Diagnosis and Treatment of Idiopathic Bone Cavity in the Mandible: A Case Report

ABSTRACT

Idiopathic bone cavity of the mandible can often be identified in a radiographic exam. If detected, physicians should conduct follow‐up every 3–6 months, with surgical intervention considered only if the lesion becomes large or symptomatic.

1. Introduction

Idiopathic bone cavity (IBC), also known as simple bone cyst or traumatic bone cyst, is an uncommon asymptomatic lesion that lacks an epithelial lining [1]. Although they can affect any bone, about 10% of IBCs are located in the mandible [2], usually in posterior areas [3]. In rare instances, they can be found in the maxilla [2]. The cavity either is empty or contains serosanguinous fluid [4], depending on the age of the lesion [5].

Both the pathogenesis and etiology of idiopathic bone cavity are inconclusive [4]. There are three etiological theories: bone growth abnormalities, tumor degeneration, and traumatism [6]. Other reports include developmental abnormalities, blocked lymphatic drainage, and osteolysis as other possible causes [7].

There are several ways to diagnose simple bone cysts through histological, radiographic, and surgical means [8]. A histological investigation of the lesion would analyze available tissue [9]. Lesions are typically identified through radiographic examinations [7], where they appear radiolucent [4]. Interdental scalloping and an intact lamina dura are some radiographic observations that may suggest the presence of an idiopathic bone cavity [7]. But there are limitations associated with radiographic diagnosis. Due to traumatic bone cyst's similar appearance to other bone lesions, radiographs do not always provide a definitive conclusion, so other methods are possibly needed for correct diagnosis [10]. Studies have shown that surgical exploration is maybe needed to confirm the lesion's absence of an epithelial lining [8, 9].

Although the lesion is often asymptomatic, pain is a symptom in 10% to 30% of patient cases [1, 11]. Uncommon symptoms include tooth sensitivity, delayed eruption of permanent teeth, and fistulas [1, 12]. The jaw's cortical plate can expand mostly in the buccal, which can cause both intraoral and extraoral swelling [12].

Idiopathic bone cavity's appearance differs based on factors such as size, location, sex of patient, and recurrence of the lesion [6]. The lesion is prevalent among children and young adults, specifically in their second decade of life [4, 6, 8, 9]. Some studies state that there is no link between the condition and sex [6].

Treatment for idiopathic bone cavity is still disputed and varies on a case‐by‐case basis [2]. Some cases have shown that traumatic bone cyst can heal on its own without the need for any intervention [9]. However, many studies suggest that surgical intervention is needed for large IBCs; specifically with symptomatic cases, surgery is the most viable treatment approach if there are changes with the boundary, size, and cortical bone [13]. To stimulate healing, procedures include curettage, cavity packing, exploration, and fenestration [6]. Surgical exploration and curettage are strongly advocated as treatment for IBC [8]. While surgical exploration confirms diagnosis of the lesion, curettage is done to the walls of the cavity to induce bleeding [5], causing bone production and differentiation of mesenchymal cells [2]. Similarly, injection of autologous blood into the cyst can induce the same results as curettage [2, 11]. Several benefits of surgical management include conclusive diagnosis and treatment of the lesion performed simultaneously in surgery [12].

Recurrence of the lesion can occur after surgical treatment, particularly when multiple cavities are present [14]. While older reviews reported recurrence rates of approximately 2%, recent studies suggest that idiopathic bone cavity of the mandible exhibits a higher recurrence rate than previously estimated [14]. For instance, a 2007 study found that 34 out of 132 cases (26%) showed persistence of the lesion [14]. In all 132 cases, signs of either recurrence or complete healing were observed within 3 years and 5 months following surgical treatment, suggesting this as the average timeframe to determine persistence [14]. Additionally, risk factors for recurrence include larger lesion size, the presence of multiple cavities, scalloping around teeth, and surgical access without curettage [10].

Because of its unclear nature, idiopathic bone cavity presents many diagnostic and treatment challenges to oral health clinicians. We explore a case focused on the diagnosis and treatment of an enlarged and symptomatic idiopathic bone cavity, which was confirmed through surgical exploration and biopsy.

2. Case History/Examination

A case examined at the University of Southern California's Herman Ostrow School of Dentistry displayed an idiopathic bone cavity in a young patient. A 19‐year‐old Hispanic male was referred to the oral medicine clinic after radiolucency was incidentally discovered on the right side of the patient's mandible, as shown in Figure 1. The patient reported a dull, intraoral sensation of pain in his right mandible, only occurring when he bites on the right side. He described his pain as having a severity of 4 out of 10, noting that it had been present intermittently for 1 year since it first began. Regarding past medical history, the patient does not have systemic conditions or take medication. The patient exhibits expansion of the buccal alveolar plate from tooth #30 until tooth #31. He exhibited no facial or mandibular asymmetry or deformities, and temporomandibular joint (TMJ) function was normal. Salivary function is normal, including salivary flow, ducts, and tissue hydration. There is no observable tissue lesion noted.

FIGURE 1.

A panoramic image, taken in 2018, of the patient displayed a radiolucent entity in the right posterior mandible.

