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fixed pros. > Metal ceramic crowns > Flashcards

Metal ceramic crowns Flashcards

1
Q

how is this possible?

The Morphology Of Metal Ceramic
Single Crowns & Fixed Partial Dentures
Should _______ simulate natural morphology

A

Closely Simulate Natural Tooth Morphology
possible with adequate tooth prep

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2
Q

how tall must an anterior crown prep lingual wall be

A

3mm

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3
Q

what is an MCC? what is advantage of it?

A
  • 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.
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4
Q

what could this be due to?

Indication for Metal-Ceramic Restorations

A
  • Need for full coverage with esthetic demands due to:
  • Extensive tooth destruction
  • Large restorations / undermined enamel
  • Opposing ceramic surfaces
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5
Q

appearence? R and R? fracture? strength? prep?

Advantages of Metal-Ceramic Restorations

A
  • 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
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6
Q

what finish lines can be used with a MCC

A

chamfer, shoulder, shoulder bevel

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7
Q

are shoulder bevels superior for MCC

A

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

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8
Q

thickness of porcelin? overcontouring?

shoulder finsih lines provide?

A

provide greater cervical space for an esthetic thickness of porcelain without overcontouring the crown and can be used with porcelain margins

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9
Q

why use a shoulder finish line

A

Need for optimal porcelain thickness near the margin for esthetics and particularly when optimal reduction is not possible

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10
Q

finish line form and gingival trauma

A

form can influence trauma to gingiva

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11
Q

ease? needed for what crowns? compared to sharp?

Why Use A Shoulder With A Rounded
Axiogingival Line Angle?

A
  • 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)
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12
Q

when to use a metal collar at the margin

A

ease of fabrication in non esthetic zones

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13
Q

how could a metal collar be used in an esthetic zone

A

subgingival margin

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14
Q

Metal-Ceramic Facial Margin Designs and Finish Line Geometry

A

metal collar would be in non esthetic zones usually
porcelin shoulder should only be used when occlusal forces are low
disappearing margin can allow metal to support the porcelin

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15
Q

MMC have what finish line on the lingual

A

light chamfer

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16
Q

what should not be violated with a metal collar or any margin?

A

biologic width (2mm)

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17
Q

minimal reduction helps prevent?

A

overcontouring= impingment on soft tissue and possible food trap

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18
Q

esthetics/ improving gingival response?

why use a shoulder finish line

A
  • 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
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19
Q

caries?

previous restorations?
tooth fx?
root?
R/R?
Esthetics?

Legitimate Reasons for Extending
Margins Subgingivally…

A
  • Existing caries
  • Extensions of previous restorations
  • Subgingival tooth fracture
  • Root sensitivity
  • Retention/ Resistance
  • Esthetics
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20
Q

To hide a ceramic or metal-ceramic margin for esthetics, subgingival margin must:

A
  • Should not extend more than ½ way into sulcus.
  • Well-adapted, smooth, proper axial contour
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21
Q

preserving perio with axial contours

A
  • Emergence Profile: 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
22
Q

* fx?

  • ?stresses
  • thickness?

Problems with Porcelain / Ceramics

A
  • Porcelain is subject to brittle fracture if thin
  • Internal stresses
  • Excessive thickness (>3mm) with no support
23
Q

porcelin abrassion

A

can be abrasive to teeth in occlusion, must adjust occlusion or have procelin antagonist

24
Q

how to prevent porcelin wear

A

porcelin antagonist
polish porcelin
occlusal adjustment

25
Q

Metal-Ceramic Crown vs. Complete Metal
Crown

A

*Advantages:
* Esthetics
*Disadvantages:
* Increased removal of tooth structure

26
Q

Metal-Ceramic Preparation
Requirements are based on:

A
  1. Fundamentals of Tooth Preparation:
  2. Material requirements (components):
  3. Esthetic requirements
27
Q

_____ angle of margin / ________ finish line → allow for? accomplished how?

A

acute; obtuse
decreased marginal gap.
accomplished with Bevel

28
Q

MCC cervical finish line depends on

A

shape and bulk of the margin
marginal adaptation
degree of seating

29
Q

ideal bevel angle

A

45

30
Q

Margin angles of less than ___ may produce a metal
margin that is too thin and weak.
ideal margin angles range?

