Cementoblastoma Mimicking Pathology of Endodontic Origin: A Case Report

The lesion usually presents with pain and associated swelling due to bony expansion of the buccal or lingual alveolar ridges.⁵ In rare cases, cementoblastoma has been reported to be associated with a primary or impacted tooth.^2,3,6 Histologically, cementoblastoma is characterized by deposits of cementum-like tissue directly on the root of a tooth. Given its high rate of recurrence, the treatment of choice for cementoblastoma is complete surgical excision of the lesion with concurrent extraction of the affected tooth.^4,5

This article documents a case initially referred to an endodontist due to suspicion of pathology of endodontic origin. The final diagnosis, however, was ultimately determined to be a cementoblastoma.

A healthy (American Society of Anesthesiologists class I) 38-year-old female patient was referred to an endodontics practice for evaluation of a radiopaque apical lesion. On general examination, the patient presented in good physical health. She reported neither daily medication use nor medication allergies. She said that her general dentist identified the radiopacity at the apex of tooth No. 20 during her recent intraoral full-mouth series radiographs (FMX). Since then, the patient experienced mild, occasional palpation tenderness associated with the tooth but denied having experienced any spontaneous pain or biting discomfort. Although the patient presented for regular preventive care, she reported having had no dental radiographs for the previous 10 years due to multiple pregnancies.

Both extraoral and intraoral examination of the soft tissues revealed no swelling, discoloration, or asymmetries. Partial-coverage porcelain restorations with sound margins were present in the mandibular left posterior teeth. Palpation and percussion elicited mild tenderness associated with teeth Nos. 20 and 19, respectively. Pulp sensibility testing using a refrigerant spray (EdgeIce^™ Pulp Vitality Spray, Edge Endo, edgeendo.com) elicited sharp pain of short duration on teeth Nos. 19 through 21. All teeth presented with physiological mobility, probing depths less than 4 mm circumferentially, and normal occlusion. No visible cracks or fractures of tooth structure, nor soft-tissue swelling or sinus tracts were evident.

Intraoral radiographs revealed shallow restorations with intact margins, no caries, and normal periodontal ligament (PDL) space, lamina dura, and bone associated with teeth Nos. 19 and 21, and a radiopacity overlying the apex of tooth No. 20 (Figure 1). A cone-beam computed tomography (CBCT) scan of the region revealed a well-circumscribed, ovoid, radiopaque lesion attached to the lingual aspect of the apical third of tooth No. 20. The lesion had no delineation from the root structure and presented with a peripheral radiolucent halo (Figure 2 and Figure 3). Localized thinning of the buccal cortical plate was evident, suggesting tumor-related cortical bone degradation over a non-neoplastic entity like hypercementosis. As the pulp status was determined to be normal, the differential diagnosis of the radiopacity at this time included cementoblastoma, periapical cemento-osseous dysplasia, hypercementosis, and, less likely, condensing osteitis. The patient was promptly referred to an oral and maxillofacial surgeon (OMFS) for further evaluation and treatment.

The OMFS presented the patient with treatment options that included observation, nonsurgical root canal therapy (NSRCT) followed by apical surgery (with biopsy), and surgical extraction with an excisional biopsy, bone grafting, and future implant placement. Given the relatively large size of the lesion, the surgeon informed the patient of the unpredictable prognosis for NSRCT followed by apical surgery, and that an extraction represented a more predictable option. Because of the tenderness associated with tooth No. 20, the patient elected to proceed with an extraction and excisional biopsy.

Intraoperatively, the tooth was extracted separate from the lesion, given fracture of the two segments during luxation. The lesion was accessed for removal via a lateral bone window leaving the coronal buccal cortical plate intact. Tooth No. 20 and two fragments of firm tan tissue, 1.5 cm and 0.8 cm, were submitted for pathologic analysis. Histologic examination of the lesion revealed a nodule of dense cementum-like material centrally that contained scattered enlarged cementoblasts peripherally and was intimately associated with the tooth root. The overall features supported a diagnosis of cementoblastoma (Figure 4 and Figure 5).

This case report illustrates the importance of multidisciplinary care in the evaluation, diagnosis, and treatment of complex pathology, such as cementoblastoma. It demonstrates how dental practitioners need to be familiar with a wide spectrum of clinical entities to both facilitate a broad differential diagnosis and provide patients with the appropriate referral.

