Background <p>Children’s oral health continues to be a key issue, with dental caries remaining one of the most prevalent non-communicable diseases. One of the main ways to prevent dental caries is to carry out adequate toothbrushing with fluoridated toothpaste. Connected or ‘smart’ toothbrushes can provide real-time feedback on brushing behaviour to individuals or be used to provide feedback to groups for example within a school setting. This study aimed to identify the engagement level of school children with a smart, connected toothbrush, explore brushing frequency, timing, coverage, and duration during the research period, and compare data to observed changes over time.</p> Methods <p>Data on brushing behaviour were obtained from a feasibility cluster randomised controlled trial exploring smart, connected toothbrush use in a school-based brushing programme. Participants, aged 8–11 with access to a smart device, were recruited from six primary schools located in deprived areas of Manchester, England. Randomisation at the school level allocated participants to receive either a smart, connected toothbrush and text message intervention (intervention group) or the smart, connected toothbrush only (control group).</p> Results <p>Of the 409 participants provided with a smart, connected toothbrush, 289 (71%) connected and used the device during the study. Of those who engaged with the connected devices, participants brushed at least twice a day on 48.2% of the days they brushed. On completed questionnaires, 78.8% of parents indicated their children brushed their teeth twice a day. Brushing frequency appeared to decrease over the weekends, particularly on weekend mornings.</p> Conclusions <p>The results from this feasibility trial suggest that toothbrushing habits remain a fundamental area of importance, with a substantial proportion of children not brushing according to recommendations. Not all children connected or consistently used their devices during the study. Twice-daily brushing was infrequently recorded. Consideration must be given to the potential omission of brushing sessions, as the data may miss out sessions until the user syncs the brush with the app. Further research is needed to identify how frequency of brushing, particularly at the weekends, could be improved.</p> Registration <p>The study was retrospectively registered at ISRCTN, registration number ISRCTN77803149 on 28/12/2023.</p>