L4 - FPD's Flashcards
retention will be
retainer vs pontic
is silver a noble metal?
NO
List the nobel metals
1-7 Au - gold Pt - platinum Pd - palladium Rh - rhodium Ru - ruthenium Ir - iridium Os - osmium
material with the highest density
gold
describe metal-resin
metal framewor with resin retention by macro, micro, and chemical
limited esthetic and durability
thermal epansion coefficient - general
want these to be equal between materials if using two different ones
example of metal - ceramic
the feldspathic porcelain
two failures of porcelain bond in PFM’s
which is more prelevant?
- cohesive
- adhesive
adhesive - have to remake whole thing
tooth abutment considerations with premolars
anatomy may be less ideal
more posterior – general consideration
shorter teeth and smaller opening
more posterior – general consideration
shorter teeth and smaller opening
three things that go into treatment planning considerations
- resistance form
- retention form
- ferrule effect
three things that go into treatment planning considerations
- resistance form
- retention form
- ferrule effect
definition of ferrule
band or ring used to encompass the root or crown of a tooth
any short tube or bushing for maing a tight joing
treatment considerations for connectors
- require sufficient thickness – height
- may require occlusal and gingival metal surface
- may require apical repositioning surgery of pontic area
pontic designs
- ridge lap
- modified ridge lap
- ovate – hard to do but esthetic
pontic design that is not hygeinc
ridge lip – like never use this one
if have an insufficient gingival embrassure – use?
all metal - connector
if have an insufficient gingival embrassure – use?
all metal - connector
if do not have enough room here then will irritate the tissues in that area
maintenance considerations with FPD’s
floss and proximal brushes
maintenance considerations with FPD’s
floss and proximal brushes
elements used in all ceramic FPD’s
lithium
zirconium
silicon
dopant
contraction of doping agent
an element incorporated into a dental material to alter its mechanical properties, for example yttriea incorporated in a small amount into zirconia, resulting in stabalization
phase transformation toughening
zirconia micro structure change arrangment to beocme more resistance to crack propagation - slows down the crack but does not stop it
goes from TETRAGONAL PHASE TO MONOCLINIC PHASE – this transformation does not prevent crack but prevent from spreading
phase transformation toughening
zirconia micro structure change arrangment to beocme more resistance to crac propagation - slows down the crack but does not stop it
layered zirconia
can have core of zirconia and can put ceramic on the top
layered zirconia
can have core of zirconia and can put ceramic on the top
cementation layer thickness
20-50 microns
um
no more than ___ for veneering porcelain
no more than 2 mm
examples of metal -ceramic
high noble, noble, base
examples of all-ceramic
alumnious oxide, lithium dislicate, zirconia
all polymer examples
fiberkor, fiber glass
noble are
Au, Pt, Pd, Rh, Ru, Ir, Os
high noble vs noble vs base
high nobel - 60% nobel or greater than 40% gold
nobel is 25 % noble (<40% gold / Au)
base less than 25 % noble
meaning % of weight of Au, Pt, and or Pd comp
characteristics of all metal - gold
high density
cast in gypsum investment
thin castings, beveled tooth prep margins
partial crown retainers
metling of gold
1550-1700 F (850-925 C)
partial crown retainers?
