This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
An endodontic reamer is least likely to fracture when inserted in a: 
Select and explain. 
A. Dry, clean canal, B. Wet, clean canal, C. Wet, debris laden canal, D. Dry, debris laden canal
B: Wet, clean canal
Answer: B: Wet, clean canal 
Explanation: Irrigants perform physical and biologic functions. Dentin shavings get removed from canals by irrigation.
Thus, they do not get packed at the apex of root canal.
Instruments do not work properly in dry canals. 
Their efficiency increases by use in wet canals. 
Instruments are less likely to break when canal walls are lubricated with irrigation.