Extracoronal precision attachments for removable partial dentures are recommended when:
Extracoronal Precision attachments are normally resilient to allow free movement of the prosthesis to distribute potentially destructive forces or loads away from the abutments to supportive bone and tissue. Three distinctive movements are defined in function: (1) Hinge, (2) Vertical, and (3) rotational.
The fewer abutments remaining, and the weaker the abutments are, the greater the need for resiliency or free movement to direct the forces away from the abutments to the supportive bone and tissue via the base of the prosthesis.