1
Q
90% of fixed restorations are…
A
Full coverage crowns
2
Q
What material related parameters influence material selection? (5)
A
- Mechanical properties
- Optical properties (esthetic potential)
- Minimal wall thickness necessary
- Wear behavior
- Bonding possibilities
3
Q
What are the different types of full coverage crowns? (4)
A
- metal
- PFM
- all ceramic
- acrylic resin
4
Q
What are the different types of metal full coverage crowns? (2)
A
- Preformed
- Cast
5
Q
What are the different types of PFM full coverage crowns? (4)
A
- Veneer crowns
- Full ceramic coverage
- Porcelain with metal collar
- Porcelain with ceramic shoulder
6
Q
What are the different classifications of all ceramic full coverage crowns? (2)
A
- by manufacturing method
- by material
7
Q
What are the different manufacturing methods of all ceramic full coverage FC crowns? (3)
A
- layered
- pressed
- CAD/CAM
8
Q
What are the different materials of all ceramic full coverage FC crowns? (3)
A
- feldspathic
- aluminous
- zirconia based (Y-ZTP)
9
Q
What materials can be used for metal preformed FC crowns? (2)
A
- Gold
- Steel / cobalt-chromium
10
Q
What do we use steel or cobalt chromium metal preformed FC crowns for?
A
Provisionals, mainly in pediatrics
11
Q
When do we use gold metal preformed FC crowns?
A
Uncoperative patients
12
Q
What size of preparation do we need for gold metal preformed FC crowns?
A
small prep
13
Q
Properties of gold metal preformed FC crowns? (4)
A
- Soft
- Malleable
- Have to be adapted
- Easy to handle
14
Q
How is a metal cast FC crown prepared in comparison to PFM?
A
Metal cast crown has less reduction
15
Q
What type of finish line is prepared for a metal cast FC crown?
A
0.5mm chamfer
16
Q
How much space does a noble alloy metal cast FC crown need?
A
1mm
17
Q
How much space does a non-noble alloy metal cast FC crown need?
A
0.8mm
18
Q
What are the pro’s of a metal cast FC crown? (2)
A
- good occlusal anatomy
- good marginal fit
19
Q
Veneer PFM FC crowns are less… (2)
A
- less esthetic
- less occlusal preparation = less prothestic space required
20
Q
Where is the porcelain and metal in veneer PFM FC crowns
A
- metal occlusal surface
- porcelain buccal/labial layer
21
Q
Indication of veneer PFM FC crowns?
A
- Short teeth OR
- patients that tend to break occlusal porcelain
22
Q
What layers is a PFM FC crown made of?
A
- Thin layer of cast metal (coping) in contact with tooth
- Covered by feldspathic porcelain
23
Q
What is the purpose of each layer in a PFM FC crown?
A
Metal: toughness and fit
Porcelain: esthetics
24
Q
Which FC crown is the most versatile?
A
PFM crown
25
How can you be more conservative for a PFM crown?
L/P metal collar
26
How can you inhance asethetics in PFM crowns? What occurs as well?
- Ceramic shoulder
| - Gains adhesion
27
How much of the crown is covered in conventional PFM crowns?
- Almost all the crown is covered by porcelain
| - small collar at lingual surface is not covered by porcelain
28
What does the translucency and toughness of all ceramic FC crowns depend on?
The material used
29
How are the aesthetics of all ceramic FC crowns?
High esthetic result
30
How much metal is used in all ceramic FC crowns?
No metal used
31
What are the types of zirconia-based FC crowns? (2)
- Monolithic
| - Stratified (veneers)
32
What are the types of lithium disilicate based FC crowns? (2)
- Monolithic
| - Stratified (veneers)
33
What are the different types of accrylic resin FC crowns? (4)
* Direct technique
* Indirect technique
* Preformed crowns
* Cellulose acetate
34
What are acrylic resin FC crowns used for?
Provisional restorations
35
What cement do you use for acrylic resin FC crown in the direct technique? (2)
- Bis-acrylic resin
| - PMMA
36
What are Bis-acrylic resin cements with acrylic resin FC crown used for ? (2)
- For short-term provisional dentures.
| - Can be used for long term too.
