Post and Core Flashcards
a core restoration is also known as:
a foundation
what is the purpose of a core resoration
replace missing tooth structure prior to crown preparation
posts are also known as:
dowels
what is a dowel
a post, usually made of metal that is fitted into a prepared root canal of a natural tooth. when combined with an artificial crown or core, it provides retention and resistance for the restoration
what is the function of a post
- anchor the core material with a stable post
- restore missing tooth structure
- reinforce the tooth-restoration
which endo teeth should receive a post
- when there is not adequate tooth structure to retain a core
- most FPD and RPD abutment teeth
when is there not adequate tooth structure to retain a core
- often single rooted teeth because the anatomy of the pulp chamber does not offer mechanical retention
- teeth that have lost more than 50% of the coronal tooth structure
what materials can be used for a post
- custom post
- prefab post
what materials can a pre fab post be made of
- metal post
- fiber post
what is another name for custom posts
cast post and cores
custom posts are usually cast in ______
type III gold
custom posts are often ________ in shape
tapered and ovoid in cross section (built in anti-rotation)
custom posts rely mostly on _____ for retention
cement
what percentage of clinicians use a custom post
less than 10%
custom posts are the only option when:
the crown and post have different angulations
what are the alloys for pre fab posts made of
titanium or stainless steel
describe the shape of pre fab posts
- mostly parallel walled (greater retention) and round shaped in cross section (does not provide anti rotation)
which posts have greater versatility: pre fab or custom
pre fab
how do you begin a post treatment
use isolation prior to beginning
how do you create a post space
-gutta percha removal technique
- peeso reamers
-gates glidden drills
- hot instruments
gutta percha can be removed either:
immediately or delayed
what is the ferrule effect
a minimum of 2mm vertical axial wall circumferentially must be present
what are the types of cross section post shape
- tapered post (most custom posts)
-parallel wall post (most pre fab)
the most retention would be provided with a _____ what shape post?
parallel walled
describe anti rotation in cast posts
built in (oval in cross section)
describe anti rotation in pre fab posts
lack of anti rotation (round in cross section)
how is an amalgam core used
-cement pre fab post in the canal
- condensed amalgam around the post
critical to have access to condense amalgam _____
around the post
_______ dictates post orientation
root canal morphology
describe the retention between post retained amalgam and cast post and core
similar retention
the greatest the post length, the _______ the retention of the post
greater
a ______ can cause root fracture
short post
the post should be at least as long as:
the length of the crown
retain _______ of apical gutta percha to preserve the seal of the endo tx
4-5mm
the diameter of the post should not be greater than _______ of the tooth/root diameter
1/3
choosing a post is usually based on the optimum _______
diameter
most of the time _______ per tooth is adequate
one post
what are the fiber reinforced post materials
silica fiber
-glass fiber
- quartz fiber posts
what are the names of the fiber reinforced posts
- parapost fiber white and fiber lux
- dentflex
- luscent anchors
- fibrekor
- FRC postec
- DT light post
- aestetic plus
what is the main advantage of fiber reinforced posts
better esthetics
what is the main difference of fiber reinforced posts from metal posts
modulus of elasticity similar to dentin (however the modulus decreases over time and more critically in the presence of moisture)
what are the failures of fiber reinforced posts
- less root fractures than metal posts, fracture usually occurs in the coronal part of the post itself or debonding of the post occurs
- failure rates range from 0-32.2%
what are most of the fiber reinforced post failures from
the post becomes debonded
what is the indication for use of fiber reinforced posts
only teeth that have several dentinal walls remaining
what is the main clinical consideration for fiber reinforced posts
the majority of failures with these posts occur on teeth that have little natural tooth structure remaining
describe ceramic posts
- good esthetics
- very rigid (high modulus of elasticity)
- high rates of root fracture
what are posts cemented with
- zinc phosphate cement
- resin cements
- glass ionomer cements
- modified resin glass ionomer cements
canal should be cleaned with_____ prior to post cementation
phosphoric acid
what is the step by step clinical procedure for post tx
- isolate the tooth with rubber dam
- remove GP (use peeso reamer #2, #3. avoid #5 and #6), evaluate with radiographs periodically for angulation and length (post should be as long as possible and retain 4-5mm apical GP)
- post diameter should not exceed 1/3 root diameter
- for prefab posts the final drill should be the drill that corresponds with the correct post diameter
- for prefab posts the length should be adjusted so that the head of the post is at the top of the core
- cement post (for prefab posts remove cement from most coronal part of canal to allow core material to help with anti rotation)
- 2mm ferrule (natural tooth structural) circumferentially is critical for longevity regardless of post used
amalgam is condensed into:
the pulp chamber and 2-3mm into the pulp canal
if the pulp chamber is 4mm in height:
sufficient retention from pulp chamber alone
amalgam radicular core benefits:
reduced number of visits/reduces cost
endo access results in:
reduced tooth fracture
what other factors affect strength
- previous/existing caries/restorations
- amount of root surrounded by alveolar bone
when do crowns on endo treated teeth not improve success rates
anterior teeth
when do crowns of endo treated teeth improve success rates
in posterior teeth
endo treated teeth without crowns lost at _____ the rate of those with crowns
6 times
teeth with 2 proximal contacts had ______ survival than teeth with 1 or no proximal contacts
significantly longer
2nd molars showed _______ compared to all other teeth
significantly reduced longevity
