Local Metformin Gel and Impacted Lower Third Molar

* Completed medical and dental history will take for all patients and the position of the impacted teeth will evaluate by panoramic films. Patients will fully inform about the treatment procedures, follow-up examinations and complications of surgical procedures. * The study will be carried out as a randomized controlled clinical trial. Randomly, by the use of predefined computer-generated randomization table, the eligible patients will be randomized in equal proportions between Study group: patients will receive 1% Metformin gel in the socket following removal of the impacted third molar and Control group: patients will receive placebo gel 2% hydroxymethyl cellulose.All surgeries will be performed under complete aseptic conditions. Before surgery, the patient's mouth will be rinsed with a chlorhexidine digluconate solution 0.2% for 2 minutes. Surgery will carry out under local anesthesia consisting of 4% articain hydrochloride with 1:100,000 adrenaline. * Full thickness mucoperiosteal flap will be raised to expose sufficient bone on lateral and distal aspect of the impacted molar. Removal of bone will be done with stainless steel bur under Constant irrigation with normal saline while removing bone to prevent thermal necrosis. * When necessary, sectioning of crown and roots will be performed with a fissure bur. After tooth extraction, the alveolus will be inspected, curetted, and irrigated with 0.9% sterile saline solution. * Surgical removal of impacted mandibular third molar will be done,1% metformin gel or placebo gel in the socket following removal of the impacted third molar . * The mucoperiosteal flap will be repositioned and sutured with 3-0 black silk suture.