Root canal absess(abscess) question

Hi
I have a question....I have a rootcanal in the back molar...had it about 2 years ago...I went to the dentist because it was hurting and he put me on antibiotics and said it lookes as if the root canal did not take???? Antibiotics got rid of the pain...that was about 6 months ago...now I am hurting again and a small , ***** blister keeps forming on the side of my gum where the bad tooth is...what is this blister? I pop it, it goes away for a day or so and comes back, I've never had anything like this before...
Thanks for any advice...

[Jerome Bogin, D.D.S.]

The blister is what we call a fistula--this is a tract that is formed by the infection from the tooth and it seeks the area of least resistance which is the bone on the front side of the tooth.The root canal therapy needs to be retreated. Placing you on a regiment of antibiotics is just a band-aid.

[blondie10]

Thanks for the quick response...one more question...if I dont get this treated right away will it spread to other areas or will it stay localized? Money is an issue...

[mike1105]

if the delay is too long, it can indeed spread to another tooth. the abces may also get bigger which can then cause the need to treat IT spearately from treating the tooth. You should have the situation addressed asap. waiting is a poor idea. also, the tooth should be restored with at least a post/filling asap after the root canal. A crown will most likely also be needed. Doing the root canal only is in my opnion not advisable because the tooth is very prone to decay and fracture without it being restored.