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 a lower molar, is more effective than a local anesthetic injection of lidocaine. However success rates have not been as high as hoped for. No objective study has addressed the success rate of buffering articaine in a mandibular primary buccal infiltration of the first molar. Therefore, the purpose of this prospective, randomized, double-blind, crossover study is to compare the degree of pulpal anesthesia obtained with a buffered 4% articaine with 1:100,000 epinephrine solution versus a non-buffered 4% articaine with 1:100,000 epinephrine solution as a primary infiltration in the mandibular first molar. The investigators will also record the pain of injection and postoperative pain.

Using a crossover design, 80 adult subjects will receive two injections consisting of a primary mandibular first molar infiltration of 1.8 mL of non-buffered 4% articaine with 1:100,000 epinephrine, and 1.8 mL of buffered 4% articaine with 1:100,000 in two separate appointments spaced at least one week apart. With the crossover design, 160 infiltrations will be given for the first molar and each subject will serve as his or her own control. Eighty infiltrations will be administered on the mandibular left side and 80 administered on the mandibular right side. The order of the two injections will be assigned randomly and the dentist and subject will be blinded about which anesthetic the subject is given. The anesthetics used in this study are not experimental. An electric pulp tester (EPT) will be used to test the lower first molar for anesthesia starting 30 seconds after the injection; and testing every 30 seconds for the first five minutes. After five minutes the EPT will be used to test the lower first molar every minute and the contralateral control canine every 5 minutes for a grand total of sixty minutes. The pain of injection and postoperative pain will be recorded in a survey. Patients will report any postoperative pain or discomfort on a Visual Analog Scale (VAS) for three days following each appointment. The data will be statistically analyzed.

Inclusion Criteria:

• Between the age of 18-65 years.
• in good health (ASA classification II or higher).
• able to provide informed consent.

Exclusion Criteria:

• allergy to articaine.
• history of significant medical problems (ASA classification of III or worse).
• diagnosed depression (taking tri-cyclic antidepressant medications to control).
• have taken central nervous system (CNS) depressants (including alcohol or any analgesic medications) within the last 48 hours prior to testing.
• lactating or pregnant.
• inability to give informed consent.