Servying Flashcards
(23 cards)
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
Levelled with a wax spatula.
• All gingival crevices.
• Gross tissue undercuts below areas of denture framework
• Tissue undercuts distal to the cast framework.
• Labial and buccal tooth and tissue undercuts not involved in denture design.
Material used:
• Hard baseplate wax or
• Oil-based clay
Arbitrary Blockout
Beneath lingual bar connectors or linguoplates.
Relief
Material used for relief
Adhesive wax sealed to the cast
Factors that Determine Path of Placement and Removal
• 1. Guiding Planes • 2. Retentive Areas • 3.Interference • 4. Esthetics
The interference can be eliminated by:
• 1. Mouth preparations by surgery, extraction, modification of interfering tooth surfaces, or alteration of tooth contours with restorations.
• 2. Blackout a reasonable amount of Interference.
How the esthetic factor can determine path of insertion
Through:
• 1. Location of artificial teeth • 2. Clasp metal displays • 3. Base material displays • The location of retentive areas may influence the path of placement selected;
therefore retentive areas should always be selected with the most esthetic
locations of clasps in mind.
G. P. should follow the natural curvature of the tooth surface. § Starting from
the facial line angle to the lingual line. § prepared surfaces are polished.
What is the problem of conventional reciprocal clasp arm?
It act only when the denture framework is fully seated.
