You are here:

Dentistry/Lump on Gum after Antibiotic


QUESTION: Hello Gary,

Two months ago I felt a lump on my gum above my front tooth. I never had any pain. I went to dentist and he took xrays. He said i had an infection and needed root canal. He put me on penicillin which took the lump down , but still felt small lump high up right under my nose.I went in for root canal today, and dentist started it, but said he could see some infection and pus still and didn't want to fill and seal it yet. He again gave me script for penicillin , and I am going back in two weeks. If the infection didn't clear first time on PCN , should he have given me it again?? Is he doing things properly? My brother swears he had something similar in his lower teeth, and ended up with cyst and fistula in his gums and after repeated procedures had to have his tooth pulled.

ANSWER: Hi Mike,

It's hard for me to give you a really good answer without examining you and seeing your x-rays, but I can give you some general information that might help explain things.

When a tooth dies, the nerve & blood supply inside the tooth breaks down and products from that breakdown go out the end of the tooth. Then your body tires to heal it and forms the abscess that was present 2 months ago. When we do root canals, the first goal is to remove all the "stuff" inside the tooth so the body can heal. That is what was done at your first appointment. The next goal is to seal the inside of the tooth so that any microscopic material that might be left is sealed inside the tooth. That's what will happen at your next appointment.

The sequence and timing of all this can vary from dentist to dentist. There is no STANDARD way to do all this. In our office, and I think in most endodontist's offices, we clean out the tooth and fill it all in the same appointment. In most cases, this reduces the chances of problems and makes the patient only come in one time for treatment. We are also VERY careful with prescribing any antibiotics so the patient doesn't develop and tolerance for them. We only use then in cases when there is an acute infection with pain & swelling as a general rule. However, there are always exceptions to all the rules, so it's hard for me to say whether you should have been on the antibiotics a 2nd time or not. Usually just cleaning out the tooth will allow your body to heal the abscess without needing another course of antibiotics. Most likely the reason there wasn't much change after the 1st penicillin was that the tooth had not been cleaned out yet. We see that a lot. Had your abscess been active, with pain & swelling, the antibiotics would probably have had a more noticeable effect.

I hope this helps with your question. Write back if you need more info or clarification.

Gary Backlund DMD, MSD

---------- FOLLOW-UP ----------

QUESTION: Dr. Backlund,

Thank you so much for your professional prompt reply. I ended up having my antibiotic switched to Keflex because I was having reaction to PCN??? never had before but ended up with swollen glands and throat that went away immediately with Benadryl. Away, as I said above have not had pain through any of this just the lump high up in gum . If the lump is still there, should I proceed with finishing the root canal and subsequent crown. My dentist says the lump may take awhile to go away totally.

Thanks again,

Hi again Mike,

I'm sorry to hear about your glands & throat swelling. While this is not a typical true allergic reaction, the swollen throat certainly could be, especially when it went away with the Benadryl. If the lump is hard & firm, it probably means the bone has been deformed and that can take some time resolve completely heal....probably weeks or even months depending on how big the swelling is. Finishing the root canal in this case would not be a problem.

If the swelling is soft, like a boil, that means pus is still under the tissue. As long as the tooth has been well cleaned out, then completing the root canal should also not be a concern since you have not had any real symptoms with all this except for the swelling. Like I said before, we do most root canals in one visit. If you were having pain or increased swelling, I might advise you to wait awhile, but that's not the case.

Bottom line, I think you will be fine finishing the root canal at this point. As for the crown, probably OK to do that as well.

Best of luck!

Gary Backlund DMD, MSD


All Answers

Answers by Expert:

Ask Experts


Gary Backlund, DMD, MSD


I am an Endodontist ( root canal specialist ) and can answer questions about root canals and their treatment. I cannot diagnose or treat online, but can answer general questions. I have been a specialist for 25 years and am Past President of the Washington State Association of Endodontists.


25 years practicing as a specialist

American Association of Endodonists, Past President Washington State Association of Endodontists.

©2017 All rights reserved.