Which type of gingival retraction is accomplished by placement of a retraction cord?

The type of gingival retraction accomplished by the placement of a retraction cord is mechanical retraction. This method involves the physical placement of a cord into the gingival sulcus, which helps push the gingival tissue away from the tooth and creates a clear impression area for dental procedures.

Mechanical retraction is particularly useful during restorative dental work, as it allows for better visibility and access to the margin of the preparation by temporarily displacing the gingival tissue. The retraction cord can be impregnated with a chemical agent to enhance the retraction effect, but the fundamental action of the cord itself is mechanical.

In contrast, the other options refer to different methods. Chemical retraction involves using a hemostatic agent that causes blood vessels to constrict, resulting in tissue displacement without the physical cord placement. Surgical retraction would imply a more invasive approach, typically involving cutting or manipulating tissue directly. Ligature retraction might suggest using sutures or ligatures for tissue displacement, which would not apply in this context focused on retraction cords.