Here is the design of a clinical trial:

Official Title: Preventing Early Childhood Caries with Silver Diamine Fluoride - a 12-month Randomised Clinical Trial

Included conditions:
- Dental Caries

Study Armgroups:
- {'label': 'SDF', 'type': 'EXPERIMENTAL', 'description': '38% silver diamine fluoride solution', 'interventionNames': ['Device: SDF']}
- {'label': 'NaF', 'type': 'ACTIVE_COMPARATOR', 'description': '5% sodium fluoride varnish', 'interventionNames': ['Device: NaF']}

Interventions:
- {'type': 'DEVICE', 'name': 'SDF', 'description': '38% silver diamine fluoride solution', 'armGroupLabels': ['SDF']}
- {'type': 'DEVICE', 'name': 'NaF', 'description': '5% sodium fluoride varnish', 'armGroupLabels': ['NaF']}

Primary Outcomes:
- {'measure': 'caries prevention', 'description': 'the number of sound tooth surfaces that become cavitated caries per child', 'timeFrame': 'at 12-month follow-up'}

Please estimate the sample size based on the assumption: 
The statistical power was set at 0.9 and the type I error was set at 5%. The dropout rate was estimated at 15%.
Sample size calculation
        The data utilised for the sample size calculation is from a previous study conducted in Hong Kong [12]. The mean number of decayed teeth of 3-year-old children was 5. The mean numbers of newly developed carious surfaces in SDF and NaF groups were 0.47 (SD 0.87) and 0.70 (SD 0.84), respectively. The difference in the preventive effects between the two groups was 33%. When the statistical power was set at 0.9 and the type I error was set at 5%, 292 children were required in each group. With the dropout rate estimated at 15%, 688 children should be enrolled at baseline, with 344 children in each group.