Correctly differentiating between periodontal abscess (localized, acute suppurative infection of the periodontium) and osteomyelitis (the extension of an infection into the bone medullary cavity) is crucial since the former may not require antibiotics for resolution, while the latter will. Initial assessment and treatment of osteomyelitis should be based on clinical examination, radiographic interpretation, and experience. Three case histories of osteomyelitis are presented, ranging from a periodontally well-localized case to one involving a hemimandible and crossing the midline. Successful early diagnosis and case management may benefit from scintigraphic interpretation and culture-and-sensitivity studies.