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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