Administration of Oral Probiotic Streptococcus Salivarius K12

The clinical trial is investigating the oral administration of probiotic Streptococcus salivarius K12 in the form of lozenges in healthy adults. The main outcome measures are: * Potential for Streptococcus salivarius K12 to colonise the oral cavity * Effect on other bacteria and Candida albicans in the oral cavity * Possible anti-inflammatory effect Participants will: * Take one lozenge containing Streptococcus salivarius K12 daily for 4 weeks * Attend 3 dental check-ups (before starting the probiotic treatment, and after 4 and 8 weeks) * Collect their own saliva samples in accordance with a sampling schedule