Effect of chlorhexidine rinses on the morphology of early dental plaque formed on plastic film

Abstract

The effect of chlorhexidine on early plaque formation was studied in vivo in order to assess potential structural and quantitative changes. 3 subjects with healthy gingiva were used. Plastic films were applied to the buccal surfaces of the maxillary right first premolars and plaque was allowed to form for either 4 or 24 h. A single 1-min rinse with 0.2% chlorhexidine digluconate was used for the 4-h experiments, 1 min after film placement, whereas, for the 24-h experiments, an additional 1 min rinse was used at 12 h. In total, 62 films were obtained, half treated and half controls. These were processed for light and transmission electron microscopy, using standardized techniques for area sampling and cell counting. All plastic films were covered by a surface coating of acellular material in or on which bacteria, epithelial cells and leukocytes were observed. In the controls, an important increase in bacterial count was seen between 4 and 24 h, whereas the increase with chlorhexidine was slight. There were fewer bacteria in the chlorhexidine as compared to the water specimens, for both time periods. Many microorganisms in the chlorhexidine samples appeared to be undergoing degeneration with coagulated cytoplasm and disrupted cell walls.

Real-Time Microsensor Measurement of Local Metabolic Activities in Ex Vivo Dental Biofilms Exposed to Sucrose and Treated with Chlorhexidine

“…Since the primary effect of CHX on the bacterial structure is based on damaging the cell membrane (3,49), the effect of CHX can be visualized by vital staining based on membrane integrity of cells. General mechanisms and limitations concerning the application of SYTO 9 and PI for the detection of bacterial cell viability are reported by Stocks (41).…”

“…After removal from the stent, the enamel coupons with biofilm were immediately placed in a small flow cell (6.75 cm 3 ) for subsequent microelectrode measurements. The flow cell was fed from a total volume of 250 cm 3 of 1:10 saliva by use of two peristaltic pumps connected to both the inlet and outlet of the flow cell at a flow rate of 3 ml/min.…”

“…The biofilm was mechanically detached from the enamel surface by scraping and transferred into sterile saline, followed by sonification on ice to disrupt larger clumps and chains, and then homogenized by vortexing. The total bacterial counts (BC) were measured by using a bacterial counting chamber (System Helber, Saaringia, Germany; counting volume, 0.8 ϫ 10 Ϫ3 mm 3 ) under a dark-field microscope (magnification, 500ϫ). For this purpose the number of single cells and particles (small remaining chains were counted as one count) were enumerated.…”

“…During application it immediately shows bactericidal effect and continuous bacteriostatic effect due to its high substantivity in the oral cavity (20). Electron microscopic examinations showed that CHX binds to and damages bacterial cell membranes and leads to structural changes and leakage of cytoplasm (3). Furthermore, contraction of in vitro grown biofilms after CHX exposure was shown in addition to cell damage (19,44), which could cause changes in the diffusion behavior by changes to extracellular polymeric slime density.…”

Interaction of Chlorhexidine with Cytoplasmic Membranes of Streptococcus mutans GS-5

“…Previous studies indicated that CHX at concentrations of 0.05 and 0.2% caused changes in the ultrastructure o f some bacterial species including S. mutans [Hugo and Longworth, 1965;Brecx and Theilade, 1984;Meurman, 1986]. CHX at both concentrations has also been used in dental caries prevention [Loe et al, 1972;Spets-Happoncn ct al., 1991], Thus, in the present study 0.05 and 0.2% CHX were used to determine the effects of this drug on membrane proteins.…”