Nitrous oxide analgesic effect on children receiving restorative treatment on primary molars

Pain experienced during dental treatment increases the risk of developing dental anxiety in children who will became anxious adults, avoiding dental care. It is therefore essential to provide pain-free dental treatment. The strongest fears are often associated with injections: being able to successfully complete painless restorative treatment without the need for local anesthesia injection is therefore an important goal. Nitrous oxide administration by means of Langa's Relative Analgesia (RA) technique has been demonstrated to have both sedative and bland analgesic properties: the mechanism by which N2O exerts its analgesic effects is now understood. The purpose of this study was to test the analgesic effectiveness of Nitrous Oxide used in the RA technique as the only analgesic agent for restorative treatment of primary molars presenting caries lesions without pulp involvement.

Ninety patients aged between 3.2 and 9.4 years, 38 males and 52 females, ASA I and II, were included in the study. One hundred and thirty-four restorations were completed on primary molars with caries lesions without pulp involvement (1/3 to 2/3 into dentin): 72 restorations were completed on 48 patients under RA in the Study Group and 62 restorations were performed on 42 patients under RA and local anaesthesia (LA) in the Control Group. At the end of each session, the perception of pain experienced during treatment was rated by each patient using the Wong-Baker FACES® Pain Rating Scale.

No statistical difference on self-reported pain perception was seen in the Study Group (treatment under RA) and in the Control Group (treatment under RA plus LA administration). The results also showed no significant difference in pain sensation between males and females; age as well as gender did not affect the results between groups.

Nitrous oxide as used in the Langa's RA technique is effective in providing a sufficient analgesic outcome during restorations of primary molars when there is no pulp involvement, with no need for LA supplement.