Randomized Clinical Trial Protocol to Study Caries-Arresting Effect of Silver Nitrate and Fluoride Varnish with Functionalized Tricalcium Phosphate

Background: Dental caries in primary teeth remains prevalent, affecting millions of children worldwide. To improve the remineralization process, functionalized tricalcium phosphate (fTCP) has been incorporated into sodium fluoride (NaF) varnish. The adjunctive application of silver nitrate (AgNO₃) solution and NaF varnish is effective in arresting dentine caries. So far, there is no published randomized clinical trial studying the effectiveness of the adoption of AgNO₃ solution and NaF varnish containing fTCP in arresting dentine caries in preschool children. The objective of this study is to compare the effectiveness of a 25% AgNO₃ solution plus a 5% NaF varnish containing fTCP and a 25% AgNO₃ solution plus a 5% NaF varnish in arresting coronal dentine caries among preschool children when applied semi-annually over a 30-month period.

Method: This is a randomized, controlled trial (Trial registration: ClinicalTrials.gov (U.S.): NCT03423797). The null hypothesis tested is that there is no difference between the effectiveness of a 25% AgNO₃ solution plus a 5% NaF varnish with fTCP and a 25% AgNO₃ solution plus a 5% NaF varnish in arresting dentine caries in preschool children when applied semi-annually. According to the sample size calculation, approximately 2,000 3- to 4-year-old kindergarten children will be screened, and at least 408 children with dentine caries will be recruited. The children will be allocated to two treatment groups randomly via stratified randomization. Clinical examinations will be conducted semi-annually to assess whether the carious lesions have become arrested (primary outcome). Confounding factors will be collected through a parental questionnaire.

Discussion: The effectiveness of the application of a 25% AgNO₃ solution followed by a 5% NaF varnish containing fTCP in arresting dentine caries among preschool children remains unknown. If this simple, noninvasive and low-cost treatment is effective in caries arrest, it can be widely recommended for caries control in young children.