Accessing through the modern crowns is a new challenge to clinicians who end up with the prospect of the need for root canal therapy following cementation of a zirconia or an EMax crown (Lithium Disilicate).
Accessing through a crown is very different than cutting it off. A round bur rotates along its axis and its cutting ability is compromised when you try to cut with it tip (vs. its side.) This specially designed bur called Dura Cut Bur (BrasselerUSA) was chosen by RealWorldEndo to be in the modern Endo Access kit because it addresses the challenges of cutting through the harder modern crown materials.
In this Video, Dr. Nasseh demonstrates the use of Dura Cut for an access preparation through a crown.