Aim: To test whether there is any difference in pain perception during the week following placement of initial aligning archwire in active and passive self-ligating bracket systems. Methods: Seventy patients (mean age ± SD, 16.1 ± 2.3 years; 35 males and 35 females) were enrolled in this prospective randomized clinical trial. After appliance placement and engagement of a 0.016-inch round martensitic nickel-titanium (Ni-Ti) alloy archwire, pain levels were recorded after 4 hours; at bed time on the day of the appointment; after 24 hours; and after 2, 3, 4, 5, 6, and 7 days using a nine-page visual analog system (VAS) questionnaire. The use of pain medication self-administered by the patient was also recorded. Independent sample t tests were used to analyze normally distributed data obtained from VAS measurements. Results: Sixty (85.71%) patients completed the trial. The type of self-ligating bracket had a significant influence on the pain experienced at 4 hours (P = .03), bed time (P = .05), 24 hours (P = .04), and 2 days (P = .05) after placement of initial aligning archwire. Conclusion: The type of self-ligating bracket system had a significant difference on subjective pain experience after placement of the initial aligning archwire. Patients treated with active self-ligating appliances experience significantly higher pain levels until the second day compared with patients treated with passive self-ligating appliances. ORTHODONTICS (CHIC) 2012;13:e58–e65.

Key words: aligning archwire, orthodontic pain, self-ligating