WhatsApp Messages to Improve Mothers' Oral Health Knowledge and Children's Toothbrushing

This is an open-label, two-arm, parallel-group randomized controlled trial with 1:1 allocation, conducted at the Pediatric Dentistry Clinics of King Abdulaziz University Hospital, Jeddah, Saudi Arabia.

Mothers of children aged 3 to 6 years will be approached in the clinic waiting area. After electronic informed consent, participants will complete a baseline self-administered questionnaire delivered through Google Forms on their own smartphones, covering demographic characteristics, maternal oral health knowledge, and child toothbrushing behavior. All participants will then receive a standardized 10 to 15 minute individual face-to-face oral health education session delivered in Arabic by the principal investigator, using visual materials from the American Academy of Pediatric Dentistry and the Saudi Ministry of Health.

Randomization will follow the baseline questionnaire and education session. A computer-generated block randomization sequence with varying block sizes of 4, 6, and 8 will be prepared in advance by an independent person not involved in recruitment or data collection, and concealed in sequentially numbered, opaque, sealed envelopes opened only after baseline assessment and education are complete.

Participants allocated to the intervention arm will additionally receive individually delivered WhatsApp messages twice weekly for eight weeks, sixteen messages in total, reinforcing the same toothbrushing content covered in the education session. Messages will be delivered in Arabic and may include text, images, or short videos drawn from evidence-based sources; all content will be reviewed by a pediatric dentist before delivery. Participants allocated to the control arm will receive the face-to-face education session only, with no further contact during the intervention period.

At eight weeks, all participants will be invited by WhatsApp to complete the same questionnaire through a secure Google Forms link, omitting the demographic and eligibility sections. Non-responders will receive up to three reminders at 3 to 5 days, 7 to 10 days, and 14 days after the initial invitation, after which they will be classified as lost to follow-up.

Blinding of participants and of the investigator is not feasible given the nature of the intervention, so the trial is open-label. Analysis will follow the intention-to-treat principle and will use analysis of covariance comparing eight-week scores between arms with the corresponding baseline score as covariate; results will be reported as adjusted mean differences with 95% confidence intervals. Missing follow-up data will be handled by multiple imputation under a missing-at-random assumption, with estimates pooled using Rubin's rules.

The target sample size of 106 participants, 53 per arm, was derived for ANCOVA with alpha of 0.05, power of 0.80, effect size f of 0.31, and one covariate, giving 42 per arm before inflation for 20 percent anticipated attrition.