Effectiveness of Silver Diamine Fluoride for Preventing Occlusal Caries in the Primary Teeth of Preschool Children: Protocol for a Randomized Controlled Trial

Background: Tooth decay is a significant public health problem globally. The caries-arrest effectiveness of 38% silver diamine fluoride (SDF) has been well documented. However, information on the caries-preventive effect of SDF on primary teeth is insufficient. Objective: The aim of this trial is to investigate the effectiveness of semiannual application of 38% SDF and that of 5% sodium fluoride (NaF) varnish when compared with placebo control for preventing occlusal caries in the primary molars of preschool children over 30 months. Methods: This 3-arm, parallel design, double-blind, randomized controlled trial involves 791 preschool children. Children are randomly allocated to receive 1 of 3 interventions as follows: Group 1, 38% SDF; Group 2, 5% NaF varnish; and Group 3, placebo control (tonic water). The intervention and dental examination will be carried out every 6 months. A parent-administered questionnaire, including the children's demographic background and oral health-related behaviors, has been collected at baseline. Follow-up examinations to detect new caries development will be conducted every 6 months by a masked examiner. Caries development will be diagnosed at the cavitation level. Chi-square tests and logistic regression analyses will be adopted. A 2-level logistic regression analysis will be performed to investigate the effects of the study interventions and other potential confounding factors on the development of occlusal caries. Results: This study was started on September 1, 2020, and the recruitment process ended on September 30, 2021. At present, a total of 791 children are participating in the study. This 30-month clinical trial is expected to be completed in March 2024. Conclusions: If SDF application is more effective than NaF varnish for preventing caries on occlusal surfaces of primary teeth, it can be a preferred choice for caries prevention in a kindergarten-based program. Results of this trial will provide valuable clinical evidence for the development of oral health strategies and policies on the promotion of child oral health.