Objective To evaluated the outcomes of the teeth avulsed from alveolar bone in accidents for a 1 year follow up when endodontic root canal therapy was performed at different time points. Materials and Methods According to the inclusion criteria, 109 patients diagnosed with teeth avulsion due to accidents were enrolled at base-line and 103 patients finally completed follow-up in this trial. 115 teeth were firstly assigned to two groups according to storage condition. Then they were randomly assigned to one of two groups respectively. The teeth were treated with root canal therapy at different stages. All of patients were recalled at baseline, in the first, third month, sixth month and first year (end of follow-up) for clinical and radiological evaluation. Results 103 patients finally completed follow-up in this trial. As for periodontal healing, cases with before-replantation treatment were significantly more than post-replantation treatment in dry storage. On the contrary, more periodontal healing cases were obtained in ideal storage. In the first year after treatment, there was no difference of success rate between G21 and G22 (P < 0.05). Significant difference was found between G11 and G12 (P < 0.05). Conclusion In clinical practice, root canal therapy should be performed prior to replantation in dry storage condition for more than 60 minutes. In contrast, if not, root canal therapy could be postponed.