External Root Resorption
External root resorption is the breakdown of root structure that begins on the outer surface of the root and works inward. It is driven by specialized cells called odontoclasts that have been stimulated to attack the cementum and dentin from the outside. Most early-stage external resorption is painless and discovered incidentally on a routine X-ray — by the time symptoms appear, a significant amount of root has often already been lost.
Signs & symptoms
- Most cases are completely asymptomatic in the early stages and are first noticed on a routine periapical X-ray.
- A pink or pinkish-red discoloration of the crown near the gumline (the resorbing tissue showing through thinned dentin) — the classic visible sign of invasive cervical resorption.
- Mild sensitivity to cold or sweets that does not match a visible cavity.
- A tooth that feels slightly loose or that has shifted position in advanced cases.
- A radiolucent (dark) defect on an X-ray that begins on the outer surface of the root rather than inside the canal.
What causes it
Past dental trauma is the leading cause and the resorption may start years after the original injury. Orthodontic forces, internal bleaching of a previously root-canal-treated tooth, chronic pressure from an adjacent impacted tooth, and chronic periodontal inflammation can all trigger it. A subset of cases (invasive cervical resorption in particular) has no clear identifiable cause despite a thorough history.
How we diagnose it
Two-dimensional X-rays usually under-report external resorption because the defect can be hidden behind the buccal or lingual root surface. Three-dimensional CBCT is the standard of care for staging, classifying the subtype, and deciding whether the tooth is salvageable. We scan every suspected resorption case on the J. Morita Veraview X800 in Endo Mode (80 µm voxel, 40 × 40 mm limited field of view) — the small-volume, high-resolution protocol the AAE/AAOMR Joint Position Statement on the Use of CBCT in Endodontics recommends.
Treatment options
Early, localized external resorption defects that have not yet perforated the root canal can often be surgically accessed, the resorbing tissue removed, and the defect repaired with bioceramic material — sometimes with a root canal added if the pulp is involved. Advanced invasive cervical resorption that has hollowed out a large portion of the root, or any defect that extends below the alveolar crest, generally cannot be predictably restored and the tooth requires extraction. The AAE Treatment Options for the Compromised Tooth (2014) decision guide is the standard framework we use to communicate favorable / questionable / unfavorable prognosis honestly to patients.
Concerned you may have external 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 usExternal Root Resorption diagnosis and treatment — serving 30+ Bay Area cities
Dr. Jason Kung provides external 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.