Objective:To explore the influence of Nance traction device combined with edgewise technique on postoperative swelling,pain and complications in patients with maxillary impacted canines.Methods:105 patients with maxillary impacted canines were enrolled.By means of clinical treatment method,they were divided into control group(n=52)and study group(n=53).The control group used conventional orthodontic fixed correction technique and the study group adopted Nance traction device combined with edgewise technique.The differences in treatment success rate,impacted teeth eruption time,postoperative swelling degree,pain score,cytokines[matrix metalloproteinase-3(MMP-3),interleukin-1β(IL-1 β)]and oral microenvironment were compared between the two groups,and the incidence rates of complications were recorded.Results:The success rate of treatment in study group was higher than that in control group(P＜0.05).The eruption time of impacted teeth in study group was shorter than that in control group(P＜0.05).At different time points after surgery,the postoperative swelling degree and pain score were lower in study group than those in control group(P＜0.05).After treatment,the levels of MMP-3,IL-1 β,gingival index(GI)and plaque index(PLI)were increased in both groups,and the study group had lower levels(P＜0.05).The incidence rates of complications in study group were lower than those in control group(P＜0.05).Conclusion:The application of Nance traction device combined with edgewise technique can signifi-cantly improve the postoperative swelling degree and relieve the pain level of patients with maxillary impacted canines,and it has few complications,good safety and good clinical application prospect.