Abstract: Objective  To investigate the effect of malocclusion on the psychological status of adults. Methods  A total of 91 adult patients with malocclusion were selected, and Symptom Checklist 90 (SCL-90) was employed to evaluate their mental health status before orthodontic treatment. Psychological status of 70 adult patients (non-malocclusion patients) in Stomatology Hospital of Shandong University was also assessed with SCL-90. Results  Patients with malocclusion scored significantly higher than the control group on factors of interpersonal sensitivity, anxiety and schizophrenia (P<0.05). There was no significant difference between male and female patients (P>0.05). 57.14% of malocclusion patients had at least one factor scored 2 or over, and 6.59% of them had at least one factor scored more than 3, which meant that 57.14% of malocclusion patients had mild psychological problem and 6.59% had moderate or severe psychological problem. Conclusion  Malocclusion can not only cause disorder of stomatognathic function and facial defects, but also do harm to the mental health of adults. It is very important for orthodontists to value such patients’ mental problem, and provide necessary psychological rehabilitation at appropriate time.

Key words: Malocclusion, Mental health, Adult orthodontics, Symptom Checklist 90