What is primarily responsible for the tooth movement when a force is applied not through the center of resistance?

When a force is applied to a tooth and it does not act through the center of resistance, the resulting movement is characterized by both rotation and translation. The center of resistance is the point through which the force is most effectively applied for bodily tooth movement. When the force is applied elsewhere, two distinct movements occur.

Firstly, the tooth will rotate around the center of resistance due to the unequal distribution of forces acting upon it. This rotational movement is a response to the unbalanced forces created by applying an external force at a point that is not aligned with the center of resistance.

Simultaneously, translational movement occurs because the overall force applied still generates a net displacement of the tooth in the direction of the applied force. However, the groove of these two movements is the determining factor for tooth movement outcomes during orthodontic treatment.

In clinical orthodontics, understanding that both rotation and translation contribute to tooth movement when forces are applied off-axis is crucial for effective treatment planning and execution. This integrated approach ensures comprehensive tooth repositioning.