Rigid shanks are indicated for what purpose?

Rigid shanks are particularly useful for the removal of heavy calculus deposits due to their strong and stiff construction. The rigidity of these instruments allows for greater force to be applied during scaling, which is essential when dealing with large or tenacious calculus formations. This design minimizes flexing during use, thereby enhancing efficiency and control when breaking down and removing significant deposits. Instruments with rigid shanks are typically used in conjunction with more aggressive techniques to facilitate effective calculus removal, especially in areas where the deposits are firmly adhered to the tooth structure.

In contrast, lighter calculus removal, detection of subgingival calculus, and maintenance procedures often require instruments with more flexible shanks or different design features tailored to those specific tasks.