dental ceramics processing classification types of bonding bond failures strengthening of ceramics recent advances in ceramics

1. DENTAL CERAMICS
DR. SHIVA SAI VEMULA
DEPARTMENT OF
PROSTHODONTICS
1

2. CONTENTS
• Introduction
• Composition
• Manufacture of ceramics
• Classification
• Application
• Classification
• Properties
• Processing
– Wax coping methods
– Removal of oxide layer
– Assembling into cramic crowns
– Method of porcelain cndensation
– Stages of firing
– Bonding and bond failures in
PFM 2
• Strengthening of ceramics
• Recent advancements
• References

3. • The materials used for the reconstruction of decayed,
damaged or missing teeth are :–Metals, Polymers, Ceramics
( major), Composites
INTRODUCTIONN
• ETHYMOLOGY: ‘KERAMOS’(GREEK) - ‘BURNT STUFF Also called
dental porcelain.
• Porcelain – MARCOPOLO from ‘Porcellana, or cowrie shell’.
• In 18th century RICHMOND- 1st metal ceramic crown
• Ceramic – combination of metals and non metals.
3
• “The attractions of ceramics lie partly in its contradictions.”

4. • DEFINITION :
DENTALCERAMIC (Anusavice):-
• A specially formulated ceramic material that exhibits
adequate strength, durability and color that is used
intraorally to restore anatomic form and function, and/or
esthetics.
4

5. Glass
Modifiers
2-7%
Metallic
oxides
9-15%
Feldspar
60-80%
Silica
15-25%
Feldspathic
porcelain
COMPOSITION
5
Kaolin
3-5%

6. LIQUID/
DISTILLED WATER
PORCELAIN
POWDER
PLASTIC MASS
FIRING IN
FURNACE
QUENCHING
GROUND TO
FINE
POWDER
FRITTING
MANUFACTURE OF CERAMICS
6

7. CRYSTALLINE NON CRYSTALLINE
QUARTZ CRYSTOBALLITE
FUSED
SILICA
TRIDYMITE
SILICA
DISSEMBLING THE CERAMICS
7

8. BALANCE
HIGHER
LOWER
DECREASED
STRENGTH
LESS DURABILITY
DEVITRIFICATION
GLASS MODIFIERS
HIGH
FUSION
TEMP
Si
O
O
O
Si
O O
OXIDES OF Na,K,Ca.
8

9. FELDSPAR WITH METAL
OXIDES WATER
FIRED
GLASS
PHASE
LEUCITE
PARTICLES
COALESCE
INCONGRUENT
MELTING
LIQUID PHASE
SINTERING
FELDSPAR
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10. • Flux
• Viscosity
• Forms a separate
lattice & interrupt
more rigid silica.
BORIC OXIDE KAOLIN
•BINDER
COLOUR PIGMENTS
PIGMENT COLOUR
COPPER OXIDE GREEN
TITANIUM OXIDE YELLOW
MANGANESE
OXIDE
LAVENDER
COBALT OXIDE BLUE
IRON OXIDE BROWN
10

11. • Inlays and onlays
• Esthetic laminates over natural teeth
• Single crowns
• Short span (all ceramic) bridges
• As veneer for cast metal crowns and bridges
• Artificial denture teeth
• Ceramic orthodontic brackets
APPLICATIONS
11

12. CLASSIFICATION
ACCORDING TO THE FUSION TEMPERATURE
12
1.

13. 13
2.

14. BASED ON ITS USE
• Core ceramic
• Margin ceramic
• Opaque dentin (also body or
gingival) ceramic
• Enamel (incisal) ceramic
• Stain ceramic
• Glaze ceramic
Difference in fusion
temperature
BASED ON TRANSLUCENCY
• Opaque
• Translucent and
• Transparent
14
3.
4.

15. BASED ON THE
CRYSTALPHASE/MATRIX PHASE
• Feldspathic porcelain
• Leucite reinforced
• Aluminous porcelain
• Alumina
• Glass infiltrated porcelain
• Glass infiltrated alumina porcelain
• Glass ceramics
• Glass infused alumina/zirconia
• CAD – CAM Ceramics
15
5.

