This pilot trial is randomized, double-blind, and placebo-controlled trial with two parallel arms: an intervention group using silver diamine fluoride (SDF) and a placebo group (control). 144 eligible healthy adults will be enrolled in the study and randomly assigned to one of the two treatment groups. Both groups will receive the traditional preventive measures including cleanings, Fluoride varnish, diet analysis and counseling. Study participants will be followed for two years and caries progression will be radiographically monitored.