I had a tooth abscess, then root canal, but the abscess has not completely gone.

See your dentist. He/she must be certain that the infection is fully eliminated before the tooth is restored with final restoration. If the infection remains it increases the risk of post treatment pain and root canal failure. See your dentist for re-evaluation.
Time Frame ? How long ago was the root canal finished? Is this the same infection that necessitated the root canal? Either way, see your dentist to have the tooth re-evaluated.
Failure? that means ether abscess was not treated properly before the root canal treatment,or the root canal treatment was not successful,and led to recurrent infection . Proper examination needed to determine the condition and treat it weather by re treatment for the RCT,or extracting the tooth and replacement options discussed. Good luck ;)
Reevaluate. Return to the Dentist that did the root canal. May have untreated small canals, residual infection, fracture. Evaluation by a root canal specialist, an Endodontist, is in order.

Related Questions

How can a root canal stop the pain from a tooth abscess?

Remove Infection. When the nerve of the tooth gets infected, the dead nerve and blood vessel are removed from the canal in the root of the tooth (like taking a bad electrical wire out of a conduit). Then after the bacteria has been cleaned out, a special type of filling material is packed in this open canal to seal it from having bacteria seep in from the end of the root in the bone. Read more...
It cleans. Root canal treatment cleans out the bacteria inside the canals and seals the space to prevent bacteria from reinfecting it. When there no new bacterial keep reinfecting the area, the body's immune system wins by cleaning out the abscess outside of the canals. Read more...

Is there a way to find out why did the tooth abscess form when there is no root canal to be infected?

Necrotic pulp. The pulp which is in the center of the tooth , contains blood vessel and nerve , if the tooth has cavity , and in very close proximity to the pulp , chances are higher for the pulp to become inflamed and eventually cause infections leads to abscess. Read more...
Periodontal abscess. An abscessed tooth with a nerve or root canal infected would need a root canal and termed endodontal abscess. An abscessed tooth with severe bone loss and gum disease would be called periodontal abscess. Treatment would be debridement, laser, occlusal adjustment, and followed up. Read more...

Is it possible for a tooth abscess to make you feel dizzy. My dentist told me I need a root canal due a deep cavity although it was filled.

Root canal. If the cavity is in close proximity tonthe pulp(nerve) often times the tooth becomes non vital and if root canal is not done in due time abscess does occur due to the infected pulp, not sure if the abscess caused you to swell and have fever , you might become malaise and unable to eat good nutrit ional foes may lead you to be dizzy, get to a root canal specialist or a competent general dentists . Read more...
Anything is. Possible. Im assuming if there is an abscess that your dentist has instructed you on the treatment options / medications etc... The reason for a root canal in a filled tooth can be that the filling is just too close to the nerve and the nerve space is violated causing discomfort, pain, swelling, etc. The need for root canals in teeth with very large, deep fillings is fairly common. Hope this h. Read more...
Possible. A tooth infection can effects your whole body. If you have had this infection for a long time than it may effect your immune system and a range of different symptoms. See a dentist as soon as you can. Read more...