materials like gold are good because conserve tooth structure and allow for supra gingival preps
*more advanced prepping - grooves and boxes needed
metal ceramic aka
feldspathic porcelain
high fusing temp - 90-980
low fusin 750-770 C
veneering porcelain
must have opalescence and translucency
stimualte natural teeth
need coefficient of thermal expansion to be simialr as possible
must not abrade opposing
less then 2mm thicjness (average 1.2 -1.5 mm)
breakdown of porcelain bond
chemical and physical
failure with cohesive and adhesive is possible
failure of porcelain bond
adhesive – metal can be exposed
cohesive – fracture - ceramic chips off
metal ceramic abutment tooth prep details - include requirement of reduction
functional cusp reduction 1.5- 2 mm
cervical reduction - 1.5mm
lingual reduction - 1 mm
must break interproximal contact
biplanar buccal reduction
minimum thickness for alloy in metal ceramic design
0.3-0.5 mm
use a chamfer prep
what to consider in molars when looking for abutments
2nd and 3rd molar roots may be too tapered
molar root proximity creates difficulty for preparation, impression, maintenance
antes law
the abutment should have total periocemental area - PDL equal or greater than the area of replacement teeth
span deflection details
1 unit of deflection is 8x greater if ditance is 2 units
and 27 x greater if distance is 3 units
pontic with worst esthetics
ridge lap
for three unit posterior - consenus on material choice
zirconia- based systems are indicated ; chippping of veneering ceraic on zirconia restorations remains an issue
pressed on zirconia ceramics
technique designed to produce a deired form by injecting a molten homogenoius ceramic material into a mold containing a zirconia framework that may be veneered with porcelain
ideal thickness of the adhesive layer
20-50 um
multi-link
what we use to bond - like with emax crowns
rely-x
what we use to cement - like with zirconia
effect of the cement interface
critical load to radial fracture rises as the adhesive elastic modulus increases but drops for thicker cement layers
want thinner cement / but adequate when possible
fracture in the connector area?
usually starts at the gingival embrassure of the connector
do NOT adjust the gingival side of the connector after ceramming
if zirconia going to fail in FPD likely due to
biologic and technical complications other than the framework fracture
common reason for failure with FPD’s made of glass ceramics or glass infiltrated ceramics
fracture of the reconstruction (framework and veneering ceramic)
porcelain thickness in metal - ceramic
1.5-2.0 mm with metal support
metal ceramic surface degrees?
at least 90 degrees
occlusal contacts with metal ceramic
occlusal contacts 1.5 mm away from metal ceramic junction
lingual supporting collar?
in a metal- ceramic it is at the HOC - height of contour
metal - ceramic deign thickness
less then 2mm
mutually protected occlusion
anterior teeth protect the posterior teeth by disclusoin during excursions and preventing lateral impact force vectors
while the posterior teeth protect the anterior teeth by providing stable maximal intercuspal position at occlual vertical dimension
in diagnosis and tx plan what do you need to assess
smile line, phonetics, anatomy, midline, vertical overlap, horizontal overlap, anterior guidance
do wax up!
- mock up and interim FPD
tetragonal and cubic temps
tetragonal – above 1170
cubic – above 2370b
zirconia require?
sintering after milling and is not as dimensionally stable as hot isostatically pressed zirconia which doesnt need sintering
monolithic at ? tetragonal at?
monolithic = room temp
tetragonal - above 1170
what is lithium dislicate
classified as a glass-ceramic, in the class of particle filled glass materials
materials that can be used for veneers
intra-coronal resotrations and crowns for anterior teeth
effective material for anteiror 3 unit FPD’s
evidience shown effectiveness in lithium dislicate, alumina, and zirconia
3 units involving a molar material to use?
research suggests that only zirconia based systems are indicated
as chipping of veneering ceramic on zirconia restorations remains an issue
T/F there is evidence to support the universal application of a single ceramic material and system for all clinical situations
FALSE
– no one material good for every place
internal stresses in veneering porcelain?
low thermo conductivity –which can lead to internal stresses in the veneering porcelain (rate of cooling)
chipping relationship to venner thickness
if veneer thickness greater than core thickness than two-fold greater the chipping
so Zr-oxide core needs to support the veneering porcelain
adhesive resin
any resin material with incorporated adhesive chemical such as MDP, an organophosphate, or 4-META ad related carboxyl - modified acrylic resins
1.5 mm thick ceramic on dentin? in terms of adhesive layer thickness
10 um adhesive layer has a critical load of about 80% of its theoretical value
a 100 um thic adhesive layer has a 50% critical load of its theoretical value
higher fracture loads related to?
thinner cement film thickness
zirconia modifications for adhesive resins
for practical purposes - ZIRCONIA DOES NOT BOND
- but experiments looking into things like plasma sprayed – 3x increased bonding and micro pearls of low fusing porcelain - can increase bonding
do not adust ____ of connector ____ ceramming
do not adjust the GINGIVAL SIDE of the connector AFTER ceramming
minimum dimension for an anterior 3 unit all ceramic FPD in terms of incisal cervical and buccal - lingual
3mm for I-C and 2 mm in B-L
increasing the gingival embrassure can increase the fracture resistance
