Post and core

Prosthodontic Management
Of Endodontically Restored
Teeth
Presented by
Dr R Padmini Rani
2nd year P.G
Department of prosthodontics
KIDS

CONTENTS
• INTRODUCTION
• HISTORIC BACKGROUND
• CHARACTERISTICS OF ENDODONTICALLY TREATED TEETH
• DIAGNOSIS AND TREATMENTPLANNING
• DEFINITION
• INDICATIONS FOR POST AND CORE
• PRINCIPLES OF POST AND CORE

• METHODOLOGY
•Post selection
•Removal of endodontic filling
•Post space preparation
•Preparation of coronal structure
•Post fabrication
•Core fabrication
•Temporization
•Try-in & cementation
• FAILURES IN POST AND CORE
• POST REMOVALTECHNIQUES
• CONCLUSION
• REFERENCES

INTRODUCTION
• Endodontic treatment is largely performed on teeth significantly
affected by caries, multiple repeat restorations and/or fracture.
• Already structurally weakened, such teeth are often further weakened by the
endodontic procedures designed to provide optimal access and by the restorative
procedures necessary to rebuild the tooth.
• Hence it is accepted that these teeth tend to have a lower lifetime prognosis.

• They require special considerations for the final restoration, particularly where
there has been extensive loss of tooth structure.
• The special needs involve ensuring both adequate retention for the final
restoration and maximum resistance to tooth fracture, which can be
collectively termed as anchorage
• Ensuring optimal anchorage while maintaining adequate root strength for the
particular clinical situation can be challenging and the problems encountered
have resulted in the development of many different materials and techniques.

•
As early as 1728, Pierre Fauchard
described the use of “tenons,” which were
metal posts screwed into the roots of teeth
to retain bridges.
• In the mid-1800s, wood replaced metal as the post material,
and the “pivot crown,” a wooden post fitted to an artificial
crown and to the canal of the root, was popular among
dentists.
Often, these wooden posts would absorb fluids
and expand, frequently causing root fractures
• In 1869 Black introduced the metal posts in
which a porcelain-faced crown was secured
by a screw passing into a gold-lined root
canal.
HISTORICAL PERSPECTIVE

Clark in the mid-1800s developed a device
that was extremely practical for its time
because it included a tube that allowed
drainage from the apical area or the canal
(Prothero JH; 1921).
• The Richmond crown was introduced in 1878
and incorporated a threaded tube in the canal
with screw retained crown.

It was later modified to eliminate the threaded tube
and was redesigned as a 1-piece dowel and crown
(Hampson EL et al; 1958, and Demas NC et al;
1957), which lost its popularity quickly because
they were not practical.
During the 1930s, the custom cast post-and-core was developed
to replace the one-piece post crowns.
This procedure required casting a post-and-core as a separate
component from the crown.
This 2-step technique improved marginal adaptation and allowed
for a variation in the path of insertion of the crown.

Changes occurring in an endodontically
treated teeth
• The loss of tooth structure from caries, trauma or both
• The moisture content of dentine from ET teeth is reported to be about
9% less than teeth with vital pulp (GV Black, Helfer et al ).
• But this was contradicted by Huang et al who reported that neither
dehydration , nor endodontic treatment – caused any degradation of
physical or mechanical properties of dentin .

• The dentine undergoes changes in the collagen cross linking
• Loss of structural integrity of tooth due to access preparation which may
increase cuspal deflection during function
• Loss of proprioception
• Alteration in the light refraction of dentin as well as discolouration of tooth
due to the ill effects of microbial action, endodontic irrigants and
medicaments, old restorations on dentine

Diagnosis and treatment
planning

Endodontic Considerations
1. Good apical seal
2. No sensitivity to pressure
3. No exudate
4. No fistula
5. No apical sensitivity
6. No active inflammation
7. Retreatment should occur if there are
signs or symptoms indicating failure
Periodontal Considerations
1. Extent of underlying periodontal
disease
2. Adequate biologic width
3. In cases with extensive coronal destruction
crown lengthening can be considered
4. Presence of enough coronal tooth
structure to incorporate ferrule into cast
restoration

