I read with interest "Complications of an Intra-Arterial Injection From an Inferior Alveolar Nerve Block" by Dr. Brian Webber and colleagues (December JADA).
Although I am a clinical dentist and not a researcher or anatomist, I question the logic supporting the authors’ supposition that the complications were a result of injecting into the inferior alveolar artery.
In order for the symptoms listed to occur, the anesthetic had to travel superiorly to reach the internal maxillary artery. I find this to be very unlikely if the injection is administered properly. The arterial pressure present each time the heart contracts would make it highly unlikely that the anesthetic would reach the internal maxillary artery. In addition to the arterial pressure, it would be necessary for the anesthetic to travel superiorly, which defies the law of physics. The only way this could occur would seem to be a rapid, forceful injection of anesthetic.
If the injection was done slowly and without excessive pressure, I think the anesthetic must be deposited directly into the internal maxillary artery in order to achieve the symptoms noted.
We are instructed to hold the syringe in a horizontal position when administering a block injection. If it is angled superiorly instead, I believe it would be possible to enter the internal maxillary artery. Perhaps a greater likelihood is that the patient’s head is positioned incorrectly with the chin superior to the angle of the ramus. In this position it would be very easy to inject into the inferior maxillary artery.
I also don’t see the need for a vasoconstrictor for routine dental procedures, if bleeding is not anticipated. The effects of intravascular administration of epinephrine are very unsettling to the patient and the practitioner. The presence of the vasoconstrictor also prolongs the adverse effects of the unintended intravascular injection.
I believe that proper positioning of the patient’s head, holding the syringe in a horizontal position, and using non-epinephrine local anesthetic makes this type of anesthetic reaction very unlikely.
