IRCT138711221674N1 IRCT 2012-01-28 Vice chancellor for research, Shiraz University of Medical Sciences The effect of intravenous acetaminophen in reducing Post-operative opioid requirements after maxillofacial surgery. A Clinical trial of paracetamole administration after maxillofacial surgery in Post-operative opioid requirements. 2011-12-22 anticipated 100 Complete https://irct.ir/trial/1143 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment. 2-3 Maxillofacial Surgery( correction after injury). Intervention 1: Equal to 50 divided randomly into two groups, so that odd numbers - received paracetamol (Group A) and even numbers - receiving placebo (group II) are divided. Complete questionnaires in the surgery's not the type of drug (double blind). After transfer the patient to the recovery room and extubation of trachea, and eventually the patient returned to full consciousness, with relation to the patient's pain is measured and recorded. An intravenous infusion of the paracetamol up to one gram in 100 cc normal salin within ten minutes as a single dose , is prescribed after the surgery in recovery room. Intervention 2: After transfer the patient to the recovery room and extubation of trachea, and eventually the patient returned to full consciousness, with relation to the patient's pain is measured and recorded. Placebo as an intravenous infusion of 100 cc normal salin within ten minutes , is prescribed after the surgery in recovery room.