What is mechanical retention use for in dentistry?

Answer 1

Removable Partial Dentures utilize mechanical retention. They have clasps that engage undercuts in existing teeth to stay in the mouth. The clasp has a spring effect to flex over a "high" spot on a tooth as the RPD is placed in the mouth. As the clasp flexes past the high spot it springs back to it's original shape and engages the "undercut" creating mechanical retention.

This is one of many ways mechanical retention is used for Dentistry.

The Gayso Bridge technique is another procedure that utilizes mechanical retention, where undercuts are created on the side of a tooth and a corresponding undercut is made on a restoration creating a "tube effect" with half of the "tube" being in the restoration and the other half of the "tube" on the adjacent tooth utilizing a retentive pin to be placed through the "tube." This keeps the restoration from moving up or down to work in conjunction with preparations made in the adjacent tooth for preventing buccal-lingual movement.

There are many other ways mechanical retention can be used in Dentistry but I would be required to write a book !