Abstract: Objective To estimate the effect of nitrous oxide anesthesia on patient pain perception during local anesthesia administration in children. Methods A simple randomized, double-blinded, placebo-controlled study was designed and implemented. 60 patients (aged 6 to 10) with anterior maxillary region impacted supernumerary teeth extraction surgery were randomly allocated to 2 groups: nitrous oxide-oxygen sedation (group A, n=30) and oxygen (group B, n=30). Frankl behavioral rating scale was adopted to evaluate the cooperation of each patient, depth of sedation using Modifed Observer's Assessment of Alertness/Sedation (OAA/S) scale. Pain perception for local anesthesia was assessed using face, legs, activity, cry and consolability (FLACC) behavioral pain assessment scale. Physiological parameters like respiratory rate (RR), heart rate (HR), and oxygen saturation (SPO2) were recorded. Results The Frankl behavioral rating scales in group A were better than those in group B (P<0.05). The FLACC scale in A group was lower than in B group (P<0.05). The patients were significantly more sedated in the group A compared to group B (P<0.05). The HR, SPO2 and RR in two groups had no significant difference (P＞0.05). Conclusion Nitrous oxide and oxygen enable a better management of acute pain related to local anesthesia procedures.

Key words: Nitrous oxide, Pain on injection , Sedation, Local anesthesia, children