Objective: The authors conducted two double-blinded, randomized, multicenter clinical trials to determine the efficacy and clinical anesthetic characteristics of 4 percent articaine hydrochloride (HCl) with 1:200,000 epinephrine (A200) as compared with those of 4 percent articaine HCl with 1:100,000 epinephrine (A100) and 4 percent articaine HCl without epinephrine (Aw/o).
Methods: During separate testing sessions, members of the authors' research team used three articaine study formulations to induce either inferior alveolar nerve block anesthesia (Trial 1) or maxillary infiltration anesthesia (Trial 2). In each trial, subjects received, in a randomized sequence, each of the three formulations to determine efficacy (success rate) and anesthetic characteristics (onset time and duration). The authors evaluated pulpal anesthesia via subjects' response to electric pulp testing (EPT).
Results: A total of 126 subjects were enrolled in the two studies (63 subjects in each trial). In both mandibular and maxillary trials, the success rates for inducing profound anesthesia (EPT score > 80), the mean onset times and the mean durations of anesthesia were similar for both epinephrine-containing formulations (A200 and A100). In subjects who received the formulation containing no epinephrine (Aw/o), the success rate for profound anesthesia was significantly less.
Conclusion: These studies demonstrated that the inclusion of epinephrine in 4 percent articaine anesthetic formulations is essential for achieving profound anesthesia. The authors found that the A200 formulation provided a level of pulpal anesthesia comparable with that of the A100 formulation.