Do Root Canals Hurt?
What About a "Hot Tooth"?

Sometimes a patient will ask me the question "Do root canals hurt?" when we are talking about possible root canal treatment for a hot tooth.

A hot tooth is what dentists call a tooth with a very inflamed nerve. It aches constantly, and it reacts painfully to hot drinks.

There seems to be a general feeling out there that getting a root canal treatment is one of the worst things that can happen at a dentists' office!

One patient even asked me "why do root canals hurt so much?"

Do Root Canals Hurt? They Should Not!

I believe that there is no good reason why having a root canal treatment should hurt any more than any other dental work. In fact, it shouldn't hurt at all!

Dentists are trained how to get teeth numb. It's an essential part of being a dentist. But sometimes they don't get it exactly right.

There are two main reasons why a tooth may not be as numb as you'd wish.

  • I believe that the main reason is time. The dentist may not take enough time to give the local anesthetic shot properly. He needs to make sure he gets the local anesthetic in exactly the right spot.
A dental syringe loaded with an anesthetic carpule and a needle with a blue needle anesthetic

And then he needs to wait long enough for the shot to work. You can read more about this at my guide to Dental Anesthetics.

If you tend to clench your teeth when asleep at night, it frequently takes longer for the numbing effect to work. This is because your jaw muscles are more active, and therefore have more lactic acid in them. This can slow down the numbing effect.

  • I think the second main reason is that some dentists really don't understand enough about exactly how anesthetics work, and how to give a great shot every time.

Sure, modern local anesthetics are very good, and they will work if they are given half a chance. So if the dentist gets it more than half right, there's still a good chance that the tooth will be numb enough.

But not always!

If you have a hot tooth and need a root canal, the dentist needs to use ALL the dental anesthetic tricks to get it numb.

There are several reasons why a tooth may be slower or more resistant to numbing.

  • A hot tooth with a very inflamed nerve will need MORE anesthetic, and MORE time before the dentist starts to work. The dentist should use a "plain" dental anesthetic (ie. without any Adrenalin in it) first, wait 60 seconds, then add TWO MORE shots, this time with a stronger anesthetic containing Adrenalin. Then he should wait for 15 minutes.
  • Patient "resistance" to local anesthetics. This is actually quite uncommon, but if you are in the habit of clenching your teeth at night, the anesthetic will take longer to work. This is because all your jaw muscles are producing lactic acid when they work, like every muscle in your body. The acidic environment of the muscles will slow down the numbing action of the anesthetic.
  • An anesthetic solution that is out of date. This is down to the dentist keeping track of his stock, and getting rid of solutions that have expired.
  • An anesthetic solution that has lost effectiveness due to storing it somewhere too warm. Some dentists like to warm the anesthetic solution before injecting it. If it is at body temperature or slightly above, it hurts less.
  • But it is best to only warm the solution shortly before using it. If the anesthetic carpules are left in a warmer for days on end (it happens), then the chemistry of the solution is altered, and it has less anesthetic effect.
A dentist wearing a green top and white gloves holding a dental syringe.A warm local anesthetic

These are all reasons for a tooth to be not numb enough - but I don't believe that they are VALID reasons! A dentist should be able to deal with these issues.

If you are worried about a root canal hurting, ask your dentist. If he can't give you complete reassurance, I'd suggest that you ask around your friends and workmates for a recommendation with regard to a dentist who always gets his tooth numb!

Listen out for the comment "Oh, I never feel a thing when I go to Dr. Smith's office". These are the words that tell you that Dr. Smith will get your tooth numb.

Quite a bit of research has been done into how to get a tooth properly numb. The American Association of Endodontists has published excellent guidelines, which every dentist should read.

You can read all about Dental anesthetics here.

So when a patient asks me "do root canals hurt?", I always tell them "Not in this office!"

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