Biofilm formation within endotracheal tubes is a concern from both an infection control and an imposed work of breathing standpoint. There is insufficient evidence in the adult literature to make a recommendation on the timing of endotracheal tube changes due to suspected biofilm formation.  The infant literature is even less clear.  There are commercially available devices on the market that allow the biofilm to be removed without the need to change the endotracheal tube. I've attached several articles that may help.  

Tom

Thank you sir. But my doubt was actually regarding grommets/ventilation tubes used in the ear. I am sorry for not being clear. 

A persistent grommet could also increase the chances of leaving behind a permanent residual perforation ,isn't it ?