Efficacy of the Combination Mepivacaine-Tramadol on the Success of Inferior Alveolar Nerve Block in Patients With Symptomatic Irreversible Pulpitis: a Randomized Clinical Trial.

The treatment of pain is an integral part of Endodontics, this must be controlled before, during and after treatment. The inferior alveolar nerve block is the most common anesthetic technique used in mandibular teeth during endodontic treatments. Several studies have reported that it is more difficult to obtain anesthetic success in patients with irreversible pulpitis. There is a 33-80% of failure in the inferior alveolar nerve block in patients with irreversible pulpitis.

Some of the more accepted theories for local anesthetic failure establish that inflammation induce tissue acidosis causing ion traping of the local anesthetics enabling the molecules to cross the cell membrane, also inflammatory mediators may sensitize the neurons by interacting with specific receptors leading to periphery sensibilization. Tissue injury may alter the composition, distribution and activity of sodium channels expressed on nociceptors and this may have profound implications in local anesthetic failure. On the other hand, there is a specific group of tetrodotoxin resistant sodium channels four times less sensitive to lidocaine which increase their activity during inflammation.

Some ways to control pain is through pharmacological synergism. Tramadol has been proposed as pharmacological adjuvant to local anesthesia and it can improve the anesthetics success and the duration of the anesthetic effect. However, oral administration of drugs can cause adverse systemic effects, and that's why local application is an alternative to increase its concentration on the local damaged tissue reducing the possibility of interactions with other drugs and adverse effects. Another advantage of the combination of Mepivacaine with Tramadol is that it reduces the number of injections in patients and it is less traumatic.

Tramadol is centrally acting drug but also a local anesthetic and analgesic effect it has been reported. It acts at multiple sites producing different action mechanisms. Some studies suggest that the use of Tramadol can improve the effect of Mepivacaine in the inferior alveolar nerve block. The blockade of the nervous conduction with Tramadol is 80% more effective if it is compared with some anesthetics like lidocaine.

There are few studies evaluating local application of tramadol. In the field of dentistry tramadol using for local anesthetic adjuvant has been studied in oral surgery, so it is important to evaluate it in the field of endodontics to provide better pain management during treatments.