RPD Manual 11 - Removable Prosthodontics - Dalhousie University

Rests and Rest Seats - 24
A. Definitions
Rests and Rest Seats
i. Rest: A rigid component of a removable partial denture which rests in a recessed
preparation on the occlusal, lingual or incisal surface of a tooth to provide vertical support
for the denture. Although a rest is a component of a direct retainer (retentive unit, clasp
assembly), the rest itself is classified as a supporting element due to the nature of its
function.
a. Occlusal rest - a rest placed on the occlusal surface of a bicuspid or molar.
b. Lingual (cingulum) rest - A rest placed on the cingulum of an anterior tooth (usually
the canine). Rests may also be placed on the lingual of posterior teeth by creating a
ledge of the tooth surface (prescribed for surveyed crowns).
c. Incisal rest - A rest placed on an anterior tooth at the incisal edge.
d. Intracoronal (precision) rest - A rest consisting of precision manufactured
attachments that are placed within the coronal contours of a crown or retainer.
ii. Rest Seat: A portion of a tooth selected and prepared to receive an occlusal, incisal or
lingual rest.
B. Functions of Rests
1. To direct forces along the long axis of the abutment tooth.
2. To prevent the denture base from moving cervically and impinging gingival tissue.
3. To maintain a planned clasp-tooth relationship.
4. To prevent extrusion of abutment teeth.
5. To provide positive reference seats in rebasing and/or impression procedures.
6. To serve as an indirect retainer by preventing rotation of the partial denture (Class I or II
RPD’s only).