Efficacy of novel DHATRI mHealth intervention in modifying oral health status and behavior among preschool child mother dyads: Randomized controlled study

Introduction: Early childhood caries prevention requires understanding both intervention efficacy and psychological mechanisms driving behavioral change. This study evaluated DHATRI (Devising Home Assisted child Tooth-brushing Related Initiative), a novel Theory of Planned Behavior-based mHealth application, examining which psychological predicted sustained toothbrushing behavior among mother-child dyads in resource-constrained populations. 
Methodology: A cluster-randomized controlled trial enrolled 90 mother-child dyads (intervention n=45; control n=45) from Lucknow preschools. The intervention group received the DHATRI app featuring animated toothbrushing timer and multimedia oral health videos/tips in Hindi/English (6-month delivery), while controls received conventional pamphlet-based education. Primary outcomes included plaque index reduction and mechanistic assessment of Theory of Planned Behavior constructs (attitude, subjective norms, perceived behavioral control, self-efficacy) as behavioral predictors via linear regression. 
Results: At six months, the intervention group achieved 44.8% plaque index reduction versus 10.7% control (p<0.001) with 40.81% prevented fraction for decayed surfaces. Behavioral determinants differed significantly between groups: at baseline, control mothers' brushing was predicted by attitude (B=0.023, p=0.026) and perceived behavioral control (B=0.064, p=0.009), while intervention mothers responded to subjective norms (B=0.034, p<0.001) and income (B=0.085, p=0.050). By 6 months, subjective norms sustained exclusively in intervention group (B=0.030, p=0.010), while attitude ceased predicting behavior in both groups, indicating transition from intention-driven to habit-driven execution. Clinical improvements were mechanistically explained by sustained social influence activation and incremental competence-building through app scaffolding. 
Conclusion: Theory-based mHealth design produces clinical efficacy through sustained social influence pathways and competence-building rather than pre-existing confidence. This integrated mechanistic evidence demonstrates a paradigm for designing digital interventions.