Complications caused by nitrous oxide in dental sedation.

The first clinical application of nitrous oxide (N2O) was in 1844, by an American dentist named Horace Wells who used it to control pain during tooth extraction. Since then, N2O has shared a 170-year history with modern dental anesthesia. N2O, an odorless and colorless gas, is very appealing as a sedative owing to its anxiolytic, analgesic, and amnestic properties, rapid onset and recovery, and, in particular, needle-free application. Numerous studies have reported that N2O can be used safely and effectively as a procedural sedation and analgesia (PSA) agent. However, N2O can lead to the irreversible inactivation of vitamin B12, which is essential for humans; although rare, this can be fatal in some patients.