of the infection (such as a necrotic tooth pulp) have a greater therapeutic benefit and are much more important. If abscess drainage has been achieved, antibiotics are not usually necessary. Antibiotics tend to be used when local measures cannot be carried out immediately. In this role, antibiotics suppress the infection until local measures can be carried out. Severe trismus may occur in when the muscles of mastication are involved in an odontogenic infection, making any surgical treatment impossible. Immunocompromised individuals are less able to fight off infections, and antibiotics are usually given. Evidence of systemic involvement (such as a fever higher than 38.5 °C, cervical lymphadenopathy, or malaise) also indicates antibiotic therapy, as do rapidly spreading infections, cellulitis, or severe pericoronitis. Drooling and difficulty swallowing are signs that the airway may be threatened, and may precede difficulty in breathing. Ludwig's angina and cavernous sinus thrombosis are rare but serious complications of odontogenic infections. Severe infections tend to be managed in hospital. Prognosis Most dental pain can be treated with routine dentistry. In rare cases, toothache can be a symptom representing a life-threatening condition, such as a deep neck infection (compression of the airway by a spreading odontogenic infection) or something more remote like a heart attack. Dental caries, if left untreated, follows a predictable natural history as it nears the pulp of the tooth. First it causes reversible pulpitis, which transitions to irreversible pulpitis, then to necrosis, then to necrosis with periapical periodontitis and, finally, to necrosis with periapical abscess. Reversible pulpitis can be stopped by removal of the cavity and the placement of a sedative dressing of any part of the cavity that is near the pulp chamber. Irreversible pulpitis and pulp necrosis are treated with either root canal therapy or extraction. Infection of the periapical tissue will generally resolve with the treatment of the pulp, unless it has expanded to cellulitis or a radicular cyst. The success rate of restorative treatment and sedative dressings in reversible pulpitis, depends on the extent of the disease, as well as several technical factors, such as the sedative agent used and whether a rubber dam was used. The success rate of root canal treatment also depends on the degree of disease (root canal therapy for irreversible pulpitis has a generally higher success rate than necrosis with periapical abscess) and many other technical factors. Epidemiology In the United States, an estimated 12% of