[Show abstract][Hide abstract] ABSTRACT: A microtitre assay has been developed using hydroxyapatite-coated wells and Streptococcus sanguis NCTC 10904 at 10(7) cells per ml. A number of models representing toothpaste and mouthwash usage were adopted to detect the anti-adherent efficacy of a polyvinylmethylether maleic acid copolymer (PVM/MA), polyoxypropylene/polyoxyethylene block copolymer (PO/EO), two casein-derived peptides and selected silicones. The results not only confirmed the anti-adherence property of the selected components but also indicated possible molecular interactions leading to the observed performance. To account for the diversity of oral microbial cells in vivo, a further testing system was developed. This involved submerging a hydroxyapatite disc in a mixed culture of human salivary microbial cells, and exposing it to different treatments using the active component either in an aqueous dispersion or in a toothpaste. The effect of toothpastes containing PO/EO, dimethicone copoyol or PVM/MA was investigated over a 4-h incubation with microflora. These tests showed that in a toothpaste formulation the anti-adherent efficacy may be reduced when compared with an aqueous dispersion containing the same or nearly the same concentration of the active component.