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Can’t Get Numb



I went to my regular dentist for a crown prep on #16/17. This had a crown build-up which she did after excellent local. Alas, she could not get me numb after 5-6 attempts. She thought that caffeine use (I’m a big coffee drinker) may have an effect (she had seen two cases before but nothing in the literature) so I avoided caffeine for 24 hrs and returned. Same thing. She did a mental foramen block with excellent anesthesia. These are NOT angry, inflammed teeth and I am fairly tolerant to pain. The irony of this is I am a Nurse-Anesthetist with a specialty in regional anesthesia. Any thoughts would be greatly appreciated.


Thank you for your question. I assume your problem was with the lower tooth as inferior alveolar nerve block has a success rate of approximately 80+%. Second, and especially third molars, are more prone to inadequate local. The reason may be accessory innervation but this is not completely understood. Mental block will allow for excellent lip numbness but is not effective for a tooth as proximal to the site of injection as was your situation. Clearly, you can achieve good local anesthesia in the posterior mandible and you may be fine the next time.

Some alternative options would be to continue with conventional inferior alveolar nerve block but supplement with intraosseous (small hole drilled into marrow near roots of teeth with infiltration of local anesthetic around the roots, all with a specialized system) or buccal infiltration with articaine and epinephrine. These are good supplemental techniques. Likely, you dentist attempted PDL injection into the space between the tooth and the bone. Alternatively, Gow-Gates technique can be used but only some dentists are familiar with this technique. Good luck.

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