Servying Flashcards
It is the forces acting on one part of a RPD are counterbalanced, counteracted or negated by another part of the RPD.
Reciprocation
Resistance to movement of the prosthesis away from the edentulous ridge along the path of placement
Retention
The resistance to horizontal force from mastication and the tongue.
Bracing
Surveying the Diagnostic Cast
• 1. Determine the most desirable path of Insertion
• Usually a single path
So what are the advantages of single path ?
1- Equalizes retention
2- CROSS-TOOTH RECIPROCATION
3- CROSS- ARCH RECIPROCATION
4- Allows insertion and removal of RPD without interferences.
• Minimizes torque on abutments
• Directs forces on long axes of teeth.
• Provides frictional retention.
Why we Tilt the cast?
to obtain maximum parallelism for guiding planes.
Where is Heights of contour?
the occlusal part of gingival third or cervical part of medial
third.
• Equal amounts of undercut.
Where is Heights of contour?
the occlusal part of gingival third or cervical part of medial
third.
• Equal amounts of undercut.
Modify tilt to
1- eliminate Soft tissue interferences
2- to improve esthetics
proximal tooth surfaces that are or need to be made parallel, so they act as guiding planes during placement and removal.
Guiding Planes
Guiding Planes
– proximal tooth surfaces that are or need to be
made parallel, so they act as guiding planes
during placement and removal.
– Flat surfaces parallel to path of insertion
– Control & limit movement of RPD
– Initial contacts for RPD.
– Parallel to each other.
– More than one common axial surface.
Guiding plane dimensions
On the occlusal half , middle 1/3
Retentive tip designed to be placed in the
gingival 1/3
Surveying the Master Cast (Surveying the master cast follows mouth preparations)
• 1. Selected path of placement followed mouth preparations should satisfy the requirements of guiding planes, retention, non interference, and esthetics.
• 2 . Identify the location of clasp terminals and measure the undercut areas (retentive areas) in proportion to the flexibility of the clasp arm.
• 3 . Locate undesirable undercut areas that will be crossed by rigid parts of the restoration during placement and removal (blockout).
• 4. Trim blockout material parallel to the path of placement before duplication .
Can you explain that
• Proximal tooth surfaces to be used as guiding planes.
• Beneath all minor connectors.
• Tissue undercuts to be crossed by rigid connectors.
• Tissue undercuts to be crossed by the origin of bar clasps.
• Beneath bar clasp arms to gingival Crevice Material used
• Hard baseplate wax or blockout material.
Paralleled blockout
• On buccal and lingual surfaces to locate wax patterns for clasp arms.
• Ledges for location of reciprocal clasp arms to follow height or convexity and ledges for location of retentive clasp arms to be placed as cervical as tooth contour permits .
Material used:
• Hard baseplate wax.
Shaped blockout