37
What are PMMA cements with acrylic resin FC crown used for ? (2)
- Short-term provisional dentures (2-3 weeks).
| - Options for indirect techniques also exist: milling technique or conventional.
38
How long can the indirect technique acrylic resin FC crown last for?
Medium-long term provisional dentures (2-3months)
*reline in mouth (self curing)
39
When do we use the indirect technique for acrylic resin FC crowns?
- esthetic cases
| - medium to longer term
40
What is the advantage of the indirect acrylic resin FC crowns?
Tougher
41
Polycarbonate acrylic resin FC crowns? (4)
- Preformed crowns for provisionals.
- Reline into the patient’s mouth.
- For provisional dentures.
- Mostly used in case of emergency
42
What occurs if you did too little of a preparation for a FC crown?
Weak restoration
43
What occurs if you do too much of a preparation for a FC crown?
not conservative with tooth structure
44
How much space is needed for a PFM FC crown?
1.2-1.5mm rounded shoulder/ 0.5mm chamfer L or P
45
How much space is needed for full ceramic layered FC crown?
1mm rounded shoulder
46
How much space is needed for full ceramic monolithic FC crown?
0.5 chamfer or rounded shoulder
47
How much space is needed for full metallic FC crown?
0.5 chamfer
48
What is the importance of keeping the anatomic profile (emergence profile) for FC crowns? (2)
* To respect the periodontal health
| * Preservation of the integrity of the margins
49
Why is a smooth preparation important for a FC crown? ($)
• Better impression taking=better reproduction of details
• Enhances waxing and casting (better fit).
• Enhances the digital workflow.
• Forces spread out over a greater and even surface:
- Lower risk of restoration or tooth fracture.
50
What is the relevance of the smooth and roundish preps when working digitally?
Point cloud -> Mesh -> STL-file
51
Why is having a neat finish line important for a FC crown? (4)
* No undercuts, smooth.
* Better reproduction.
* Eases laboratory work.
* Better fit -> less / no marginal leakage
52
TWO-PLANE PREPARATION FOR CONVEX SURFACES in FC crown? (3)
- Opaque porcelain may show through
- Overcontoured Surface
- The pulp may be encroached upon or invaded
53
What are the parts of the PFM crown? (2)
- metal coping
| - 3 layers of veneering porcelain (1mm)
54
What size is the metal coping for FC PFM crowns?
- 0.5 mm for noble alloys.
| - 0.3 mm for non-noble alloys.
55
What are the layers of porcelain used in FC PFM crowns? (3)
- Opaque porcelain
- Dentin porcelain
- Incisal / enamel porcelain
56
What is the purpose of opaque porcelain in PFM crowns? (2)
- Hides the color of the underlying metal framework.
| - Joins and links the metal to the rest of porcelain layers.
57
What is the purpose of dentin porcelain in PFM crowns? (2)
- Main part of veneering porcelain.
| - Provides the shade to the restoration
58
What is the purpose of incisal/enamel porcelain in PFM crowns? (3)
- Provides translucency.
- Can be stained.
- It is the outermost layer
59
What are the characteristics of the metal margin in PFM crowns? (4)
- Metal collar at lingual surface.
- 0.3 – 0.5 mm thick.
- 2-3 mm high.
- Good fit and hygiene
60
What are the characteristics of the metal-porcelain margin in PFM crowns? (2)
- Metal coping gets thinner as it gets near the margin.
| - Contraction of porcelain can put the coping out of fit.
61
What are the characteristics of the ceramic shoulder/chamfer margin in PFM crowns? (4)
- Low fusing ceramic in contact with margin.
- Good esthetics.
- Needs adhesive technique cementation at the porcelain.
- Enough thickness to avoid fractures.
62
How do you prepare a FC PFM crown occlusally? (2)
- Functional cusps: 2 mm.
| - Non-functional cusps: 1.5 mm.
63
How do you prepare a FC PFM crown on the axial surface?
1.2-1.5mm
64
How do you prepare the buccal/labial finish line for a FC PFM crown ?
Rounded shoulder 1-1.5mm
65
How do you prepare the lingual finish line for a FC PFM crown ?
