Infiltration (injecting next to the tooth) injections are common in dentistry and a number of studies have shown that articaine anesthetic, when injected next to the tooth as a supplemental injection, works very well following a typical inferior alveolar (lower jaw) nerve block. No study has compared 4% articaine with 1:100,000 epinephrine, 4% prilocaine with 1:200,000 epinephrine, and 4% lidocaine with 1:100,000 epinephrine in mandibular (lower jaw) infiltration injections of the first molar. The purpose of this prospective, randomized, double-blind, crossover study is to compare the degree of anesthesia obtained from the three solutions as a primary infiltration injection next to the mandibular first molar. The investigators also will record the pain of injection and postoperative pain.