Surveying maxillary cast Mark the ideal survey lines

Surveying maxillary cast

Mark the ideal survey lines

Tooth modifications

1. Contour modifications2. Guide planes3. Rest seats

DISTAL VIEW OF DISTAL & LINGUAL GUIDING PLANE ON A

CUSPID.

LINGUAL LABIAL

DISTAL VIEW OF LINGUAL ANDDISTAL GUIDING PLANES.

LINGUAL BUCCAL

LINGUAL VIEW OF DISTAL & LINGUALGUIDING PLANES.

MESIAL DISTAL

Buccal View of Distal Guiding Plane

DISTAL MESIAL

RESTS

Prevent vertical movement of partial into tissue

The term rest designates any component of the framework that is placed on a tooth. It must be in a PREPARED REST SEAT. It limits the movement of the prosthesis in a gingival direction and transmits forces to the long axis of the teeth.

Contact on a tooth surface incline without a rest seat could result in tooth movement converting the RPD to an ORTHODONTIC APPLIANCE.

1o SUPPORT

RestsTransmits forces through long axis of

toothTransmits forces through periodontal

ligamentStabilizes against rotational forces

Rest seats can be located on the occlusal and incisal sufaces of a tooth as well as the cingulum and in some instances the marginal ridges of canines.

REST AREA - REST SEAT

1 That portion of the tooth selected and prepared to receive an occlusal, incisal, marginal ridge or cingulum / lingual rest.

2 The portion of the tooth structure or of a restoration in a tooth prepared so it is spoon shaped on posterior teeth and V, U or hook-shaped on some anterior teeth, into which seats the metallic rest of a removable partial denture framework.

DESIGN CHARATERISTICS OF RESTS

1. Large enough to fit a casting to2. Forms acute angles with minor connectors -

prevents tooth from moving away frompartial

3. Does not interfere with occlusion

TYPES OF RESTS

1. Occlusal

2. Cingulum

3. Incisal

OCCLUSAL RESTS

Maxillary premolar

Mandibular First Premolar

Occlusal Rests

Rounded triangular shape-”teaspoon” Approximately one-third width of tooth Marginal ridge should be lowered to permit

bulk of metal for strength. Floor of rest apical to marginal ridge. No sharp edges or line angles. Angle formed by minor connector and rest

should be less than <ninety degrees.

Definitive rest

CINGULUM RESTS

Mandibular Cingulum Rests

Cingulum Rest-Restoration-Natural tooth

Cingulum Rests

Most effective on maxillary canines.Slightly rounded inverted “V” shape.When mandibular canines / incisors are

utilized a rounded ledge at the level of the cingulum can serve as a rests.

Care must be taken to avoid enamel undercuts.

INCISAL REST

Incisal Rests

Prepared in form of rounded notch at incisal angle of canine or incisal edge of incisor.

Should be approximately 2.5 mm wide and 1.5 mm deep.

Notch is beveled both labially and lingually.

Marginal Ridge Rest

45o

Bonded Resin Cingulum Rest