Life-threatening infections of odontogenic or upper airway origin may extend to potential spaces formed by fascial planes of the lower head and upper cervical area. Complications include airway obstruction, mediastinitis, necrotizing fascitis, cavernous sinus thrombosis, sepsis, thoracic empyema, Lemierre's syndrome, cerebral abscess, orbital abscess, and osteomyelitis. The incidence of these “space infections” has been greatly reduced by modern antibiotic therapy. However, serious morbidity and even fatalities continue to occur. This study reviews complications of odontogenic infections. The search done was based on PubMed and Google Scholar, and an extensive published work search was undertaken. Advanced MEDLINE search was performed using the terms “odontogenic infections,” “complications,” and “risk factors.”

CRP displayed a more consistent relation with clinical severity of the infection than TLC. Hence it could be more reliably employed to judge the progress in a patient with OSI.