Antimicrobial activity of effervescent denture tablets on multispecies biofilms.

PURPOSE: To investigate the impact of peroxide-based solutions in reducing viability and metabolic activity of multispecies biofilms on denture base acrylic resin surfaces and for removing them from these surfaces. BACKGROUND: Denture cleansers are effective in reducing monospecies biofilm; however, studies evaluating their action on multispecies biofilms are scarce. MATERIALS AND METHODS: Sixty-nine denture base acrylic resin specimens (Ø 15 × 3 mm) were sterilised then contaminated with Candida albicans, Staphylococcus aureus and Pseudomonas aeruginosa to form multispecies biofilms. Biofilms were grown for 24 hours; subsequently, specimens were immersed in three different cleansing solutions (n = 9): nitradine (NI), fixodent (FX) and phosphate-buffered saline (Control), according to the respective manufacturer's instructions. After applying the hygiene protocols, viability of microorganisms was evaluated by counting colony-forming units and assessing metabolic activity. Moreover, biofilm removal capacity was estimated based on extension of cell-covered areas visualised in fluorescent microscopy micrographics. RESULTS: Microbial counts were solution-dependent; NI was effective against all microorganisms (P < .05). FX exhibited moderate antimicrobial action, reducing P aeruginosa (P < .05) and S aureus (P < .05) viability by approximately 2 logs. Both peroxide-based solutions reduced metabolic activity (P < .001) and biofilm-covered areas on specimen surfaces (P < .001). CONCLUSION: Under the experimental conditions tested, these results demonstrated that peroxide-based solutions had favourable antimicrobial activity but promoted no broad elimination of aggregated multispecies biofilm. NI might be more suitable as complementary chemical agent for controlling multispecies denture biofilm.

Comparative analysis of biofilm levels in complete upper and lower dentures after brushing associated with specific denture paste and neutral soap.

OBJECTIVES: The objective of this study was to compare and correlate biofilm levels in complete upper and lower prosthesis after brushing, associated with specific paste and soap, by means of computerised methodology. MATERIALS AND METHODS: Forty-five complete denture wearers were selected and instructed to brush their prostheses (Soft Oral B 40) three times a day for 3 weeks with water (Control), specific paste for complete dentures (Corega Brite) (Experiment 1) and neutral soap (Experiment 2). The study was based on a cross-over model and a wash-out period was not included. For biofilm quantification, the internal surfaces were dyed (neutral red 1%), photographed (Canon EOS Digital) and the disclosed biofilm was measured with the Image Tool 2.0 software. The products were assessed by means of a questionnaire regarding their hygiene properties and acceptance. RESULTS: The variance analysis indicated that the lower prostheses exhibited a mean biofilm percentage, significantly higher than the upper prostheses and that brushing with paste (Experiment 1) was more effective than soap (Experiment 2) and, in turn, this was more effective than water (Control). There was a high biofilm correlation (Pearson correlation) between both prostheses. Both products were well accepted by the patients, but the most favoured one was the paste. CONCLUSIONS: This was effective in controlling the biofilm and can be used preventatively in the maintenance of oral health by wearers of complete dentures. This is important where the lower prosthesis can harbour microorganisms which may act as a reservoir for other areas of the mouth and thus enhance the importance of proper hygiene.