Methods: Baseline readings for Streptococcus Mutans (SM) count, Lactobacilli (LB) counts and salivary buffer capacity were taken for 15 volunteers using Dentocult SM (Strip Mutans®), Dentobuff® Strip, and Dentocult LB® (Orion Diagnostica, Espoo, Finland) test kits respectively. The plaque pH challenge after sucrose challenge (“Stephan curve”) was evaluated at the distal surface of the right upper canine with a palladium-touch pH microelectrode (Orion Research, Inc., Cambridge, MA). In addition, plaque samples retrieved from the same sites were analyzed using RT-PCR techniques. Subjects rinsed daily one bottle of 100ml Yakult® for one week before they returned for follow-up measurements. The difference between baseline and follow-up measurements of the aforementioned variables was analyzed using related parametric and non-parametric statistical tests.
Results: The Stephan Curves of participants before and after the intervention period exhibited statistically significant changes. Mean lowest pH increased from 5.02 to 5.22 (p =0.02), mean recovery time decreased from 9.79min to 6.10min (p<0.001) and AUC decreased from 3424 to 1339 (p =0.01). Microbiological analysis with RT-PCR revealed the significant decrease of SM counts (p<0.05). The average log value of S.mutans DNA copies decreased from 11.43 to 7.03.
Conclusion: This study confirmed that the short term consumption of Yakult® may cause cariostatic ecological shift of oral biofilm through the reduction of SM and acid production.