Zekrya Endo-Z Carbide Bur Surgery/Bone Cutter Cone FG 0.9mm 21mm 152 This side cutting bur is indicated for enlarging and shaping the root canal access cavity, whilst preserving the original pulp floor anatomy. It produces a funnel-shaped opening of the pulp cavity to give access to the root orifices.. It also produces fewer vibrations due to its 6 helicoid blades.