Metal Ceramic Restorations Flashcards
- A metal casting (coping) which fits over the prepared tooth with ceramic fused to it.
- Combines the strength and accuracy of cast metal with esthetics of porcelain.
Metal-Ceramic Restorations
Indications for \_\_\_\_\_ restorations: •Need for full coverage with esthetic demands: •Extensive tooth destruction •Large restorations / undermined enamel •Opposing ceramic surfaces
Metal-Ceramic Restorations
Advantages of ______ restorations:
•Natural appearance -esthetics
•Retention and resistance qualities of full crown
•More resistant to fracture than all-ceramic / dependable fabrication of FPD
•Greater strength w/ less reduction than all-ceramic
•Ability to have metal occluding surfaces
•Preparation is less demanding than Partial Veneer Crown
Metal-Ceramic Restorations
The key tooth prep form decision is the ____
Finish line
What 3 finish lines can be used in metal ceramic restoration?
Shoulder
Shoulder w bevel
Chamfer
_____ finish line
•Some people think it makes for a better fitting crown
•It is certainly acceptable to use such a finish line but it does not make the crown fit better and it does not work with a porcelain margin
-Must be all in metal
Shoulder finish line w bevel
______ finish lines provide greater cervical space for an esthetic thickness of porcelain without over contouring the crown and can be used with porcelain margins
Shoulder
______ finish line:
Need for optimal porcelain thickness near the margin for esthetics and particularly when optimal reduction is not possible
Shoulder finish line
_______ finish line:
•Easier to prepare than a sharp angle
•Required for any crown that will be milled
•Produces less tooth weakening than sharp axiogingival line angles for small teeth or RCT, teeth that will be subjected to greater force since they are FPD abutments, and teeth with substantial secondary dentin where there is very little pulp space remaining (older patients)
Shoulder with rounded angles
_____ finish line:
–ease of fabrication for non-esthetic situations
•Metal thinned to a fine line that is barely visible –improved esthetics compared to metal collar but more opacity than porcelain margin
- Must be placed subgingivally and not used for esthetic cases
Metal collar
All of the margin designs have a chamfer on the ____ portion of the prep to accomodate a metal margin
Lingual
What are the 3 margin designs for metal ceramic designs?
Metal Collar
Porcelain Shoulder
Disappearing Margin
_____ finish line with ____ margin
•Enhanced cervical esthetics
•When there is gingival inflammation due to overcontoured crowns and you want to make slightly undercontoured crowns to improve the gingival response
Shoulder finish line with Ceramic Margin
The following are reasons for extending margins \_\_\_\_\_\_ •Existing caries •Extensions of previous restorations •Subgingival tooth fracture •Root sensitivity •Retention/ Resistance •Esthetics
Subgingivally
The subgingivally placed finish line should not extend more than ____ into sulcus
1/2 way into sulcus
:the part of the axial contour that extends from the base of the gingival sulcus past the free margin to the height of contour.
•Straight or slightly concave; not bulky or excessively convex
Emergence Profile
-______ is subject to brittle fracture if there is internal stresses and excessive thickness
Porcelain/Ceramics
_____ abrasiveness –wear to opposing enamel / metal
•Hardness and microscopic roughness
Porcelain
If a porcelain crown is polished to a glaze, how will this affect abrasiveness to opposing dentition?
More abrasiveness
_______
•Advantages:•Esthetics
•Disadvantages:•Increased removal of tooth structure
Porcelain
______ angle of margin / obtuse finish line → decreased marginal gap.-Bevel -(Only if infinitely closable)
Acute
The ________ of the cement can prevent complete seating of a casting with near parallel bevels
film thickness
Margin angles of less than ______ may produce a metal margin that is too thin and weak.
25o
What is the angle of margins that is best for cavosurface margins?
35-55
______ margins are difficult to evaluate
Subgingival
- The combined connective tissue-epithelial attachment from the alveolar crest to base of the gingival sulcus (approximately 2 mm).
- (+ 1 mm for a healthy gingival sulcus= 3mm free gingival margin to alveolar crest.)
Biologic width
In an anterior metal ceramic prep, the F-L taper is necessary for ______ form
Resistance
In an anterior metal ceramic prep, the M-D surfaces provide ______ form
Retention
What is the ideal taper for an anterior metal ceramic prep?
10 degrees
What is the ideal linguogingival height for an anterior metal ceramic prep?
1.5 mm
How many mm thick should the metal coping be for veneered areas in a metal ceramic restorations?
.3-.5mm
How many mm thick should the metal coping be for non-veneered areas in a metal ceramic restorations?
0.8-1mm
How many mm thick should the opaque porcelain be in a metal ceramic restorations?
.1-.2mm
How many mm thick should the shoulder porcelain be in a metal ceramic restorations?
.8mm
How many mm thick should the gingival, body, and incisal porcelain be in a metal ceramic restorations?
.8-1.5/2mm
Should the facial reduction on an anterior metal ceramic prep be in one plane or 2 planes?
-Allows adequate reduction for uniform color / contours and resistance.
2 planes
_______ reduction of facial surfaces of an anterior prep→ bulky contour or opaque “bright spot”
Inadequate
_______ reduction of facial surfaces of an anterior prep-decreased resistance / pulpal insult.
Over-reduction
______ reduction results in light reflection from the opaque porcelain
Inadequate
•Pulpal “blush” / pulpal exposure•Axial reduction → approaches pulp quickly•1.2 –1.5mm at cervical is often too much•Amount removed ↑ with ↑ TOC preparation•↑TOC = ↓Resistance form
Overreduction
_____ proximal reduction facilitates the development of normal appearing proximal color and translucency
Uniform
_______ of preparation→ metal in proximal → blocks light transmission
Proximal wing
In an anterior metal ceramic prep, Extension of facial shoulder reduction slightly greater than ____mm ______ (which way) to contact; gradual blend to lingual
1mm lingual to contact
How deep should a porcelain shoulder be on an anterior metal ceramic crown?
1.2 mm
How wide should a metal collar be?
.3-.5mm
Should a metal collar be supra or subgingival usually?
Subgingival
reasons to use a _______
•Ease of fabrication
•Include thin, unsupported tooth structure
•Extend margin apically with less tooth reduction
Metal collar
For the posterior occlusal metal ceramic crown, how thick should porcelain be?
1.5mm
For the posterior occlusal metal ceramic crown, how thick should metal be?
.5mm
\_\_\_\_\_\_\_\_\_ occlusion •less tooth reduction •less opposing tooth wear •stronger restoration •1.5mm occlusal reduction Esthetic Requirements Extent of Porcelain Coverage
Metal Occlusion
\_\_\_\_\_\_ occlusion •Esthetic zone •Generally NOT 2nd Molars •Opposing ceramic surfaces •2.0mm occlusal reduction
Porcelain Occlusion
