According to the American Association of Endodontists (AAE) Endodontic Case Difficulty Assessment Form, what level of complexity is assigned to a single-rooted tooth with INTERNAL ROOT RESORPTION?

The AAE Endodontic Case Difficulty Assessment Form classifies INTERNAL ROOT RESORPTION under the HIGH DIFFICULTY category. Internal root resorption (IRR) involves progressive loss of dentin from the internal canal walls due to clastic activity following pulpal trauma or infection. It is HIGH DIFFICULTY because: the resorptive cavity creates highly irregular canal anatomy; risk of perforation is elevated when the defect is large; complete debridement requires specialized techniques (ultrasonics, thermoplastic obturation with bioceramic materials); prognosis is more uncertain than standard cases. Treatment is non-surgical RCT if no perforation; MTA is used for perforation repair. The AAE form uses three tiers: Minimal (routine cases), Moderate (complicated but manageable), High (exceptional challenge even for experienced practitioners). Internal resorption = HIGH.