Partial dentures – setting the retentive force of a partial denture, Part 3

Partial dentures – Setting the retentive force of a partial denture, Part 3
Partial dentures – Setting the retentive force of a partial denture, Part 3

The anchoring of the denture or the force necessary to remove the denture (withdrawal force) is essentially defined through the undercut value and the clasp length. This undercut value results from the tooth status, the clinical, structural, as well as mechanical and geometric circumstances. The number and functional value of the retention areas used determine the withdrawal force. Ideally the clasp tooth should not be subjected to any horizontal shear when the denture is removed. A requirement for this is that the tooth is supported by a strong clasp element positioned opposite (reciprocator / embracement) at the same moment when the active clasp arm bends at the equator. The exact position of the embracement, which must be mounted at the same height, is determined with the analyzing rod. Often the requirement of an embracement cannot be structurally implemented. The horizontal shear on the clasp tooth should then be counteracted by means of a smaller undercut depth.

Source: Partial dentures – setting the retentive force of a partial denture, Part 3, Henning Wulfes, BEGO