Chlorhexidine gel and less difficult surgeries might reduce post-operative pain, controlling for dry socket, infection and analgesic consumption: a split-mouth controlled randomised clinical trial.

Reports on post-surgical pain are a few, controversial and flawed (by statistics and analgesic consumption). Besides, it is not known if chlorhexidine can reduce post-extraction pain adjusting for its effect on prevention of infection and dry socket (DS). We assessed these. A total of 90 impacted mandibular third molars of 45 patients were extracted. Intra-alveolar 0·2% chlorhexidine gel was applied in a split-mouth randomised design to one-half of the sockets. None of the included patients took antibiotics or analgesics afterwards. In the first and third post-operative days, DS formation and pain levels were recorded. Predictive roles of the risk factors were analysed using fixed-effects (classic) and multilevel (mixed-model) multiple linear regressions (α = 0·05, β≤0·1). In the first day, pain levels were 5·56 ± 1·53 and 4·78 ± 1·43 (out of 10), respectively. These reduced to 3·22 ± 1·41 and 2·16 ± 1·40. Pain was more intense on the control sides [both P values = 0·000 (paired t-test)]. Chlorhexidine had a significant pain-alleviating effect (P = 0·0001), excluding its effect on DS and infection. More difficult surgeries (P = 0·0201) and dry sockets were more painful (P = 0·0000). Age had a marginally significant negative role (P = 0·0994). Gender and smoking had no significant impact [P ≥ 0·7 (regression)]. The pattern of pain reduction differed between dry sockets and healthy sockets [P = 0·0102 (anova)]. Chlorhexidine can reduce pain, regardless of its infection-/DS-preventive effects. Simpler surgeries and sockets not affected by alveolar osteitis are less painful. Smoking and gender less likely affect pain. The role of age was not conclusive and needs future studies.