What causes inflammation at the tooth root?
It is a condition in which bacteria inside the tooth have spread past the root tip into the surrounding bone. It shows up as a dark area at the root tip on an X-ray, and dentists call it apical periodontitis, or a periapical abscess when it fills with pus. “The X-ray shows inflammation — does the tooth have to come out?” is a question I hear very often in the treatment room.
It commonly starts with deep cavities, cracks or fractures, recurrent decay under old restorations, or trauma. Even in a tooth that has already had root canal treatment, the shadow comes back if infection remains inside the canals or bacteria get back in through gaps in the restoration.
If it doesn't hurt, is it okay?
Inflammation can remain even if it doesn't hurt. In the acute phase it hurts when you chew or the tooth feels like it's sticking up, and once it becomes chronic it may show up only on the X-ray, without pain.
If a pimple-like drainage tract has opened on the gum, the pressure is released and some days it hurts less. If you take that as a sign it has healed and leave it, the bone around the root keeps dissolving. That is why I look at the X-ray, the response to tapping, and mobility together.
When can a tooth with root inflammation be saved?
I look at four things together. If all of them apply, I go toward saving the tooth.
- Can the infected canals be re-entered, cleaned, and sealed?
- Is the root free of vertical fractures?
- Is there enough tooth wall left to support a restoration after treatment?
- Is there enough alveolar bone (jawbone) holding the tooth?
The diagnosis is not “extract if the shadow is large, save if it is small.” For a tooth that hasn't been treated before, root canal treatment comes first, followed by a build-up and crown depending on the remaining walls.
What are the treatment options?
| Current tooth | Treatment |
|---|---|
| A tooth treated for the first time | Root canal treatment, then a crown depending on the remaining walls |
| A tooth that hurts again after root canal treatment | Root canal retreatment: removing the old filling material and finding missed canals or reinfection |
| A tooth whose canals are hard to reopen | Consider an apicoectomy, opening the gum to remove the inflammation and part of the root tip |
| Pus that started in a gum pocket | Gum treatment that removes tartar and inflamed tissue first, before the nerve |
| Vertical fracture, no wall left to crown, almost no bone | We look at alternatives such as an implant after extraction |
If a cavity or fracture has gone deep below the gum and there is no wall left to crown, the tooth can't take chewing forces even if the canals are cleaned. A tooth that has lost a lot of bone to gum disease and is very loose also can't hold up if only the root tip is treated.
How we do it at Wonjin Dental
I don't decide on extraction from a single X-ray. I look together at when and how it started hurting, the response to tapping or pressing, the response to cold and heat, and the depth of the gum pocket and the tooth's mobility. I check the root tip and old fillings with a periapical X-ray, and if a fracture or the extent of inflammation can't be seen, I add a 3D image (CT) for that area only.
For patients who come in after being advised to have the tooth extracted, I go through things in order, since extraction can't be undone: whether there is a vertical fracture, whether a wall remains to crown, and whether root canal retreatment or an apicoectomy is possible. If the tooth can be saved, we go with preserving it; if not, I explain the limits first.
Frequently asked questions
Will antibiotics make the root inflammation go away?
No. Medication cannot clear out infected canals or fractures. Even if the swelling goes down, the same spot is likely to hurt again, so the cause needs to be treated.
If a dark shadow remains after treatment, did it fail?
Not necessarily. It can take several months or more before damaged bone appears filled in on an X-ray. I judge by comparing symptoms with follow-up X-rays.
My face is swollen and I have a fever — can I wait until my appointment?
Don't wait. If your face is swollen and you have a fever, or you can't open your mouth well and have trouble swallowing, get seen the same day. If you are short of breath, go to the emergency room.
Does root canal retreatment take longer than the first root canal treatment?
Generally, yes. The old filling material has to be removed, and thin canals missed the first time or newly infected areas have to be found, so the number of visits and time tend to increase. Whether the canals can be cleaned again determines the outcome.
