Topical anesthetics, generally, are only effective on the 2-3mm of the surface mucosa. This depth, however, is enough to allow for atraumatic needle penetration of the mucous membrane. 20% benzocaine and 5% lidocaine are the most common preparations used by dentists. The setup time for benzocaine is 30 seconds or so, whereas, lidocaine can take several minutes to set up. Pressurized spray containers are no more effective than viscous or gel forms and should not be used intraorally unless the spray dose is measured and fixed.
Most EDs have two choices when it comes to injectable anesthetics, lidocaine or bupivacaine. The addition of epinephrine lets us tailor each to a particular patient’s needs. Bupivacaine results in complete anesthesia for 6-8 hours with residual pain control lasting up to 48 hours. This has been demonstrated in several studies and the implications for use in odontalgia is obvious. Why not give people with true odontalgia the chance to have decent pain control for 2 days until they can see a dentist? Seems reasonable to me.
The problem with using standard syringe systems in the mouth is that they don’t allow the operator to adequately aspirate and visualize at the same time. We know that side effects and complications of oral injections are primarily a result of intravascular injection. Dentists and oral surgeons learned this a long time ago, so they typically use stainless steel ringed aspirating syringes and carpule anesthetics. The introduction of plastic reusable ring syringes has now made carpule anesthetic systems more efficient to use and clean in emergency departments.
The Blocks The EP Should Know!
Following are listed the regional facial anesthetic procedures that emergency physicians should be familiar with. A complete discussion on the performance of these procedures is beyond the scope of this text. Detailed instructional videos of the following blocks can also be seen by going to the link in the left-hand column.