Introduction
Benign cementoblastoma is currently classified by the World Health Organization as an odontogenic mesenchyme or ectomesenchyme tumor, with or without involvement of the odontogenic epithelium (Hubber and Folk, 2009). It is characterized by proliferation cementum-like tissue that is attached to the roots of teeth (Ohki et al., 2004). BC is usually found in the mandible, most commonly in the pre-molar and molar region (Sumer et al., 2006). Its prevalence is higher in young male adults under 30 years of age (Zaitoun et al., 2007). Cementoblastomas are slow growing lesions and are usually asymptomatic; however pain, and swelling may occur (Neville et al., 1995). Radiographically, the lesion presents as a radiopaque mass that is attached to the root tooth, which is usually vital and is surrounded by a radiolucent halo (Infante-Cossio et al., 2008). Histologically, cementoblastoma tissue is similar to cementum. The clinical and radiological findings are of great importance for the differential diagnosis of odontogenic neoplasms which must include osteoblastoma and focal sclerosing osteomyelitis (Hirai et al., 2010). The recommended treatment consists of the surgical removal of the tumor and associated teeth. Cases in which an early diagnosis is made, the lesion can be removed in association with the endodontic treatment of the involved tooth. If the lesion is not completely removed, recurrence and continued growth can be observed due to its unlimited growth potential, but this is not common (Brannon et al., 2002). We present an rare case of a cementoblastoma involving the left mandibular body of a 28- years-old female.

Case Report
A 28-year old female patient presented with mild pain in left mandibular first molar of one month duration. On clinical examination tooth was tender with temporary restoration (Figure 1). The remainder of the examination was within normal limits and oral hygiene was excellent. Panoramic radiograph showed a circular radio-opaque mass, approximately 1 cm in diameter, associated with the distal root of the left mandibular first molar. The lesion was well demarcated by a radiolucent halo (Figure 2).

Figure 1 Intraoral photograph showing temporary restoration in left mandibular first molar

Figure 2 Panoramic radiograph showing well defined radiopaque lesion attaching the distal root of left mandibular first molar

The provisional diagnosis of benign cementoblastoma was made, and the patient was scheduled for surgical removal of the tumor and extraction of the associated tooth under local anesthesia. The surgical plan was revised and the tooth was luxated with extraction forceps and delivered buccally. The associated tumor mass was also removed along with the tooth. The periphery of the bony cavity was curetted and the wound was closed primarily. Post-operative period was uneventful. The excised tumor specimen was hard tissue, it was decalcified and then processing was done. The microscopic study showed presence of sheets and trabeculae of cementum like material and few bony trabeculae surrounded by a cellular fibro vascular stroma, adjacent to the apical portion of the root. At places few osteoclastic multinucleated giant cells were seen (Figure 3). The diagnosis of BC was achieved. The patient was followed up for one year and no evidence of recurrence was noted.

Figure 3 Photomicrograph showing sheets and trabeculae of cementum like material surrounded by a cellular fibro vascular stroma

Discussion
BC is a relatively rare slow growing odontogenic neoplasm of the jaws arising from cementoblasts. It was first described by Dewey in 1927. BC generally occurs in young persons, most frequently tends to be associated with an erupted permanent tooth, most often the first molar or second premolar in the lower jaw. Most patients initially present with mild pain and bony swelling in the area of the lesion. At least 50% of the reported cases occurred in patients under the age of 20 years and 75% under the age of 30 years (Regezi et al., 1978). These clinical features were well correlated in the present case with respect to age and site of tumor. Radiographically it appears as a well-defined solitary circular radio-opacity with a radiolucent halo (Matteson, 2000). The radiographic features also be well correlated with the present case which showed a radio-opaque mass attached to the distal root of mandibular first molar. The clinical and radiographic findings led to the diagnosis of BC. Differential diagnosis of BC includes periapical radio-opacities like osteoblastoma, odontome, periapical cemental dysplasia, condensing osteitis and hyper- cementosis (Slootweg, 1992).

The BC and osteoblastoma are closely related lesions that are histologically very similar. The cementoblastoma is distinguished from the osteoblastoma by its location in intimate association with a tooth root. The osteoblastoma arises in the medullary cavity of many bones, including the long bones, vertebrae and jaws. The odontome is usually not fused to the adjacent tooth and appears as a more heterogeneous radio-opacity, reflecting the presence of multiple dental hard tissues. Periapical cemental dysplasia usually produces a smaller lesion than BC and shows a progressive change in radiographic appearance over time, from radiolucent to mixed to radio-opaque. Condensing osteitis lacks a peripheral radiolucent halo. The radiopaque lesion of hypercementosis is usually small, and there is no associated pain or swelling. Condensing osteitis lacks a peripheral radiolucent halo. BC has been described as a benign, solitary, slow-growing lesion, although there have been reports of aggressive behaviour (Krausen et al., 1977; Goerig et al., 1984; Costa et al., 2011; Mounesh et al., 2012).

Due to the benign neoplastic nature of the lesion, the treatment of choice is complete removal of the lesion with extraction of the associated tooth. A more conservative technique, to retain the involved tooth and remove the lesion using a surgical endodontic approach, has been reported (Costa et al., 2012; Suresh et al., 2012; Suresh et al., 2013). It can be used for small lesions on strategic teeth that can be completely enucleated without compromising adjacent teeth and that will maintain a sufficient crown-to-root ratio after apicoectomy. In present case, surgical removal of the tumor along with the extraction of the involved tooth was carried out.

Conclusion
Although the occurrence of BC is not common, the lesion should be considered in differential diagnosis of periapical radio-opacities. It is important for the dental practitioner to be aware of the clinical features which can lead to an early diagnosis and treatment of this lesion. The diagnosis is established by its attachment to the root of tooth. It deserves high academic interest because of its pathogenesis, clinical/radiographical presentation and attachment to the tooth root.

References
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