Abstract: Abstract： Objective To study the healing and long-term retention rate of replantation in treatment of avulsion of apical closure of permanent teeth with different fixing methods, fixing time and pulp remove time , root canal filling time. Methods 56 patients were included and 83 apical closure of permanent teeth avulsion were randomly divided into two groups, the conventional treatment groups using traditional treatment, and the improved groups using replantation and fixing for 2-3 weeks. After 2 weeks, the pulp was removed and root canal was filled with VITAPEX (Cataplasm of iodoform calcium hydroxide).1 months later, it was treated by routine root canal therapy. A following-up study of 5 years was carried out then, and the recent and long-term healing and retention were compared. Results The Periodontal ligament healing rate of improved groups was higher than that of the conventional groups after replantation, while the bone adhesion rate and inflammatory absorption rate were lower and the difference was statistically significant (P<0.05). The retention rate of the improved groups was a little higher than the conventional group after 1 and 2.5 years, but there was no significant difference (P> 0.05).The retention rate of improved groups(86.50%) was higher than the conventional groups (67.50%) after 5 years, and there was a significant difference(P <0.05).Conclusions The improved methods have better clinical effect on improving the Periodontal ligament healing, reducing the root resorption and improving the long-term efficacy than the conventional methods in the replantation to the apical closure of permanent teeth avulsion.

Key words: replantation, fixation, root canal therapy