In some cases, impacted wisdom teeth should be extracted. Surgical extraction of these impacted third molars may provide special complication as pain, swelling, and trismus. In previous studies, some techniques as sutureless flap closure, modified flap designing, antibiotic usage, and injection of corticosteroids were presented. These methods are reducing post operative complications to moderate level. In this study, pain, swelling, trismus, general patients’ satisfaction, and associated quality of life after the surgical removal of third mandibular impacted molars will be compared while injection of dexamethasone (8mg) does not need excessive time, effort, and equipments and it will be injected in numbness area into medial pterygoid muscle and pterygomandibular space to non-corticosteroid method. To achieve this aim, 60 non pregnant participants have single impacted mandibular third molar in healthy and without pericoronitis manner, after provision of written informed consent will be entered to the study. During the study, unwilling participants to continue the study and those with abnormality of wound healing process will be excluded. The included participants will be assigned into two 30-people groups. The surgeries were done by 3 same instructed experienced oral and maxillofacial residents. After the surgery pain, swelling, trismus, general patients’ satisfaction, and associated quality of life were evaluated using interview of questionnaire in 48 hour, 96 hour, and one week period of time. The comparison was done between these two groups.