This document discusses various types of root resorption including their causes, characteristics, diagnosis and treatment. It describes internal and external root resorption, further dividing external resorption into surface, inflammatory, replacement and invasive types. The key causes are trauma, pressure from impacted teeth or tumors, and systemic conditions. Diagnosis involves history, clinical exams, and radiographs to identify patterns of tooth structure loss. Treatment aims to arrest the resorptive process through root canal therapy or surgery depending on the type and severity.