Transcript Ceramics in Dentistry

Ceramics in Dentistry
Dr. Saad B. H. Farid
Department of materials engineering,
University of Technology, 10066, Baghdad, Iraq
3M ESPE
Shofu Ceramage
Esthetics and strength
VITA VM®:
NobelProcera™ Crown Alumnia
Ivoclar e.max® HT
Microstructural Classification
Composition:
1: Glass-based systems (mainly silica)
2: Glass-based systems (mainly silica) with fillers
usually crystalline (typically Lucite or a
different high-fusing glass)
3: Crystalline-based systems with glass fillers
(mainly alumina)
4: Polycrystalline solids (alumina and zirconia)
1: Glass-based Systems, Amorphous Glass
Glass-based systems are made from materials that contain mainly silica which
have various amounts of alumina.
Figure 2 Anterior porcelain veneer restoration.
Figure 1 Scanning electron micrograph of the
microstructure of a glass veneer porcelain.
Figure 3 Anterior porcelain veneer restoration.
2: Glass-based Systems with Crystalline Second
Phase, Porcelain
The glass composition is similar to the pure glass Category 1. The difference is varying
amounts of crystal types have either been added to or grown in the glassy matrix.
2.1 Low-to-moderate Lucite-containing Feldspathic glass
Figure 4 Scanning electron of the microstructure
of a Feldspathic veneer porcelain. Acid-etching
removes the glass and reveals the Lucite crystals.
Figure 5 Metal-ceramic restoration.
2.2 High Leucite (approximately 50%)-containing glass, glass-ceramics:
Figure 6 Scanning electron of the microstructure
Figure 8 Pressed ceramic restorations.
of a pressable ceramic. Leucite crystals reinforce
the glass.
Figure 7 Pressed ceramic restorations.
2.3 Lithium disilicate glass-ceramics:
Figure 11 IPS e.max restorations replacing
existing amalgams.
Figure 9: Scanning electron of the microstructure
of a lithium-disilicate glass-ceramic. Acid-etching
reveals the fine crystal structure.
Figure 10 IPS e.max restorations replacing existing
amalgams.
3: Interpenetrating Phase Ceramics
Interpenetrating phase materials are generally fabricated by first creating a
porous matrix; (alumina and magnesia matrix) or (alumina matrix) only
The pores are then filled by a second-phase material, lanthanum-aluminosilicate
glass, using capillary action to draw a liquid or molten glass into all the pores to
produce the dense interpenetrating material.
Figure 13
Figure 14
Figure 15 Spinel Crown.
Figure 12 Scanning electron of the microstructure
of In-Ceram Alumina.
4: a- Polycrystalline Solids, Alumina
Solid-sintered monophase ceramics are formed by directly sintering crystals
together without any intervening matrix to form a dense, air-free, glass-free,
polycrystalline structure. Several processing techniques allow the fabrication of
either solid-sintered aluminous oxide (alumina, Al2O3) or zirconium oxide
(ZrO2) framework.
Figure 18 Alumina
anterior crowns.
Figure 16 Scanning electron of the microstructure
of an alumina ceramic.
Figure 17 Alumina anterior crowns.
4: b- Polycrystalline Solids, Zirconia
Figure 21 Zirconia crown
tooth No. 9
Figure 19 Scanning electron of the microstructure
of a zirconia ceramic.
State of the Art
Microwave Sintering
Figure 20 Zirconia crown tooth No. 9
Classification Based on Processing Technique
in general for dentistry, they can be classified as:
1) Powder/Liquid glass-based systems; a. Conventional, b. Slip casting
2) Machinable or Pressable blocks of glass-based systems; and
3) CAD/CAM or Slurry die-processed mostly crystalline (alumina or zirconia) systems.
Figure 22 Slip casting an In-Ceram framework.
Figure 23 Scanning electron of the microstructure of a hand-layered
porcelain, a pressed crown, and a Vitabloc Mark II CAD/CAM block.
Processing techniques,
… continued
Figure 26
Diagram
of a hot
isostatic
press.
Figure 24 Milled crown.
Figure 25 Milled crown.
Processing techniques,
… continued
The Future is for
Dental Laser Technology
Types of Lasers used in Dentistry:
Gas Lasers: CO2, HeNe, Excimer, Ion Lasers
Semi Conductor – Diode Lasers: Argon Lasers
Dye Lasers: Rhodamine 6G
Solid State Lasers: Nd: YAG Lasers, Er: YAG lasers,
Er.Cr:YSGG laser, Ho: YAG laser, KTP laser
Dental Ceramics
Unreinforced porcelain
Aluminous porcelain
Cast glass ceramic
Sintered alumina core ceramic
Sintered alumina with Zirconia
Pressed glass with Lucite
Yttrium tetragonal Zirconia polycrystals
Minimum for core ceramic (ISO Standard)
Minimum for dentine/enamel ceramic (ISO
Standard)
Flexural
strength
[MPa]
70–120
120–180
100–150
400–600
800
120–180
900–1200
100
50
Classification of Dental Cements
Type (matrix bond)
Phosphate
Class of cement
Zinc phosphate
Zinc silicophosphate
Phenolate
Zinc oxide-eugenol
Polycarboxylate
Calcium hydroxide
salicylate
Zinc polycarboxylate
Glass ionomer
Resin
Acrylic
Dimethacrylate
Adhesive
Resin-modified glass ionomers Hybrid ionomers
Formulations
Zinc phosphate
Zinc phosphate fluoride
Zinc phosphate copper
oxide/salts
Zinc phosphate silver salts
Zinc silicophosphate
Zinc silicophosphate mercury
salts
Zinc oxide-eugenol
Zinc oxide-eugenol polymer
Zinc oxide-eugenol
EBA/alumina
Calcium hydroxide salicylate
Zinc polycarboxylate
Zinc polycarboxylate fluoride
Calcium aluminum
polyalkenoate
Calcium aluminum
polyalkenoatepolymethacrylate
Poly(methyl methacrylate)
Dimethacrylate unfilled
Dimethacrylate filled
4-META
Self cured Light cured
What can be learned from the Dentist?
What can be learned from the Materials researcher?
An example………
Opaquer +
Pigments
Dentin
Glaze
o Firing temperature mismatch, (950⁰C) ±30
o Thermal expansion mismatch, ≤ 0.3 ppm ⁰K-1
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Exploring the role of starting materials
Setting up the firing temperature (200 poise)
Setting up their thermal expansions
Modeling