Clinical and radiographic presentation of the patient's lesion led to a differential diagnosis of cementoblastoma, enostosis, condensing osteitis, hypercementosis, and periapical cemento-osseous dysplasia.² Radiographically, cementoblastoma presents as a well-circumscribed, radiopaque lesion attached to the root of a tooth with a surrounding thin radiolucent zone. In particular, blending of the lesion with the affected root, without delineation between the lesion and root, is nearly pathognomonic for this entity-a feature that was evident from the patient's CBCT scan (Figure 2 and Figure 3).⁵ Additional radiographic features of cementoblastoma may include pressure-related root resorption, bony expansion, loss of the root outline, displacement of adjacent teeth and anatomic structures, cortical bone perforation, and obliteration of the PDL space.^1,2,6 Although radiographic features of cementoblastoma may strongly support the diagnosis, only a biopsy can truly distinguish the lesion from other pathoses, in particular hypercementosis.^7,8

Histologic examination of the patient's lesion revealed a dense proliferation of hypocellular cementum immediately adjacent to the affected tooth (Figure 4). Peripherally, the lesion showed increased cellularity of cementoblasts within matrix and a fibrovascular stroma consistent with cementoblastoma.^2,3,7,9 Furthermore, the cementum displayed prominent basophilic reversal lines and cementoblastic rimming (Figure 5), another feature characteristic of this pathosis. The periphery of cementoblastoma typically contains a rim of connective tissue and columns of unmineralized cellular tissue, thus creating the radiolucent zone visualized on radiographs.^2,3,7,9 Molecularly, cementoblastoma has recently been shown to harbor FOS gene rearrangements, similar to the morphologically overlapping tumors osteoid osteoma and osteoblastoma, suggesting these entities may represent a spectrum of the same disease entity.¹⁰

A principal differential diagnostic consideration in the current case was hypercementosis, a non-neoplastic proliferation of cementum involving the root of a tooth. However, the symptoms of palpation tenderness and radiographic cortical bone thinning pointed more to cementoblastoma. While the central portions of the lesion in the current case were histologically reminiscent of hypercementosis, peripherally the increase in cementoblast cellularity with slight disorganization and subtle columnar arrangement of matrix favored a diagnosis of cementoblastoma. The other main radiographic differentials, condensing osteitis and periapical cemento-osseous dysplasia, could be excluded due to association with a vital tooth and lack of a fibro-osseous component histologically, respectively.

The treatment of choice for cementoblastoma is complete surgical excision of the lesion with concurrent extraction of the affected tooth.^5,7 Other treatment modalities reported in the literature include: en bloc resection, root amputation with concurrent tumor excision, curettage of the lesion without tooth extraction, and root canal therapy followed by an apicoectomy with concurrent tumor excision.^3,4,8 Due to the extent of the lesion in conjunction with the surgeon's concerns, the patient elected surgical excision of the lesion with concurrent extraction of the involved tooth.

The clinical outcome of this case was critically dependent on collaboration among a multidisciplinary team of oral healthcare professionals. Given that the lesion was initially identified during a routine FMX series, the essential role that general practitioners play in the identification of complex pathology cannot be understated. Evaluation by the endodontist ruled out any endodontic etiologies for the patient's symptoms and ensured referral to the appropriate specialty for definitive diagnosis and treatment. The cross-specialty collaboration between endodontics and oral surgery helped ensure that this patient pursued a treatment modality rooted in predictable, evidence-based measures. This case underscores the importance of interdisciplinary care in the management of complex pathology.

Cementoblastoma is a benign neoplasm with predilection for the mandibular permanent first molar that may manifest with pain and associated swelling of the periapical region.^2,3 Endodontists are well-versed in diagnosing dental pain and are often referred complex cases involving painful odontogenic and non-odontogenic lesions. It is essential that clinicians are aware of this clinical entity and proper management strategies to ensure evidence-based clinical care for patients.

This clinical case demonstrates how, although a rare entity, cementoblastoma can mimic endodontic pathology with potential pain and radiographic findings involving the periapical tissues. Dental professionals should be aware of this entity and its manifestations. Cementoblastoma should be considered in the differential diagnosis of patients presenting with a compatible clinical and radiographic presentation.

The authors thank Gary Hammond, DDS, and his colleagues at Hanover Oral Surgery PLLC for their expeditious treatment of this patient, and sharing of clinical documents.

Shraya Sharma, DMD, Certificate in Endodontics
Private Practice, Norwood, Massachusetts
Brooke Blicher, DMD, Certificate in Endodontics
Assistant Clinical Professor, Department of Endodontics, Tufts University School of Dental Medicine, Boston, Massachusetts; Lecturer, Department of Restorative Dentistry and Biomaterials Science, Harvard School of Dental Medicine, Boston, Massachusetts; Co-founder, Pulp Nonfiction Endodontics; Private Practice limited to Endodontics, White River Junction, Vermont

Rebekah Lucier Pryles, DMD, Certificate in Endodontics
Assistant Clinical Professor, Department of Endodontics, Tufts University School of Dental Medicine, Boston, Massachusetts; Lecturer, Department of Restorative Dentistry and Biomaterials Science, Harvard School of Dental Medicine, Boston, Massachusetts; Co-founder, Pulp Nonfiction Endodontics; Private Practice limited to Endodontics, White River Junction, Vermont

Darcy A. Kerr, MD
Associate Professor of Pathology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire; Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire

Rocco Addante, DMD, MD
Professor of Surgery, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire

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