The efficacy of a repeated infiltration in prolonging duration of pulpal anesthesia in maxillary lateral incisors

Background. Previous studies have shown declining rates of pulpal anesthesia over 60-minute periods in patients who have received 1.8 milliliters of 2 percent lidocaine with 1:100,000 epinephrine in the maxillary lateral incisor. Methods. The authors conducted a prospective, randomized, single-blind, crossover study comparing the degree of pulpal anesthesia obtained in 40 adult subjects with two sets of maxillary lateral incisor infiltrations, given in two separate appointments: an initial infiltration of 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine plus a repeated infiltration of the same anesthetic and dose given 30 minutes after the initial infiltration, and an initial infiltration of 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine plus a mock repeated infiltration given 30 minutes after the initial infiltration. The authors used an electric pulp tester to test the lateral incisor for anesthesia in two-minute cycles for 90 minutes after the injection. Results. The repeated infiltration improved pulpal anesthesia significantly in the maxillary lateral incisor in the period from 37 through 90 minutes postinjection. Conclusion and Clinical Implications. A repeated infiltration of 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine given 30 minutes after the initial infiltration significantly improved the duration of pulpal anesthesia in the maxillary lateral incisor.