7. Light Dynamics in Natural Teeth
Tooth colours are
produced by the colour of
the dentine and pulp
reflecting through the
enamel layer which is
influenced by the amount
of demineralisation
8. Raptis et al. 2006
The Effect of Light Transmission
Four crowns placed on tooth 11
Which two are PFM and which two are All-ceramic crowns?
9. In-Ceram Spinell
IPS Empress
PFM
PFM (with porcelain shoulder)
Note how light is blocked by the metal copings
Raptis et al. 2006
11. Charles Land
• Invented dental porcelain in 1886
• Granted Patent 1887
• Platinum foil matrix
Land CH (1903) Porcelain dental art: No II. Dental Cosmos 45:615-620
John McLean & TJ Hughes
• Replaced metal reinforcement with Alumina (Al2O3) to develop first all-
ceramic core
The reinforcement of dental porcelain with ceramic oxides. (1965) BDJ
119(6):251-267
Evolution of Ceramic Crowns
13. Three main types of ceramics in dentistry 1
1. Predominantly glass
• Veneering porcelains for PFM and
all-ceramics
• Most translucent – high aesthetics
2. Particle-filled glass (Glass-ceramics)
i. High glass content
• Lost wax system (Dicor) [no longer
available]
• Machinable feldspar-based ceramic
(Vita Mark II blocks)
• Heat-pressed Leucite reinforced
(Empress I)
(Kelly 2008)
14. Three main types of ceramics in dentistry 2
2. Particle-filled glass (Glass-ceramics)
ii. Low glass content
•
Heat-pressed or CAD/CAM Lithium
Disilicate (IPS emax)
•
Slip-cast or CAD/CAM Glass-infiltrated
alumina (In-Ceram)
3. Polycrystalline (Ceramic oxides)
i. Alumina Oxide (Procera Alumina)
ii. Zirconia (3mol%Y-TZP) (Procera
Zirconia)
18. VITABLOCS® Materials
VITABLOCS
Block
Restoration
Indication
Mark II
Inlays, onlays,
anterior/posterior
crown and
veneer
TriLuxe
Anterior/posterior
crown and
veneer
TriLuxe forte
Anterior/posterior
crown and
veneer
RealLife
Anterior/posterior
crown/ veneer
for natural
aesthetics
21. Structural Ceramics
• In-Ceram Alumina
• Good combination of strength and
aesthetics
• Substructure for anterior crowns and
3-unit bridges
• In-Ceram Zirconia
• Very good strength
• Substructure for anterior and posterior
crowns and 3-unit bridges
23. Structural Ceramics
• In-Ceram AL
• Very good strength
• Substructure for anterior and 3-unit
bridges and posterior crowns
• In-Ceram YZ
• Excellent strength
• Substructure for anterior and
posterior crowns and multi-unit
bridges
24. Alumina and Zirconia
• The increase in crystalline content in
alumina and zirconia has:
• Improved the mechanical properties allowing
all-ceramic crowns and bridges
• Is hard to machine and resistant to etching
so resin bonding is a challenge
31. Vita Enamic
CAD/CAM Hybrid Ceramic
product description from Vita
• For the first time, this innovative hybrid materials
combines enormous strength with exceptional elasticity
• As a result, the material is perfectly suited for crown
restorations and moreover allows to achieve reduced
wall thicknesses for minimally invasive restorations
• Additionally, VITA ENAMIC excels by utmost reliability
and precise and accurate milled restorations featuring
high edge stability
• This tooth-colored hybrid material also exhibits tooth-
like material properties and produces highly esthetic
results thanks to its excellent translucency
33. Common Ceramic Core Materials
Amorphous glass - Veneering porcelains
Glass ceramics (reinforced by crystalline phases)
• Leucite reinforced - Empress I
• Lithium disilicate - Empress II
• Magnesium aluminium oxide - In-Ceram Spinnell
• Feldspathic Glass - Vita Mark II Blocks
Glass infiltrated mixtures
• In-Ceram alumina
• In-Ceram zirconia
Polycrystalline
• Alumina - Procera
• Zirconia - Lava, Everest, Cercon, Procera, Zeno, Ivoclar etc
34. 1. Amorphous glass – Vita Mark II
2. Crystalline glass ceramics
(reinforced by crystalline
phases)
1. Leucite reinforced - Empress I
2. Lithium disilicate - Empress II
3. Glass infiltrated mixture
1. Magnesium Aluminium Oxide -
Spinell
2. InCeram alumina
3. InCeram zirconia
4. Polycrystalline
1. Alumina - Procera
2. Zirconia – Lava
35. All-Ceramic Material
Type!
Aesthetic Properties! Applications!
