The ESX File is unique in the way that it has different algorithms of use for different kinds of canals. This allows minimum use of files depending on the case at hand and what makes ESX a modular instrumentation technique. 

This is why 2 ESX files can be used as a minimum to complete a Basic Canal and 4-5 ESX files is needed to complete an Advanced canal. 

This differentiation helps practitioners use the minimum number of files in a given case and yet provide responsible, safe instrumentation for their patients. 

In this tutorial Dr. Nasseh demonstrates the use of ESX files and the Advanced protocol  in a mandibular second molar. 

Please see PDF attachment below.