In dentistry, a dry socket is a layman's term for alveolar osteitis , an infection of the alveolar bone surrounding a tooth socket following extraction of the tooth.

Alveolar osteitis occurs when the blood clot at the site of a tooth extraction is disrupted prematurely. This leaves the alveolar bone unprotected and exposed to the oral environment. The socket packs with food and bacterial infection follows, typically 3-4 days following the extraction. This is often extremely unpleasant for the patient, as symptoms include extreme pain (sometimes worse than the toothache that caused the extraction!), a bad taste in the mouth, bad breath, and swelling in the infected area. There may be lymph-node involvement leading to a palpatable submandibular lymph node.

Smokers have been shown to have a greatly increased risk of developing alveolar osteitis after tooth extraction. This is thought to be due to the decreased amount of oxygen available in the healing tissues as a result of carbon monoxide in tobacco smoke. It is advisable to avoid smoking following tooth extraction for at least 48 hours to reduce the risk of developing this "dry socket".

Treatment for alveolar osteitis is mainly preventative. Dentists encourage maintaining good oral hygiene during the healing period. The blood clot should not be disturbed, and a hot salt water mouth rinse is often advised. Once a patient develops dry socket, treatment is usually to debride (clean) the socket to remove debris and pus, and encourage new clot formation. This is followed by packing the socket with Alvogyl. Its fibrous consistency allows for easy filling of the socket and good adherence during the entire healing process. The active ingredients of Alvogyl include eugenol for analgesic action, butamben for anesthetic action, and iodoform for anti-microbial action. Sometimes analgesics are prescribed. If the infection is severe an antibiotic such as metronidazole may be indicated.