- chamfer or
| - deep chamfer 0.5 when metal collar
66
Where should the margin be prepared normally for FC PFM crowns?
Yuxta or supragingivally
67
When should a FC PFM crown be prepared subgingivally? (3)
- Esthetics.
- Short teeth.
- Cervical caries or restorations.
68
Young patients and PFM crowns? (2)
◦ Teeth partially erupted.
| ◦ Big pulp chambers
69
Old patients and PFM crowns? (2)
◦ Gingival margin over cementum.
| ◦ Lack of cooperation
70
The longer the edentulous space the ___ the load over abutment teeth
greater
71
In what cases should you have a metal occlusal surface for FC PFM Crowns? (2)
Bruxers and epileptics
72
Contraindication for FC PFM crowns
Bad hygiene
73
Indications of PFM FC crown? (5)
* Single crowns to strengthen the tooth.
* Single crowns to change the shape of the tooth.
* FPD retainer.
* RPD retainer.
* Combined prosthesis retainer
74
When do you use a single FC PFM crown to change the shape of the tooth? (2)
- To change the contour (crowding, conoid...).
| - Occlusal modification.
75
When do you use a single FC PFM crown to strengthen the tooth? (2)
- Great tooth wear.
| - Hyploplasia.
76
When do you use a single FC PFM crown as FPD retainer? (4)
- For maximum retention
- Reinforce the abutment tooth
- Intermediate abutment tooth.
- Tooth splinting
77
When do you use a single FC PFM crown as RPD retainer? (4)
- Improves path of insertion.
- Control the amount of retention.
- Reinforces the abutment tooth.
- Prevent caries over abutment tooth.
78
What are the different lab procedures for FC PFM crowns? (2)
- Copihng
| - Veneering porcelain build up
79
What are the different types of lab procedures for FC PFM coping? (3)
- Lost-wax procedure (waxing and casting).
- CAD/CAM.
- CAD + laser sintering.
80
What is the lab procedure to create FC PFM crowns?
1. Cast prep
2. waxing
3. investment
4. oven
5. centrifuge
6. removal of the coping
7. trimming and finish
81
What is the waxing procedure in lab for FC PFM? (4)
- The wax pattern is the precursor of the finished cast
- Made in the lab it is called Indirect waxing technique
- Once the waxing of the core is over
- Rods are attached to the non-functional cusps
82
What happens during the investment lab procedure for FC PFM? (2)
- Powder and liquid mixture.
| - 30 min setting time.
83
What happens during the oven lab procedure for FC PFM? (2)
When molten the metal is cast through the sprue inside the negative left by the
wax.
84
What happens during the centrifuge lab procedure for FC PFM? (2)
CASTING STEP: step where the wax pattern is converted to his metal replica
85
What are the solutions for volume changes during casting? (3)
- Oversized wax pattern.
- Correction of the crown. Manually.
- Investment expansion
86
What is used for investment expansion? (2)
- INTERNAL, for pin cores.
| - EXTERNAL, for crowns.
87
What is the lab procedure for CAD/CAM FC crowns? (4)
1. scanning
2. design of CAD structure
3. manufacturing CAM structure
4. veneering porcelain
88
What the different types of manufacting CAM structure? (2)
- Mechanized or milling technique
| - Laser sintering
89
What does the mechanized or milling technique for CAM consist of?
- drill of the milling machine
| - material blocks can be different materials, non-noble metal alloys, zirconia, LDS, PMMA
90
How does the laser sintering technique for CAM work? (2)
- Printing technique
| - Layers of the material poder is fused by a scanning laser
91
Milling technique for CAM?
- More accurate.
- More material is wasted (the blocks used are nonrecyclables)
- More polished surface.
- Used for fixed prosthesis over teeth and implants
- More indicated to work with over implants restorations.
92
What are the layers in PFM FC crowns? (4)
1. Opaquer: to block the light and
mask the metal color.
2. Base layer: thick layer, it gives the
shape and the shade.
3. Characterization layer: to make the tooth
look more natural and mimics the adyacent teeth.
4. Finishing or Glaze layer: thin layer that gives
smoothness and translucency
