Ⅰ. INTRODUCTION
Various cystic diseases and benign tumors can develop in the jaw, and constitute a large portion of specimens in oral and maxillofacial pathology practice, making accurate diagnoses through comprehensive analysis essential. Diagnosis typically involves a combination of clinical, radiological, and histopathological examinations to differentiate lesions in the oral cavity.
During clinical examinations, objective tests such as palpation, percussion, and pulp vitality tests are performed based on the patient’s subjective symptoms. Radiological examinations include panoramic radiographs, intraoral radiographs, and, when necessary, cone beam computed tomography (CBCT) to evaluate the lesion’s characteristics in detail. Pathohistological examination is conducted by collecting a specimen during surgery and analyzing it to confirm the diagnosis.
These three methods—clinical, radiological, and histopathological examinations—are integrated to perform a diagnosis of radiolucent lesions in the jaw. In particular, radiolucent lesions often share similar patterns, necessitating careful evaluation to distinguish between different types of cysts and tumors.
This study focuses on four common radiolucent lesions in the jaw: ameloblastoma, dentigerous cyst, odontogenic keratocyst (OKC), and radicular cyst. The primary objective is to analyze their incidence rates, anatomical locations, and recurrence rates to provide a clearer understanding of their clinical characteristics.
Ⅱ. MATERIALS and METHODS
From 2016 to 2020, a total of 1,293 patients diagnosed with cystic diseases or benign tumors presenting radiolucent features at Pusan National University Hospital underwent cyst enucleation or excision under general anesthesia. The excised specimens were sent to the Department of Pathology at Pusan National University Hospital in Yangsan for definitive histopathological diagnosis.
Patients were included in the analysis only if their diagnoses were consistent across clinical, radiological, and histopathological examinations. The incidence rate, anatomical location, and recurrence rate of these lesions were assessed. Lesion locations were classified into four categories: anterior maxilla, posterior maxilla, anterior mandible, and posterior mandible. Recurrence was defined as the reappearance of the lesion at the same site within five years following surgery.
Ⅲ. RESULTS
In the past five years, a total of 1,293 patients have been diagnosed with oral cystic diseases and benign tumors that exhibit radiolucent features in the jaw through clinical and radiological examinations. All patients underwent surgical intervention under general anesthesia, including cyst enucleation or excision. Diagnoses were confirmed through consistent findings across clinical, radiological, and histopathological examinations, ensuring the accuracy of the results.
There were 1,184(91.57%) odontogenic lesions and 109(8.43%) non-odontogenic lesions. (Table 1) Among the odontogenic cysts, dentigerous cysts were the most common, accounting for 39.75% of all cases, followed by radicular cysts (28.31%) and odontogenic keratocysts (15.24%). Less frequent odontogenic cysts included residual cysts (1.24%) and benign cysts (1.62%), representing a smaller proportion of the total lesions.
In contrast, non-odontogenic cysts were less prevalent in this study. The most common was the incisive canal cyst, which comprised 7.35% of all cases. Other non-odontogenic cysts, such as post-operative maxillary cysts (0.54%), simple bone cysts (0.39%), mucous retention cysts (0.08%), and central giant cell granulomas (0.08%), were identified at much lower frequencies.
The dist ribution of the identified lesions is detailed in Fig. 1, highlighting the frequency of various jaw lesions diagnosed in this study.
Anatomical location analysis revealed notable patterns in the distribution of these lesions. (Table 2) Radicular cysts are primarily localized in the maxillary anterior region, accounting for 48.56% of cases, while dentigerous cysts and odontogenic keratocysts (OKCs) show a strong predilection for the mandibular posterior region, with 67.11% and 64.53% of cases, respectively. Ameloblastomas are also most frequently observed in the mandibular posterior region, comprising 70.42% of cases, indicating this area is a hotspot for odontogenic lesions. In contrast, the mandibular anterior region demonstrates the lowest lesion frequency overall, suggesting a reduced susceptibility to both odontogenic and non-odontogenic lesions. Non-odontogenic lesions, such as incisive canal cysts, are predominantly found in the maxillary anterior region, accounting for 7.35% of all cases. Less common lesions, including post-operative maxillary cysts, simple bone cysts, and mucous retention cysts, are distributed sparsely, with minimal frequencies, reflecting their rarity.
