When the Tooth Still Hurts Despite Anaesthesia: Why “Numb” Doesn't Always Mean Pain-Free
Published by Dr. Niyati Devada, BDS
Director, Orca Dental, Malad East, Mumbai
Published in the International Journal of Applied Dental Sciences, 2026
Have you ever wondered why your lip and tongue feel completely numb at the dentist, yet the tooth itself still seems to hurt?
It may sound surprising, but this is a recognised clinical challenge in dentistry—particularly when treating certain lower molars and wisdom teeth.
As dentists, we often expect local anaesthesia to completely eliminate sensation before beginning treatment. However, soft-tissue numbness does not always guarantee complete pulpal anaesthesia.
This question recently became the focus of my clinical review, which was published in the International Journal of Applied Dental Sciences in 2026.
Article: When the lip is numb but the tooth still hurts: Understanding local anaesthetic failure in mandibular molars and wisdom teeth: A narrative review inspired by a challenging clinical caseAuthor: Dr. Niyati DevadaJournal: International Journal of Applied Dental SciencesVolume: 12, Issue 7, 2026, Pages 54–57DOI: 10.22271/oral.2026.v12.i7a.2466
[Read the original published article →]
If the lip is numb, why can the tooth still hurt?
One of the most important things to understand is that numbing the surrounding tissues and completely anaesthetising the dental pulp are not always the same thing.
An inferior alveolar nerve block, commonly used for lower molars, can produce obvious numbness of the lower lip and tongue. Yet, in some situations, the tooth may continue to respond to stimulation.
This is particularly challenging when a tooth is severely inflamed.
The “hot tooth” phenomenon
A tooth with significant pulpal inflammation is sometimes referred to clinically as a “hot tooth.”
These teeth can be particularly difficult to anaesthetise.
Inflammation can alter the local environment around the nerve tissue and may influence how effectively a local anaesthetic works. Changes in neural sensitivity, anatomical variations and other patient-related factors can also contribute to incomplete pulpal anaesthesia.
This does not necessarily mean that the injection was given incorrectly.
It means that achieving profound anaesthesia in certain clinical situations can require a different approach.
Why is this more common in lower molars?
Mandibular molars can present a particular challenge because of their anatomy and the way their nerve supply is distributed.
The conventional inferior alveolar nerve block (IANB) is a widely used technique for achieving anaesthesia in the lower jaw. However, even when the expected lip numbness is achieved, pulpal anaesthesia may sometimes remain inadequate.
This is one reason why a dentist may test the tooth and ask you how you are feeling before starting treatment.
What happens if the tooth is still sensitive?
The important principle is simple:
Dental treatment should not be continued through significant pain simply because the lip is numb.
If adequate anaesthesia has not been achieved, the dentist can reassess the situation and consider alternative or supplemental anaesthetic techniques depending on the tooth, diagnosis and clinical circumstances.
These may include different approaches to local anaesthesia or supplemental techniques designed to improve pulpal anaesthesia.
The appropriate approach depends on the individual patient and should always be determined by the treating dentist.
Why communication with your dentist matters
Patients sometimes hesitate to tell their dentist that they can still feel pain because they assume that some discomfort is “normal.”
It is important to communicate.
If you feel sharp pain during a procedure, tell your dentist immediately.
A sensation of pressure, vibration or movement can be very different from sharp pain. Your dentist can use your feedback, along with clinical tests, to determine whether additional anaesthesia or a different approach is required.
At Orca Dental, we believe that patient comfort should be an important part of every dental procedure—not an afterthought.
What inspired this article?
This review was inspired by a challenging clinical case involving inadequate pulpal anaesthesia despite achieving satisfactory soft-tissue numbness.
The case highlighted an important clinical question:
Why can a tooth remain painful when the surrounding tissues are clearly numb?
Exploring this question led to a review of the biological mechanisms behind local anaesthetic failure, the “hot tooth” phenomenon and the different strategies clinicians can consider when conventional anaesthesia is insufficient.
The full review discusses these clinical considerations in greater detail.
What does this mean for patients?
The key takeaway is reassuring:
If a tooth is difficult to numb, it does not mean that pain-free dental treatment is impossible.
There can be several reasons why local anaesthesia does not initially produce the desired level of pulpal anaesthesia. Recognising this allows the dentist to reassess the situation rather than simply repeating the same approach.
Good dental care involves understanding the individual tooth, its condition, the patient's response and the most appropriate anaesthetic strategy.
A step towards more comfortable dentistry
Modern dentistry has come a long way in making procedures more comfortable.
Whether you are undergoing a filling, root canal treatment, wisdom tooth procedure or another dental treatment, your dentist should assess your comfort throughout the procedure and respond appropriately if adequate anaesthesia has not been achieved.
The goal is not simply to make your lip numb.
The goal is to achieve the level of anaesthesia required to perform the procedure comfortably and safely.
Read the published research
I am pleased to share that this clinical review has been published in the International Journal of Applied Dental Sciences.
Niyati Devada. When the lip is numb but the tooth still hurts: Understanding local anaesthetic failure in mandibular molars and wisdom teeth: A narrative review inspired by a challenging clinical case. Int. J. Appl. Dent. Sci. 2026;12(7):54–57.
DOI: 10.22271/oral.2026.v12.i7a.2466
[Read the full published article →]
About Dr. Niyati Devada
Dr. Niyati Devada, BDS, is a dentist and the founder of Orca Dental, Malad East, Mumbai.
With clinical experience across multiple areas of dentistry, her areas of practice include root canal treatment, dental implants, braces, Invisalign and clear aligners, cosmetic dentistry, smile makeovers and restorative dentistry.
Her approach combines evidence-based clinical practice with a strong focus on patient comfort and personalised treatment planning.
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