If Mf is greater than Mc, what type of movement occurs?

When the moment generated by the force at the crown level (Mf) is greater than the moment generated by the force at the root level (Mc), the result is a tipping movement of the tooth.

In orthodontics, tipping refers to the movement of a tooth where the crown moves in one direction while the root moves in the opposite direction. This effect occurs because the force applied at the crown creates a larger moment compared to the stabilizing moment at the root, resulting in the tooth tilting around its center of resistance.

Pure translation involves moving the tooth without any tipping or rotation, which is not the case when Mf exceeds Mc. Root movement would require parallel movement of both the crown and root in the same direction, which again does not apply here. Reverse tipping, conversely, refers to a situation where the root moves in the direction of the applied force and the crown moves opposite to it, which occurs in different force scenarios.

Thus, under the condition where Mf is greater than Mc, the most appropriate description of the tooth’s movement is tipping.