Osteonecrosis is defined as non-vital bone tissue as a result of abnormal process of osseous healing, and is caused by several reasons such as infection, radiation, and medication. Osteomyelitis, osteoradionecrosis, and medication related osteonecrosis of the jaws (MRONJ) which have necrotic bone in common are confused clinically due to similar symptoms and radiographic findings, and are difficult to diagnose definitively. Because each disease represents a separate clinical progress and requires a different treatment approach, it is very important to distinguish each disease. The aim of this study was to analyze the histopathologic features of osteomyelitis, osteoradionecrosis, MRONJ and to understand their different pathogenesis.

Recently, oteomyelitis from oral and maxillofacial region which is an acute or chronic inflammatory process in medullary spaces or cortical surfaces of bone is uncommon in Korea. And the clinicopatholgic study of osteomyelitis in Korea has been rarely reported. The purpose of this study were to examine the clinicopatholgic analysis of osteomyelitis patients and to apply its results for treatment. Retrospective analysis of 103 cases of osteomyelitis patients treated in the Department of Oral and Maxillofacial Surgery at DKUDH from 1991 to 2000. There was a male predominance with a 2.3:1 ratio. The mean age of onset of disease was almost the same in cases of acute and chronic osteomyelitis: 29.4 years(range 1-81 years). Swelling, pain, pus discharge, and sequestration were main characteristic features of this disease entity. Acute chronic osteomyelitis of the jaws is caused mostly by a bacterial focus(odontogenic disease, periapical lesion, pericoronitis, periodontal disease, postextraction wounds, and infected fractures). It suggested that acute and chronic osteomyelitis could be basically the same disease separated by the arbitrary time limit of 1 month after onset of the disease by a true bacterial infection. And these results could play an role in the diagnosis and treatment of osteomyelitis of the jaws

A case of chronic osteomyelitis caused by prolonged intake of bisphosphonate showed multiple recurrences involving extensive area of mandibular body. After saucerization the removed bony fragments were decalcified, microsected in 4 ㎛ thickness, and stained with hematoxylin and eosin, Masson trichrome, von Gieson, and periodic acid Schiff reaction. The inflammatory lesion contained fragile osteophytes easily propagated into sequestra. Histologically, this osteomyelitis was relatively less suppurative but almost granulomatous, highly infiltrated with small round cells and macrophages. The osteophytes were frequently deposited on the old lamellate bone, but their ossification was extremely immature and frequently filled with sclerosed collagen bundles positive for von Gieson stain. In the polarizing microscope observation under Masson trichrome stain the newly deposited osteophytes were lack of birefringence image of Haversian system contrast to the old bone nearby. Therefore, we presume that the prolonged intake of bisphosphonate may induce the immature osteophytes lack of Harversian system, which are partly filled with sclerotic collagen bundles, and the immature bone is easily undergone extensive degeneration and necrosis, resulted in the inflammatory foci for multiple recurrent osteomyelitis.

Although the sparganosis involving soft tissues, i.e, tongue, cheek, etc., has been frequently reported, the mandibular involvement of sparganosis is not reported up to date. We present a case of intraosseous sparganosis involving whole mandible, which was clinically diagnosed as chronic osteomyelitis. After surgical operation of saucerization for the treatment of chronic osteomyelitis the removed specimens were pathologically examined and finally turned out intraosseous sparganosis. Radiological findings showed irregular multiple radiolucencies in round to ovoid shape throughout both mandibular body areas, of which peripheral rarefying radiopacity was less remarkable compared to the ordinary osteomyelitis. However, the radiolucencies of periapical granuloma, #34-36, were closely associated with the osteolytic lesions of mandibular body. Pathological examination showed a tunnel like space for the passage of sparganum larva, and heavy infiltration of eosinophilicleukocytes. And more, the parasitic tegument materials were found admixed with eggs in the granulomatous lesion, which were gradually degraded and resolved. Taken together, we presumed that the mandibular inflammatory lesion was primarily involved with sparganosis and secondarily aggravated by the periapical infection of #34-36.