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
For cutting dentin by Gates Glidden drills, it should be used at: 
Select and explain. 
A. 200-300 rpm, B. 450-800 rpm, C. 750-1000 rpm, D. None of the above
C: 750-1000 rpm
Answer: C: 750-1000 rpm 
Explanation: It is ideally used to cut dentin as it is withdrawn from the canal. 
It cuts on the outstroke, and it is used to open canal oriﬁce. 
It is used in 750-1000 rpm.
Long shaft is designed so as to break at the neck, the narrowest diameter that lies adjacent to the handpiece. 
If the drill binds during use, it will fracture at the neck of the shaft.