Introduction:Third molar impaction is a chronic disorder that often necessitates tooth extraction. Impaction is characterized as the inability of a tooth to erupt at its proper location in the dental arch during its usual growth time.The surgical extraction of lower third molars is the most frequent intervention in oral surgery. This procedure is often associated with significant postsurgical sequelae that may have both biological and social impact. Besides severe complications such as dysaesthesia, severe infection, fracture, and dry socket, patients frequently complain of pain, swelling, and limitation in mouth opening (Trismus) throughout the postoperative course due to the inflammatory response following the surgical injury. To control postoperative inflammation and symptoms associated, it is necessary to provide an adequate anti-inflammatory therapy and various medications have been prescribed for the same. For several decades surgeons administered corticosteroids before or just after third molars' surgery to reduce inflammation and associated symptoms after oral surgery. Corticosteroids mechanism of action is the inhibition of the enzyme Phospholipase A2 (PLA 2), which reduces the release of arachidonic acid in the cells of the inflamed area.This will decrease prostaglandins and leukotriene synthesis; therefore reducing the accumulation of neutrophils has been the greatest advantage of corticosteroids compared to non-steroidal anti-inflammatory drugs. The aim of this study was to evaluate the effect of preoperative versus postoperative administration of submucosal Dexamethasone on postoperative discomfort including pain, edema, and trismus following lower third molar surgery in order to allow a better welfare of the patient and to return the patient to the normal activity following the surgery. And to determine the efficacy of single dose 2 ml/8 mg submucosal dexamethasone injection in the buccal vestibule in proximity to the surgical site.

Rational:Pain and edema are the most frequent postoperative sequelae to surgical removal of impacted teeth, all of which are due to the local inflammatory response. The inflammation induced by tissue damage is the primary cause of acute postoperative pain after third molar extraction. Edema after third molar surgery is caused by extravasation of fluid by traumatized tissues as a consequence of the disruption or obstruction of lymph arteries, culminating in the termination of lymph drainage, which accumulates in the tissues. Adjunctive use of corticosteroids to decrease tissue mediators of inflammation and reduce fluid transudation and edema is common in surgical procedures. Corticosteroids inhibits the enzyme Phospholipase A2 (PLA 2), which reduces the release of arachidonic acid in the cells of the inflamed area.Dexamethasone has higher potency, lower sodium retaining ability and longer half-life. Long-acting steroids outperform short-acting steroids, and submucosal steroid administration has similar consequences as intravenous and intramuscular routes. Also rate of absorption is highly dependent on the blood flow to the site.Submucosal dexamethasone is quite simple, less invasive, painless, convenient for the surgeon and the patient and offers a low cost solution for the typical discomfort associated with the extraction of impacted lower third molar. Also,submucosal injection offers advantage of concentrating the drug near the surgical area with less systemic absorption and no further manipulation of the tissues.