Nitrous Oxide/Oxygen Effect on IANB Injection Pain and Mandibular Pulpal Anesthesia in Asymptomatic Subjects

The inferior alveolar nerve block (IANB) does not always result in successful pulpal anesthesia. Nitrous oxide may increase the success of the IANB. The purpose of this investigation was to study the effect of nitrous oxide/oxygen (N(2)O/O(2)) on IANB injection pain and mandibular pulpal anesthesia in asymptomatic subjects. One hundred five asymptomatic subjects received an IANB after the administration of N(2)O/O(2) or room air/oxygen (air/O(2)) at 2 separate appointments. After the IANB, subjects rated their level of pain for each phase of the injection (needle insertion, needle placement, and solution deposition) using a Heft Parker visual analog scale. Pulpal anesthesia was evaluated with an electric pulp tester for 60 minutes. The mean pain rating for all 3 injection phases showed a statistically significant reduction in pain when N(2)O/O(2) was used compared with Air/O(2) (P < .05). Odds ratios demonstrated a statistically significant increase in IANB success for the N(2)O/O(2) group compared with the air/O(2) group. N(2)O/O(2) administration statistically decreased pain for all 3 injection phases of the IANB. In addition, nitrous oxide statistically increased the likelihood of pulpal anesthesia for posterior mandibular teeth. However, the incidence of pulpal anesthesia was not 100%.