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ISSN : 1225-1577(Print)
ISSN : 2384-0900(Online)
The Korean Journal of Oral and Maxillofacial Pathology Vol.46 No.6 pp.143-147

Clinical and Radiological Factors Related to the Recurrence of Ameloblastoma: A Retrospective Study

Jin-Ju Kwon1), Sang-Wook Ann1), Gyu-Bong Ha1), Sang-Hun Shin1),2)*
1)Department of Oral and Maxillofacial Surgery, Dental Research Institute, Pusan National University Dental Hospital, Yangsan,
South Korea
2)Dental and Life Science Institute, Pusan National University, Busan, South Korea

# These authors contributed equally to this manuscript.

* Correspondence: Sang-Hun Shin, DDS, PhD, Department of Oral and Maxillofacial Surgery, School of Dentistry, Pusan National University, Yangsan 50162, South Korea. Tel: +82-55-360-5113 Fax. +82-55-360-5104 Email:
October 31, 2022 November 8, 2022 December 16, 2022


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.

법랑모세포종 재발과 연관된 임상 및 방사선 요인

권 진주1), 안 상욱1), 하 규봉1), 신 상훈1),2)*
1)부산대학교 구강악안면외과학교실, 치과병원 치의학연구소
2)부산대학교 치의학 생명과학연구소



    Ameloblastoma is the most common odontogenic tumor of the jaw bone, and its origin is known from gingival residues, degenerated enamel epithelium, Malassez epithelial residues, and basal cells of the superficial oral mucosa epithelium. Histologically, it is a benign tumor, but it shows local infiltration into adjacent tissues and destructive growth patterns, and facial deformation and dysfunction, showing a clinically similar course to malignant tumors and a high recurrence rate.(1)

    According to an article by Andrii Hresko and his colleagues, the recurrence rate of ameloblastoma was 35%.(2) Moreover, Hong J reported that the recurrence rate after conservative treatment was 29.3%.(3) Due to the similar tendency to malignant tumors of ameloblastoma and the high recurrence rate, it is necessary to evaluate the risk factor that can cause recurrence for surgery, and in-depth studies on clinical characteristics and prognosis are significantly required.

    The radiographic characteristics of ameloblastoma are variable according to the stage and type of tumor progression. The margin of lesion is usually clear, but depending on the location of the lesion, the boundary of tumor may be unclear. The internal structure may be observed as a unilateral radiographic image in the case of early ameloblastoma or as polymorphic by an internal septum in maxillary area.(4) Compared to other tumors, root resorption is significantly common and tooth displacement could be occurred. As the tumor progresses, perforation of cortical bone could be observed and invasion of adjacent anatomical structures can occur. Because of these characteristics, the recurrence and progression of ameloblastoma is significantly difficult to predict.

    The purpose of this study was to identify the risk factors for recurrence in patients histopathological diagnosed with ameloblastoma after undergoing surgery at Pusan National University Dental Hospital over the recent 5 years.


    1. Patients

    The 64 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 histological examination were selected. They were divided into two groups: 28 patients with recurrence and 36 patients without recurrence.

    2. Dada analysis

    They were classified according to gender, site of lesion, dental involvement, inferior alveolar nerve (IAN) involvement, cortical bone erosion, and radiographic features. The site of occurrence, size, destruction of the maxillary cortical plate, and IAN involvement were confirmed by panoramic radiography, Cone Beam Computed Tomography (CBCT), Magnetic Resonance Imaging (MRI), and surgical operative records.


    1. Sex

    Recurrence occurred in 19 out of 48 male patients and 9 out of 16 female patients, respectively.

    2. The site of lesion

    Out of 64 cases, there were 9 anterior region cases and 6 were recurred. In the premolar area, there were a total of 16 cases and 8 cases of recurrence were observed. The posterior area showed the most cases with 39 cases. There were 14 recurrence cases. Moreover, by site, a total of 29 cases occurred in the left side of patient, among which there were 15 cases without recurrence and 14 cases with recurrence.

    3. Teeth involvement

    In the case of teeth involvement, 13 cases did not recur and 5 cases did. In the case of lesions separated from the teeth, 23 cases did not recur and 23 cases did.

