What is the primary function of flexible shanks?

The primary function of flexible shanks is to enhance the detection of subgingival calculus. Flexible shanks provide the ability to adapt to the contours of the tooth surface, allowing for better tactile sensation and feedback as the instrument traverses the area. This adaptability is crucial for identifying the subtle irregularities and deposits that may exist below the gumline, where visibility is limited.

In contrast, the other options involve the physical removal of calculus, which is usually associated with instruments that have stiffer shanks. While detection and removal are both important aspects of dental hygiene, the specific design of flexible shanks is primarily intended for aiding the hygienist in finding the deposits rather than directly removing them. This nuanced function highlights the importance of instrument selection based on the specific clinical task at hand.