Effective Implementation Control Trial

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.