The association between attention deficit hyperactivity disorder and orthodontic outcomes: a systematic review

BACKGROUND: ADHD is a prevalent neurodevelopmental condition characterized by inattention, impulsivity, and hyperactivity, which may influence cooperation and compliance in dental settings. In orthodontics, where long-term treatment adherence and patient cooperation are critical, the presence of ADHD may pose specific challenges that affect treatment success, appliance maintenance, and clinical workflow. Despite growing interest in the behavioral dimensions of orthodontic care, the extent to which ADHD alters treatment outcomes remains insufficiently understood. OBJECTIVES: This systematic review aimed to examine the association between ADHD and orthodontic treatment outcomes. Specifically, it investigated whether individuals with ADHD exhibit different patterns of compliance, appliance breakage, treatment relapse, and behavioral cooperation compared to neurotypical peers. The review question was developed in accordance with the PICO framework to ensure clarity and clinical relevance. METHODS: Following PRISMA 2020 guidelines and a pre-registered protocol with PROSPERO (ID #1024195), six databases were searched through February 2025. Eligible studies included observational research that reported on orthodontic treatment outcomes in individuals formally diagnosed with ADHD. Outcomes of interest included appliance-related complications, cooperation or compliance ratings, relapse risk, treatment discontinuation, and reported differences in oral habits. Risk of bias was assessed using the ROBINS-I tool. A narrative synthesis was conducted due to heterogeneity in outcome definitions, measurement tools, and study designs. RESULTS: Twenty studies met inclusion criteria, including 14 cross-sectional studies, 3 retrospective cohorts, and 3 prospective observational designs. Individuals with ADHD consistently exhibited higher rates of appliance breakage, lower cooperation scores, and more frequent treatment disruptions compared to neurotypical controls. Oral habits such as bruxism, nail biting, and poor oral hygiene were more commonly reported in ADHD populations. However, variability in diagnostic criteria, outcome measurement, and adjustment for confounders limited comparability across studies. Risk of bias ranged from moderate to serious in most studies, with only three rated as low risk. CONCLUSIONS: Individuals with ADHD appear to face elevated risks of orthodontic treatment complications and reduced behavioral cooperation. These findings underscore the importance of early identification, interdisciplinary collaboration, and tailored behavioral strategies to support successful orthodontic outcomes in this population.