Abstract: Objective To analyze the effect of Non-surgical Root canal therapy for large Periapical cyst-like lesions. Methods From January 2015 to December 2020, 60 cases of periapical cystic lesions with the maximum diameter of more than 10mm were treated in the Affiliated Stomatological Hospital of Nanjing Medical University, in which，there are 32 cases only treated with none-surgical root canal treatment in group A , and the other 28 cases in group B with apical surgery after root canal therapy. Then regular follow-up observation was carried out after treatment. Results After 3-18 months of follow-up, 12 of the 32 patients in group A healed, 16 improved, 4 did not see significant changes in the root lesion, the effective rate was 87.5%. Of the 28 patients in group B, 16 were cured and 12 were improved, with an effective rate of 100%. Statistically, there was no significant difference between the two groups (P>0.05). Conclusion Non-surgical treatment has a high success rate for large periapical cyst-like lesions, which can be used as the preferred method for large apical cystic lesions without acute symptoms.

Key words: Periapical cyst-like lesions , Non-surgical treatment Root canal therapy , effective