Incidence of missed inferior alveolar nerve blocks in vital asymptomatic subjects and in patients with symptomatic irreversible pulpitis.

The purpose of this retrospective study was to determine the incidence of missed inferior alveolar nerve (IAN) blocks by using a 1- or 2-cartridge volume of 2% lidocaine with 1:100,000 epinephrine in vital asymptomatic teeth and in emergency patients with symptomatic irreversible pulpitis. As part of 37 studies, 3169 subjects/patients were evaluated for missed IAN blocks. The study included 2450 asymptomatic subjects and 719 emergency patients presenting with symptomatic irreversible pulpitis. Each subject or patient received either a 1- or 2-cartridge volume of 2% lidocaine with 1:100,000 epinephrine. A missed block was defined as no lip numbness at 15-20 minutes after the IAN block. The effect of anesthetic volume on the incidence of missed blocks was assessed by using mixed models logistic regression with individual studies as a random effect. The incidence of missed blocks for asymptomatic subjects was 6.3% for the 1-cartridge volume and 3.8% for the 2-cartridge volume. For patients presenting with irreversible pulpitis, the incidence of missed blocks was 7.7% for the 1-cartridge volume and 2.3% for the 2-cartridge volume. In both asymptomatic subjects and patients with irreversible pulpitis, the 2-cartridge volume was significantly (P = .0395) better than the 1-cartridge volume. There were no significant effects for pulpal diagnosis (P = .7523) or the pulpal diagnosis and anesthetic volume interaction (P = .3973). Concerning missed IAN blocks, we concluded that administration of a 2-cartridge volume was significantly better (P = .0395) than a 1-cartridge volume in both asymptomatic subjects and emergency patients presenting with irreversible pulpitis.