A clear trend can be observed in the localization of certain lesions, and the significant majority of ameloblastomas (70.42%), dentigerous cysts (67.11%), and odontogenic keratocysts (64.53%) were localized to the mandibular posterior region. In contrast, 48.56% of radicular cysts were predominantly observed in the maxillary anterior region. These findings highlight a clear predilection for posterior mandibular involvement among ameloblastomas, dentigerous cysts, and OKCs, while radicular cysts demonstrated a strong association with the anterior maxilla.
The recurrence analysis revealed that, among the total 1,293 patients, a subset exhibited disease recurrence at the same site within five years post-surgery. Specifically, recurrence was observed in 17 cases of ameloblastoma, accounting for a recurrence rate of 24.29%, and in 46 cases of OKC, corresponding to a recurrence rate of 23.35%. Additionally, recurrence occurred in 1 case of radicular cyst, 1 case of incisive canal cyst, and 1 case of POMC.
Ⅳ. DISCUSSION
This study provides valuable insights into the incidence, anatomical distribution, and recurrence rates of cystic diseases and benign tumors presenting with radiolucent features in the jaw. Among the 1,293 patients analyzed, 88.71% were diagnosed with one of the four major lesions—ameloblastoma, dentigerous cyst, odontogenic keratocyst (OKC), or radicular cyst. Dentigerous cysts were the most commonly observed (34.75%), followed by radicular cysts (28.31%), OKCs (15.24%), and ameloblastomas (5.41%). These findings are consistent with the report by Johnson et al.1, who identified radicular cysts as the most common odontogenic cysts, followed by dentigerous cysts and keratocystic odontogenic tumors.
The study conducted by Tom D. et al.2, revealed that radicular cysts were the most common odontogenic cysts (65.15%), followed by dentigerous cysts (24.08%) and odontogenic keratocysts (4.88%). Among odontogenic tumors, odontomas were the most frequently observed (51.53%), with ameloblastomas (13.52%) being the second most common. These findings highlight the significance of geographic variations in lesion incidence and provide valuable insights for clinicians in patient counseling and diagnosis.
The findings of this study differ from those of Tom D. et al. in several aspects, particularly in the relative frequencies of odontogenic cysts and tumors. While radicular cysts were the most common in both studies, their incidence was notably lower in this study (28.31%) compared to the 65.15% reported by Tom D. et al. Similarly, dentigerous cysts were more prevalent in this study (34.75%) compared to their incidence in the study by Tom D. et al. (24.08%). Moreover, odontogenic keratocysts showed a significantly higher incidence in this study (15.24%) compared to 4.88% reported by Tom D. et al. These differences may reflect variations in geographic location, patient demographics, or diagnostic practices, underscoring the importance of regional studies in understanding the true epidemiology of these lesions.
Jing W. et al. reported a retrospective analysis of 1,642 odontogenic tumor cases from Sichuan University, China3, revealed that 97.0% were benign and 3.0% were malignant, based on WHO 2005 histopathological classification. Ameloblastoma (40.3%) was the most common tumor, followed by keratocystic odontogenic tumor (35.8%), odontoma (4.7%), and odontogenic myxoma (4.6%), and this aligns with the tumor rankings observed in the present study.
The anatomical distribution of these lesions demonstrated clear patterns. Ameloblastomas (70.42%), dentigerous cysts (67.11%), and OKCs (64.53%) predominantly occurred in the posterior mandible, while radicular cysts were most frequently found in the anterior maxilla (48.56%). This aligns with previous studies.
Aborisade A. et al.4 reported a predominant predilection for the mandible, observed to be as high as 80 % and predominantly in the posterior body–ramus axis and Koivisto et al.5 reported 58.8% of ameloblastomas in the posterior mandible, and Tamiolakis et al.6 observed similar mandibular tendencies for dentigerous cysts and OKCs. However, this study noted slightly lower localization rates of ameloblastomas in the posterior mandible (70.42%) compared with Cadavid et al.7, who reported 83.1%. Such variations may result from differences in sample sizes or demographic factors, which warrant further investigation.
