Objective: The purpose of this study was to discuss the concept of delaying the use of chlorhexidine mouthrinse (CHX) until some time after the use of dentifrice.

Method and materials: Sources included 13 electronic databases, 7 international drug reference books, and the World Wide Web; references of all relevant papers; and further information requested from authors and organizations. Inclusion criteria were a predefined hierarchy of evidence. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity.

Results: CHX, a cation, interacts and forms salts of low solubility and antibacterial activity with anions, such as sodium lauryl sulfate (SLS) and sodium monofluorophosphate (MFP). CHX and MFP are not compatible in clinically relevant concentrations in vitro. A 30-minute interval between SLS and CHX rinsing gave a significantly reduced antiplaque effect of CHX, whereas after 2 hours the neutralizing effect of SLS disappeared. Rinsing with dentifrice slurry and CHX produced a significantly increased plaque score compared to CHX and water. In regard to tooth staining by CHX mouthrinses, use of dentifrice before CHX showed a reduction in staining of 18%, whereas CHX followed by dentifrice showed a reduction in staining of about 79%. Literature relating to this interaction is limited; more controlled microbiologic and clinical studies are needed to certify the inaccuracy of this modality of administration.

Conclusion: To optimize the antiplaque effect of CHX, it seems best that the interval between toothbrushing and rinsing with CHX be more than 30 minutes, cautiously close to 2 hours after brushing.