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Is a nerve block injection needed for the 2nd half of a root canal on lower jaw molar



Aug 15, 2021
I had the first half of a root canal done on my lower jaw molar, and the endodontist told me he had to do a nerve block injection because it was the lower jaw. I found the nerve block injection tough to recover from, with a stiff/sore jaw afterwards.

In the first half of the root canal, the pulp was taken out and a temporary filling put in. I will be going back for the second half where it will be cleaned again, filled with gutta percha and a permanent filling put in.

For the second half of the root canal, will I need a nerve block injection again, or can a normal anaesthetic injection be used?
To be on the safe side so that you'll definitely not feel anything during the treatment, then it needs a block again, if you want to take a risk on feeling some pain then you could try an alternative technique. Up to you?

It sounds easy to say but hard to do, but try to keep as still as you possibly can during the injection, moving and clenching the muscles as the needle has passed through them can cause micro-tearing of the fibres and gives you some stiffness afterwards.
Also try loading up with some NSAIDs like Ibuprofen before the appointment, assuming you can take them and use ice packs/heat packs afterwards.
OK, maybe I will go through the nerve block again. If I go for a different method (like the normal injections in my top jaw), then I suppose if it starts hurting then he would have to stop everything and give me a nerve block on top of the normal injection?

I was wondering if he could do a nerve block, but inject less quantity of it. I'm quite small and sensitive, I wonder if I need less than a muscular man would need for example.

I didn't know about keeping still. I did move backwards slightly during the injection as I didn't expect it to hurt that much. I can take aspirin, will the injection still work as well?

I will try heat packs on it now. The injection seems to have set off some nerve pain on that side of my face (a few days later from injection).
Yes, afraid so. It's basic anatomy. The "upper" injections don't work well for lower molars, the way the nerve travels to the tooth is completely different.

In the upper jaw the nerve runs along the outside of the bone and then dives in towards the root of the tooth. So it's easy to flood the nerve with local solution and switch it off. In the lower jaw the nerve runs through a tunnel in the middle of the mandible and sends branches up to the roots from there. So you need to get the solution around the nerve before it goes into the tunnel, which is quite far back and buried in the face.

Some of the new locals can "diffuse" through the bone a bit better than the old ones, so they can occasionally get enough fluid through to numb things.

There's no point in giving a half dose, the act of inserting the needle is the most traumatic bit, so why mess about giving less solution and then have to go back and do it all again if it's not enough.

Yes, you can take an aspirin first, the local will work just as well. Ibuprofen would be better though.

I'd try ice first it's usually more effective than heat.