Question 209 · LDEK · Biomechanics and tissue response to treatment
Which of the below mentioned sentences describes torque?
- A. the centre of rotation lies in infinity, and the force acts through the centre of gravity. The M/F ratio is 10/1.
- B. the centre of rotation lies at the apex. In this case the torque to force ratio is between M/F=4/1 to M/F=7/1.
- C. it occurs when the point of application lies apically to the centre of tooth resistance, and the centre of rotation is located coronally. In order to achieve only this movement, the torque to force ratio must be at least 12/1 of root movement or torque.
- D. the centre of rotation lies at the neck of the tooth. In such case the torque to force ratio is between M/F=10/1 to M/F=12/1.
- E. it occurs when the point of application lies coronally to the centre of tooth resistance, and the centre of rotation is located apically. In order to achieve only this movement, the torque to force ratio must be at least 15/1.
Hint
Torque means mainly root movement; consider where the centre of rotation must lie and how large the moment-to-force ratio has to be.
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