A comparison of the detachment of an adhering oral streptococcal strain stimulated by mouthrinses and a pre-brushing rinse

The effects of two mouthrinses, Hibident(R) and Scope(R), and a pre-brushing rinse, Plax(R), on the detachment of an oral bacterium adhering to enamel, with and without a salivary conditioning film, were compared. Furthermore, the influence of the hydrophobicity of the substratum on the detachment of adhering microorganisms as stimulated by the oral rinses was studied. All experiments were carried out in a parallel plate flow chamber with Streptococcus sobrinus HG 1025 adhering to enamel, hydrophilic glass and dichlorodimethylsilane-coated, hydrophobic glass. Perfusion of the flow chamber with the two mouthrinses did not stimulate any significant detachment of adhering S. sobrinus HG 1025, whereas perfusion with the pre-brushing rinse stimulated up to 100% detachment. Moreover, the pre-brushing rinse Plax(R) was more effective in stimulating bacterial detachment from salivary conditioning films than from bare substrata. Plax(R), and possibly to a lesser extent also Scope(R), weakened the bond between adhering S. sobrinus HG 1025 and the substrata, thereby facilitating removal of adhering cells during high shear, as exerted here by the passage of a liquid-air interface through the chamber and as occurring in vivo by eating, speaking, drinking or swallowing. It is hypothesized that the controversies over the clinical efficacies of Plax(R) may be due to the inability of its, otherwise effective, detergent system to penetrate the plaque and stimulate detachment of the linking film, i.e. the initially adhering bacteria.