture acrylic resin displayed antiseptic properties after a 4-week soaking period in artificial saliva. Such antiseptic denture base could help geriatric patients to improve their oral health.