Monetary incentives for improving smartphone-measured oral hygiene behaviors in young children: A randomized pilot trial

Abstract

Aims: To assess feasibility, acceptability, and early efficacy of monetary incentive-based interventions on fostering oral hygiene in young children measured with a Bluetooth-enabled toothbrush and smartphone application.

Design: A stratified, parallel-group, three-arm individually randomized controlled pilot trial.

Setting: Two Los Angeles area Early Head Start (EHS) sites.

Participants: 36 parent-child dyads enrolled in an EHS home visit program for 0-3 year olds.

Interventions: Eligible dyads, within strata and permuted blocks, were randomized in equal allocation to one of three groups: waitlist (delayed monetary incentive) control group, fixed monetary incentive package, or lottery monetary incentive package. The intervention lasted 8 weeks.

Outcomes: Primary outcomes were a) toothbrushing performance: mean number of Bluetooth-recorded half-day episodes per week when the child's teeth were brushed, and b) dental visit by the 2-month follow-up among children with no prior dental visit. The a priori milestone of 20% more frequent toothbrushing identified the intervention for a subsequent trial. Feasibility and acceptability measures were also assessed, including frequency of parents syncing the Bluetooth-enabled toothbrush to the smartphone application and plaque measurement from digital photographs.

Findings: Digital monitoring of toothbrushing was feasible. Mean number of weekly toothbrushing episodes over 8 weeks was 3.9 in the control group, 4.1 in the fixed incentive group, and 6.0 in the lottery incentive group. The lottery group had 53% more frequent toothbrushing than the control group and 47% more frequent toothbrushing than the fixed group. Exploratory analyses showed effects concentrated among children ≤24 months. Follow-up dental visit attendance was similar across groups. iPhone 7 more reliably captured evaluable images than Photomed Cannon G16.

Conclusions: Trial protocol and outcome measures were deemed feasible and acceptable. Results informed the study protocol for a fully powered trial of lottery incentives versus a delayed control using the smart toothbrush and remote digital incentive program administration.

Trial registration: ClinicalTrials.gov identifier NCT03862443.

Conflict of interest statement

I have read the journal’s policy and the authors of this manuscript have the following competing interests: Dr. Gansky’s brother is a 3M employee, in a different division than the one that provided in-kind product. This paper includes discussion of “off-label” use of the following: The US FDA only has approved fluoride varnish as a device to be used for tooth sensitivity in a cavity lining preparation; caries prevention is an off-label use. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Study flowchart.

S4K (Sonicare for Kids) is a Bluetooth-enabled powered toothbrush and accompanying smartphone app.

Fig 2. Number and percent (of 14) of toothbrushing episodes by study group and week.

Fig 3. Effects of each incentive package on toothbrushing episodes per week.

Linear mixed-effects model with a random effect for dyad. Purple text refers to contrasts of each incentive group against the control group. Error bars represent 95% confidence intervals.

Fig 4. Effects of each incentive package on toothbrushing episodes by study week and child age group.

This figure shows a linear prediction of the fixed portion of mixed-effects models with a random effect for child-parent dyad, stratified by child age (≤24 months in Panel A, 25+ months in Panel B). Error bars represent 95% confidence intervals.

Fig 5. Number and percent (of 3) of syncing episodes by study group and week.

Fig 6. Camera feasibility comparison for photographs for asynchronous plaque rating.

McNemar’s test yielded p = 0.0003. The camera order was randomized by participant.