Methods: The randomized double blinded clinical trial will recruit 414 healthy kindergarten children aged 3-5 years old with caries and with parental consent. The sample size is sufficient for the appropriate statistical analyses. The children will receive 0.004 mL 38% SDF (typical amount applied per manufacturer's instructions) to treat each caries lesion. The children will be classified into high and low caries rates and equably allocated into nine groups of SDF application time: 3, 5, 15, 30, 45, 60, 120 and 180 seconds. The children will be followed up for 6-months in their kindergartens. Clinical examinations after 6-months will be conducted to assess whether the caries is arrested. Information on confounding factors, such as oral hygiene habits and the use of other fluoride agents, will be collected through a parental questionnaire at the baseline and 6-months follow-up. The examiner, the children and the children's parents will be blind to the treatment allocation. The analysis will determine the significance of differences between the means of arrested caries at the various follow-ups; and Cochran-Armitage test will be used to evaluate the exposure (SDF-application time) to response relationship.~Significance: This study will help determine the optimal application time in SDF treatment. The study provides an evidence-based protocol for the use of silver diamine fluoride to arrest tooth decay in primary teeth of young children.
To determine the optimal application time of silver diamine fluoride (38% SDF) in arresting dental caries in the primary teeth of preschool children.