From the theory of tooth shape design: the tooth of general carbide rotary file is composed of straight line or curve. Commonly used tooth shape is:
(1) straight tooth back, characterized by convenient manufacturing, but weak tooth strength.
(2) broken tooth back, which increases the strength and processing difficulty of cutter teeth.
(3) curved tooth back, the strong points on any section point of tooth back are basically equal, but the production difficulty is higher.
According to the cutting mechanism of tooth shape and filing principle, it is required that the teeth are hard and sharp, and there is a certain chip space between the teeth to ensure rapid chip removal. Otherwise, it will block the cutter teeth and affect the processing of the rotary file.