Читать книгу Oral Biofilms - Группа авторов - Страница 78

In our own laboratory, different periodontitis biofilm models have been used to evaluate therapy. In several studies, chlorhexidine digluconate formulations were applied mostly as a comparative. Four species were applied in a continuous flow system for 24 h before chlorhexidine in different formulations was applied for 1 min [19]. In static models, 6 or 12 species or a microcosm was used to form biofilms on polystyrene surfaces [13, 20]. Surprisingly, total counts of the untreated biofilms (CFU) did not differ much, with values between log₁₀ CFU = 7.21 and log₁₀ CFU = 7.68. After flushing the 4-species biofilm with 0.1% chlorhexidine solution, no colony was growing anymore, and application of a 1% gel reduced the CFU counts by 3.47 log₁₀ CFU [19]. When applying 0.1% chlorhexidine digluconate for 1 min and 0.01% chlorhexidine digluconate for 18 h in the 6-species model, the reduction was 4.55 log₁₀ CFU [20] (Fig. 1). Using the microcosm biofilm and forming the biofilm for 10 days with application of 0.1% chlorhexidine gel for 1 min and diluting to 10% for 1 h, the reduction was 0.64 log₁₀ CFU [13]. Using dentine discs as the surface, the number was 5.95 log₁₀ CFU. Applying a chlorhexidine-containing air-polishing powder for 10 s reduced the CFU counts by 4.06 log₁₀ CFU [21]. The results suggest that a biofilm-reducing activity was shown in each of the different models; however, the extent of reduction seemed to be depended not only on the concentration and the antimicrobial formulation, but also on the biofilm model used.

Fig. 1. SEM images of a 5-day-old 6-species biofilm without exposure to antimicrobials (control, a) and exposed to 0.1% chlorhexidine digluconate for 1 min and 0.01% chlorhexidine digluconate for 18 h (b). (Photographs taken by Sandor Nietzsche, Center of Electron Microscopy, University Hospital of Jena, Jena, Germany.)