A non-vital anterior tooth is treated with the walking-bleach (internal bleaching) technique. Which complication is most characteristically associated with this procedure?

Correct answer: A. Cervical external root resorption

• A. CORRECT. CERVICAL EXTERNAL (invasive) ROOT RESORPTION is the classic complication of internal bleaching. Bleaching agent diffuses through dentinal tubules and any gap in the cementoenamel junction, denatures cervical periodontal tissue, and triggers an inflammatory resorptive response. Risk rises with heat activation, 30%+ hydrogen peroxide, and prior trauma. Placing a coronal barrier (glass ionomer/RMGI 'plug') 1–2 mm below the CEJ over the gutta-percha is the preventive step.
• B. Hypercementosis is excessive cementum apposition seen with Paget disease, acromegaly, or chronic low-grade periapical irritation — it is not a bleaching sequela.
• C. Ankylosis follows extensive periodontal ligament necrosis, typically after avulsion/intrusion trauma or prolonged extraoral dry time — not bleaching.
• D. Internal resorption is driven by vital, inflamed pulp tissue with active odontoclasts. A walking-bleach tooth is already endodontically treated and has no pulp, so internal resorption cannot occur.