Background: Oral diseases are highly prevalent in childhood, and modifiable behaviours such as toothbrushing, diet and use of preventive products are key determinants of risk. Dentists and pharmacists are well placed to deliver behavioural interventions that may improve children’s oral health. Methods: This systematic review followed PRISMA 2020 guidance. Electronic databases were searched for original quantitative studies evaluating behavioural interventions delivered wholly or partly by dentists, dental team members or pharmacists to children and adolescents (≤18 years). Eligible designs included randomized and non-randomized intervention studies reporting behavioural and/or clinical oral-health outcomes. Data were extracted on study characteristics, intervention content and outcomes, and synthesised narratively because of heterogeneity. Results: Seven studies met the inclusion criteria. Most interventions were delivered by dental professionals in clinical or community settings and used approaches such as motivational interviewing, theory-based health education and school-based toothbrushing programmes. Across studies, interventions frequently improved oral-health knowledge, self-efficacy, toothbrushing practices and sugar intake, and several trials reported modest reductions in caries experience or plaque indices. However, effects on clinical outcomes were inconsistent, with some high-risk populations showing little difference between intervention and control groups. No pharmacist-led behavioural intervention targeting paediatric oral health was identified, although existing literature suggests that pharmacists commonly provide informal oral-health advice in practice. Conclusion: Behavioural interventions led by dental teams can improve children’s oral-health behaviours and sometimes clinical outcomes, but effects are variable and often short-term. There is a striking absence of evaluated pharmacist-delivered behavioural interventions for children. Future research should develop theory-based, multi-component, interprofessional models that explicitly integrate pharmacists into paediatric oral-health promotion.