Feldspathic Glass
(predominantly glass)
Intrinsically tooth
coloured
Anterior veneers &
crowns
Can be stained & glazed
Crystalline Ceramics
(particle-filled glass - high
glass content)
Intrinsically tooth
coloured
Anterior veneers &
crowns
Can be stained & glazed
Glass Infiltrated Mixtures
(particle-filled glass – low
glass content)
Core material
Core can be pigmented
Anterior and posterior
crowns
Are veneered with
porcelain
Polycrystalline Ceramics
(no glass content)
Core material
Core can be pigmented
Anterior and posterior
crowns & bridges
Are veneered with
porcelain
52. Systematic Review
Goodacre et al 2003!
Mean fracture rate for all-ceramic crowns
increases as you move posteriorly
Anteriors
3%
Premolars
7%
Molars
21%
This review did not distinguish between:
• fracture modes (core or veneer chipping)
• or types of ceramic systems
53. Systematic Review
Pjetursson et al 2007 - All-ceramic vs PFM crowns
5yr survival rates:
PFM
95.6%
All-ceramic
93.3%
85% of all-ceramic crowns failures due to core fracture
Chipping usually repairable
Anteriors:
All-ceramics = PFM
Posteriors:
Material dependent
ü Alumina oxide
95%
ü Reinforced glass ceramics (Empress)
94%
² In-Ceram
90%
² Glass-ceramics (Dicor)
85%
54. Systematic Review
Wang et al 2012 - All-ceramic single crowns
5 yr Fracture rate: (veneer + core)
all systems
Overall
7.7%
Posteriors
10%
Anterior teeth
4.4%
Core fracture:
Overall
7.2%
Posteriors
9.5%
Anteriors
3.9%
Veneer chipping: Overall
3%
Molars
3%
Premolars
1.5%
Canines
2.5%
Incisors
2%
No clear difference found
Statistically significant
Statistically significant
55. Systematic Review
Sailer et al 2007 - fixed partial dentures
5yr survival rates:
Metal-ceramic FPDs
94.4%
All-ceramic FPDs
88.6%
Frequency of:
core #
veneer #
Metal-ceramic FPDs
1.6%
2.9%
All-ceramic FPDs
6.5%
13.6%
Mainly Lithium disilicate and In-Ceram
Rare in zirconia FPD
Annual rate:
Zirconia
1.98 – 12.2
Empress/emaxP
0.83 – 1.55
In-Ceram
no chipping reported
56. Recommended Indications
Class 1 Ceramics
• Aesthetic ceramic for coverage of a metal
or ceramic subsurface
and/or
• Aesthetic ceramic for single-unit anterior,
veneers, inlays, or onlays
Example IPS Empress, IPS e.max Ceram (Ivoclar)
Della Bona, 2009
57. Recommended Indications
Class 2 Ceramics
• Aesthetic ceramic for adhesively cemented,
single unit, anterior or posterior prostheses
and/or
• Adhesively cemented, substructure ceramic
for single-unit anterior or posterior
prostheses
Example IPS Empress (Ivoclar), Cerec MkII (Vita)
Della Bona, 2009
58. Recommended Indications
Class 3 Ceramics
• Aesthetic ceramic for non-adhesively
cemented, single-unit, anterior or posterior
prostheses
Example IPS e.max Press or CAD (Ivoclar)
Della Bona, 2009
59. Recommended Indications
Class 4 Ceramics
• Substructure ceramic for non-adhesively
cemented, single-unit, anterior or posterior
prostheses
and/or
• Substructure ceramic for three-unit
prostheses not including molar restoration
• Example IPS Empress 2, (Ivoclar), Cerec MkII (Vita)
Della Bona, 2009
60. Factors that Influence Ceramics
• Ceramics are susceptible to chemical corrosion
and fatigue mechanisms
• This reduces their lifetime
• Unfavourable oral conditions include:
• Chewing forces from 100-700 N
• Moist environment at 37ºC
• Small contact area; stresses generated 3.5-890
MPa
Della Bona, 2009
61. Survival of Ceramics
To improve mechanical behaviour of ceramics
• Select the ceramic considering location
• Consider substructure similar to metal for PFM
• Minimise surface roughness
• Rougher surfaces have more cracks so need fewer
cycles of stress to fail
• Chemical interaction between ceramic (crack tips) and
environment (water) results in accelerated crack growth
due to stress corrosion
Della Bona, 2009
63. Considerations in Fixed
Prosthodontics 3
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64. Crown Margin
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65. Length of Edentulous Span 1
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66. Length of Edentulous Span 2
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67. Minimum occlusogingival and buccolingual connector
dimensions as a function of position of the bridge
connector and occlusal forces!
