This study utilizes healthy volunteers to determine, via electronic pulp tester, such basic clinical parameters as time of onset and duration of action for an infiltration and mandibular block utilizing the recently available local anesthetic preparation, 2 per cent lidocaine with 1:200,000 epinephrine (Octocaine 200). This study showed Octocaine 200 to be both safe and efficacious, producing times of onset and duration within the clinically useful range. The rationale for vasoconstrictor use in dentistry is also reviewed.