Achieving Profound Anesthesia: Current Concepts and Helpful Hints
Many of our patients requiring endodontic therapy present to the office in some degree of discomfort.
The ability to achieve proper levels of anesthesia so that we can painlessly treat our patients may be as important as any other aspect of clinical practice. A comfortable visit instills confidence and trust in our patients and allows the clinician to work efficiently and with minimal stress.
Most clinical problems arise with the inferior alveolar nerve block. Today’s blog will focus on pulpal anesthesia of the mandibular teeth. After establishing a proper diagnosis and discussing the case with our patient we then proceed to anesthetize the patient. My choice of anesthetic for a mandibular block is always 4.0 percent Citanest plain followed by 2.0 percent Lidocaine, with 1.100k epi. I find that anesthetics without the epinephrine seem to be less uncomfortable for patients. The epi containing solutions have a lower PH and the acidity of these anesthetics can cause a sting upon delivery. A carpule of Citanest plan expressed slowly through the tissue allows for an easier pass of the subsequent needle and solution to the desired location. I approach the nerve from the opposite side of the mouth over the contra lateral bicuspids. As the needle is inserted, the goal is to bury the hub of the needle on the medial border the ramus lateral to the pterygomandibular fold. There is evidence in the literature that supports a slower injection results in a higher success rate of pulpal anesthesia. The slower rate of delivery can also ease the patient’s awareness of the injection. After delivery, I usually like to wait ten to fifteen minutes prior to re-testing the tooth in question.
Before starting any treatment, I ask the patient if their lip feels numb; however please note that lip numbness is not necessarily an indication of pulpal anesthesia. Numerous studies have found that the two do not always coincide. If lip numbness is achieved, I always like to expose the tooth question to endo ice (from the buccal or lingual surface). When a patient cannot sense the cold with the endo ice, at that point I am comfortable placing the rubber dam. If the patient still experiences a sensation, I will then move to a supplemental injection.
I prefer lidocaine, however many clinicians that we work with advocate the use of articaine. Most of the current research and clinical trials have not demonstrated any statistical superiority of articiane over lidocaine for inferior alveolar injections. With that said, I do know many colleagues who are adamant about their success with articaine and I do not believe that enthusiasm can necessarily be discounted or ignored based solely on published research.
Most of the negatives with articaine stem from research that found a higher incidence of paresthesia with articaine and prilocaine relative to the other commonly used anesthetics. What is not often mentioned is that the incidence was extremely rare, 14 cases out of 11 million injections! The paper most often referenced is from the Journal of Canadian Dental Association : Haas DA, Lennon D. A 21 year retrospective study of reports of paresthesia following local anesthetic administration. J Can Dent Assoc 1995;61:319-20.
The best explanation to date for teeth that do not respond to a conventional nerve block is the central core theory. It states that nerves on the outside of the nerve bundle innervate the molars and nerves on the inside supply the mandibular incisors. The concept is that the solution may not diffuse throughout the nerve trunk adequately to reach all the nerves needed for a proper block.
In our office our adjunctive anesthesia techniques of choice are both the intraligamentary and intraosseous injection.
The intraosseous injection delivers anesthetic directly into the cancellous bone adjacent to the tooth. This injection works well but does take some experience before a comfort level is reached. The X-Tip or Stabident systems are examples of the intraosseous delivery systems.
The intraligamentary injection involves placing a short needle in the gingival sulcus, ideally between the attachment and the bone. A significant amount of pressure is needed to overcome the tissue resistance. We use the Ligmajectt for this technique. Usually the tissue will blanch when administered properly. A small volume is needed to obtain the desired result. I customarily use 2.0 percent Lidocaine for this injection and administer roughly .2mL of solution in the distal and mesial aspects of the tooth. The duration of anesthesia is shorter for the PDL injection; however this technique allows enough time to extirpate the pulp resulting in a comfortable appointment for the patient. I personally like the intraligamentary injection and find it very effective for the dreaded “hot” tooth.
Achieving anesthesia is crucial to everyday endodontics. I hope this blog provides some good ideas and techniques to achieve proper anesthesia for your endodontic patients.
** In writing this blog, I utilized information from the AAEs Colleague for Excellence.
Full access to this report can be found here http://www.aae.org/uploadedfiles/publications_and_research/endodontics_colleagues_for_excellence_newsletter
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