Table 1.

Eligibility criteria

Patients will be eligible for the study if they meet the following criteria:

- Boys or girls aged 12 to 16.

- For at least 6 weeks, they must have maxillary and mandibular fixed orthodontic appliance therapy, which consists of bonding at least premolar-to-premolar with edgewise appliances and their modifications.

- They have not been scheduled for removal of fixed orthodontic treatment before the end of the study.

- They have no physical and/or mental disabilities that will impede their ability to perform their own oral hygiene activities.

- They are not engaged in other oral-health education or research program.

- They do not have enamel and dentine dysplasia and/or craniofacial malformation (e.g. cleft).

- They have a sufficient command of the Dutch language.

- They possess a smartphone with software IOS ≥7 or Android ≥4.1.

- Patients and their parents are able or willing to give informed consent.

- Patients must not use medication that may affect plaque accumulation, for example antibiotics and antibacterial mouth rinses.