16. BASED ON THE PROCESSING
METHODS
• Condensation and sinteting
• Pressure molding and
sintering
• Casting and ceramming
• Slip casting
• Sintering and glass infiltration
• Machining
16
6. 7.BASED ON TYPE OF FIRING
• Air fired porcelain
• Vacuum fired porcelain
• Diffusible gas firing.

17. PROPERTIES
General properties
Chemical properties
Thermal properties
Dimensional properties
Mechanical properties
• COTE – 12 x 10-6/ o C
• Thermal conductivity-
0.0030
• Insulator
• Good
Biocompatibility
• Inertness
• Excellent Aesthetics
• Low Solubility
• Unaffected by pH
varaitions
• Resistant to chemicals and
solvents.
• Volumetric shrinkage: 30 -40%
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18. MECHANICAL AND PHYSICAL PROPERTIES
• Compressive strength : 330 Mpa – High
• Tensile strength : 34Mpa – Low
• Transverse strength : 62 to 90 Mpa
• Shear strength : 110 Mpa – low - Brittle nature, lack of ductility
• Surface hardness : 460 KHN – High abrasion resistance
• Super cooled liquids
• No deformation under stress, instead develops cracks.
18

19. METAL CERAMICS
METAL CORE
• Good corrosion resistance.
• Melting temp less than that of
veneered ceramic.
• High modulus of elasticity
• COTE similar to porcelain
• Should not discolor porcelain
• Allow good wetting of
porcelain
• Fusion temp less than the
melting temp of alloys
• Compatible COTE
• Low contact angles – good
wetting
CERAMIC VENEERING
19

20. WAX PATTERN FABRICATION
1. DIPPING
MEHTOD.
2.PLASTIC SHELL
TECHNIQUE.
3.CUT BACK
METHOD
20

21. CUT BACK METHOD.
• Thickness should be
measured with rounded tip
IWANSON PATTERN GAUSE
• It should be from 0.3-0.5
21

22. Spacer disk over
coping disk
Arranged in wire
holding frame
Holder is placed over
flame
Press the die forcefully
against the softened disks
Till the finish line Cut unadapted skirt of disk with iris scissor 1mm short and filled with wax
22

23. Removing the oxide layer for PFM
Acid treatment
(chemical method)
Hydrofluoric
Hydrochloric
Dilute sulfuric acid.
(10-15 min)
Nonacid treatment
(mechanical method)
Sand blasting
23

24. ASSEMBLING INTO CERAMIC CROWNS
PORCELAIN
POWDER
LIQUID
PLASTIC
MASS
ADAPTATION ON
PREPARED TOOTH FIRING
COOLING
STAINING
GLAZING
CONDENSATION
CERAMIC
CROWN
24

25. CONDENSATION
• Vibration
• Spatulation
• Brush technique or capillary action
• Whipping
• Ultrasonic condensation
PROPER CONDENSATION
• Greater compaction
• Decreased voids
• Decreased shrinkage
• Regular contraction
MANUAL CONDENSATION
25

26. Methods of porcelain condensation.
1.Capillary action:-
The technique of blotting a wet built up
with absorbent paper uses surface
tension.
2.Vibration:-
Is created by passing a serrated
instrument over the neck of a hemostat in
which the restoration is held.
3.Spatulation:- A spatula is used to
apply , then rub the porcelain built up to
force the liquid to the surface.
4.Whipping:-
A no. 10 sable brush is rapidly moved over
the porcelain surface with a whipping
motion. The whipping motion brings the
liquid to the outer surface for blotting.
5.Dry powder addition:- Requires dry
porcelain powder be sprinkled on an
area of wet porcelain, using the existing
liquid to moisten the powder addition
26

27. OPAQUE MAJOR FUNCTIONS
establish the
porcelain-metal
bond
mask the dark
color of the metal
substructure
development of
the selected shade
of porcelain
BODY MODIFIERS :-
• They are used to distinguish the dentin, enamel & translucent
porcelains.
• All these powders are basically same materials & have the same
basic physical & chemical properties, they do differ in the appearance
because of the modifiers
GLAZES :-
Glazes are generally colorless, low fusing porcelains. 27

