Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
28 Cards in this Set
- Front
- Back
|
What are the Basic PFM Margin Designs?
|
1.Conventional metal facial margin
2. "Collarless" facial margin 3. Shoulder porcelain Labial margin |
|
|
What is the range for the conventional facial metal collar?
|
-Facial: 0.2-1.0 mm wide
-Lingual: as wide as you want |
|
|
What margin design is described as "disappearing facial collar"?
|
"Collarless" Facial margin
|
|
|
In collarless facial margin what end at the margin/tooth interface?
|
Porcelain, opaque, metal all end at the tooth interface
|
|
|
List the range of mm for the layers in the PFM Crown/Abutment "Sandwich"?
|
-Prepared tooth
-Cement layer: < 25 microns -Metal Substructure: 0.3-0.5mm -Opaque layer: 0.3 mm -Body Porcelain: 1.0mm - more |
|
|
How do you get metal, opaque and body porcelain to all converge at a finite, discrete, sharp margin position?
|
It impossible-three materials cannot occupy the same location spatially simultaneously-you either have metal, opaque or porcelain that is exposed at the margin
|
|
|
What is design flaw of having metal, porcelain, opaque exposed?
|
-Metal can be polished
-Porcelain can be polished and glazed -Opaque can't neither occur, so it plaque retentive (causes periodontal and recurrent caries issues) |
|
|
What is the design "flaw" of the margin?
|
If the margins do not fit, there's no metal to be able to burnish it closed (it fits, or remake)
|
|
|
What affect alloy type on the crown?
|
Depending on the alloy type, porcelain applicaiton cause cause the margin to distort (porcelain firing contraction) and become open
|
|
|
What describe Shoulder porcelain margin?
|
-360 circumferential porcelain margins, metal substructure
-Difficult to make form lab standpoint |
|
|
What is the advantages and disadvantages of Shoulder porcelain PFM crown?
|
Advantage: Improve (maximize) esthetics by 1) eliminate the display and discoloration of metal, 2) Maximize thickness of gingival porcelain
Disadvantage: Agressive preparation: potential pulpal embarrassment, weakens remaining prep. tooth structures Note: Perhaps weaker and more brittle margin |
|
|
What is preparation parameters for Shoulders margin?
|
-Occlusal reduction: 2.0 mm
-Labial Shoulder reduction: 1.3-1.5 mm infal shoulder width -Shoulders extend from mid-mesial to mid-distal -Metal chamfer reduction on lingual half of tooth (0.8-1.3 mm) -Transition sonize in mid-proximal areas |
|
|
What instrument is used to do a shoulder margination?
|
-TGE 1.4:
|
|
|
Shoulder facial margin should be in what range of degree?
|
90-110
|
|
|
-If the angle formed between shoulder and the external root surface is < 90m there is unsupported ____ ____ .
-If the angle is > 110, there is unsupported ____ on the crown |
-Unsupported tooth structure
-Unsupported porcelain on the crown when over 100. Note: Margin must be smooth |
|
|
What type of margin is on the lingual margin?
|
Chamfer margin
|
|
|
The end-cutting diamond for shoulder prep can be used for smoothing and lower the prep. ledge (T/F)
|
False: Primarily for smoothing not lower the prep. ledge
|
|
|
What would happen you keep don't keep the diamond moving and use water spray on the shoulder diamond bur?
|
You will preare facets on the margins
|
|
|
Margins should be smooth, "_______" on natural teeth
|
Glassy
|
|
|
What are the marginal configurations?
|
-Light chamfer
-Heavy chamfer -Shoulder -Combination (Labial shoulder, lingual chamfer) |
|
|
What restoration uses light chamfer margin?
|
-0.3-0.5 mm
-Gold restorations -Wide metal lingual collars of PFMs |
|
|
Why would you ever leave the metal collar exposed on an anterior tooth
|
-Porcelain/metal junction still have the same design flaw as collarless margin. Most optimum material to place in contact with tissue is either metal, or porcelain (not opaque)
-Lower lip will over this exposure of metal 99% of all pt. |
|
|
What restorations uses heavy chamfer margin?
|
-1.0-1.5 mm dimension
-Narrow collars/collarless PFM restoration -Procera (allceramic) and other all-ceramic restorations |
|
|
How much space would you want vertically in a narrow metal collar PFM crown?
|
-0.2-0.3 mm vertical height to facial collar
|
|
|
Ceramic coping-has same dseign requirements as metal as for margin (T/F)
|
True
|
|
|
What restoration use Shoulder Margin?
|
-1.0 -1.5 mm
-Shoulder porcelain PFM restorations: 1.3 - 1.5 mm collar width -All-ceramic restorations: 1.5 - 1.8 mm |
|
|
-Gold Restoration: ___ chamfer
-Procera (Allceram) restoration: must have ___ ___ -All other all-ceramic crowns: can have ____ or ___ ____ -PFM restoration: 1. Wide metal collar: __ __ 2. ____ / ____ : heavy chamfer 3. Procelain margin: ____ ___ |
- Gold: light chamfer
-Procera: Heavy chamfer -Other all ceramic: heavy chamfer or shoulder -PFM restoration: 1. Wide: light chamfer 2. Narrow metal collar / collarless 3. Shoulder margin |
|
|
What is the procedure in crown construction?
|
-Impress, pour working cast
-Fabricate metal framework- stop metal at shoulder/axial wall junction, or 1-2 mm short (coronal to shoulder) - Apply opaque porcelain (2 firings) -Apply shoulder porcelains (may take 2-3 applications/firings) -Apply body/incisal porcelain -Adjust, occlude, characterize, glaze and polish |
