FDP Framework Design Flashcards by Marjorie Wolfe

In fixed dental prosthodontics the portion of a fixed dental prosthesis that unites the retainer and pontic

Connector

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What is the function of the framework

support and marginal fit

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Framework
strong or weak?
rigid or flexible?
Brittle?

Strong
Rigid
NOT brittle

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Overlaying ceramics are a __ material

brittle

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Function of the overlaying ceramics

Esthetics

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What is the minimum required for overlaying ceramics

1mm

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Overlaying ceramics need to be resistant to

compressive load

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Overlaying ceramics are fragile under

tensile stress

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ceramic should not exceed __ to avoid fracture

2mm

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Texture of overlaying ceramics

highly polished/glazed to prevent wearing opposing dentition

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Ideal wear of overlaying ceramics

10 um per year

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Darker the color polishing disc the __ the grit

heavier
(blue = 1st, pink = 2nd, white = 3rd)

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Framework design should be considered during the __ stage

Tx planning

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Framework design should allow and even __

porcelain thickness

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Framework design should have proper connector __

configuration and design

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Framework design should have optimally located __

occlusal contacts

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Framework design should have no abrupt contour change between

metal/porcelain

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The ideal way to design framework is by waxing/ designing to ideal contours and then do an even __ of the anatomy contours desired. This way the porcelain has an even __

cutback
porcelain thickness

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Metal occlusion should be used with a __ preparation

more conservative (as thin as maybe 1mm)

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This provides a stronger occlusal surface (may be indicated for bruxism)

metal occlusion

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Metal occlusion may be indicated when theres limited __

interocclusal clearance

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Downside to metal occlusion

compromised esthetics (discuss with patient while tx planning)

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With metal occlusion, what cusps should be in metal surface

Functional cusps / centric occlusion contacts
- ideally 1.5 mm away from interface
- try to avoid eccentric movement contact going over interface

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Interproximal should be on either __

ONlY metal or ONLY porcelain

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What is used ideally for interproximal

ideally in porcelain, it will be easier if porcelain needs to be added to close contact Esthetics are also better

Where is plaque accumulation more common

In the interface

3 types of metal extensions/ margins

Conventional - tooth-metal-porcelain margin interface Metal Collar -tooth-metal margin interface Porcelain Butt Margin (shoulder) - tooth-porcelain margin interface

How is light transmission different between a conventional and porcelain butt margin (shoulder)

With a conventional margin light coming in is reflected by the metal at the interface making a grey ish look to the gingiva making it less esthetic The porcelain butt margin has enough porcelain that it reflects less light in the cervical region so its more esthetic

This provides an excellent margin seal

metal collar

This helps to preserve periodontal health

metal collar

With a metal collar, distortion of framework is __

avoided during crown fabrication

Metal collar provides __ during cementation and function

rigidity

Metal collars are usually designed with a __ to __ collar

0.5mm to 1mm

Disadvantages of metal collar

esthetics (more common on posterior teeth)

Hairline collar, disappearing margin

Conventional margin

The metal and opaque porcelain layer meet simultaneously on the preparations margin

conventional margin

What prep is recommended for conventional margin

Deep chamfer (1mm) or shoulder - for rigidity of metal and better esthetics

Disadvantages of conventional margin

Exposed opaque porcelain layer difficult finishing marginal adaptation may distort after porcelain firing

This margin is commonly used on the anterior restorations

porcelain butt margin

what are the esthetic improvements with porcelain butt margin

metal elimination on margin depth in cervical translucency light transmission through the root

Disadvantages of porcelain butt margin

Requires a 1.2mm margin depth to achieve optimum esthetics Difficult to obtain excellent marginal seal due to contraction of porcelain towards the greatest bulk during firing

How should the framework design be prepped

You have the freedom to design the framework design as you want, as best it fits each individual case

Agent applied to the die to provide space for the cement when cementing the restoration

Die spacer

what is the film thickness of the die spacer

25-50 um

Die spacer is applied within __ from the margin

1mm

What materials are used for the die spacer

Mostly resins are used Model paint Thermoplastic polymers disolved in colatile solvents

What is a cast connector

Convenient - are incorporated in the wax pattern so it minimizes the number of steps during fabrication

Disadvantage to cast connector

fit may be compromised due to distortion of the wax

What is a soldered connector

involved the use of an intermediate metal alloy with a lower melting point than the rest of the framework

with a soldered connector, the parts being joined don't fuse but must be __ to attain a successful soldering

wetted

When is a soldered connector useful

when a framework doesn't fit the abutments as a whole unit (FDP) but does as independent abutments (possible distortion on the connector/pontic area) (look at steps in powerpoint to achieve this)

What is a welded connector

adjacent surfaces, the parts being connected are fused by heat or pressure - a filler metal with a similar melting temp as the framework can be used during the procedure

What is a loop connector

sometimes are required when a diastema needs to be incorporated to a FDP

This is a weak design and is rarely used

loop connectors

where is the loop on the loop connector

Loop on the lingual aspect of the FDP

Loop connectors may be cast with the rest of the framework or shaped with a __

Pt-Au-Pd alloy wire

Connector design where one component goes inside another

Nonrigid connector (rarely used nowadays)

Mortise and tenon

Mortise = female component of non rigid connector Tenon = male component

Path of insertion of nonrigid connector must be the same as the one of the FDP component with the

Tenon

The design of the nonrigid connectors are incorporated in the

wax pattern fabrication stage

With a nonrigid connector, paralleling usually accomplished with a

surveyor

4 indications for using a nonrigid connector

To overcome different path of insertion of abutments Segmenting large, complex FDPs into shorter components that are easier to replace or repair Questionable distal abutment Relieve stresses on long FDPs

What are the rigid connectors

Cast connector Soldered Connectors Welded connectors Loop connectors

What are the 3 ways the nonrigid connector can be prepared

Freehand (most difficult) Precision machine Prefabricated plastic patterns

A metal coping is designed to correct the path of insertion of an abutment that is tilted (usually mesially)

Telescopic crown

The coping / telescopic crown is used as a __ to fabricate the FDP

retainer

Telescopic crowns can prevent __ and even the need of __

over-preparing teeth endodontic treatment

The Telescopic crown requires an additional __ of clearance to fit the additional metal coping

+/- 1 mm

The fabrication of a __ is always required when treating a patient for a FDP where multiple abutments will be splinted

solid cast

The solid cast should be made from the __

2nd pour of the same final impression used to fabricate the master cast (1st pour - master cast)

Should the solid cast be pin indexed and sectioned

What is the reason for the solid cast

For the technician to verify the frameworks fit on a cast that has not been altered and has no removable components (master cast)