70. The image cannot be displayed. Your
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Ceramic Crown
Form
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73. Bonding Ceramic Crowns
• The crystalline content in alumina and zirconia
is resistant to etching so bonding is a challenge
• Silica coating systems (eg Rocatec and Cojet,
3M ESPE) creates a silica layer
• High-speed surface impact of silica-modified
alumina particles promotes resin bonding by:
• Rough surface allowing micromechanical bonding
to resin
• Promotes a chemical bond between the silanated
silica coated ceramic and the resin bond material
82. Custom Fabrication
• All-ceramic restorations are custom-fabricated
increasing susceptibility to fabrication defects
• Variety of techniques
• Sintering
• Heat-pressing
• Slip-casting
• CAD/CAM
• Combined with staining or veneering step
Each technique produces fabrication defects
[from Janine Tiu]
83. Diamond grinding is a major source of failure-inducing
flaws in dense ceramics. (Rice 2002)
Zirconia CAD/CAM machining creates damage that is
not fully healed by sintering process. (Kim et al 2010)
Effects of Abrasive Grinding
Thermal shock
85. Veneer Chipping in Zirconia-based Restorations
Systematic reviews confirm chipping of veneering
ceramic is the most frequent complication
More common than with metal-ceramic or other all-
ceramic restorations
(Al-Amleh et al 2010, Hientz et al 2010, Schley et al 2010,
Raigrodski et al 2012)
86. Al-Amleh et al 2010 “Clinical trials in zirconia: A systematic review
Summary:
• 17 clinical trials based on 3Y-TZP
• Posterior FPD
13 studies
• Single crowns
2 studies
• Implant abutments
2 studies
• 8 brands of zirconia
• Longest trial 5yrs (only 2 studies)
Chipping of veneering porcelain
• Two of 15 studies did not report chipping
• Was common for all brands
• Incidence ranged from 0 – 54%
• Not always noticed by patients – incidental finding
• Also found at non-load bearing areas
89. Reasons for Zirconia Veneer Chipping
High tensile residual stresses locked within
the veneering porcelain (Swain 2009)
Zirconia is a very poor thermal conductor:
• Gold:
315 W/m-K
• Alumina:
40 W/m-K
• Zirconia:
2 W/m-K
Substructure core design
• Cap-like core do not support veneering
porcelain
• Suggested “PFM-style” cut back method
[Tholey, Swain & Thiel 2011]
90. PFMs cool from the inside to the outside producing systematic
compression bonding from the inside to the outside.
YZr crowns cool from both the inside and the outside at a similar
rate resulting in a compression layer in the outer veneer and YZr
coping, and an inner zone of tension within the porcelain veneer.
W/(m.K), of a gold coping =
315
W/(m.K), of a zirconia coping
= 2
Thermal conductivity, W/(m.K),
of porcelain = 1.4
Zone of
tension
91. Loading Zirconia Crowns to Failure
fast cooled v slow cooled
Procera Zirconia
IPS e.max ZirPress
Al-Amleh 2011
92. Fast Cooled Samples
Common features:
• Midline fissure crack
• Cracking on mesial non-loaded side
• Average 902 N
93. Fracture after 2 days
Courtesy: Dr. L. Gruetter (University of Geneva)
94. Courtesy : Dr. L. Grütter (University of Geneva)
Occlusal
contact point
responsible for
shearing off
veneering
ceramic
95. 1. Clean (cotton pellet with
alcohol), rinse & dry
2. Inject siloxane impression material
(light body)
3. Cover the whole crown with
silicon material
Procera Alumina AllCeram (veneering
ceramic failure after 4 years)
96. Zirconia Abutment Fracture
Case description:
1. The zirconia
implant abutment
was screwed in
tightly
2. Contact points
M, D, were
adjusted in situ
3. On the first bite for
occlusal adjustment
the crown fractured
97. Zirconia
abutment CARES
(Straumann)
Zirconia Abutment Try-in Failure
The first bite to check
the occlusion created a
stress concentration at
the distal margin (white
arrow). The crack path
is marked by the red
arrows and result in the
crown splitting in half.
origin
Ø Fabrication defect
99. Poor framework design
• Not enough palatal clearance
• Thin tip zirconia framework
Both cause high stress concentrations
Take home message:
Always try-in zirconia frameworks before veneering
103. origi
n
Conclusion from the replica SEM analysis: The origin of the failure was
located on the occlusal-palatal cusp (wear facette). The crack continued along the arrows
downwards (interproximally) to the gingiva without reaching the margins.
