Table 1. Eligibility criteria for patient selection (inclusion and exclusion criteria).

Inclusion Criteria

Exclusion Criteria

1. Impacted third molars symmetrically positioned on both sides of the mandible 2. At least one healthy lower first or second molar on both sides (i.e. without caries or restoration) 3. Consent provided for the study 4. Aged between 18 and 45 y 5. Non-smoker and not an alcoholic 6. Bilateral impacted lower third molars, which require flap opening, bone removal, and tooth separation during the operation 7. Ability to understand and carry out the instructions given by the investigators

1. Systolic blood pressure (> 140 mmHg, < 90 mmHg) 2. Diastolic blood pressure( > 90 mmHg, <60 mmHg) 3. Heart rate (>100 bpm, < 60 bpm) 4. Pregnancy or current lactation 5. Cardiovascular problems, renal and/or liver failure, or other serious medical condition 6. Allergy to local anesthetics 7. Facial deformities that may interfere with the injections, surgery, or evaluation 8. Swelling and/or infection associated with the third molar site 9. Any medication within 5 d prior to surgery that would alter thepatient's perception of pain (analgesic, ntidepressants,etc.) 10. Inability to follow the instructions or cooperate during the study

Note: y, years; bpm, beats per minute; d, days.