Insight Track Session Preview: Local Anesthesia for Pain Management and Prevention

By Dr. Sara Fowler

Fear of pain has been reported as the most common reason people avoid going to the dentist (1). Whether this fear is a result of previous personal experience, or from society’s historic view about dental care and endodontics being a painful experience, we never want to lose sight of the idea that our ability to relieve and prevent pain is arguably the most important thing we do as endodontists. Being an excellent endodontist is not only about being great at doing root canals. Our patients don’t care nearly as much as we do about those perfectly tapered white lines on the final radiograph, but are more concerned with the manner in which we provide that excellence of care. 

Our referring dentists may be more interested in how beautiful that final radiograph looks, but when the patient returns to their office relieved that the endodontist didn’t hurt them, it is that care and compassion that the patient perceives as the endodontist’s skill and expertise. The endodontist cared about their discomfort.  They showed compassion toward them by managing and preventing their pain throughout the endodontic procedure.  They completed the procedure efficiently, further demonstrating a genuine consideration for the patient’s condition. We rarely get the opportunity to hear that conversation between the referring dentist and the patient, but we know that when a patient has a positive experience in the hands of the endodontist, that is a victory not just for the patient, but also for the endodontist, as well as for our specialty as a whole.  

Failure to relieve pain can lead to decreased patient satisfaction (2), but fortunately our profession’s dedication to better understanding the nature of odontogenic pain and how best to overcome it should be a comfort to patients and practitioners alike. Even with our specialty’s extensive body of research on the efficacy of local anesthetic agents and different methods of delivery, combined with the practitioner’s desire to provide painless endodontic treatment (to the extent that is possible), the so-called “perfect” anesthesia protocol has not been discovered.  The “perfect” anesthetic or technique may not exist, but we approach every patient with the goal of providing the most ideal experience we possibly can. 

Determining an appropriate evidence-based anesthesia plan prior to treatment is a good way to prepare for the challenges that often arise when attempting to profoundly anesthetize the most difficult to numb teeth – mandibular molars with the diagnosis of symptomatic irreversible pulpitis. In Successful Local Anesthesia for Restorative Dentistry and Endodontics, Reader and coauthors (3) have published algorithms that outline approaches to anesthetizing teeth prior to root canal therapy.  

Multiple authors have reported no significant difference between clinical effectiveness of 2% lidocaine 1:100,000 epinephrine versus 4% articaine 1:100,000 epinephrine (4,5), so we start with an IAN block with 2% lidocaine with 1:100,000 epinephrine.  We may use two cartridges (a 3.6 mL volume) as a two cartridge volume has been shown to be less likely to result in a missed block (4% with two cartridges, versus 6% with one cartridge) (6). For some patients, conscious sedation with nitrous oxide may be indicated and fortunately, there is evidence that administration of 30%-50% nitrous oxide results in a statistically significant increase in the success of the IAN block in patients with symptomatic irreversible pulpitis (7). Once lip numbness is achieved and we know we have a successful block, we test for pulpal anesthesia by applying cold refrigerant to the tooth. Here is another opportunity to gain the patient’s trust and reassure them that we are keeping their comfort as our highest priority.  If the tooth responds to the cold, we can give a buccal infiltration with 4% articaine with epinephrine which has been reported to increase efficacy of the IAN block (8).  Again, we test the tooth with cold refrigerant to ensure that pulpal anesthesia has been achieved before we proceed.  It is always worth the short amount of time it takes to test the tooth with cold prior to picking up the hand piece and accessing the tooth. 

Although uncommon, the tooth may still respond to cold testing even after a successful IAN block and articaine infiltration.  At this point, an intraosseous or intraligamentary injection would be recommended.  For the intraosseous injection, a solution of 2% lidocaine 1:100,000 epinephrine or 3% mepivacaine is recommended (3). The plain mepivacaine solution is preferable when the clinician wants to avoid the transient increase in heart rate which occurs with administration of an epinephrine-containing solution, and has been reported to be successful as well (9). Yet again, we are testing the tooth with cold refrigerant to ensure that the intraosseous or intraligamentary anesthesia was successful.  When the patient is expecting to feel the cold sensation as they have previously, but they don’t (finally!), you can see the relief in their eyes. We have a similar feeling of relief as we know our plan has been effective.  We can be confident that we can complete the endodontic therapy efficiently, excellently, and without pain – everyone wins!

References

1. ADA Survey. Influences on dental visits. ADA News 1998;11(2):4.
2. Stahlnacke K, Soderfeldt B, Unell L, Halling A, Axtelius B. Patient satisfaction with dental care in one Swedish age cohort. Part II – What affects satisfaction. Swed Dent J 2007;31:137-146.
3. Reader A, Nusstein J, Drum M. Successful Local Anesthesia for Restorative Dentistry and Endodontics 2nd Ed. 2017 Quintessence Publishing. 
4. Mikesell P, Nusstein J, Reader A, Beck M, Weaver J. A comparison of articaine and lidocaine for inferior alveolar nerve blocks. J Endod 2005;31:265-270). 
5. Brandt RG, Anderson PF, McDonald NJ, Sohn W, Peters MC. The pulpal anesthetic efficacy fo articaine versus lidocaine in dentistry: A meta-analysis. J Am Dent Assoc 2001;142:493-504. 
6. Fowler S, Reader A, Beck M. Incidence of missed inferior alveolar nerve blocks in vital asymptomatic subjects and in patients with symptomatic irreversible pulpitis. J Endod 2015;41:637-639. 
7. Stanley W, Drum M, Nusstein J, Reader A, Beck M. Effect of nitrous oxide on the efficacy of the inferior alveolar nerve block in patients with symptomatic irreversible pulpitis. J Endod 2012;38(5):565-569. 
8. Haase A, Reader A, Nusstein J, Beck M, Drum M. Comparing anesthetic efficacy of articaine versus lidocaine as a supplemental buccal infiltration of the mandibular first molar after an inferior alveolar nerve block. J Am Dent Assoc 2008;139:1228-1235. 
9. Gallatin E, Stabile P, Reader A, Nist R, Beck M. Anesthetic efficacy and heart rate effects of the intraosseous injectin of 3% mepivacaine after an inferior alveolar nerve block. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:83-87. 

Dr. Sara Fowler is associate professor at Ohio State with tenure in the Division of Endodontics. She is the director of Predoctoral Endodontics and the Emergency Dental Care Clinic, maintains private practice in the Ohio State Dental Faculty Practice, and actively participates in teaching and research with the Advanced Endodontic Residency Program. Don't miss her presentation at Insight Track.