The goal of this clinical trial is to test whether the autism-friendly app improves toothbrushing outcomes compared to a control app with only a digital mirror and countdown timer among children and teens (ages 8-17 years) with autism.

The main questions it aims to answer are:

1. Will toothbrushing distribution, duration, and frequency be greater in the experimental arm than in the control arm?
2. Will toothbrushing habit formation be higher in the experimental arm than in the control arm?
3. Is caregiver and child self-efficacy a mediator of toothbrushing habit formation?
4. Do children who exhibit habit formation report better oral health-related quality of life?

Participants will:

1. Use either the autism-friendly app or the control app during their daily toothbrushing routine for 3 months.
2. Complete surveys and assessments about toothbrushing behaviors and oral health over the course of the study.

The UH3 RCT will be conducted over four years. We will obtain a list of eligible participants from the main study recruitment site (Seattle Children's Hospital). We will obtain a list of individuals who express interest in participating in the study from other recruitment sites. UW staff will contact potential participants, describe the study, verify interest and screen for eligibility, and obtain informed consent and assent. The caregiver and their child/teen, aged 8-17 years, will be enrolled (N=270) as dyads and randomly assigned (1:1) to an experimental or control arm, accounting for sex and autism severity. The study participation will span one year. The participants in both arms will follow the same procedures.

After enrollment, caregivers from both control and experimental groups will complete all surveys according to the determined schedules. Caregivers will complete a demographics survey and a toothpaste survey via phone. Caregivers will also complete an online survey, Social Responsiveness Scale-2 (SRS-2), via WPS Publishing, to provide data on the user's autism severity. Before the app use, caregivers will be asked to complete a 9-item Oral Health Behavior Survey (OHBS), 30-item Behavioral Survey (BS) and 38-item Short Sensory Profile (SSP) via REDCap at baseline.

Caregivers will then be given a unique link to install a modified Brush Up/Brush Down app, depending on their assignment in the experimental or control arm respectively. The Brush Up app (experimental) features a cartoon character that helps guide the child through toothbrushing with a catchy song. It also includes a digital mirror where the child can watch themselves brush and a matching game where they earn stars by matching their toothbrushing movements with the character. The Brush Down app (control) includes only a digital screen mirror and a timer. We will ask the user to use the app twice a day for 3 months. The app will record the user's toothbrushing sessions. Users will be made aware of this during consent/assent process. The 9-item OHBS will be re-administered at 1 month, 2 months and 3 months of app use via REDCap. The 30-item BS will be re-administered at 2 weeks, 1 month, 2 months, and 3 months of app use via REDCap. Study staff will recruit 60 dyads (N=30 from each arm) for a post-trial debriefing interview lasting about 60 minutes using a semi-structured interview script to elicit responses about the experiences of using the app, the effects of the app on their child's long-term toothbrushing habit formation as well as ways the intervention could be further strengthened in the future to meet the needs of individuals with autism. The interviews will be audio recorded, transcribed, and verified for accuracy, and coded deductively using standard methods.

After 3 months of app use, the caregivers will be asked to complete a 6-item BS, an abridged version of a 30-item BS, to assess long-term habit formation and oral health quality of life from months 4 to 12 of participation via REDCap.

Study staff will reach out to the dyads who participated in post-trial interviews to obtain feedback on their experiences of using the app. The interviews will be audio recorded, transcribed, and verified for accuracy, and coded deductively using standard methods.

Inclusion Criteria:

1. Child participants will have Autism Spectrum Disorder that will be confirmed by: (1) chart review by clinical staff at the recruitment sites to determine if the child meets the DSM-5 criteria for autism spectrum disorder; OR (2) affirmative caregiver self-reporting: (YES) to the question, "Has a healthcare provider ever diagnosed your child with autism?" which has been used in previous studies as a valid method of identifying ASD in children.23,24
2. Willingness to take the SRS-2 [Social Responsiveness Scale-2], which will be completed through an online link sent by University of Washington study staff.
3. Child brushes independently. The child needs to be able to hold a toothbrush and move it around their teeth, mostly unassisted.
4. Child uses touch screen devices (e.g., iPhone, iPad, Android).
5. Ages 8 to 17 years at enrollment.
6. Caregiver and child able to communicate in English.
7. Caregiver age ≥18 years and able to provide informed consent to participate; and willing to provide assent on behalf of a child who is not capable of comprehending the assent process and materials.
8. Children ages 8 and older willing to provide assent, if they can comprehend the assent process and materials and communicate a voluntary willingness to participate.
9. Caregiver and child live in the same home.
10. Caregiver must have a valid and active email address to receive study related materials and study related communications.
11. Child has ready access to a mobile device with a front-facing camera onto which apps can be installed (iPad or iPhone with iOS 17.0+; Android tablet or phone with Android 14.0+).
12. Family has a Wi-Fi or cellular data plan to allow app data to be transmitted with confirmation of via tools like the Ookla Speed Test to help problem solve and ensure that app data can be transmitted.

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in the study:

• Children with autism younger than age 8 years at enrollment.
• Children with autism who cannot brush their teeth without assistance (e.g., if caregiver needs to hold the toothbrush).
• Children with autism who have a sibling enrolled in the trial. o For families with more than 1 eligible child with autism, we will enroll the youngest eligible child. Any other children from the same family who are not enrolled in the study will be given access to the app their sibling is using (experimental or control) after 3 months, if they are interested.

The outcomes assessing team including the coders and the lead will be masked in the clinical trial.