Dental treatments, particularly third molars extraction, can become extremely uncomfortable and painful. They are associated to anxiety, fear and many other unpleasant sensations. During surgery, patients can present cardiorespiratory repercussions of these sensations. This fact generally justifies the employment of methods of monitoring and appliance of safer therapeutic alternatives. Local anesthetics are the most frequently drugs used in dentistry. Vasoconstrictors, particularly epinephrine, are important components of anesthetic solutions to increased time for anesthetic absorption and consequently increasing the duration of anesthesia. The use of smaller amounts of anesthetic solution can reduce the risk of systemic toxicity, however decrease the total surgical time. It is well known that the amount of epinephrine injected into patients during anesthetic procedures can produce adverse hemodynamic effects. Levonordefrin was adding to dental cartridges promising to reduce cardiac stimulation due it less β activity, and maintain the same clinical and systemic effects. But some studies for maxillary or intraosseous infiltrations showed no difference in heart rate and any anesthetic success over epinephrine. Thus, this study aims to compare the clinical efficacy and safety of anesthetic mepivacaine 2% with epinephrine 1:100,000 or 1:20,000 levonordefrin employing a clinical trial model of third molars extractions in healthy adults.

30 healthy patients, both gender between 18 and 40 years-of-age with the necessity of bilateral third molar removal with similar surgical difficulty will be recruited from a Dental Public University Clinic. Inclusion criteria includes: non-smoking participants, minimum of 50 Kg of weight. After clinical and radiographic examination, they will be randomized accordingly to the side to be operated in two groups: MEPI-LEVO and MEPI-EPI. There will be a memory-washout of 15days between surgeries. In the MEPI-LEVO group, the patient will receive local anesthesia employing 2% chloridrato mepivacaine with 1:20.000 levonordefrin at a maximum of four cartridges of anesthesia. The other side will receive 2%chloridrato mepivacaine with 1:100.000 epinephrine in the same maximum amount. The surgery in both groups will follow strictly patterns of minimum surgical trauma and high cautious antiseptic conditions. The same surgeon will do the tooth extractions but the anesthesia will be done by another oral surgeon in order to blind the type of anesthetic solution from the operator (type of vasoconstrictor used). The amount of bleeding will be quantified just immediately after suture by a blinded observer that will record in a visual analogical scale between 0 and 10 points, where 0 correspond to absence of bleeding and 10 to excessive bleeding.

Blood pressure and heart rate will be accessed in five different moments:

1. 20minutes before surgical procedure with patients in awaiting room;
2. 5 minutes before procedure with patient seated in dental chair;
3. 5 minutes after anesthesia procedure;
4. during osteotomy/tooth sectioning and
5. after 10 minutes of suturing.

Patients after surgery will receive a diary to record the time when anesthesia sensation had ended, the amount of analgesics they had consumed and the level of pain in a visual analogic scale. The data will be submitted to statistical analysis with p<0.05 of significance.

Inclusion Criteria:

• minimum body weight of 50Kg, necessity of bilateral impacted third molar removal

Exclusion Criteria:

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