The aim of this in vitro study was to compare the remineralization efficacy between dentine carious lesions in primary teeth after an application of a silver diamine fluoride Thai product or a commercial SDF. The samples comprised 30 primary molar blocks with natural dentine carious lesions. The baseline mineral density (MD) was 
 determined using a micro-computed tomography (micro-CT) that was used to calculated lesion depth (LD) and mean mineral density (mean MD). The samples were randomized into three groups: SDF (Thai product), commercial SDF (Saforide®: Toyo Seiyaku Kesei, Japan) and deionized water (control group), respectively. After undergoing a bacterial pH-cycling challenge, the samples were re-evaluated for MD and the LD, mean MD, %LD change and %MD change was calculated. The results demonstrated that the mean %MD change of the three groups were 38.9 ± 18.1, 60.2 ± 30.6 and 4.5 ± 7.6 respectively. The mean %MD change in the SDF (Thai product) and Saforide® groups were comparable but significantly different higher that the control (p<0.001). The LD at baseline and post-test of each group did not significantly change (p>0.05). In conclusion, SDF (Thai product) and Saforide® have a similar efficacy in remineralizing dentine carious lesions in primary teeth