This clinical trial aims to investigate whether dexamethasone decreases edema and trismus in adults undergoing lower third molar surgical extraction.

The main question it aims to answer is:

Does dexamethasone submucosal injection have a positive impact on trismus and edema after third molar surgery compared to conventional postoperative prescription?

Participants will:

• Be administered with dexamethasone submucosal injection or a placebo after the surgery.
• Visit the clinic three times the week after the extraction for follow-up.

Patients will be randomly allocated to the test group or the control group by an allocation sequence that is done by the statistician.

To ensure that the patient and OMFS resident are blinded in this study, the corticosteroid and placebo injections are of the same color and size, are stored in similar bottles, and are coded as drug 1 or drug 2. Additionally, they will be placed in sealed envelopes by a dental assistant.

The OMFS resident will withdraw an envelope randomly. The number is recorded in the patient file. Then, the drug will be administered in the buccal vestibule next to the site of extraction after surgery. Thus, the patient, surgeon, and the person responsible for the assessments of swelling and trismus are masked to the type of medication used during each surgical procedure. The drugs used in the different surgeries are only revealed after the acquisition and analysis of all data. Baseline and follow-up measurements will be measured by a standardized ruler. At the first visit, interincisal distance will be recorded to measure trismus. Distance from the angle of the mandible to the outer canthus of the eye, distance from the tragus of the ear to the corner of the mouth, and distance from the tragus of the ear to soft tissue pogonion will be recorded and their mean will be calculated to measure edema. Pell and Gregory classification of the tooth and impaction angulation will be recorded. Facial symmetry and whether the angle of the mandible is palpable or not will be recorded as well. The number of drug that was given to the patient will be recorded.

At the 2nd, 4th, and 7th visits, interincisal distance will be recorded to measure trismus. Distance from the angle of the mandible to the outer canthus of the eye, distance from the tragus of the ear to the corner of the mouth, and distance from the tragus of the ear to soft tissue pogonion will be recorded to measure edema. Facial symmetry and whether the angle of the mandible is palpable or not will be recorded. Whether the patient is able to interact socially or not. If not, was it due to edema, feeling sick, or bad mood. The patient's ability to work, the patient's ability to eat the food he is used to eating, and the presence of sleep impairment will be recorded as well.

Surgery will be done by calibrated OMFS residents. After the surgery, the surgeon will use the preassigned randomly picked envelope and administer it in the buccal vestibule next to the surgical site. Patients will be followed up in the 2nd, 4th, and 7th postoperative days.

Inclusion Criteria:

• Patients with impacted lower third molars requiring surgical extraction.
• Adults over the age of 18 years old.
• American Society of Anaesthesiologists (ASA) 1, and ASA 2

Exclusion Criteria:

• Patients with preoperative intraoral or extraoral swelling.
• Patients requiring simple extraction (Class I group A according to Pell and ---Gregory classification).
• Patients with uncontrolled systemic disease such as uncontrolled diabetic - patients.
• Patients who are allergic to corticosteroids.
• Patients who are contraindicated to use corticosteroids such as uncontrolled diabetic patients, and osteoporotic patients.
• Patients who require extraction of additional teeth at the same visit.

All data gathered and agreed upon by the institution's research ethical committee throughout the conduction of the clinical trial will be shared at the time of publication.

To ensure that the patient and OMFS resident were blinded in this study, the corticosteroid and placebo injections were of the same color and size, were stored in similar syringes, and were coded as drug 1 or drug 2. The OMFS resident received the syringe corresponding to the patient's random allocation prior to the beginning of the procedure. The number of the drug was recorded in the patient file. Then, the drug was administered in the buccal vestibule next to the site of extraction after surgery. Thus, the patient, surgeon, and the person responsible for the assessments of swelling and trismus were masked to the type of medication used during each surgical procedure. The drugs used in the different surgeries were only revealed after the acquisition and analysis of all data.