Osteoblastoma(OB) is a rare tumor of bone representing less than 1 % of all tumors of the maxillofacial region. The lesion usually appears in vertebral column, sacrum, long bones but rare in mandible or maxilla. The lesion occurs most commonly at age from 3 to 78 years with the mean age of 22-23 years. In this article, we report one case of OB occurred in mandible. With clinical examination and radiological diagnosis, preliminary diagnosis was made as Fibro-osseous lesion, osteomyelitis or cementoblastoma. Under general anesthesia, associated tooth was extracted and excisional biopsy was done. After microscopic examination, it was diagnosed as OB. The patients which we presented did not complain any specific complications, and showed good prognosis.

Abstract
 Ⅰ. INTRODUCTION
 Ⅱ. CASE REPORT
 Ⅲ. DISCUSSION
 Ⅳ. CONCLUSION
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