Background: Ameloblastoma are benign but locally invasive neoplasms that represent 10% of all odontogenic tumors. Despite its benign characteristics, ameloblastoma has a high recurrence rate after treatment with a recurrence rate of 55-90%. It is important to identify the risk factors of recurrence to improve patient’s quality of life in oral and maxillofacial surgery. Methods: Patients who underwent surgery at the Department of Oral and Maxillofacial Surgery at Pusan National University Dental Hospital for 5 years from 2017-2021 and were diagnosed with ameloblastoma as a result of postoperative histological examination were included. The patients were divided into two groups, recurrent and non-recurrent, and comparative analysis was performed according to various factors. Results: First, when the lesion was involved with the inferior alveolar nerve (IAN), recurrence was more likely than when it was not. Next, recurrence occurs more often when cortical bone perforation is observed than when it is not. In particular, when resorption is shown on the lingual cortical bone, a remarkable tendency of recurrence is shown. Moreover, in radiographic characteristics, the multicystic type showed a higher recurrence tendency than the unicystic type. Conclusion: When the lesion is multicystic, perforating the cortical bone, infiltrating the adjacent soft tissue, or involving the IAN, a high recurrence rate is shown. The results of this retrospective analysis of the recurrence trend of ameloblastoma over a 5 years period are to contribute significantly to insight and reduction of recurrence rates in treatment for polymorphic lesion in oral and maxillofacial area.

Abstract
Ⅰ. BACKGROUND
Ⅱ. METHODS
    1. Patients
    2. Dada analysis
Ⅲ. RESULTS
    1. Sex
    2. The site of lesion
    3. Teeth involvement
    4. Inferior alveolar nerve (IAN) involvement
    5. Buccal cortical bone resorption
    6. Lingual cortical bone resorption
    7. Radiographic characteristic
Ⅳ. DISCUSSION
Ⅴ. CONCLUSIONS
ACKNOWLEDGMENTS
REFERENCES

• 권진주(부산대학교 구강악안면외과학교실, 치과병원 치의학연구소) | Jin-Ju Kwon (Department of Oral and Maxillofacial Surgery, Dental Research Institute, Pusan National University Dental Hospital)
• 안상욱(부산대학교 구강악안면외과학교실, 치과병원 치의학연구소) | Sang-Wook Ann (Department of Oral and Maxillofacial Surgery, Dental Research Institute, Pusan National University Dental Hospital)
• 하규봉(부산대학교 구강악안면외과학교실, 치과병원 치의학연구소) | Gyu-Bong Ha (Department of Oral and Maxillofacial Surgery, Dental Research Institute, Pusan National University Dental Hospital, Yangsan)
• 신상훈(부산대학교 구강악안면외과학교실, 치과병원 치의학연구소, 부산대학교 치의학 생명과학연구소) | Sang-Hun Shin (Department of Oral and Maxillofacial Surgery, Dental Research Institute, Pusan National University Dental Hospital, Yangsan, Dental and Life Science Institute, Pusan National University) Corresponding author