Recurrence analysis revealed significantly high rates for ameloblastomas (24.29%) and OKCs (23.35%), emphasizing the need for careful surgical management and long-term follow- up in these cases. These findings are consistent with other studies reporting a high recurrence tendency for these lesions. De Ac Almeida, R. et al. reported an ameloblastoma recurrence rate of 18.37% through a meta-analysis.8 Milman, T et al. reported 24% recurrence of ameloblasomas.9 Chrcanovic inducted a systematic study of recurrences of OKCs in different variables and treatment protocols.10 Among 6427 KCOTs, 1464 recurrences (22.78%) were reported, and the recurrence was not affected by sex or location in the jaw, but by locularity (Unilocular vs. multilocular, RR 0.67, P = 0.007).
In contrast, no recurrences were observed for dentigerous cysts or radicular cysts. The absence of recurrence in dentigerous cysts is likely due to the surgical extraction or eruption of impacted teeth during the procedure, effectively addressing the underlying cause. Similarly, the lack of recurrence in radicular cysts can be attributed to root canal treatment performed before cyst enucleation, which eliminates the pathogenesis.
While the findings of this study align with many previous reports, it is important to note its limitations. The study was conducted at a single institution, potentially limiting the generalizability of the results. Additionally, the retrospective nature of the study may have introduced selection bias. Future studies should focus on larger, multicenter cohorts to validate these findings and explore the genetic or molecular factors contributing to the high recurrence rates observed in ameloblastomas and OKCs.
Ⅴ. CONCLUSION
There are many cystic diseases and benign tumors with radiolucent lesions in the jaw. In this study, the incidence rate, location, and recurrence rate of ameloblastoma, dentigerous cyst, OKC, and radicular cyst were analyzed. In the future, it will be helpful in diagnosing cystic diseases and benign tumors in the jaw by examining the lesions caused by various conditions such as age and sex, systemic diseases, and daily life habits of patients.
This study provides clinically significant insights into the management of cystic diseases and benign tumors with radiolucent features in the jaw. The findings highlight that while lesions such as dentigerous cysts and radicular cysts are effectively managed with current treatment protocols, ameloblastomas and odontogenic keratocysts (OKC) present considerable challenges due to their high recurrence rates.
The recurrence of ameloblastomas and OKCs underscores the need for meticulous surgical techniques, combined with long-term monitoring to improve patient outcomes. In contrast, the absence of recurrence in dentigerous cysts and radicular cysts demonstrates the importance of addressing their underlying causes, such as impacted teeth and root canal pathology, as part of the treatment strategy.
To advance the management of these lesions, further research should explore innovative surgical approaches and adjunct therapies aimed at minimizing recurrence, particularly for lesions prone to relapse. Additionally, investigations into the genetic and molecular factors associated with recurrence may provide new avenues for treatment and prevention.
In conclusion, this study highlights the critical importance of accurate diagnosis and personalized treatment strategies for managing cystic diseases and benign tumors of the jaw. Effective treatment planning, based on a comprehensive understanding of the characteristics of each lesion, is essential to ensure optimal care and improve long-term outcomes for patients. Dentigerous cysts and radicular cysts, being the most common lesions, are effectively controlled with current treatment methods, as evidenced by their absence of recurrence. However, the high recurrence rates associated with ameloblastomas and odontogenic keratocysts (OKCs) underscore the need for advanced surgical techniques and vigilant postoperative monitoring to enhance patient outcomes. To address these challenges, further research is needed to explore the biological mechanisms driving these lesions and to develop more effective surgical strategies to minimize recurrence rates.
DECLARATION
Ethics approval and consent to participate
This case report was approved by the Institutional Review Board of Pusan National University Dental Hospital (PNUDH-2022-10-002). Written informed consent was obtained from the patient's legal guardian for participation in this study.
Consent for publication
Written informed consent was obtained from the patient's legal guardian for publication of this case report and accompanying images.
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.
Competing interests
The authors declare that they have no competing interests, financial or non-financial, in relation to this work.
