likelihood of dry socket. Infection Dry socket is more likely to occur where there is a pre-existing infection in the mouth, such as necrotizing ulcerative gingivitis or chronic periodontitis. Wisdom teeth not associated with pericoronitis are less likely to cause a dry socket when extracted. The oral microbiota has been demonstrated to have fibrinolytic action in some individuals, and these persons may be predisposed to developing dry sockets after tooth extraction. Infection of the socket following tooth extraction is different from dry socket, although in dry socket secondary infection may occur in addition. Smoking Smoking and tobacco use of any kind are associated with increased risk of dry socket. This may be partially due to the vasoconstrictive action of nicotine on small blood vessels. Another risk can be attributed to the actual inhalation, as drawing smoke, particularly from dense filters or tightly rolled cigarettes, creates a small amount of suction that can cause the blood clot in a healing gum to become loose or dislodged over a period of time. Not smoking in the days immediately following a dental extraction reduces the risk of a dry socket occurring. Surgical trauma Dry socket is more likely to occur following a difficult tooth extraction. It is thought that excessive force applied to the tooth, or excessive movement of the tooth burnishes the bony walls of the socket and crushes blood vessels, impairing the repair process. Vasoconstrictors Vasoconstrictors are present in most local anesthetics and are intended to increase the length of analgesia by reducing blood supply to the region which reduces the amount of local anesthetic solution that is absorbed into the circulation and carried from the local tissues. Hence, use of local anesthetics with vasoconstrictors is associated with an increased risk of dry socket occurring. However, on occasion, use of local anesthetic without vasoconstrictors would not provide sufficient analgesia, especially in the presence of acute pain and infection on maxillary teeth, meaning that the total dose of local anesthetic may need to be increased. Adequate pain control during the extraction is balanced against an increased risk of dry socket. However, the use of 3% mepivacaine without epinephrine in inferior alveolar nerve blocks has been found to have a similar anesthetic effect to that of lidocaine with 1:100,000 epinephrine, save for a shorter duration of action, and, as such, this may be considered as an alternative in simple mandibular extractions. Radiotherapy Radiotherapy