Chlorhexidine has proven to be the most effective of the therapeutic plaque control agents because it is able to ionically adhere to the teeth and oral mucosal surface in high concentrations for many hours. This ability to be retained results in prolonged high levels of anti-bacterial action. Most of the other agents, such as sodium benzoate or cetyl pyridinium chloride, will produce an immediate 30% reduction in susceptible oral bacterial numbers but they regain normal concentrations within a few hours of application. This means that mouthrinses containing chlorhexidine need to be used less frequently than those containing most other antibacterial agents for effective plaque control. Note however, that they should not be used until half an hour after cleaning the teeth with traditional dentifrices as the sodium laurel sulphate saponification component in dentifrice can reduce chlorhexidine activity.
Chlorhexidine is available as a gluconate at 0.2% concentration in mouthrinses and 2.0% concentration in a gel form. The mouthrinses are also available with and without 10% ethyl alcohol as a preservative and taste enhancer, and as indicated above, only those without alcohol should be prescribed for patients experiencing hyposalivation. Twice a day rinsing at this concentration (after breakfast and on retiring) will significantly reduce plaque bacterial counts and maintain them at a low level. The more concentrated gel form requires only once a day application (on retiring) for the same antibacterial effect. It will also assist in maintaining moisture at the mucosal surface for patients with mild hyposalivation.
Alternate application of topical fluoride gels and chlorhexidine gels, fluoride in the morning and chlorhexidene at night, is recommended for patients with high caries risk. The only negative aspect of routine use of chlorhexidine is the tendency to stain any remaining plaque. This is not a permanent stain, except perhaps around leaking or defective margins, and is readily removed with professional tooth cleaning.