Root canal treated were categorized based on the AAE case difficulty assessment form. Endodontic mishaps investigated included over-instrumentation, working length loss, underfilling, overfilling, apical transportation, instrument fracture, and perforation.

The American Association of Endodontists (AAE) has developed a case difficulty form to categorize endodontic cases into three levels: minimal, moderate, and high. This form encompasses three sections: general health status, diagnostic and treatment status, and contributing factors such as trauma, previous treatment, and periodontal disease.

Endodontic mishaps were classified as follows: over-instrumentation, underfilling (≥2 mm from the radiographic apex), overfilling (≥2 mm from the radiographic apex), canal transportation, instrument separation, lateral or strip perforation.