Effective Implementation Control Trial

This study will evaluate the effectiveness and implementation of a theory-driven, WhatsApp-based family engagement intervention designed to improve oral health among primary school children. Parents or primary caregivers will be randomly assigned (individually or by school, depending on the study design) to either receive the digital intervention or usual care. The intervention will deliver structured oral health education, behaviour-change messages, reminder prompts, short videos, interactive quizzes, and parent-child brushing activities through WhatsApp over a predefined intervention period (e.g., 6-12 months). The primary effectiveness outcomes will include improvements in children's oral hygiene status (e.g., OHI-S, Plaque Index, Gingival Index, and dental caries where appropriate) and oral health behaviours such as twice-daily toothbrushing and reduced sugary snack consumption. Secondary outcomes may include parental oral health literacy, self-efficacy, and supervised brushing practices. Alongside effectiveness, the study will assess implementation outcomes-including acceptability, feasibility, adoption, fidelity, reach, and sustainability-to determine whether the intervention can be successfully integrated into routine school and community oral health programmes. Findings will provide evidence on both whether the intervention works and how it can be implemented and scaled in low- and middle-income countries.