Method: Pooled supragingival plaque samples (from nine healthy volunteers) were added to the following five different bacterial strains: 1) Lactobacillus brevis CD2 (Inersan, VSL Pharmaceuticals, USA), 2) Lactobacillus reuteri DSM 17938 (ProTectis, BioGaia, Stockholm, Sweden), 3) Lactobacillus rhamnosus LB21 (Essum AB, Umeå, Sweden), 4) Lactobacillus plantarum 931 (Essum AB, Umeå, Sweden), and 5) Streptococcus mutans (laboratory strain, positive control). Twenty-five µl (500 mM) of 4 dietary sugars (fructose, glucose, lactose and sucrose) and two sugar alcohols (sorbitol and xylitol) were added in order to initiate sugar fermentation. pH was measured, using a micro-pH electrode (Orion ROSS®Micro pH electrode, Orion 8220BNWP) at baseline after which a sugar or sugar alcohol was added to all vials, except for a pure plaque suspension (control). Changes of pH were then registered after 5, 15, 30, 60 and 90 min. All tests were run in duplicate.
Result: The reliability of the method was high. The most pronounced acidogenicity was found for the plaque suspension containing S. mutans. For most sugars, the plaque suspension to which Lactobacillus Brevis CD2 had been added resulted in the least pronounced pH fall (p<0.01). When comparing the different sugars, the most pronounced pH fall was found for glucose followed by sucrose and fructose. Only minor changes in plaque acidogenicity were found for the two sugar alcohols. Two-way factorial ANOVA showed statistically significant results for Lactobacillus Brevis CD2in comparison to the other bacterial strains.
Conclusion: The Lactobacillus Brevis CD2 has the potential to inhibit plaque acidogenicity when added to a plaque suspension of mixed oral microbiota.