In 1984 Pashely described the smear layer as being composed of two phases; an organic phase, composed of collagen residues and glycosaminoglycans from extracellular matrix of pulp cells, which acts as a matrix for an inorganic phase. This organomineral content is composed of two distinct superposed layers. The first layer covers the canal wall and is loosely adherent and easy to remove. The second layer however occludes the dentinal tubules and strongly adheres to the canal walls