Aim: To determine and compare the pH changes and cariogenic microorganism activity in the saliva of children with early childhood caries (ECC) at different time intervals. Materials and methods: Nonrandomized clinical trial consisting of 20 children with ECC in the age-group of 3–6 years were selected. The baseline dmft score was recorded. Unstimulated saliva samples were collected before, 1 hour, and 1 day after the application of nanosilver fluoride (NSF) and subjected to pH measurement and microbiological analysis. The salivary pH values were analyzed using analysis of variance (ANOVA) followed by Bonferroni's post hoc test. Colony-forming unit (CFU) counts were compared using Friedman's test followed by Wilcoxon signed-rank post hoc test. The level of significance was set at p < 0.05. Results: The mean salivary pH level was significantly highest in the posttreatment 1-hour period (7.615 ± 0.230), followed by posttreatment 1-day (7.332 ± 0.285) and least in pretreatment (6.546 ± 0.308). The mean CFU counts at posttreatment 1 hour (4.237 ± 1.121) and posttreatment 1 day (3.592 ± 1.687) were also significantly lower compared to pretreatment (5.044 ± 0.976), and the difference was statistically significant at p < 0.001. Conclusion: NSF has displayed antibacterial as well as remineralization potential, which is also noninvasive, nonstaining, economical, and emerging as an effective anticaries agent. Clinical significance: NSF is a boon to children as it has great potential in preventing and arresting dental caries, and it has overcome the drawbacks of other silver-containing materials.