The purpose of this pilot study was to investigate the prevalence of trauma to incisor teeth in children with normal overjet and lip competence, treated with methylphenidate (Ritalin) for attention deficit hyperactivity disorder (ADHD). The study group consisted of 24 children (19 boys, 5 girls) aged 5-12 years (mean 8.45 +/- 2.25), diagnosed with ADHD and treated with methylphenidate at a minimal dosage of 10 mg per day. The control group consisted of 22 healthy children (13 boys, 9 girls) aged 5-12 years (mean 9.15 +/- 2.28). The dental examination included incisor relation measurements in the anterior segment (overjet), which was recorded using an orthodontic ruler. Lip competence was clinically determined, and anterior teeth were examined for dental trauma. The prevalence of dental trauma was significantly higher in the study group than in the control group (29.1% vs. 4.5% P = 0.02, t-test one tail). In conclusion, children with ADHD treated with methylphenidate have a high-risk for dental trauma. We believe that preventing dental trauma in this high risk group is possible. Consequently, the pediatrician and all medical staff attending to these children should encourage parents to consult frequently with a pediatric dentist to diagnose dental trauma and provide early treatment when needed.