3. Methods (Differntial Diagnosis, Investigations and Treatment)

During the panoramic examination, a unilocular, well‐defined radiolucent area associated with the roots of teeth #29, #30, #31, and the mesial surface of the unerupted tooth #32 was observed. The borders of the lesion appear sclerotic, and it extends below the inferior alveolar canal, closely related to the lower cortical bone of the mandible. The percussion test results show that teeth #29, # 30, and # 31 responded positively, in which the patient rated the pain 4 out of 10. Probing results were between 3 and 4 mm. A cone beam computed tomography (CBCT) scan of the lower right side of the jaw was taken, displaying nerve tracing, as shown in Figure 2, and thin cortices and expansion of the buccal alveolar plate, as shown in Figure 3. A cold vitality test was performed, with the contralateral teeth tested first to familiarize the patient with the normal response. Assessment of the area was consistent with non‐pathologic pulp.

FIGURE 2.

CBCT of lower right area with nerve tracing. Well‐defined expansile low‐density lesion from distal of #29 to mesial of #32. The lesion has expanded bucco‐lingually, thinning the cortices.

FIGURE 3.

CBCT of lower right showing the expansion and thin cortices in the right mandible compared to the left.

Based on radiographic findings by an oral radiologist, the condition was described as a well‐defined, expansile radiolucency in the area of teeth number 29–32, which suggests the presence of a benign neoplasm of the lower jawbone. Differential diagnosis includes ameloblastic fibroma, ameloblastoma, and possibly a keratocyst, but a biopsy is advised for definitive diagnosis.

4. Conclusion and Results (Outcome and Follow‐Up)

A biopsy was performed. A full‐thickness flap was elevated. A surgical bur was used to open a window in the buccal cortical bone. The content of the cavity was aspirated, finding that there was only heme and no evidence of cystic fluid or pus. Then, the walls of the lesion were curetted, and the surgical site was cleaned with saline, which triggered bleeding within the cavity. There was no evidence of a lining epithelium, cyst or cyst wall, vascular tissue, or any abnormal tissue inside the cavity.

Several clinicians suggested that the condition was traumatic bone surgery based on the clinical appearance. For further confirmation, a buccal cortical bone sample was placed in formalin for pathologic analysis and histologic diagnosis. Ultimately, the biopsy's results concluded that the patient had a traumatic bone cavity.

The surgical site on the right alveolar mucosa healed within normal limits at the one‐week follow‐up, with no signs of infection. The patient reported mild pain to palpation during the healing process.

Following the surgery, the patient was advised to avoid vigorous physical activity to minimize the risk of trauma to the mandible until normal bone formation was observed. He was prescribed NSAIDs for pain and trained to look for abnormalities or bony expansions, contacting the clinic if necessary. He was recommended to have a 6‐month follow‐up. At a 5‐month follow‐up, the panoramic radiograph showed evidence of healing and bone formation in the posterior area that was initially radiolucent, as shown in Figure 4.

FIGURE 4.

Five month follow‐up radiograph displaying evidence of bone formation and healing.

Idiopathic bone cavity is a lesion devoid of an epithelial lining located in the mandible. If found, the condition should be actively monitored for changes. Radiographic screening may provide a baseline, but it is suggested that surgical exploration and induced bleeding are necessary for the diagnosis and treatment of lesions that grow in size and become symptomatic. Follow‐up screenings are recommended to assess the progress of healing and monitor for any signs of recurrence.

Given the uncertain etiology, factors such as genetic predispositions, clinical presentation, and radiographic findings may all play a role in influencing lesion recurrence. Further research is needed, particularly in exploring genetic factors and the long‐term outcomes of various treatment approaches. A deeper understanding of these aspects will contribute to improved diagnosis, treatment, and management of idiopathic bone cavities.

5. Discussion

Panoramic and CBCT radiographic images depicted radiolucency in which the clinicians identified as a benign neoplasm in the lower jaw bone, but were insufficient in diagnosing the condition. Differential diagnosis included odontogenic keratocyst, ameloblastoma, hemangioma, ameloblastic fibroma, and traumatic bone cavity. According to the World Health Organization, odontogenic keratocyst is a cyst that has a stratified, squamous epithelium [15], which was not observed during the surgery. Similarly, ameloblastoma is a lesion that possesses an epithelial lining [16], which was absent. Hemangiomas are described as a proliferating mass of blood vessels [17], which was not present during the procedure. While ameloblastic fibroma can occur in the mandible and is often found in the posterior region, like idiopathic bone cavity, it is characterized by epithelial islands [18], which were not identified. The surgical procedure revealed the absence of an epithelial lining, a definitive characteristic of traumatic bone cavity, and the biopsy of the buccal cortical bone plate sample confirmed the diagnosis of idiopathic bone cavity.

Follow‐up imaging confirmed progressive bone healing. The healing was surgically induced; fenestration of the buccal cortical bone, irrigation of saline, and curettage of the walls triggered bleeding within the cavity, stimulating subsequent bone formation. Both curettage and fenestration are methods to cause healing within the cavity [6]. Bone production and differentiation of mesenchymal cells are caused when bleeding occurs inside the lesion [2].

Recent studies on idiopathic bone cavity have shown higher rates of recurrence than previously estimated [14]. As a result, longer‐term follow‐up, typically extending beyond a few years, is essential to accurately determine whether the patient's lesion has recurred. Studies have suggested that signs of recurrence or healing can be observed within approximately 3 years and 5 months after surgical treatment, making extended follow‐up crucial for detecting persistent lesions [14].

Author Contributions

Bryan Do Nguyen: formal analysis, writing – original draft, writing – review and editing. Elham Radan: project administration, resources, supervision, writing – review and editing.

Consent

Written patient consent has been signed and collected in accordance with the journal's patient consent policy.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.