My Inferior Alveolar Nerve Block Didn’t Work. Now What?

Achieving anesthesia of the mandibular teeth can be a challenge. Traditionally, schools have taught the inferior alveolar nerve block as the primary technique for anesthetizing mandibular teeth.

Yet while the IANB technique has been considered the standard method for delivering anesthesia for mandibular teeth, it isn’t always successful. This is especially true in treating teeth with symptomatic irreversible pulpitis. It can be particularly frustrating when a patient’s lip and tongue are anesthetized, but their mandibular teeth are still sensitive. Fortunately, we can use a few additional anesthetic techniques to help ensure our patients are comfortable.

Supplementary Anesthesia Techniques

If our patient has soft tissue anesthesia but is still experiencing discomfort, a few supplementary techniques can help ensure profound pulpal anesthesia. One of the more common and simple techniques is mandibular infiltration.

This technique delivers an additional amount of anesthetic solution adjacent to the symptomatic tooth. For mandibular anterior teeth, infiltration of anesthetic to both the buccal and lingual cortical bone is more effective than administering to the buccal aspect alone. However, for mandibular posterior teeth there is no difference when delivering solely to the buccal aspect vs. both buccal and lingual aspects. For mandibular infiltrations, 4% articaine solutions have been shown to be more effective at increasing the likelihood of pulpal anesthesia than 2% lidocaine solutions.¹

The intraligamentary injection (also known as the periodontal ligament injection, or PDL) can be a useful supplementary technique. It can be performed using a traditional aspirating syringe or a PDL injection system (such as a Ligmaject). In this technique, an anesthetic solution is delivered into the PDL of the tooth and spreads to the cancellous bone surrounding the tooth. When positioning the needle, it’s essential to have the bevel face the tooth (rather than the gingiva) and to ensure that significant back pressure is felt when delivering the anesthesia. Only a minimal amount of solution (approximately 0.2 mL, about the size of the carpule plunger) is delivered for the root of the tooth being anesthetized.²

In a similar fashion to the PDL injection, the intraosseous injection technique delivers an anesthetic solution to the cancellous bone surrounding the tooth. In the intraosseous injection, a hole is created through the buccal cortical bone, exposing the cancellous bone adjacent to the tooth. A small amount of anesthetic solution is delivered into the cancellous bone, which anesthetizes the adjacent tooth. Care must be taken to avoid contacting the tooth roots when perforating the buccal cortical bone.

This technique is not advised for patients in their primary or mixed dentition to avoid perforating a tooth due to the risk of damaging the unerupted teeth. Special delivery systems, such as the X-Tip and the Stabident, are necessary to perform intraosseous injections predictably.²

Additional Techniques to Achieve Mandibular Anesthesia

While the IANB has been taught as the standard technique for a mandibular block, other techniques are present that can predictably produce a mandibular nerve block. One of these techniques is the Akinosi-Vazirani technique. In the Akinosi-Varzirani technique, the needle is inserted between the coronoid process and the maxillary tuberosity, at the height of the mucogingival junction. With this technique, the patient will close down to facilitate access to the injection site. This technique can be particularly useful in patients with trismus or an overactive tongue that may inhibit the ability to perform a traditional IANB.³

A second alternative to the traditional IANB is the Gow-Gates technique. This technique achieves a mandibular block by delivering an anesthetic solution adjacent to the condyle.

To perform the Gow-Gates technique, locate three landmarks: The intertragic notch (just below the tragus of the ear), the coronoid process, and the corner of the mouth. Once these are identified, the barrel of the syringe will be adjacent to the contralateral canine, and the needle will be adjacent to the mesiopalatal cusp of the second molar. Have the patient open as wide as possible during the injection and remain open for approximately 20 seconds after delivering the anesthetic solution. This helps maintain the nerve’s position as close to the solution as possible, maximizing the chances of successfully achieving mandibular pulpal and soft tissue anesthesia.

Buffered Anesthetics

Recently, buffered anesthetics have been gaining popularity as a reliable way to predictably achieve pulpal anesthesia. Various systems are available that mix sodium bicarbonate with local anesthetics to increase the pH of the anesthetic solution.

Altering the pH of an anesthetic can be particularly useful for symptomatic teeth, where the inflammatory response leads to a more acidic, lower pH environment. Recent studies on buffered anesthetics have shown that a buffered anesthetic solution can be up to twice as effective to achieve adequate anesthesia in symptomatic teeth than non-buffered local anesthetics.⁴

Spear Online’s Mandibular Nerve Blocks coursework, taught by Dr. Stanley Malamed, reviews these supplementary and alternate techniques for achieving mandibular anesthesia. The nine-lesson, two-part course has been especially helpful for me in cases where achieving mandibular anesthesia has been a challenge.

Hopefully these additional techniques can help you predictably, reliably and confidently keep your patients comfortable and happy.

References

1. Meechan, J. G. (2011). The use of the mandibular infiltration anesthetic technique in adults. The Journal of the American Dental Association, 142, 19S-24S.
2. Moore, P. A., Cuddy, M. A., Cooke, M. R., & Sokolowski, C. J. (2011). Periodontal ligament and intraosseous anesthetic injection techniques: alternatives to mandibular nerve blocks. The Journal of the American Dental Association, 142, 13S-18S.
3. Haas, D. A. (2011). Alternative mandibular nerve block techniques: a review of the Gow-Gates and Akinosi-Vazirani closed-mouth mandibular nerve block techniques. The Journal of the American Dental Association, 142, 8S-12S.
4. Kattan, S., Lee, S. M., Hersh, E. V., & Karabucak, B. (2019). Do buffered local anesthetics provide more successful anesthesia than nonbuffered solutions in patients with pulpally involved teeth requiring dental therapy?: A systematic review. The Journal of the American Dental Association, 150(3), 165-177.