 Clinical sampling In order to monitor the oral microbiota in the 2 study groups during the course of the study, saliva samples will be collected at baseline before intervention and at the 6 and 12 months follow-ups according to Barfod and co-workers 9. A cotton bud is placed by the parents in the mouth of their child under supervision of the clinical staff. When soaked, the bud will be transferred to a small plastic tube, marked with the patients study number, and immediately frozen and stored. After the full completion of the trial, all samples will be shipped on expense of the manufacturer to Oragenics, FL, USA for further handling and processing. The running costs for the clinical samplings are covered by a separate agreement. 