Clinical CasesProcedures and Treatments
Draining fistula on a necrotic tooth. Edmonton Dentist. Summerlea Dental

The yellow arrow is pointing to a red spot on the gums. The tooth above the spot has no cavity or previous filling.

I think most people would agree that the last thing they want to hear from their dentist is “that tooth needs a root canal”.  Root canals have a history of being painful and uncomfortable and usually requiring multiple lengthy appointments to complete.  The other problem with root canal treatment is that many people do not fully understand why a particular tooth needs one in the first place.  Luckily with dental advancements, today root canals can usually be completed in one visit and with the proper anesthesia, pain free as well.  This article is going to focus on one particular reason why a tooth would need a root canal.  You can read my page about root canals to learn about different reasons a tooth may need root canal treatment.  You may also refer to a post I wrote regarding a tooth with a large cavity and why it needed a root canal.  Today’s post is a little different.

The patient presented for a filling on his first bicuspid on the top left.  He had no pain or problems otherwise.  As I lifted his lip to apply the topical numbing gel I noticed a red spot on his gums in front of his canine tooth.  This tooth is one forward to the one with the cavity that we had planned to fill.  I asked him if he was aware of this red area.  He said that over time it had come and gone.  It was not there when he was last in and didn’t think to mention it.

The red area looked consistent with a fistula.  A fistula is a tunnel or channel that is created when an infection works its way from the source (usually a tooth) to the surface of the gums or tissue.  I tested the teeth surrounding the affected area.  All tested normally except the canine tooth (eye tooth), which did not respond to cold.  Most teeth respond to cold stimulus and if they don’t, it means that the tooth is dead or already root canaled.  There can also be false negatives.  It makes more sense that the tooth we were about to fill would be causing this infection since it had a large filling and a history of being filled multiple times.

My next step was to trace the fistula to get a better idea of the source of the infection.  I inserted a gutta percha cone (blue) into the opening of the fistula and pushed it in as far as it would go without resistance.  An x-ray was taken to confirm that the tip of the eye tooth was the source of the infection.

Blue gutta percha is placed into opening of the fistula.

Blue gutta percha is placed into opening of the fistula.

Gutta percha point is fully seated in the opening.

Gutta percha point is fully seated in the opening.

Xray showing the blue gutta percha in the fistula. It ends at the tip of the root where there is an abscess forming.

Xray showing the blue gutta percha in the fistula. It ends at the tip of the root where there is an abscess forming.

Dental caries is the most common reason that a tooth needs a root canal. In this case there is no cavity or previous filling on this tooth. The second most common reason is that the tooth has a history of trauma. Trauma can be a blow to the face, a fall, etc. I questioned the patient and he said his front tooth was hit but it was many years ago. This is most likely the etiology (cause) of this infection.  When the tooth was hit it may have lost it’s blood supply during the blow and this caused the nerve tissue to die off.  There may also be a small crack in the tooth that is allowing an entry point for bacteria to get into the nerve.
Based on clinical findings and the x-ray, the infection is definitely of tooth origin.  The treatment is to do a root canal.  A root canal would involve drilling a small access into the tooth, cleaning out the dead/infected tissue, and then sealing it off to prevent re-infection.