Odontogenic cysts are encountered relatively commonly in dental practice. Dentigerous cyst is the most common type of developmental cyst. The usual treatment for a dentigerous cyst at the mandibular angle is careful enucleation with removal of the impacted third molar. Most of all, bone grafting is a usual treatment method for the remaining bone defect. However, there is a possibility of some complication according to the size of the cyst and conditions of the soft tissue. we report a case of intra-osseous dentigerous cyst in a 49-yearold male patient. We introduce a bone readaptation method for the treatment and that presents a favorable treatment results.