METHODS	One hundred asymptomatic adult subjects randomly received 2 sets of injections consisting of a primary mandibular second premolar infiltration of 1 cartridge of 4 % articaine with 1:100,000 epinephrine plus a repeat infiltration 20 minutes later ( using the same volume of articaine ) or a mock repeat infiltration in 2 separate appointments spaced at least 1 week apart .\