ceramics 1&2 Flashcards
(25 cards)
dental ceramics are made of what? 4
silicate glass, porcelains, glass ceramics or highly crystalline solids
what is a negative of dental ceramics
brittleness
Properties of ceramics are dependant on what?
crystalline structure
preparation and design characteristics for dental ceramics
Rounded preparation to reduce stress
Bridges: rounded connectors with a large diameter to maximise connector area
can Glass ceramics be milled or hot pressed
can be milled and pressed into a mould
can lithium disilicate be milled or hot pressed
can be hot pressed and milled
can zirconia be milled or hot pressed
can only be milled from a solid block
zirconia comes in 3 phases: cubic, tetragonal and monoclinic based on temperature
Tetragonal is the strongest but is unstable
what is added to stabilise the tetragonal phase?
what is this called?
yttria
yttria stabilised tetragonal zirconia polycrystals -> Y-TZP
how does Y-TZP increase fracture toughness and high flexural strength or zirconia
phase transformation toughening
Crack triggers tetragonal form to transform into monoclinic form, this increases the volume (4%) blocking crack propagation
how does yttria content affect translucency of zirconia
increases translucency as more cubic phase and less tetragonal phase
can zirconia be bonded conventionally
no, only used in retentive restorations and Requires MDP for bonding - adhesive resin cement
can zirconia be etched
Cant be etched as no glass
can zirconia be sandblasted
Can be sandblasted but causes transformation toughening reducing future fracture resistance
what does monolithic ceramic mean
solid block milled into a shape
what does veneered ceramic mean
feldspathic veneered over monolithic restoration to improve aesthetics
put the following in order of flexural strength highest to lowest
monolithic lithium disilicate
veneered lithium disilicate
monolithic zirconia 3y/4y-TZP
monolithic zirconia 5y-TZP
veneered zirconia
monolithic zirconia 3y/4y-tzp
monolithic zirconia 5y-tzp
monolithic lithium disilicate
veneered lithium disilicate
veneered zirconia
put the following in order of fracture toughness highest to lowest
monolithic lithium disilicate
veneered lithium disilicate
monolithic zirconia 3y/4y-TZP
monolithic zirconia 5y-TZP
veneered zirconia
monolithic zirconia 3y/4y-tzp
monolithic lithium disilicate
monolithic zirconia
veneered lithium disilicate
veneered zirconia
put the following in order of aesthetics best to worst
monolithic lithium disilicate
veneered lithium disilicate
monolithic zirconia 3y/4y-TZP
monolithic zirconia 5y-TZP
veneered zirconia
veneered lithium disilicate
veneered zirconia
monolithic zirconia 5y-tzp/lithium disilicate
monolithic zirconia 3y/4y-tzp
group the following into strong bonding and weak bonding
monolithic lithium disilicate
veneered lithium disilicate
monolithic zirconia 3y/4y-TZP
monolithic zirconia 5y-TZP
veneered zirconia
strong bonding
monolithic lithium disilicate
veneered lithium disilicate
weak bonding
monolithic zirconia 3y/4y-TZP
monolithic zirconia 5y-TZP
veneered zirconia
what should be used instead of monolithic zirconia 5y-tzp and veneered zirconia?
lithium disilicate
what are monolithic lithium disilicate used for
single unit crowns - ant and posterior
inlays/onlays - and and posterior
bridges up to premolar
indications for veneered lithium disilicate
high aesthetic requirements
indications for monolithic zirconia 3y/4y-tzp
multiple unit bridges
bruxism
posterior bridges
implant retained bridges
posterior restorations
summary
what ceramic of choice for strength?
monolithic zirconia 3y/4y-tzp
