Abstract: Objective: To evaluate the effects of endodontic microsurgery in large persistent periapical lesions combined with guided tissue regeneration (GTR) and anorganic bovine bone. Methods: A total of eighty patients with persistent apical periodontitis (≥10 mm in periapical radiographs) were included and randomly grouped into two groups. During the endodontic microsurgery, the defect in the test group was filled with anorganic bovine bone and covered by resorbable collagen membrane. In the control group, neither graft nor membrane was used. Six months and one year later, the clinical index was recorded. Results: The success rate of the experimental group was significantly higher than that of the control group after 6 months (P＜0.05), while the difference was not statistically significant after one year. There was no significant difference in the success rate after 6 months, when the lesion had a perforated palatal/lingual cortical plate. However, the difference was statistically significant after one year (P＜0.05). Conclusion: GTR combined with anorganic bovine bone can significantly promote the regeneration of the bone and reduce the healing time, which is beneficial to the healing of the large periapical lesion with a perforated palatal/lingual cortical plate.

Key words: Endodontic microsurgery, Guide tissue regeneration, Collagen membrane, Anorganic bovine bone