Dipyrone Versus Acetaminophen in the Control of Postoperative Pain

Thirty patients scheduled for surgical removal of impacted third molars at the Discipline of Oral and Maxillofacial Surgery and Traumatology of the Dental School of Araçatuba, São Paulo State University, Brazil, were selected for the study after review and approval of the research protocol by the institutional Research Ethics Committee (Protocol #2006-01083). All patients received verbal and written explanations about the study purposes and procedures, and all of them signed an informed consent form prior to enrollment.

Patients should be in good general health and those who fulfilled any of the following criteria were excluded: systemic disorders; known hypersensitivity to any of the study medications; pregnancy or nursing; local contraindication to surgery as judged by the oral surgeon; and use of any analgesic agent 24 hours before surgery.

All patients were premedicated with oral dexamethasone 4 mg one hour before surgery for modulation of the postoperative edema. The surgical procedures were performed by a single operator according to a standardized surgical protocol and in compliance with all principles of the surgical technique. All patients received standard verbal and written postoperative instructions regarding diet, oral hygiene and general care.

The patients were randomly assigned to 2 groups of 15 patients, according to the drug prescribed as postoperative medication: Group I: dipyrone 500 mg every 6 hours (4 males, 11 females, mean age = 25.2 years) and Group II: paracetamol 750 mg every 6 hours (3 males, 12 females, mean age = 26.8 years). Amoxicillin 500 mg was prescribed for all patients. All surgeries were completed within 1 hour and were performed under local anesthesia with injection of an average volume of 3.6 mL of 2% mepivacaine with 1:100,000 adrenaline per surgical site. No relevant perioperative complications were observed.

In Group I, 3 maxillary right third molars, 9 maxillary left third molars, 10 mandibular left third molars and 9 mandibular right third molars were extracted. The following impaction positions were observed: vertical (n=22), horizontal (n=4) and medio-angulated (n=4). During surgery, osteotomy was necessary in 2 surgical sites and osteotomy associated with tooth sectioning was required in 8 cases. In Group II, 1 maxillary right third molar, 9 maxillary left third molars, 12 mandibular left third molar and 3 mandibular right third molars were extracted. The following impaction positions were observed: vertical (n=18), horizontal (n=2) and medio-angulated (n=3). During surgery, osteotomy, tooth sectioning and osteotomy associated with tooth sectioning were performed in 6, 3 and 6 cases, respectively.

Pain intensity was rated by the patients using a 4-point visual analog scale (VAS): 0 (no pain), 1 (mild pain), 2 (moderate pain), 3 (severe pain), 4 (unendurable pain). Measurements of pain intensity were performed in the immediate postoperative period and every 6 hours after surgery until completing 48 hours. Reports on the relief of the different pain intensities were obtained from the patients at the pre-established intervals (6 hours) using an ordinal scale in order to obtain the mean pain intensity scores for each patient and for each group. The use of a nonparametric statistical test was thus required for data comparison. Mann-Whitney test was used to compare the study groups by analyzing the mean pain intensity scores obtained every 6 hours, in the first 24 hours, in the final 24 hours and in the total 48-hour period. Significance level was set at 5%