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.

Inclusion Criteria: 1. Parent or primary caregiver of a child enrolled in a participating primary school. 2. Child aged 5-12 years (or the age range specified by the study). 3. Parent or caregiver owns or has regular access to a smartphone with an active WhatsApp account. 4. Parent or caregiver is able to read and understand the study language(s) (e.g., Urdu and/or English). 5. Parent or caregiver is willing to receive WhatsApp messages throughout the intervention period. 6. Parent or caregiver provides written informed consent; child provides assent where age-appropriate. Exclusion Criteria: 1. Parent or caregiver declines or withdraws informed consent. 2. Child has a medical, developmental, or cognitive condition that would prevent participation in routine oral health assessments or toothbrushing activities, as determined by the investigators. 3. Child is currently participating in another oral health intervention or clinical trial that could influence the study outcomes. 4. Parent or caregiver plans to relocate or anticipates being unavailable during the study follow-up period. 5. Child requires urgent medical or dental care that would preclude participation, as judged by the study dentist (children identified with urgent dental needs during screening will be referred for appropriate care and their eligibility will be determined by the study protocol). 6. More than one eligible child from the same household is enrolled; in such cases, one child will be selected according to the study protocol to maintain independence of observations.