Periostitis ossificans managed with endodontic treatment.

Periostitis ossificans (PO) is a specific type of chronic osteomyelitis. Radiographically, it is characterized by the presence of lamellae of newly formed periosteal bone outside the cortex, giving the characteristic appearance of "onion skin." The most common cause of PO is periapical infection of the mandibular permanent first molar, which occurs primarily in children and young adults. Treatment in these cases is directed toward eliminating the source of the infection, either by extraction of the offending tooth or endodontic therapy. The purpose of this paper is to present a case of PO involving a permanent mandibular first molar managed with endodontic treatment.