Objective:To investigate changes of interlukin-1β (IL-1β) and prostaglandin E2 (PGE2) levels in gingival crevicular fluid (GCF) during distal movement of canines with Damon Q self-ligating brackets and traditional brackets,and to investigate the effect of Damon Q self-ligating brackets on the periodontium. Methods:Fifteen patients,aged 11-13 years and treated with maxillary first premolar extractions,participated in this study. The upper canines were bonded with self-ligating bracket and conventional MBT bracket,respectively. After leveling dentition, the upper canines were retracted with continuous forces of 100 g using nickel-titanium coil springs on 0.018 stainless steel archwire. GCF was collected from the distal site of each canine before activation and at 1 h,24 h,72 h,1 w,2 w,3 w and 4 w after initiation of the experiment. IL-1β and PGE2 concentrations were determined by enzyme-linked immunoadsordent assay (ELISA). Results:After 24 h of activation,the IL-1β in GCF of the self-ligating bracket group was significantly increased. At the self-ligating bracket group,the IL-1β and PGE2 levels in GCF were significantly higher than those of the traditional bracket group from the 72 h after the activation,and there were still significant differences at 4 w after activation. Conclusion:There were differences of IL-1β and PGE2 levels in GCF during distal movement of canines with Damon Q self-ligating brackets and traditional MBT brackets. Higher and more permanent biological effects were detected in the self-ligating group.