Background and objectives: Ideally every child must have access to preventive and restorative care of greater quality. However, in rural areas, resources and dental care services are limited. Silver diamine fluoride (SDF) has been identified as an efficient topical cariostatic and preventive medicament for managing ECC in children who cannot be treated conventionally. Since SDF is an emerging alternative for caries prevention and arrest, AAPD recommends more practice-based research to evaluate its efficacy. The aim of this study was to evaluate the effectiveness of silver diamine fluoride at different time durations of application in treatment of carious primary teeth in children with least access to dental care. Methodology: This was a prospective, randomized, field trial that included patients with primary tooth. Primary tooth presenting carious lesion in ICDAS 3–6 category were randomly assigned to one of the three groups. Results: At 3-week mean rank of lesions arrested in Group 1 and Group 2 were 73.3 and 72.29, whereas it was 86.9 in case of Group 3. At 6 months it was 79.15, 77.29, and 75.96 in Group 1, 2, and 3 , respectivel (p > 0.05). Conclusion: SDF is effective in controlling caries progression in both cavitated and non-cavitated lesion with minimal time duration of application (30 seconds). This approach may be of great utility as an alternative to other expensive preventive and therapeutic methods in communities with limited resources. Nonetheless obtaining caregiver consent is mandatory.