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Root Canal Infection, how long till antibiotics work?



Well-known member
May 28, 2009
SW Herts
I would really appreciate some advice on a problem I am having with a root canal I had done last Monday. The tooth is one of the big molars on the top and I'd already had root canal work done on it about 7yrs ago.

Having recently changed to a new dentist I was told that only one of the three nerves had been removed from the tooth and the the one that had been removed hadn't been totally removed.

I had one long appointment a few weeks ago to take out the two nerves that the dentist thought might be infected and she put some topical antibiotics into them and then temporary fillings. Over the next couple of weeks for the most part I was pain free, but I did have a couple of days when the tooth was hurting.

So last Monday I went for an appointment that lasted an hour and twenty minutes. The two temporaries were cleaned out and filled and the original filling on the third root was removed and the tip taken out, cleaned and filled. I had a few x rays taken too and the dentist seemed very happy with everything.

I had hoped this would be the end of the problem and that all I would now need was a crown for the tooth. However over the few days following the treatment I was still in a bit of pain and this was followed by that familiar bitter taste in my mouth that made me think the tooth was still infected.

The dentist prescribed me 500mgs of Amoxycillin 3 x 7 days and which I have taken since Friday afternoon, so it's been less than 48hrs, but nothing seems to have changed and I thought the pain and bad taste would have gone away by now or at least started to subside.

I guess I am more worried as I won't finish these antibiotics till Christmas Day and I don't know what to do if the tooth is still playing up over Christmas and I can't get to a dentist. I don't know if I am expecting too much too soon.

Any advice would be appreciated, thanks.
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Hi - I'm not a dentist, but antibiotics for dental problems usually take at least a few days to show any difference. I've been prescribed virtually everything over the years - and they've always worked. I wouldn't mind betting that by Xmas day you'll be pain free.

Also, I've been told that pain from tooth infections is caused by pressure from swelling more than anything, so the very best thing to take is something like Ibuprofen which reduces inflammation. Perhaps a dentist can confirm, but it works for me.

Good luck :)
Again, sorry, I'm only a new member with no dental knowledge but would just like to say I know how you feel about the Christmas holiday coming up. I'm in quite a bit of pain and I'm currently on antibiotics (for gums) but not noticed a difference yet but the Christmas holiday is a bit scary (especially as my dentist has more or less "sacked" me and I'm not sure if I even have one any more). I've bought a large box of Nurofen to get me through the holiday if need be.
sounds like you have a good dentist who is responsive to your needs.

Infection & symptoms can take a while to go away. But you are on the right treatment. You mention just a bit of pain. What type of pain is it?
Thanks for all your replies. I know I am a lot more worried because it's nearly Christmas and everything just shuts down for such a long time here.

The pain I am feeling is like a recurring nagging pain, it isn't painful enough to take any painkillers for, but I think I'm noticing it more at night when my mind is focusing on it. I'm also aware of that awful taste you get when a tooth is infected and that plays on my mind as I keep thinking the antibiotics aren't working.

I've had so many long appointments and I'm really anxious at the dentist as I suffer with agoraphobia and I feel 'trapped' in the chair. I need 3 root canals in total, pluse 3 crowns and some other work which in all is going to cost me over £3,000. It's a lot of money and when I started the treatment a couple of months ago I had expected to be well on the way to having the treatment completed, whereas in fact all I have is one temporary root canal and the other one that is now infected :(
I guess if you are noticing a pain more when your mind focuses on it then you need to try not to worry about it. Im sure you know what a true infection pain is like. Give your treatment a chance to settle down. I am sure if you relax a bit over Christmas it will give your immune system a better chance to deal with it.

Ive had several infections in my teeth during my life and I don't know what taste you mean. After treatment I remember a taste of the disinfectant before the permanent filling was put in. But before that I don't remember anything. I do remember during the first part of treatment there was a nasty smell. But I didn't notice that before as it was all stuck in the tooth. I only smelt that when the root was being drilled. Ive never tasted anything.

But perhaps I am unusual and someone else will mention they had a taste.

It may however be that the antibiotics are affecting your taste receptors. Antibiotics can make things taste funny. I think amoxy is particularly known for causing a weird taste in your mouth. Are you sure you are not associating other times youve had antibiotics when you had infections before with the taste you are experiencing now?
Hi again,

As I said before, I'm NOT a dentist, but I've been in your position so many times I may be able to help a bit.

Amoxicillin is really fantastic for abscesses - it's ALWAYS worked for me, and I know it's the antibiotic of choice for most dentists. I would be massively surprised if they failed to work for you.

The thing with antibiotics though, especially for abscesses, is that you won't notice any difference overnight. This doesn't mean they're not doing their job - but all those bacteria take time to die. Plus, the pain you're feeling is from the inflammation (it's all swollen around the base of the tooth, pushing it up - ouch) and this will take time to go down.

You'll find either today or tomorrow that it hurts just a little less than it did, there won't be any sudden cessation of pain, it'll just gradually start to ease up.

Also - if your pain hasn't gotten any worse - this is a good sign, and shows that the antibiotics are actually working. If they weren't, your pain would probably be worse.

Good luck :)
Thanks once again for all your helpful replies. I am getting some days when the pain isn't there at all, then it comes back a bit and I get the bitter taste in my mouth. I am sure I'm more worried with Christmas being this week as I know the dentist will be closed for a whole four days. I also hate taking the antibiotics as they are making me feel very tired and wiped out.

I think I am also wondering why I have an infection. The tooth in question had all three nerves removed and I'm sure my dentist wouldn't have filled the tooth if she had any doubts as she has left another root canal with a temporary filling as she wasn't sure that all the nerve had been taken out. I know very little about how all this stuff with root canals work except that logically I would have expected no infection and not much pain afterwards.
if you have a temp filling in another tooth then that might be where the funny taste is coming from.
if you have a temp filling in another tooth then that might be where the funny taste is coming from.

Yes I had wondered about that, although the other tooth has been pain free since the temporary filling, but I guess that doesn't mean anything. I also have another filling that is 'leaking' and I have no idea at all what that means, but that tooth is next to the one that is giving me the current problem.