70 - Elements of RPD. Retentive and support elements. Equators.

section

• anatomical equator

• prosthetic equator

• support of clasp assembly

• support of attachment

• retention of clasp assembly

• retention of attachment

• elements of rpds

• anatomical equator

Anatomical equator of the tooth (the bigger contour)

• prosthetic equator

prosthetic equator (equator in relation between all the teeth).

• support of clasp assembly

provided by positive contact of the rest of the clasp assembly with the rest preparation of the abutment tooth.

• support of attachment

provided by contact of a rigid element on the denture with a rigid element on the abutment tooth

• retention of clasp assembly

provided by resistance to flexure of retentive clasp arm as it engages the height of contour of the tooth as the RPD moves occlusally/incisially.

• retention of attachment

provided by frictional contact of the long parallel walls of the attachment, mechanical locking devices, resistance to deformation of resilient locking materials, and other such imaginative systems.

It is requently provided, or supplemented, by a retentive clasp arm on the lingual surface of the abutment.

• elements of rpds

• Major connector

• Minor connector

• Direct retainer

• Indirect retainer (clmass I and II RPDs only)

• Replaced teeth

• Base

major connector

part of partial removable dental prosthesis that joins components on one side of the arch to those on the opposite side.

minor connector

connecting link between major connector or base of a partial removable dental prosthesis and other units of prosthesis, such as clasp assembly, indirect retainers, occlusal rests, or cingulum rests.

direct retainer

component of a partial removable dental prosthesis used to retain and prevent dislodgment, consisting of a clasp assembly or precision attachment.

indirect retention

effect achieved by one or more indirect retainers of a partial removable denture prosthesis that reduces the tendency for a denture base to move in an occlusal direction or rotate about the fulcrum line.

Assists direct retainer(s) in preventing displacement of distal extension denture base by functioning through lever action on the opposite side of fulcrum line when denture base moves away from tissues in pure rotation around fulcrum line.

denture base

• part of a denture that rests on the foundation tissues and to which teeth are attached.

• Replaced teeth:

  • Functions:

    • Prevent migration of the remaining teeth 130

    • Restore Masticatory efficiency

    • Retain proper interarch space

    • Maintain esthetics of a normal facial contour

    • Achieve distinct enunciation

      Types of materials:

    • Acrylic (on class IV RPD, the standard type used for RPDs and CDs)

    • Porcelain (rarely used because difficult to set)

    • Metal: gold and chrome