Posts Flashcards
(28 cards)
what is the purpose of a post
retain core
redistribution of forces on root, reduce fracture risk
what’s the purpose of core
provides retention for crown and cements to prosthesis
indications for post
extensive tooth structure loss
RCT
short clinical crown
generally, not molars
contraindications for post
inadequate root structure [thin, curved]
perio
mobility
root resorption
post requirements
4-5mm GP apically
post width no more than 1/3 of root
1mm circumferential dentine
at least 1/2 post length in root
minimum 1:1 post:crown length ratio
ferrule 1.5mm height and width of remaining coronal dentine
what is a ferrule
dentine collar
encirclement of 1-2mm vertical axial wall tooth structure
prevents root fracture
how to manage tooth with insufficient ferrule
ortho extrusion
crown lengthening
characteristics of an ideal post
parallel = avoids wedging, more retentive
non-threading = smooth surface, less stress
cement retained = less retentive but acts as buffer between masticatory forces and post/tooth
post materials
metal = cast gold, ss, brass, Ti
ceramic = alumina, zirconia
fibre = glass, quartz, carbon
adv and disadv of metal posts
adv =
rigid, strong
disadv =
poor aesthetics, root fracture, corrosion, nickel sensitivity
adv and disadv of ceramic posts
adv =
aesthetic, high flexural strength and fracture toughness
disadv =
weaker so thicker, root fracture, can’t be etched so not bonded to comp core, hard to retrieve
adv and disadv of fibre post
adv =
flexible, aesthetics, bonds to dentine, conservative prep, biocompatible, high bond strength, even stress distribution along post/root, reduced fracture risk, easier, reduced chair time
disadv =
cyclic loading, technique sensitive, hard in re-tx
list core materials
composite
GIC
amalgam
adv and disadv of composite core
most used
adv =
bond to dentine, crown prep same day, aesthetic
disadv =
technique sensitive
GIC core adv and disadv
adv =
bond to dentine, fluoride release
disadv =
weak, expansion via water sorption, compromises stability
amalgam core adv and disadv
adv =
easy to prepare
disadv =
destructive, doesn’t bond to dentine
what is a Nayaar core
done for posterior teeth, as posts not ideal
GP removed from root, amalgam/comp placed 2-3mm in canals and built up
done when loss of marginal ridge, small pulp chamber that won’t provide sufficient retention
cement used for fibre posts
resin
relyx or corecem
cement used for fibre posts
GIC, RMGI, resin
panavia
fibre post preparation
remove GP, leave 4-5mm apically
GG drills red->yellow->blue
etch/prime post space
place post with corecem[resin]
core build up
crown prep
cast post preparation
GG, peck 3x, 4-5mm GP apically
blue red purple
prefabricated provisional for pro temp restoration
definitive impression with impregum, post in ‘nail head’ to allow adhesion
provisional crown
cast post next visit
reasons for post failures
post fracture
core fracture
root fracture
caries
perio
RCT failure
RR
debonding
perforation
trauma
the post has fractured at the post-core junction
why
stress concentration
inadequate tooth structure/ferrule
bruxism
poor adhesion/cementation
fatigue of fibre post
inadequate core
improper post alignment
over prep of RC
improper ratio
corrosion of metal post
underprep problems
poor retention
weak bonding
risk of fracture
