L3- Tx on endo teeth Flashcards
proper diagnosis and tx planning occurs?
BEFORE the RCT – this is critical
questions we ask before tx planning
- is it restorable?
how much coronal and radicular tooth structure is left?
is it periodontally sound?
what is the root morphology?
what is the condition of adjacent teeth?
s the tooth an abutment for a FPD or RPD?
main restorative options for endo treated teeth
- direct restoratino
- onlay (partial coverage restoration)
- crown (full coverage restoration)
success rates of psoterior teeth without coronal coverage
1 year– 96%
2 year – 88%
5 year – 36%
*SIGNIFICANT IMPROVEMENT CAN BE MADE IF PULPESS TEETH ARE CROWNED
purpose of the core
the objective of a core buildup is primarily to replace missing coronal tooth structure sufficiently to provide adequate retention and resistance for the crown that will eventually restore the function and the aesthetics of the tooth in the treatment
post indicated?
post is indicated where there is inadequate remaining coronal tooth structure to retain a core for an artifical crown
use post when? - general
ONLY WHEN NECESSARY
Three factors for good post
- apical seal
- proper length of post
- ferrule effect
success with post was hihest when?
with a parallel sided serrated post
effects of an adequate ferrule
- reduce ris of root fracture
- reduce risk of post fracture
- reduce ris of post and core dislodgment
- reduce failure of cement seal of artifical corwn
dimensions of ferrule
must be at least 1.5 to 2.0 mm of tooth structure apical to the core
post fractures share what similarities
all post fractures showed a smiliar pattern ot a lack of a ferrule effect of the metal collar at the CROWN MARGIN AREA AND A SHARP INTERFACE between the post and core
ways to increase the ferrule
- crown lengthening
- forced eruption
- subgingival prep
length of post related to success - general
longer posts = higher success rates
if the length of post = the length of crown – increased failure rate
25% increase in failure rate if the post was 1/4 the length of the crown
posts associated with vertically fractured enfo treated teeth
2/3 of them were a result of an extremely SHORT post terminating int the CERVICAL third of the roots
what stress increases a lot when shorter ferrule
shear stresses increased substantially as post length decreased
corwn length related to length of post in terms of force
if the crown is double the length of the post, the force of the crown is doubled in the root
ratio 1:1 to post and crown?
force is equal
if post is 1/4 lnegth of crown?
the force is multiplied by a factor of 4
saw a 25% failure rate (10 fold increase compared to 2.5 % failure rate when the length of the post = length of the crown
fracture toughness proportional to?
directly proportional to bulk
width of post?
if width of post exceeds 1/2 of the width of the root – the success rate is much lower
shape and stress in the post
if tapered post – stresses are in the cervical area
if parallel post – the stresses are more apical portions (concentrates stresses more apically)
apical seal with a post?
at least 4-5 mm of apical gutta percha MUST be retained in order to avoid reindection of the peri-apical region
ranking order of strength of core materials
- silver amalgam
- composite resin
- silver modified glass ionomer cement
materials for pre-fab post
- metal
2. fiber-reinforced
techniques for cast post and core
- indirect
2. direct
GG cutting tip?
GG - HAS NO CUTTING TIP
zinc phosphate is a?
cement
indications for prefabricated posts
multiple rooted teeth with canals that are relatively ciruclar in corss section
- molars and some pre-molars , missing 1/2 of coronal dentin
indications for prefabricated posts
multiple rooted teeth with canals that are relatively ciruclar in corss section
- molars and some pre-molars , missing 1/2 of coronal dentin
contraindications for prefab posts
large, tapered canals
small single rooted teeth like mandibular anteriors
advantages of pre fab posts
one office visit
ease of placement
less expensive to fabricate
can be made with composite
cores allowing for final impression on the same day
disadvantages to prefab posts
are best used in canals that are round
the core is retained mechanically and can disengage from the post
requires dentin removal at the apical third
para-post available in what material
stainless steel and titanium
key factors in governing the longevitiy of the restoration
the number of cavity walls and the presence of a ferrule – rather than the material used for the post
key factors in governing the longevitiy of the restoration
the number of cavity walls and the presence of a ferrule – rather than the material used for the post
general rule for location of cast posts and cores
on anterior teeth and pre-molars
prefabricated and para posts general location
posts used on molars
3 factors for proper ost and core
360 degree ferulle effect
length of post
apical seal
what dictates necessity of post
amount of tooth structure
study of sorenson and martinof showed what in terms of posts?
success was highest with parallel sided serrated post
study of torbjorner in terms of post fracture
all post fractures showed a similar pattern of a lack of ferrule effect of the metal colar at the crown margin area and a sharp interface between post and core
stress that is increased when post length is not adequate
increase in peak SHEAR stresses
advantages of csat post and core
- they are custom to fit the root configuration
2. they are adaptable to large irregulary shaped canal and orifices
disadvantages of cast post and core
- expensice
- requires two appointments
- temporization appointment is more difficult
- may require the removal of additional coronal tooth structure
advantages and disadvantages of zinc phosphate cement
long history of success
inexpensive
long working time
reaches 75% of strength in 1 hr and brittle hard within 10 minutes
disadvantage
- soluble in oral fluids
- bond is mechanical
zinc polycarboxylate is
a cement
advantages and disadvantages of zinc polycarboxylate
advantages
- chemical bond (but weak)
- inexpensive
- easy to manipulate
disadvantage
- soluble in oral fluids
- undergoes plstic deformation
glass ionmer can be used as a
cement
advantages and disdvantages of glass ionmer as cement
advantages
- chemical bond
- relatively inexpensive
- easy to manipulate
- fluoride release
disadvantage
- very soluble in oral fluids
- final set takes up to days / prolonged
advantages and disadvantages to resin modified glass ionomer cement
advantages
- chemical bond (acid from cement)/ resin bond
- fluoride release
- good compressive strength
- easy to manipulate
disadvantages
- expansion - hygroscopic
- soluble in oral fluids
advantages and disadvantages to resin cement
advantages
- bond to tooth
- high compressive strength
- essentially insoluble
disadvantage
- technique sensitive (etch canal with application of bonding agent)
- expensive
- sensitive to eugenol
- inhibition layer (cement line)
coat ___ first when using cement?
coat the post with cement first always
cementation technique
use lentulo spiral to coat the canal
direct technique
uses GC pattern resin of canal then cast it
indirect technique of cast post and core
take impression and make die – do GC pattenr resin on the cast
T/F pre-fabricated posts require removal of dentin
TRUE– in the apical third
wide divergent canal use parapost?
NO – they are best used in canals that are round
cast post used where?
anterior teeth and pre-molars
prefabricated posts used?
molars
