Optimizing mHealth Interventions for Children's Oral Hygiene: A Factorial Trial

Behavioral interventions can improve children's oral hygiene practices. The multiphase optimization strategy (MOST) offers a framework to prepare, optimize, and evaluate behavioral interventions. This optimization trial tested 3 intervention components-brief motivational interviewing (MI), storytelling videos (STVs), and oral health promotion messages (OHPMs)-in enhancing mother's self-reported brushing of their preschool children's teeth. A total of 128 mothers with children <5 y old were included in a 2³ factorial trial. The primary outcome was children's plaque accumulation, assessed using the modified Plaque Index of Silness and Löe, with scores ranging from 0 to 3. The secondary outcome was mothers' self-reported frequency of brushing their children's teeth, categorized as at least once daily or less than once daily. Mothers were randomized to 8 experimental conditions based on combinations of on-off levels of the 3 components. Linear regression and generalized linear regression with logit link function were used to assess the impact of the components and their interactions on plaque score and daily toothbrushing after 3 mo. Multiple imputation was used for missing values. The principle of effect hierarchy guided the selection of components for inclusion in the optimized package, giving priority to main effects and 2-way over 3-way interactions. Plaque was reduced from mean = 1.8 at baseline to mean = 1.5 and daily toothbrushing increased from 50.8% to 69.5% after 3 mo. MI led to non-significantly less plaque and non-significantly more daily toothbrushing. Combining OHPMs and STVs together without MI canceled each other. Neither the main effects nor the 2- or 3-way interactions significantly affected the 2 outcomes. Individual or combined components did not significantly reduce plaque or increase daily toothbrushing. MI had the greatest promise for behavior change, and the m-oral health components need modification before they can be combined with MI in a health promotion package.