    4. Inferior alveolar nerve (IAN) involvement

    In the case of IAN involvement, 17 cases did not recur and 22 cases did. In cases not related to nerves, 19 cases did not recur and 6 cases did.

    5. Buccal cortical bone resorption

    Of the 64 patients, all 32 patients showed a perforation pattern of the buccal cortical bone, of which 19 patients (67.9%) showed recurrence. There were 32 patients without buccal cortical bone erosion, and only 9 of them showed recurrence.

    6. Lingual cortical bone resorption

    Of the 26 patients with perforation in the lingual cortical bone, 17 patients (60.7%) had recurrence, and 11 patients out of 38 patients without resorption findings.

    7. Radiographic characteristic

    Of the total patients, 32 radiographically showed a unicystic lesion, and the remaining 32 patients showed a polycystic lesion. In unicystic characteristic lesions, 5 cases had recurrences, whereas in multicystic lesions, 23 cases had recurrences.


    Ameloblastoma is an epithelial odontogenic tumor derived from the tissues of the odontogenic apparatus. It is a benign tumor but shows a locally invasive growth pattern and similar findings to the component of enamel hair cells. Ameloblastoma is generally classified into follicular, plexiform, acanthomatous, granular cell, basal cell, and desmo-plastic based on the histology. Histological classification has been variously classified, but there is a difference between histological and clinical forms. Several scholars have reported that there is no correlation.(5, 6) It is necessary to know about these various ameloblastoma characteristics because surgery can be performed from conservative management to radical resection.

    The careful treatment decision is required as it can invade the sinuses, orbit, nasopharynx, and even the cranial base when it occurs in the maxilla. In some cases, radiographically, it appears as a honeycomb appearance consisting of a number of locules or a soap bubble appearance consisting of relatively large chambers of various sizes.(7) As the lesion grows, ameloblastoma can partially perforate the cortical bone and involve in adjacent anatomical structures.

    When the lesion invaded the inferior alveolar nerve, 22 recurrences occurred, showing statistically significant results. This is thought to be because, when the lower alveolar nerve and the lesion are related, it is difficult to remove the lesion radically due to the possibility of nerve damage and it is difficult to accurately define the lesion boundary.

    According to the results of previous studies, there was no significant difference in the frequency of incidence according to gender. The average age at first visit of ameloblastoma patients was reported to vary from 37.6 years to 38.9 years.(8, 9) In this study, the average age was 34.3 years, and it was found to be most common in the 20s, and the highest rate was also seen in those in their 30s and 40s. Adekeye reported that unicystic ameloblastoma is 10.1% regarding the frequency of occurrence according to the shape of the lesion.(10) Moreover, Sirichitra and Dhiravarangkura reported that multifocal ameloblastoma is 89.9%, and the incidence of multifocal lesions was higher than that of monocystic lesions.(11)

    According to the study of the size of the lesion, Park et al. reported that the diameter varied from 20 mm to 150 mm, and the lesion between 40 mm and 80 mm was the most frequent with 65.2%.(12) In this study, between 10 mm and 140 mm of lesions were observed, and the incidence rate (71.4%) was high in lesions between 30 mm and 69 mm.

    Park and his colleagues reported a cortical bone perforation rate of 42.9% for ameloblastoma, which showed high invasive growth.(12) In this study, the cortical bone perforation rate was 66.0%. It is reported that most of the ameloblastoma are relatively well demarcated with respect to the surrounding normal tissue, so that the boundaries of the lesions can be easily distinguished even on radiographic findings. Despite these characteristics, it is necessary to consider that the recurrence rate is high when cortical bone erosion is observed.


    In this article, when the lesion is multilocular, perforating the cortical bone, infiltrating the adjacent soft tissue, or involving the IAN, a high recurrence rate is shown. Gender, site of occurrence and dental involvement were not significantly observed to have correlation with recurrence.

    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 decisions for polymorphic lesion in oral and maxillofacial area.


    Ethical approval statement: This study was ethically approved by the Institutional Review Board of Pusan National University Dental Hospital (IRB No.PNUDH-2002-10-001)



    Characteristics of the subjects and patient in this study


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