The veneering porcelain was unsufficiently supported by the alumina core
104. Guidelines for Restoring Chipped !
All-ceramic Restorations
Grade 1: Fracture surface can be polished
Grade 2: Fracture surface can be repaired with composite resin
Grade 3: Severe fracture requires restoration replacement
1. Fracture extends into a functional area and repair is not
feasible
2. Re-contouring will result in a significant unacceptable
alteration of the anatomic form from the original anatomy
3. Re-contouring will significantly increase the risk of pulp
trauma by the generation of heat
4. Repair with resin composite will result in unacceptable
aesthetic result
(Heintze & Rousson 2010, Anusavice 2012)
105. Success or Failure?
• Is a chipped all-ceramic restoration a failed
restoration?
• Restoration success is defined as the
demonstrated ability of a restoration to
perform as expected
• Acceptable surface quality
• Anatomic contour
• Function
• Aesthetics (where applicable)
• When should we repair or replace the
entire restoration?
• Restoration failure may be defined as
any condition that leads to replacement
of a prosthesis
• Why do all-ceramic fracture?
• How can we minimise this problem?
106. Origins of Fracture
• Fabrication flaws of various shapes
and sizes includes:
• Pores Micro-cracks
• Macro-cracks
• Machining grooves
• Air-abrasion surface defects
• Grinding adjustments surface
defects
• Location of the defect under tensile
stresses is important
• Thermal residual stresses
• Subcritical crack growth (SCCG)
• In humid environment, cracks grow
slowly but continuously
Weakest link
107. Early v Late Fractures
• Immediate failure or within a few hours or
days of cementation is likely to originate
from a major processing flaw
(Schmitter et al 2009, Lohbauer et al 2010)
• Failure after a few years is likely to involve
subcritical crack growth and/or cyclic
fatigue SCCG and/or cyclic fatigue
108. Most important factor affecting
fracture rates:
Position of restoration in the mouth
Ferrario et al 2004
Greatest forces
Molars > premolars > incisors (1/3-1/4 of
molars load)
111. Causes of Ceramic Substructure Failure
• Fracture initiating in the connector area
• Connector high stress area
• Chipping of the veneering material
• Residual stresses at the core-veneer
interface
• Differences in thermal conduction between
the core and veneer
• Thick veneer layer
• Poor bonding between the core and veneer
ceramic
• Sliding occlusal contacts more damaging
than axial contacts
112. Summary
• Stronger ceramics are more opaque than
aesthetic ceramics
• Aesthetic restorations without much structural
need – use single layer (monolithic) ceramics
• High strength needed, less aesthetic ceramics
veneers with tooth coloured porcelain
• Any ceramic system suitable for veneers and
anterior crowns
• Only a few ceramics successful for restoring
molars
• Need to consider other clinical factors such as
adequate preparation depth and cementation
113. Summary
• No equivalent long-term data as for PFMs
• ~75% at 15 years
• Many ceramics >90% after 5 years
• Reasonable evidence available for anterior 3-
unit FPDs in lithium disilicate, In-Ceram
Alumina and Zirconia
• Posterior 3-unit FPDs only zirconia indicated
• Chipping and fracture a problem
• Higher success when ceramics bonded to teeth
using resin cement rather than GIC
• Use a silica coating system or primers for acid resistant
ceramics such as zirconia
117. Ceramics
Slip Cast
• Build-up with core particles and fired
• High Strength
• Highly Abrasive
• Fair Marginal Fit
– In-Ceram: crowns
– In-Ceram Spinell: crowns (more translucent)
– In-Ceram Zirconia: 3 unit FPD’s
118. In Ceram
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143. All Ceramic Crowns
• Indications
– High cosmetic demand
– Incisal edge reasonably intact
– Favourable occlusion
• Advantages
– Cosmetics
– Good tissue response
– More conservative on labial
144. All Ceramic Crowns
• Contraindications
– High strength required
– Insufficient tooth structure for support
– Unfavourable occlusion
• Disadvantages
– Reduced strength
– Not conservative
– Brittle
– Single crowns only
145. Types of crowns
Full gold crown (FGC)
Porcelain fused to metal (PFM)
All ceramic
146. Affect of the Metal Coping
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147. Ceramic Crown Form 1
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148. Occlusal Considerations
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150. Tooth Preparation 1
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151. Tooth Preparation 2
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152. All-ceramics and Metal-ceramics
• The need to simulate in
dental porcelains the light
behaviour and
appearance of the natural
tooth
• Create the illusion of
nature within limited
space constraints and
light blocking effect of the
metal substructure or
ceramic substructure
Yamamoto 1985
Yamamoto 1985
158. Dimensions of the Preparation
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159. Light Transmission
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162. Preparation
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163. The image cannot be displayed. Your computer may not have enough memory to open the image, or
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164. v Visit ffofr.org for hundreds of
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