Kim's classification of microsurgical cases   Class A: Represents a tooth with no periradicular lesion, no mobility, and normal pocket depth. The clinical symptoms have not resolved, though non-surgical options have been exhausted. Clinical symptoms are the only reason for the surgery. Class B: Represents a tooth with presence of a small periradicular lesion with clinical symptoms. The tooth has normal periodontal probing depth and no mobility. The teeth in this class are ideal candidates for microsurgery. Class C: Represents a tooth that has a large periradicular lesion, progressing coronally; without periodontal pocket and mobility. Class D: Represents a tooth that is clinically similar to that in Class C, but has deep periodontal pockets. Class E: Represents a tooth that has a large periradicular lesion with an endodontic-periodontal communication to the apex, but no obvious fracture. Class F: Represents a tooth with an apical lesion and complete denudation of the buccal plate, but no mobility. Textbook of Endodontics Nisha GARG 3rd ED