The effect of ketamine on postoperative pain and recovery outcomes after bilateral third molar surgery

Abstract

Introduction: Surgical removal of third molars are often associated with postoperative pain, swelling and other complications. Although this physiological inflammatory response is an anticipated event, significant discomfort may affect masticatory function and social activities. Ketamine has been shown to have analgesic and anti-inflammatory effect. It may help reduce these symptoms. Aim: To investigate and compare the effect of sub-anaesthetic dose of ketamine before incision on postoperative pain, swelling, serum interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-α) with normal saline (placebo) and dexamethasone (positive control) after bilateral third molar surgery under general anaesthesia. Materials and Methods: A double-blind, randomized controlled trial was conducted. One hundred and fifty two patients with bilateral third molars were selected. Patients received an intravenous injection before the induction of anaesthesia which contained ketamine 0.5mg/kg, dexamethasone 8mg or normal saline. Surgery was performed by single surgeon. Pain was assessed by Numerical Rating Scale at postoperative 1, 2, 4, 8, 12, 24, 48, 72 hours and day 7. Swelling was evaluated by a portable three dimensional laser scanner on postoperative day 1, 2 and 7. Serum interleukin-6 and tumour necrosis factor alpha levels were measured at preoperative, 6 hours and 16 hours postoperatively. Results: Significant reduction of postoperative pain, swelling and serum IL-6 was only demonstrated in the dexamethasone group, but not ketamine group, when compared with placebo. No difference in time to first analgesic, total analgesic consumption and patient satisfaction was found among the three groups. No adverse events and complications were observed with the use of ketamine and dexamethasone. Conclusions: Intravenous sub-anaesthetic dose of ketamine before incision was not effective in reducing postoperative pain and inflammation in patients undergoing bilateral third molar surgery under general anaesthesia. Dexamethasone had superior analgesic and anti-inflammatory effect with minimal complication when used in the current clinical setting. Portable laser scanning was accurate for three dimensional evaluation of swelling and was a useful tool in clinical practice and research.