Prosthetic Considerations
1. Extent of coronal destruction
2.Tooth type (anterior vs. posterior)
3.Position in arch, Morphology, Circumference of tooth, Occlusal and prosthetic forces applied
to tooth, Periodontal support
Esthetic consideration
•Thin gingiva may transmit a dark shadow of the root through the tissue
•Metal or dark carbon fiber placed in the canal can result in unacceptable gingival discoloration
from the underlying root
•Endodontic and restorative materials in these esthetically critical cases must be
selected so as to provide the best health service with the minimum of esthetic compromise

DEFINATIONOFPOSTANDCORE
o A one-piece foundation restoration
for an endodontically treated tooth
that comprises a post within the
root canal and a core replacing missing
coronal structure to form the tooth
preparation (GPT 9)

ANTERIOR TEETH
• Anterior teeth with minimal loss of tooth structure
may be restored conservatively with a bonded
restoration in the access opening
• A post and core is only indicated when the tooth is
weakened by the presence of large or multiple
coronal restorations, presence of undermined
marginal ridges, or if they require form/colour that
cannot be achieved by bleaching
• Mandibular incisors and maxillary
incisors .
• Abutments for FPD and RPD

POSTERIOR TEETH
A) MOLAR
• Endodontically treated molar teeth should receive cuspal
coverage, but in most cases, do not require a post
• Posts are indicated in molars when large percentage of
coronal structure is missing and teeth are at high risk of
fracture
• If posts are required, they should be placed only in the
largest and straightest canals--upper palatal and lower
distal.
• INTERNATIONAL DENTAL JOURNAL OF STUDENT’S RESEARCH| Feb
2013 Volume 1

B) PRE MOLAR
• Premolars are usually bulkier than anterior teeth,
but often are single-rooted teeth with relatively small
pulp chambers and are more likely than molars to be
subjected to lateral forces during mastication. For
these reasons, they require posts more often than
molars.
•A post may be indicated if a premolar will function as
an abutment for an RPD or suffers from an attachment
loss
• The canal anatomy of premolars is delicate and in
order to succeed, the post system chosen must
require minimal reshaping and enlargement of the
canal space.

PRINCIPLES FOR POST AND CORE
1) Preservation of tooth structure
a) Preparation of the canal
b) Preparation of the coronal tissue
2) Retention
3) Resistance

1) PRESERVATION OF TOOTH
1) Preparation of the canal
RULE :1. Remove only the minimal tooth
Structure
2. Excessive enlargement results in:
a. Perforation or weakening of root
b. Splitting during cementation of post or
in function
3. Make post fit into the tooth and not the
tooth fit into the post!

b) Preparation of coronal tissue: 1.Conserve as much of tooth structure
as possible
2. Amount of remaining tooth structure
is probably the single most important
predictor of clinical success
3. More than 2mm – post design plays
little role in the fracture resistance of
the restored tooth
4. Less than 2mm – crown lengthening
is indicated

2) RETENTION:
Post retention refers to the ability of a post to resist vertical dislodging forces.
Retention is influenced by the
 Canal shape & preparation of canal space
 post’s length
 Post diameter and taper
 post design
 Tooth location in the dental arch
 the luting agent and luting method

3) RESISTANCE
• Resistance refers to the ability of the post and tooth to withstand
lateral and rotational forces.
It is influenced by the
o remaining toothstructure
o the post’s length and rigidity
o the presence of antirotation features
o the presence of aferrule.

• In areas where coronal dentin has
been completely lost, a small
groove placed in the canal can
serve as an anti rotational element.
• The groove is normally located
where the root is bulkiest, usually
on the lingual aspect

THE FERRULE EFFECT:
• A ferrule is defined as a vertical band of tooth structure at the gingival aspect of
a crown preparation.
•
The ferrule should be a minimum of 1 – 2 mm high, have parallel axial walls,
completely encircle the tooth, end on sound tooth structure and not invade the
attachment apparatus of the tooth.

