Bacterial desorption by commercial mouthwashes vs two-phase oil:Water formulations

During the past eight years, various investigators have shown that oral microorganisms tend to have hydrophobic surface properties. Most oral microorganisms isolated directly from the oral cavity, as well as many oral laboratory strains, adhere to oil droplets. The authors have recently shown that certain concentrations of the cationic antibacterial agents, i.e. cetylpyridinium chloride (CPC) and chlorhexidine (CHX) promote binding of oral and other microorganisms to oil droplets. This has resulted in development of novel aqueous:oil two-phase mouthwashes containing CPC and/or CHX. In the present manuscript, two such formulations were compared with other commercial mouthwashes for their ability to desorb microorganisms from a solid surface (polystyrene). Of the various mouthrinses tested, only the oil:water formulations efficiently removed the adherent bacterial layer. The data suggest that oil:water mouthwashes may have desorption properties superior to those of many commercial mouthwashes.