Bruce R. Pynn, M.Sc., DDS, FRCD(C)
Tim D. Sands, DDS, Dip. OMFS
Grace Bradley, DDS, M.Sc., FRCD(C)
AbstractThe case of a 23-year-old with a benign cementoblastoma is presented. The clinicopathologic features, treatment and prognosis are discussed and a brief review of the literature is presented. Although this neoplasm is rare, the dental practitioner should be aware of the clinical features that will lead to its early diagnosis and treatment. MeSH Key Words: case report; mandibular neoplasms/diagnosis; odontogenic tumours/diagnosis © J Can Dent Assoc 2001; 67:260-2
This article has been peer reviewed.
Case ReportA 23-year-old Native Canadian woman presented with mild pain in theleft mandible of 18 months duration. Clinical examination revealed a smallbuccal swelling in the caninepremolar region, and radiographs of the areademonstrated a circular radiopaque mass, 1 cm in diameter, associated with theroot of the first premolar (tooth 34). The lesion was well demarcated by aradiolucent halo (Fig. 1). The involved tooth was vital, as indicated bysensitivity to electric pulp testing and ethyl chloride. The remainder of theexamination was within normal limits and oral hygiene was excellent.
The provisional diagnosis was benign cementoblastoma, and the patient wasscheduled for surgical removal of the tumour and extraction of the associatedpremolar under general anesthesia. At the time of surgery, a buccalfull-thickness envelope flap was developed to identify the mental nerve and thelesion. The lesion was easily differentiated from normal bone as it hadperforated the buccal cortex in the region. The tooth was luxated withextraction forceps and delivered buccally with the associated mass attached intoto. The periphery of the bony cavity was curetted and the wound was closedprimarily.
The specimen was submitted for histologic evaluation. Gross examinationshowed a noncarious mandibular premolar with the root apex embedded in aspherical mass of hard tissue (Figs. 2a and 2b). A radiograph ofthe specimen revealed resorption of the apical third of the root and fusion ofthe resorbed root to a radiopaque mass with a radiating pattern at theperiphery.
Histologically, the lesion consisted of broad trabeculae of sparsely cellularcementum. These merged with areas of cemental islands in a vascular stroma withprominent cementoblasts and multinucleated cementoclasts (Figs. 3a and 3b).The peripheral zone of the tumour showed characteristic radiating columns ofcementum running perpendicular to the surface of the lesion. The diagnosis wasestablished as a benign cementoblastoma.
The patient did well postoperatively, with no complications or paresthesia.Postoperative radiographs revealed complete excision. An 18-month follow-upexamination revealed no evidence of recurrence.
DiscussionThe benign cementoblastoma or true cementoma is a slow-growing, benignodontogenic tumour arising from cementoblasts. The lesion, which was firstrecognized by Norberg in 1930,3 is rare with fewer than 100 casesever reported.4-8 In a survey of the Diagnostic Biopsy Service at thefaculty of dentistry of the University of Toronto, we found only 5 cases ofbenign cementoblastoma (including the case reported here) over the 10-yearperiod from 1990 to 1999, inclusive. The total number of accessions in thatperiod was 56,836.
Most patients initially present with mild pain and bony swelling in the areaof the lesion. At least 50% of the reported cases occurred in patients under theage of 20 and 75% under the age of 30 (age range, 6-75 years).5,9There does not appear to be any significant gender or racial predilection.10The mandible is by far the most common location; half of all reported cases wereassociated with the mandibular permanent first molar or second premolar.7When lesions in the maxilla and mandible are grouped together, over 90% of casesaffect a single tooth in the premolarmolar area; however, the tumour has beenassociated with multiple teeth, impacted molars and deciduous teeth.11-13
The cementoblastoma has a pathognomonic radio graphic appearance. It appearsas a well-defined solitary circular radiopacity with a radiolucent halo. Thelesion is fused to the partly resorbed root(s) of the associated tooth. Theinternal structure of the mass may possess a mixed radiolucent-radiopaquequality often with a radiating pattern.14 The differential diagnosisfor a periapical radiopacity includes cementoblastoma, osteoblastoma, odontome,periapical cemental dysplasia, condensing osteitis and hypercementosis. Thecementoblastoma and osteoblastoma are closely related lesions that arehistologically very similar.15 The cementoblastoma is distinguishedfrom the osteoblastoma by its location in intimate association with a toothroot. The osteoblastoma arises in the medullary cavity of many bones, includingthe long bones, vertebrae and jaws.10 The odontome is usually notfused to the adjacent tooth and appears as a more heterogeneous radiopacity,reflecting the presence of multiple dental hard tissues. Periapical cementaldysplasia usually produces a smaller lesion than cementoblastoma and shows aprogressive change in radiographic appearance over time, from radiolucent tomixed to radiopaque. Condensing osteitis lacks a peripheral radiolucent halo.The radiopaque lesion of hypercementosis is usually small, and there is noassociated pain or jaw swelling.
The cementoblastoma has been described as a benign, solitary, slow-growinglesion, although there have been reports of aggressive behaviour.16,17Due to the benign neo plastic nature of the lesion, the treatment of choice iscomplete removal of the lesion with extraction of the associated tooth. A moreconservative technique, to retain the involved tooth and remove the lesion usinga surgical endodontic approach, has been reported.18-20 It can beused for small lesions on strategic teeth that can be completely enucleatedwithout compromising adjacent teeth and that will maintain a sufficientcrown-to-root ratio after apicoectomy.
The prognosis is excellent, as the tumour does not recur after totalexcision.5,10
Dr. Pynn is an oral and maxillofacial surgeon,Thunder Bay Regional Hospital, and adjunct professor, Lakehead University,Thunder Bay, Ontario.
Dr. Sands is an oral and maxillofacial surgeon, Woodbridge, Ontario.
Dr. Bradley is an oral pathologist and associate professor, faculty ofdentistry, University of Toronto, Toronto, Ontario.
Correspondence to: Dr. Bruce R. Pynn, 326 Red River Rd., Thunder BayON P7B 1B1. E-mail: DrPynn@microage-tb.com
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