• Core ferrule – part of a cast metal core
For cast post & core a contrabevel is given. Collar of metal that
encircles the tooth and serves as a secondary ferrule – independent of
crown ferrule .
• Crown ferrule – the ferrule created by the overlying crown engaging the
tooth structure.
the ferrule must encircle a vertical wall of sound tooth structure above the margin
and must not terminate on restorative material.

In those clinical situations where there is
insufficient ferrule length, even where margins
are placed subgingivally,surgical crown
lengthening or orthodontic excrusion may be
done
.

Ferrule increases the mechanical resistance of a post/core/crown restoration by
reducing the potential for displacement (labial and axial rotation) and compressive stresses
within labial dentine and the canal wall.

Consequences of Inadequate Ferrule
 Catastrophic root fracture
 Cement failure and post loosening
 Post fracture

Methodology
1. Post selection
2. Removal of endodontic filling
3. Post space preparation
4. Preparation of coronal structure
5. Post fabrication
6. Core fabrication
7. Temporization
8. Try in and cementation

6. Torquing force
7. Stresses
8. Development of hydrostatic pressure
9.Post design
10. Post material
11. Material compatibility
12. Bonding capability
5. Amount of coronal tooth structure
13. Core retention
14. Retrievability
15. Esthetics
16. Crown material
1)POST SELECTION
FACTORS
1.Root length
2. Tooth anatomy
3. Post width
4. Canal configuration

ROOT LENGTH
oDetermines length of post
o Greater the post length, better the retention and
stress distribution
o 3-5 mm of GP in the apical region to maintain apical
seal
o Parallel sided threaded post or Reinforced composite
luting agents can compensate for reduced post
length
o For short rooted molars more than one post will
provide additional retention for core

TOOTH ANATOMY
Root anatomy such as root curvature, mesio- distal
width, and labio-lingual dimension, canal structure,
proximal root concavities, anatomic variation - all these
factors should be considered inorder to avoid any risk of
apical or lateral perforation
o Gutmann (1992) reviewed the anatomic considerations and stated
that roots of maxillary centrals and laterals, and also mandibular
premolars have sufficient bulk to accommodate most post
systems.

POST WIDTH
• Post width must be controlled to
preserve radicular dentin
reduce the potential for
perforations
permit the tooth to resist fracture.
Stern and Hirshfeld (1973) proportionist approach
suggest the post width should not be greater than one third
of the root width at its narrowest dimension.
Halle EB et al ( 1984) preservationist approach suggest
that the post should be surrounded by a minimum of 1
mm of sound dentin.
Pilo and Tamse (2000) conservationist approach
advocated minimal canal preparation and maintaining as
much residual dentin as possible .

Studies have shown that
An increase in post width has no significant effect on its retention.
The tooth restored with larger diameter posts is reported to provide the least
resistance to fracture with a decrease in the width of the remaining dentin.
Recommended post width by Tilk MA et al
• 0.6mm –mandibular incisors
• 1mm- maxillary central incisors, maxillary
and mandibular canines, palatal root of
maxillary first molar
• 0.8mm –other teeth

CANAL CONFIGURATION

• canals
walls
– prepared to have
- parallel prefabricated
Circular
parallel
posts .
• Elliptical canals/excessively flared
canals - cannot be prepared to give
parallel walls – taper restricted to 6-8
degrees - custom cast posts or tapered
prefabricated posts
Post should
Canal configuration determines
whether to use custom designed or
prefabricated post
Post should

AMOUNT OF CORONAL TOOTH STRUCTURE
• The bulk of the tooth above the restorative margin should be at least 1.5mm to
2mm to achieve resistance form
TORQUING FORCE
• Torsional forces on the post-core-crown unit
lead to loosening and displacement of the
post from the canal
• Active post designs provide greater torsional
resistance than a passive post

STRESSES
• Post and core–restored endodontically
treated teeth are subjected to various types
of stresses: compression, tensile, and shear.
• Of these stresses, shear stress is most
detrimental to the restored tooth.
• Holmes et al have demonstrated that the
variation in post dimension greatly influences
shear stresses.
An increase in the post length with
diameter kept to a minimum will help to
reduce shear stresses and preserve tooth
structure. Thus, the vulnerability of the
endodontically treated tooth to fracture is
decreased.

