Psychological preparation influences nitrous oxide analgesia: replication of laboratory findings in a clinical setting.

In an earlier laboratory study, administration of 33% nitrous oxide yielded lower, not higher, pain thresholds when combined with appropriately altered expectations of enhanced creativity and sensitivity. The present study was undertaken in an attempt to replicate this finding in a group of clinical dental patients. It was expected that anxiety would play a significant role in our findings. The present study experimentally confirms that controlled psychological preparation of the clinical subject prior to administration of conventional dental dosages of nitrous oxide can significantly modify the perception of tooth pulp pain, neutralizing and even reversing its analgesic efficacy without increasing anxiety.