Does the use of cooled saline irrigation during third molar surgery affect post-operative morbidity?

Design This study is a double-blind, single-centre, split-mouth, prospective randomised control trial. In total, 48 patients had bilateral third molars removed during two separate operations at least 21 days apart by the same maxillofacial surgeon. During the control operation, the tooth was irrigated with saline at 25°C. During the test operation, patients were randomised to tooth irrigation with saline at either 10°C (n = 24) or 4°C (n = 24). Local anaesthetic, flap design, burr design and sutures remained consistent throughout. Patients were prescribed amoxicillin, chlorhexidine and were advised to take paracetamol as needed. The patients remained blinded to which test group they were randomised to and to the order of the control or test operations performed. Participants self-recorded analgesia use and post-operative pain daily for seven days using a visual analogue scale (VAS). A second maxillofacial surgeon examined patients on days one, three and seven. Facial swelling was assessed by measuring the distance between various soft tissue points compared to pre-operative levels. Trismus was determined by measuring maximum inter-incisal opening compared to pre-operative levels.Case selection In total, 28 female and 20 male medically fit adult patients with a mean age of 24.6 ± 3.8 with bilateral mandibular asymptomatic third molar teeth were selected. Second molars with periodontal probing depths >4 mm or impacted third molars associated with cysts or tumours were excluded. Patients had no antibiotic prescription in the preceding month nor analgesic consumption in the 12 hours before surgery.Data analysis The Shapiro-Wilk test was used to evaluate if the sample fit a normal distribution. Relationships between the categorical variables of the groups was tested using chi-square statistics. Data comparisons were examined with the Duncan, Kriskal-Wallis, Dunn and Friedman test (p <0.05).Results The median duration of the control and test group operations were similar (p = 0.051). Test group patients reported lower pain VAS values and consumed less analgesics compared to the control groups (p = 0.001), with the lowest values seen in the 4°C group (p <0.001). A greater decrease in trismus levels was also seen on day three and seven in the test groups (p <0.001) compared to the control group (p = 0.07). Swelling was greatest in the control group (p <0.001) and reduced on day seven (p <0.001) in all groups. While trismus and swelling values were lower in the 10°C test group compared to the control (p <0.001), the lowest values of these parameters at all time points was in the 4°C group (p <0.001).Conclusions Early complications following third molar removal include facial swelling, trismus and pain. In this study, intraoperative cooled saline irrigation to 4°C and 10°C was more effective than saline irrigation at 25°C in reducing the intensity of these conditions.