Experiments with two-phase plaque-inhibiting mouthrinses

Reports indicate that oil/water mouthrinses with an aqueous phase containing an antibacterial agent, reduce the amount of volatile bacterial products in expiration air compared with aqueous mouthrinses. These systems have not, however, been tested concerning antiplaque activity. The aim of the present study was to examine the plaque-inhibiting effect of a mouthrinse with an aqueous phase containing 0.2% chlorhexidine (CHX) and an oily phase (soya oil) containing 0.3% triclosan. A test panel rinsed with the mouthrinses twice daily for 4 d. The mouthrinse containing CHX and triclosan in two phases was significantly better than the negative control (water). However, it was not as effective as the rinse consisting of an aqueous phase with chlorhexidine combined with an oily phase without triclosan. A two-phase mouthrinse with soya oil containing 0.3% triclosan was not superior to soya oil alone, and the combination of CHX and triclosan in a two-phase rinse was not as effective as 0.1% CHX alone in water. No beneficial effect on plaque inhibition could thus be found by using a two-phase system with two different antibacterial agents (one water soluble and one lipid soluble). Soya oil without triclosan rendered higher plaque inhibition than the control, presumably due to formation of a hydrophobic layer on the tooth surfaces.