A

25 degrees

ideally 35-55

31
Q

biologic width

A
  • 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 (must be 3mm from prep to gingival sulcus base
32
Q

MCC F-L prep

A
  • Parallel to the facial cervical 1/3 - 2/3 of prep
  • Lingual wall height is limited: need “ideal” taper for resistance form in F-L direction which prevents dislodgment in protrusive and lateral
33
Q

most retention of MCC anterior comes from?

A

parallel M-D walls

34
Q

components of MCC crown and deminsions

A
  • Metal coping: 0.3-0.5 mm veneered areas and 0.8-1.0 mm un-veneered areas
  • Opaque porcelain: ~ 0.1-0.2 mm
  • (Shoulder porcelain) ~ 0.8 mm
  • Gingival, body, and incisal porcelain: 0.8 – 1.5 / 2 mm
35
Q

why do we use a two plane facial reduction? too much or too little?

A

Allows adequate reduction for uniform color / contours and resistance.
Inadequate reduction → bulky contour or opaque “bright spot”
Over-reduction → decreased resistance / pulpal insult.

36
Q

single plane under reduction seen as

A

bright spots: light reflection from the opaque porcelain

37
Q

single plane over reduction seen as:
how much reduction at cervical is too much?
amount removed increases with increased?
increased TOC and resistance?

A
  • 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
38
Q

how to establish facial reduction

A

depth grooves

39
Q

Uniform proximal reduction facilitates:

A

the development of normal appearing
proximal color and translucency

40
Q

proximal porcelin vs proximal wing

A

Porcelain proximal surface allows light transmission
Adequate reduction through interproximal is necessary
*Proximal wing of preparation → metal in proximal → blocks light
transmission

41
Q

Elimination of proximal wings with:
also allows for?

A

Elimination of proximal wings with gradual
transition from facial to lingual allows more esthetic
proximal porcelain surface.

42
Q

how to eliminate proximal wings

A

Extension of facial shoulder reduction slightly greater than 1mm lingual to contact; gradual blend
to lingual

43
Q

ant MCC shoulder depth

A

1.2mm

44
Q
  • Finish Line Geometry of ant MCC
A
  • Modified (Radial) Shoulder or disappearing margin with heavy chamfer
45
Q

* facial is often where? why?

  • supragingival? when?
  • may depend on?
  • Margin Placement Anterior Teeth:
A
  • facial is often subgingival for esthetics
  • supragingival if no significant esthetic contraindication
  • may depend on the type of ceramic restoration used and framework design
46
Q

metal collar width/ pros and cons

A
  • Width: 0.3-0.5mm
  • Marginal integrity
  • Finish
  • Compromised esthetics
47
Q

finish lines used with metal collar

A
  • Shoulder with bevel
  • Heavy chamfer
48
Q

why use a metal collar

A
  • Ease of fabrication
  • Include thin, unsupported tooth structure
  • Extend margin apically with less tooth reduction
49
Q

MCC reduction on posterior occlusal surface

A

1.5 mm thickness – porcelain
+ 0.5 mm thickness – metal
2.0 mm total

50
Q

using metal occlusion with MCC allows for?

A

USE METAL ON FUNCTIONAL CUSPS, MAINLY USED ON MAXILLARY (LINGUAL=FUNCTIONAL)
* less tooth reduction
* less opposing tooth wear
* stronger restoration
*1.5mm occlusal reduction

51
Q

Porcelain Occlusion
* where?
generally not which teeth?
* Opposing _____ surfaces
* ___mm occlusal reduction

A
  • Esthetic zone
  • Generally NOT 2nd Molars
  • Opposing ceramic surfaces
  • 2.0mm occlusal reduction
52
Q

less than this?

minimal lingual wall height on ant preps

A

2-3mm

without this dislodged in protrusove and lateral movement

fixed pros. (11 decks)

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