Internal Root Resorption
Internal root resorption is the loss of dentin from inside the root canal, caused by odontoclast cells activated within an inflamed but still partly vital pulp. Unlike external resorption (which works inward from the outside), internal resorption widens the canal from inside out — producing a characteristic ballooned or oval-shaped enlargement of the canal on imaging. It is much less common than external resorption but is more often saved when caught before perforation.
Signs & symptoms
- Most cases are completely painless in the early stages and are discovered incidentally on a routine periapical X-ray.
- A pink discoloration of the crown if the resorption is in the pulp chamber and the overlying dentin has become thin enough for the underlying tissue to show through.
- Mild sensitivity to cold or sweets in some cases; intermittent vague discomfort in others.
- A radiographically visible symmetric enlargement of the canal space — the canal looks balloon-shaped or oval where it should be a narrow, parallel ribbon.
- Tenderness to percussion or a draining sinus tract if the resorption has perforated the root surface and become infected.
What causes it
Chronic inflammation of the dental pulp is the proximate cause. The classic triggers are deep caries that has irritated the pulp for months or years, prior traumatic injury that produced low-grade chronic pulpitis, and large or repeatedly replaced restorations. A small subset of cases is associated with herpes viral infections or with no identifiable trigger at all.
How we diagnose it
The diagnostic challenge is distinguishing internal resorption from external resorption that happens to project over the canal on a two-dimensional image — the two have opposite prognoses and opposite treatments. Three-dimensional CBCT is the only reliable way to make the distinction. We scan every resorption case on the J. Morita Veraview X800 in Endo Mode (80 µm voxel, 40 × 40 mm limited field of view) — the small-volume protocol the AAE/AAOMR Joint Position Statement on the Use of CBCT in Endodontics and the AAE position statement on resorption both recommend. Pulp testing helps confirm that residual vital pulp tissue is present and is therefore driving the process.
Treatment options
Prompt root canal therapy is the treatment of choice for internal resorption that has not yet perforated the root. Removing the inflamed pulp tissue eliminates the cells driving the resorption, and the irregular cavity is sealed with thermoplasticized gutta-percha or, more commonly today, a bioceramic obturation that adapts to the irregular internal shape. When internal resorption has already perforated the root, treatment becomes more complex — surgical repair with bioceramic material from the outside, intentional replantation, or extraction may be required, and the AAE Treatment Options for the Compromised Tooth (2014) framework guides the favorable / questionable / unfavorable prognosis conversation.
Concerned you may have internal root resorption?
Dr. Kung accepts referrals and self-referred patients. We can usually offer an evaluation appointment within a few business days, or sooner for emergencies.
Contact usInternal Root Resorption diagnosis and treatment — serving 30+ Bay Area cities
Dr. Jason Kung provides internal root resorption diagnosis and treatment to patients across Silicon Valley from our Sunnyvale office. Evening and weekend hours, same-day emergencies, free on-site parking.