Osteomyelitis of the Jaws: Definition and Classification

Abstract

Osteomyelitis of the jaws is still a fairly common disease in maxillofacial clinics and offices, despite the introduction of antibiotics and the improvement of dental and medical care. The literature on this disease is extensive. Different terminologies and classification systems are used based on a variety of features such as clinical course, pathological–anatomical or radiological features, etiology, and pathogenesis. A mixture of these classification systems has occurred throughout the literature, leading to confusion and thereby hindering comparative studies. An overview of the most commonly used terms and classification systems in osteomyelitis of the jaws is given at the beginning of this chapter. The Zurich classification system, as advocated in this textbook, is primarily based on the clinical course and appearance of the disease as well as on imaging studies. Subclassification is based on etiology and pathogenesis of the disease. Mainly three different types of osteomyelitis are distinguished: acute and secondary chronic osteomyelitis and primary chronic osteomyelitis. Acute and secondary chronic osteomyelitis are basically the same disease separated by the arbitrary time limit of 1 month after onset of the disease. They usually represent a true bacterial infection of the jawbone. Suppuration, fistula formation, and sequestration are characteristic features of this disease entity. Depending on the intensity of the infection and the host bone response, the clinical presentation and course may vary significantly. Acute and secondary chronic osteomyelitis of the jaws is caused mostly by a bacterial focus (odontogenic disease, pulpal and periodontal infection, extraction wounds, foreign bodies, and infected fractures). Primary chronic osteomyelitis of the jaw is a rare, nonsuppurative, chronic inflammation of an unknown cause. Based on differences in age at presentation, clinical appearance and course, as well as radiology and histology, the disease may be subclassified into earlyand adult-onset primary chronic osteomyelitis. Cases with purely mandibular involvement are further distinguished from cases associated with extragnathic dermatoskeletal involvement such as in SAPHO syndrome or chronic recurrent multifocal osteomyelitis (CRMO).