Biomedical Engineering Reference
In-Depth Information
Ta b l e 3
.
24
(
Contd
)
Property
TZP material
Bending strength MPa
900-1200
Compression strength MPa
2000
Fracture toughness K
IC
7-10
11 × 10
-6
Coeficient of thermal
expansion K
-1
Thermal conductivity WmK
-1
2
Hardness HV
0.1
1200
In vitro
evaluation of the mutagenic and carcinogenic, capacity
of the high-purity zirconia ceramic conirmed that it did not elicit
such effects on the cells [25]. In 1990s, zirconium material was
used as endodontic posts [70] and as implant abutments [17]. This
heralded the use of zirconium in to dentistry. Due to its excellent
physical properties, white color, and superior biocompatibility, it is
being evaluated as an alternative framework for full coverage all-
ceramic crowns and ixed partial dentures (FPD). Dental ceramics
can be classiied according to their crystalline phase and fabrication
technique (Table 3.25). From feldspathic porcelains to zirconia-
based all-ceramics, tremendous progress has been made in terms of
mechanical performance, with a 10-fold increase in lexural strength
and fracture toughness.
Ta b l e 3
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25
Classiication of dental ceramics [32]
Fabrication technique Crystalline phase
Metal-ceramics Sintering Leucite
Heat-pressing on metal Leucite, leucite &
luorapatite
All-ceramics Sintering Leucite
Heat-pressing Leucite, lithium disilicate
Dry pressing and sintering Alumina
Slip-casting & glass
iniltration
Alumina, spinel, alumina-
zirconia (12Ce-TZP)
Soft machining & glass-
iniltration
Alumina, alumina-zirconia
(12Ce-TZP)
Soft machining & sintering Alumina, zirconia (3Y-TZP)
Soft machining, sintering &
heat-pressing
Zirconia/luorapatite-
leucite glass-ceramic
Hard machining
Sanidine, leucite
Hard machining & heat
treatment
Lithium disilicate
