Method: Experimental formulations were manufactured with isoactive® technology (isopentane) and placebo variant, each with and without STP to give direct comparators for testing. The compendial method BSEN1276 was adapted in the following way: Streptococcus mutans test suspension at 1x106 CFU was held at 35oC. Product was dispensed and 5x this weight in bacterial test suspension was added and stirring commenced. At 30, 60 and 120seconds, 1ml samples of the suspension were removed, neutralised and decimally diluted with TSB and TSA pour plates used for enumeration. Antimicrobial effects of isopentane were investigated by the indirect R.A.B.I.T. impedance test, with cultures of S.mutans challenged with 2% isopentane in TSB medium.
Results: Isopentane formulations produced statistically significant difference in favour at 30s and 60s compared with control. Differences between formulations (isoactive vs non isoactive) were carried out using an analysis of variance with factors for formulation and STP (present/absent). Mean log reductions 30s 60s 120s Placebo/STP 0.40 0.72 1.52 Isopentane/STP 1.12 1.65 2.25 Placebo 0.38 1.44 1.79 Isopentane 1.43 2.00 2.62
Previous standard BSEN1276 studies demonstrated no differences in antimicrobial properties between isopentane and regular pastes conventional BSEN1276 methodology. Isopentane alone had no effect in R.A.B.I.T. conductivity measurements.
Conclusion: The significantly greater kill by isopentane products versus placebo in modified BSEN1276 test at 30s and 60s was not attributable to the presence of isopentane. This supports the hypothesis that gel-to-foam format products can result in more rapid release of bactericidal ingredients than traditional paste products.