28. STAGES OF FIRING
28

29. CHEMICAL BONDING
• Primary mechanism
• Oxide layer between metal and ceramic
• surface oxides dissolve from metal and dissolved by, the
opaque layer (chemisorpition) & atomic contact with the
metal surface for enhanced wetting and direct chemical
bonding so metal and porcelain share electrons
MECHANICAL BONDING
• Irregular metal surface
• Ceramic flow into irregularities
• SANDBLASTING
COMPRESSION BONDING
• Mismatch in COTE between metal
and ceramic
Metal Ceramic Bond
COVALENT BONDING
• Mutual exchange of electrons between
the metal and ceramic 29

30. BOND FAILURE
30

31. A Shift to Metal –Metal free ceramic
DRAW BACKS
TENSILE
STRENGTH
ELASTIC
DEFORMATION
31

32. STRENGTHENING OF
CERAMICS
REDUCTION OF
CRACK
INTERRUPT CRACK
PROPAGATION
DESIGN
MODIFICATION
DEVELOPMENT
OF COMPRESSIVE
STRESSES
CHEMICAL
TEMPERING
THERMAL
TEMPERING
COTE
MISMATCH
DISPERSION OF
CRYSTALLINE
PHASE
TRANSFORMATION
TOUGHENING
GLAZING
32

33. PATTERN AND PROPAGATION OF CRACK

34. DEVELOPMENT OF RESIDUAL COMPRESSIVE
STRESSES
Bending forces
Tensile forces
34

35. CHEMICAL TEMPERING
Sodium is replaced with potassium
Immersed in kno3 salt bath at 400
degrees for 4 hours .
K ions 35% larger than sodium.
35

36. THERMAL TEMPERING
THERMAL COMPATIBILITY/
COTE MISMATCH
HEATED PORCELAIN
QUENCHED
OUTER LAYER COOLS
RAPIDLY PRODUCING
RIGID SKIN
INNER CORE COOLS SLOWLY
DEVELOPING STRESSES
METAL(SHRINKS
MORE)
CERAMIC (SHRINKS
LESS)
36

37. AUTO GLAZE ADD ON GLAZE
 Low fusion temp
 EquaL COTE
 Selective heating
 More durable
GLAZING
37

38. DISPERSION OF
CRYSTALLINE PHASE
Al2O3
ALUMINOUS
PORCELAIN
Alumina is added which is strong.
INTERRUPTION OF CRACK PROPAGATION
38

39. TRANSFORMATION
TOUGHENING
Stress
Unstable
tetragonal
Stable
monoclinic
ZIRCONIA BASED
CERAMICS
39

40. DESIGN
MODIFICATION
Stress concentration at
sharp angles.
Marked changes in
thickness.
Metal ceramic restoration
helps in achieving it.
Abrupt changes in shape/
thickness in ceramic
Creases/folds of platinum
foil
Small particle of porcelain
along internal margin
MINIMISE TENSILE
STRESSES
REDUCING STRESS
RAISERS
40

41. METAL FREE CERAMICS
EXCEPTIONAL ESTHETICS WITH ENHANCED
MECHANICAL PROPERTIES 41

42. Reinforced
core ceramics
Resin
bonded
Metal
ceramics
Particle filled
glass ceramics
Predominantly
glass based
ceramics
Polycrystalline
ceramics
Conventional
sintered ceramics
Castable
ceramics
Slip cast
ceramics
Machinable
ceramics
Pressable
ceramics
RECENT ADVANCES IN
CERAMICS
-CAD CAM
-Copy Milling
-Alumina
based
-Leucite based
-Spinel based
-Mica based
-HA based
-Lithia based
-Leucite
reinforced
-Alumina based
-Magnesia based
Improvements in
sub structure
Improvements in
composition
Improvements in processing
techniques
42

43. Recent Advances With Improvement In Substructure
Resin bonded ceramics :
These types of ceramics are
directly bonded to the tooth
and hence becomes the
integral part of the tooth
Metal ceramics
• Improved marginal fit
eg:CAPTEK system
43

44. REINFORCED CORE CERAMICS
• Veneered ceramic is reinforced by another ceramic material.
Alumina Reinforced Ceramics
44

45. Predominantly Glass
Ips Empress
Optec
Polycrystalline Ceramics
Porcera
Lava
Particle Filled
Empress 2
Recent Advances With Improvements In Composition
45

