Chlorhexidine substantivity on salivary flora and plaque-like biofilm: an in situ model

Abstract

Objective:To evaluate thein situantibacterial activity of a mouthrinse with 0.2% Chlorhexidine (M-0.2% CHX) onundisturbedde novoplaque-like biofilm (PL-biofilm) and on salivary flora up to 7 hours after its application.Methods:A special acrylic appliance was designed, with 3 inserted glass disks on each buccal side, allowing for PL-biofilmgrowth. Fifteen healthy volunteers wore the appliance for 48 hours and then performed an M-0.2% CHX; disks wereremoved at 30 seconds and 1, 3, 5 and 7 hours after the mouth-rinsing. Applying a washout period, saliva samples werecollected from each volunteer at 30 seconds and 1, 3, 5 and 7 hours after performing an M-0.2% CHX. The PL-biofilm andsaliva samples were analysed by confocal laser scanning and epifluorescence microscopes, respectively.Results:At 30 seconds after M-0.2% CHX, the levels of viable bacteria detected in saliva were significantly lower than thoseobserved in PL-biofilm. The difference in the percentage of live bacteria detected in saliva was significantly higher than thatobserved in PL-biofilm at 5 and 7 hours after M-0.2% CHX.Conclusion:After a single mouthrinse of the 0.2% CHX formulation tested in the present study, the 2-day PL-biofilmpresented a significantly higher resistance to this antisepticin situthan that observed in salivary flora. However, this 0.2%CHX formulation showed a higher substantivity on PL-biofilm than on salivary flora at 5 and 7 hours after mouth-rinsing,which could be related to the slower growth rate of PL-biofilm and the possible reservoir function for antimicrobial agentsassociated with the undisturbedde novoPL-biofilm.