<prompt> Who has given root canal isthmus classification?KimSchielderKrasner and RankowVertucci  <response>: Kim et al ClassificationRoot apex cross-sectionNarrow ribbon-shaped connection that contains pulp or pulpally derived tissue - ISTHMUSAccording 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. 