46. Sintered Ceramics
OPTEC HSP
MIRAGE II
Recent Advances With Improvements In PROCESSING
TECHNIQUES
46

47. Pressable Ceramics
IPIPS EMPRESS 2
OPC 3G
FINESSE PRESSABLE
Castable Ceramics
DICOR
CERAPEARL
47

48. IN CERAM SPINELL
INCERAM ALUMINA
IN CERAM ZIRCONIA
SLIP CAST
CERAMICS
48

49. MACHINABLE : CAD – CAM –THE SAME DAY DENTISTRY
CAD-CAM steps CAD-CAM system
DATA ACQUISITION Optical modeling, laser scanning, CT, MRI, digital
photographs
DATA PROCESSING Digital data is process to obtain a CAD model
MODEL FABRICATION Rapid prototyping, CNC milling
CAD
CAM
49

50. EXAMPLES :CAM OF FULLY SINTERED :CEREC,BRUXZIR
CAM OF PARTIALLY SINTERED : CERCON,LAVA,EMAX
50

51. COPY MILLING
WORK-FLOW
51

52. IMPORTANT PROPERTIES OF ALL – CERAMIC CROWNS
52

53. REVIEW OF LITERATURE
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Nayana Paul et.al.(2020)
Compared the marginal and internal fit of single unit
monolithic zirconia crowns fabricated by CAD/CAM
technique and metal-ceramic crowns fabricated by
conventional technique.
They concluded that the CAD/CAM fabricated zirconia
crowns demonstrated a better accuracy of fit when
compared to metal-ceramic.
Paul N, Swamy KR, Dhakshaini MR, Sowmya S, Ravi MB. Marginal and internal fit evaluation of
conventional metal-ceramic versus zirconia CAD/CAM crowns. Journal of clinical and experimental
dentistry. 2020 Jan;12(1):e31.
53

54. REFERENCES:
• Anusavice KJ, Shen C, Rawls HR, editors. Phillips' science of dental materials.
Elsevier Health Sciences; 2012 Sep 27.
• Babu PJ, Alla RK, Alluri VR, Datla SR, Konakanchi A. Dental ceramics: Part I–An
overview of composition, structure and properties. Am J Mater Eng Technol.
2015;3(1):13-8.
• Datla SR, Alla RK, Alluri VR, Babu JP, Konakanchi A. Dental ceramics: Part II-Recent
advances in dental ceramics. Am J Mater Eng Technol. 2015;3(2):19-26.
• Srividya S, Nair CK, Shetty JM. Recent advances in ceramics. Trends in
Prosthodontics and Dental Implantology. 2010 Dec 24;1(2):38-44.
• Kwon SJ, Lawson NC, McLaren EE, Nejat AH, Burgess JO. Comparison of the
mechanical properties of translucent zirconia and lithium disilicate. The Journal of
prosthetic dentistry. 2018 Jul 1;120(1):132-7.
• Vianna ALSV, Prado CJD, Bicalho AA, Pereira RADS, Neves FDD, Soares CJ. Effect of
cavity preparation design and ceramic type on the stress distribution, strain and fracture
resistance of CAD/CAM onlays in molars. J Appl Oral Sci. 2018;26:e20180004.
54

55. • Paul N, Swamy KR, Dhakshaini MR, Sowmya S, Ravi MB. Marginal and internal fit
evaluation of conventional metal-ceramic versus zirconia CAD/CAM crowns. Journal of
clinical and experimental dentistry. 2020 Jan;12(1):e31
• Reddy NR, Padmaja BI, Devi G, Priya GK, Bindu GH, Babu NS. The effect of
commonly consumed beverages on colour stability and surface roughness of two
metal ceramic materials: An in-vitro study. Journal of Dr. NTR University of Health
Sciences. 2018 Jan 1;7(1):31.
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56. 56
• Ceramics have a great past in dentistry. Their
biocompatibility and excellent esthetics have
positioned them in the high-end segment of
restorative dentistry. The future of ceramics is
even greater since manufacturing technology and
materials which also means that newer
compounds, precisely engineered to function will
be developed
CONCLUSION

57. THANK YOU
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