To compare the effectiveness of the semi-annual application of 38% SDF with two post-treatment protocols in arresting dental caries in preschool children

Methods: The randomized clinical trial will recruit 254 healthy kindergarten children aged 3-4 years old with caries and with parental consent. All the tooth surfaces with carious lesions will receive the semi-annual application of 38% SDF solution. After the treatment, children will be allocated to two groups by an independent research assistant. Two post-treatment protocols are as follows.

Group A - Children are instructed to rinse their teeth with a cup of water containing about 50 ml immediately after SDF treatment. Afterwards, no post-treatment protocol is given to children.

Group B - Children are instructed not to eat and drink for at least 30 minutes. 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 12-months follow-up. The analysis will determine the significance of differences between the percentage of arrested caries at the various follow-ups.

Significance: This study will help determine the optimal post-op treatment 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.

Inclusion Criteria:

1. 3-5 year old children attending the first to the third year of kindergarten;
2. free from any systemic conditions and generally healthy;
3. parents sign informed consent;
4. having at least 1 tooth with cavitated dentine carious lesion

Exclusion Criteria:

1. are uncooperative to accept oral examination or treatment;
2. have a significant systematic disease or long-term medications;
3. have abnormal dentition.
4. Teeth having signs or symptoms of irreversible pulpitis and non-vitality will be excluded.