Methods: 201 children, aged 3 to 4 years, were recruited from six kindergartens in a rural area in Southern China and randomly allocated to one of three treatment groups: (1) application of silver diamine fluoride (Saforide, Tokyo Seiyaku Kasei Co. Ltd., Japan) once every 6 months, (2) application of silver diamine fluoride once every 12 months, and (3) application of a high fluoride releasing glass ionomer (Fuji VII, GC Corporation, Japan) with a free-flowing consistency once every 12 months. Treatments were provided in the kindergartens using hand instruments only. Follow-up examinations were carried out every six months by a trained examiner who was not involved in the provision of treatments. Sharp sickle probes and an intra-oral LED light source were used. Success was recorded if the caries lesion was arrested, i.e. hard to probing with a light force, or when the glass ionomer covered the whole lesion.
Results: After 12 months, the success rates were 50.0%, 31.9% and 18.8% in group 1, group 2 and group 3, respectively. The differences between groups were statistically significant (Chi-square test, p<0.01).
Conclusion: Bi-annual application of SDF was found to be more effective than annual application of SDF or a high fluoride releasing glass ionomer in arresting dentine caries in primary teeth after 12 months.