What motion should be used when packing the cord with a plastic instrument?

When packing the cord with a plastic instrument, applying a clockwise motion is considered the best practice. This technique allows for a controlled and efficient packing of the cord into the sulcus around the tooth. The clockwise motion facilitates better adaptation of the cord material, ensuring that it properly displaces the tissue without causing trauma.

This motion helps to create an adequate space for the preparation of the impression, leading to accurate impressions and effective procedures. Using a clockwise motion can also provide a more consistent and uniform packing, which is essential for achieving the desired hemostatic effect and ensuring the cord remains in place during the impression process.

In contrast, back and forth, side to side, or counterclockwise motions may not provide the same level of effectiveness or precision when packing the cord. These alternative motions might lead to less controlled packing, potentially allowing the cord to lift or move out of place, which could compromise the quality of the impression.