Any component of a partial denture on a tooth surface that prevents the tissue ward movement and provides vertical support is called a rest .
Rests should always be located on properly prepared tooth surfaces. The prepared surface of an abutment to receive the rest is called the rest seat.
Rests are designated by the surface of the tooth prepared to receive them e.g –
- occlusal rest,
- lingual rest,
- incisal rest,
- and interproximal rest.
Functions of occlusal rest :
- It prevents the vertical tissue ward movement.
- In doing this tissue ward movement some functions are happened :
1. Maintains components in their planned positions
2. Maintains established occlusal relationships by preventing settling of the denture into soft tissues
3. Prevents impingement of soft tissue
4. Directs and distributes occlusal loads towards long axis of the abutment teeth
Figure A, Occlusal rest seats have been prepared on molar and premolar teeth to provide vertical support for the removable partial denture.
Figure B, Framework for tooth-supported removable partial denture. Rests on patient’s right provide vertical support to the replacement dentition, while rests on patient’s left provide cross-arch support and stabilization.
Figure C, Tooth support for this prosthesis is provided by rests occupying definite, prepared, rest seats on the canine and occlusal surfaces of selected posterior teeth.
Figure D, Kennedy Class III Mod I maxillary arch with rest seats prepared on the lingual surfaces of the canine and lateral incisor, and the occlusal surfaces of the premolar and molar.