Objectives:
The aim of the study was to compare the prevalence of parafunctions and signs and symptoms of TMD in a population group of children with and without ADHD.

Methods:
The study included all 5th grade children of all public primary schools in Sopot (untreated, unguided children). The reporting rate was 91%. At the first stage of the psychological-psychiatric study both parents and children filled in the CBCLand YSR questionnaires. At the next stage, in the group of children selected during the screening, aqualified child psychiatrist conducted asemi-structured diagnostic interview K-SADS-PLand diagnosed ADHD. Parafunctions, signs and symptoms of TMD were assessed by conducting a direct interview with a child and a clinical examination by a dentist.

Results:
There were significant differences (p < 0.05) between children with ADHD and without ADHD associated with parafunctions such as chewing gum (76.47% vs. 46.07%), nail biting (70.59% vs. 40.45%) and bruxism (52.54% vs. 26.22%), the number of signs and symptoms of TMD (1 sign or symptom 0.0% vs. 32.21%; 4–7 signs or symptoms 17.65% vs. 3.75%).

Conclusions:
In children with ADHD, symptoms of temporomandibular joint disorders and parafunctions were significantly more frequent. These studies suggest that children with ADHD constitute agroup of increased risk for TMD in the future. Interdisciplinary treatment of an ADHD patient by a psychiatrist and a dentist is necessary.