- Method: The extension of the Consolidated Standards of Reporting Trials 2010 Statement will be followed for this 30-month, randomised, double-blinded, non-inferiority clinical trial. Approximately 2,400 kindergarten children will be screened and at least 826 children with caries will be recruited. This sample size is sufficient for an appropriate statistical analysis (power at 90% [β=0.10] with a 2-sided type-I error of α=0.05), allowing for a 18% drop-out rate. The children will be randomly allocated into 2 groups to treat their caries over a 30-month period: Group A - biannual application of a 25% AgNO3 solution followed by a 5% NaF varnish, and Group B - biannual application of a 38% SDF solution followed by a placebo varnish.Clinical examinations will be conducted at 6-month intervals to assess whether the caries are arrested. Information on confounding factors such as oral hygiene habits will be collected through a parental questionnaire.