Archives for July 2016

Dental MythBuster #15: I Don’t Have to be Numb to Have an Extraction of a Tooth That’s Had a Root Canal

This is one dental myth that I personally don’t see too often. On average, I see it approximately once a month. This myth is based on this perception: because a root canal treated tooth has no nerve, if it needs to be extracted, then you don’t have to be numb (since the nerve is gone).

On the surface, this might make sense. After all, if there is no nerve, you won’t feel anything, right? Well, it turns out that is not the case. Let’s see why:

What Root Canal Treatment Does

root canal treatment x-rays

X-rays showing completed root canal treatment. Note the vertical white lines showing the canal filling material.

When a root canal is performed, the nerve tissue that lies deep inside the tooth is removed, and then that space is filled with a special filling material. The two x-rays on the left illustrate this. The top one shows the pre-operative condition of the tooth and the bottom x-ray shows the completion of the procedure with a filling material in the root canal space.

Once complete, because the nerve is now gone, the tooth will no longer be able to feel hot or cold. So if you try to swish really cold water around a tooth that’s had a root canal, you won’t feel it.

However, there are still plenty of things around the tooth that are still “alive.” The gum tissue around the tooth is alive. The ligament that holds the tooth in the socket is still alive. If you bite down hard on the tooth – you’ll feel it. All of these things…

Why You Have to be Numb for Tooth Extractions

dental elevator used for teeth extractions

Elevator used for extractions.

This may sound slightly obvious. But, to bust this myth, we need to understand why.

When a tooth is extracted, local anesthesia is given to numb the nerves associated with the tooth. What nerves would those be? They include:

  • The nerves of the tooth itself.
  • The nerves going to the ligaments holding the tooth in the socket.
  • The nerves going to the bone immediately surrounding the ligaments and tooth.
  • The nerves going to the adjacent teeth.
  • The gum tissue around the tooth.

When that tooth is extracted, great forces are exerted on not just the tooth, but the surrounding tissue. One of the instruments used is a dental elevator, which is pictured to the right. This instrument pushes the tooth out but does so by placing reciprocal forces on the structures next to the teeth.

No Local Anesthesia = Pain

alt

Even though the tip of your fingernail can’t feel much, try pulling out the nail itself!

So what would happen if an extraction was attempted on a tooth that’s had a root canal but without local anesthesia (a.k.a no “novocaine“)?

OUCH!

When the elevator is inserted (or other instrument for that matter) – the tooth itself might not “feel” anything, but the surrounding tissue will.

An analogy to how it would feel might be like having a fingernail pulled off. Sure, you can cut the tip of your fingernail and not feel anything – but try to pull it off – and you’ll be in a lot of pain!

So, if you need to have a tooth extracted, and that tooth has had a root canal – you’ll need to very numb.