Why Root Canal Treatment Sometimes Hurts - And What I Do About It

“Will root canal treatment hurt?”

This is a common question from my patients because of their own stories from friends and family about their experiences with painful treatment. It is hard not to walk into my surgery expecting the worst.

The honest answer is that for most people, the treatment itself is comfortable. But pain during root canal treatment is a real phenomenon, it does happen and understanding why can make a big difference - both to your anxiety and how we deal with it on the day.

Why your brain makes this harder than it needs to be

Here is something that surprises many people: pain is not just physical. It is also psychological, and the two are deeply connected.

When you are anxious — really anxious — your brain goes into a state of heightened vigilance. Every sensation becomes sharper. Your perception of pain increases, not because anything has changed in your tooth, but because your nervous system is primed to detect threat. This is not weakness or imagination. It is your brain doing exactly what it evolved to do.

There is a striking example of this from military medicine. Soldiers wounded in combat often report feeling little or no pain at the time of injury, only for the pain to arrive fully once they are back at the relative safety of their base. The brain, under extreme focus and stress, can dramatically alter what we feel. The same mechanism works in reverse: when you arrive at the dental chair already dreading pain, your sensitivity is already turned up before treatment has even begun.

This is why managing anxiety is not a nice-to-have in root canal treatment. It is clinical necessity.

So why does root canal treatment sometimes hurt?

The most common reason is something called nerve wind-up.

When a tooth has been inflamed for a while, the nerve inside does not just signal pain through one pathway — it becomes sensitised, firing through multiple pathways at once. Standard local anaesthetic works well for routine dentistry, but it is less effective at blocking pain when a nerve is in this sensitised, wind-up state.

This is why some patients experience a sudden jolt or sharp sensation during treatment even after the tooth has been numbed. It is not that the anaesthetic has failed — it is that wind-up requires a different approach.

What I do about it

The answer is supplementary anaesthesia. When I see signs of nerve wind-up, I use additional anaesthetic techniques specifically designed to reach and block those additional pain pathways. This is a routine part of specialist endodontic practice, and it works.

For most patients, the experience of a numbed tooth is a slightly odd sensation — half the face feels heavy, almost jelly-like — but drilling and cleaning the tooth causes no discomfort at all. Any sharp sensation during treatment is a signal for me to find a way to make you comfortable, not something you are expected to push through.

If you are particularly anxious

If the thought of treatment is causing you significant worry, tell me before we start. I offer sedation for patients who need it — a safe, relaxing option that takes the edge off anxiety and makes the whole experience much more manageable. Many patients who arrive dreading the appointment leave wondering what they were so worried about.

The goal is simple: you should leave feeling that the experience was nothing like the stories you heard.

For the vast majority of my patients, that is exactly what happens!