Kim et al classification system deals with:
According to Kim et al Classification; there are 5 types

Type I incomplete isthmus between 2 canals.
Type II well defined, complete isthmus between 2 canals.
Type III very short but complete isthmus between 2 canals.
Type IV 3 or more canals with the complete or incomplete isthmus.
Type V 3 or more canals without any visible connection.
Apical constriction
Apical foramen
Isthmus
No. of canals