DEVELOPMENT OF HYDROSTATIC PRESSURE
During cementation, an increase in stress within the root
canal has been reported because of the development of
hydrostatic pressure. This pressure affects the complete
seating of the post and may also cause fracture of the
root.
There is evidence that the fitting stresses can be reduced
by careful placement of the post and by using a proper
post design with a cement vent to permit escape of the
luting agent and thus reduce the hydrostatic pressure
Pressure development is also dependent on the
viscosity of the cement. The more viscous the cement,
the greater the development of the hydrostatic pressure

POST MATERIALS
• Wagnild et al (2002) summarized the ideal physical
properties of a post that include:
(1) Maximum protection of the root.
(2) Adequate retention within the root.
(3) Biocompatible / noncorrosive
(4) Maximum retention of the core and crown.
(5) Maximum protection of the crown margin cement seal.
(6) Pleasing esthetics
(7) Radiopaque

Types of posts (Walton and
Torabinejad)
According to construction
•Custom made
•Preformed
According to nature of fit
•Passive
•Active
According to shape
•Parallel
•Tapered
According to surface configuration
•Smooth
•Serrated
•Threaded

Custom-cast posts
(i)Gold alloys
(ii)Chrome-cobalt alloys
(iii)Nickel-chromium
alloys

CUSTOM CAST POSTS:
Indications
•When multiple cores are being placed in the same
arch.
•It is more cost effective to prepare multiple post
spaces, make an impression, and fabricate the posts
in the laboratory.
• When post and cores are being placed in small
teeth, such as mandibular incisors.
• In this circumstance it is often difficult to retain the
core material on the head of the post.

•
When the angle of the core must be
changed in relation to the post.
Prefabricated posts should not be bent;
therefore, the custom-cast post best
fulfills this requirement.
•
•
•
When an all-ceramic noncore restoration is placed, it is
necessary to have a core that approximates the color of
natural tooth structure.
If a large core is being placed in a high-stress situation,
resin composite may not be the material of choice due
to the fact that it tends to deform under a load
In this circumstance, the post and core can be cast in
metal, and porcelain can be fired to the core to simulate
the color of natural tooth structure.
The core porcelain can then be etched with hydrofluoric
acid, and the all-ceramic crown can be bonded to the
core.

Disadvantages
• Less retentive
• Higher rate of root fracture mainly due to the wedging forces produced
by the tapered design
• Time consuming and involves an additional laboratory cost
• Requires two appointments
• Requires temporization between appointments
• The laboratory procedure is technique sensitive

PREFABRICATED POSTS
(iii) Brass
a) METAL
(i) Stainless Steel
(ii)Titanium
b) NON METAL
(i)Carbon-fiber
(ii)Fiber-reinforced
(1) Glass fiber
(2)Quartz fiber
(3)Woven Polyethylene fiber
(iii)Ceramic and zirconia

Pre fabricated metal posts
• They are very rigid, and with the exception of
the titanium alloys, very strong.
• Titanium posts were introduced in order
to compensate for corrosion
• Titanium alloys are generally weak
and therefore not suitable for thin posts
Titanium alloys have the same radiodensity as
gutta-percha and are sometimes hard to detect
radiographically.
Because they are round, they offer little
resistance to rotational forces
Advantages
Less expensive
less no. of
appointments
Disadvantages
Dislodgement
Chemical reaction
Difficult to retrieval of
active post

Prefabricated non metal posts
(1) CARBON FIBRE POSTS(Eg: composipost)
• The carbon fibre prefabricated post, introduced in the
early 1990s, is comprised of longitudinally aligned carbon
fibres embedded in an epoxy resin matrix (approx 36%).
Studies have shown that the carbon fibre post is “quite
stiff and strong, to a degree comparable to several posts
made of metal” and to have a modulus about ten times
higher than dentine.
Disadvantages:
• no radiopacity , hence impossible
to detect radiographically

2)GLASS FIBER- REINFORCED AND COMPOSITE POSTS :
Eg: parapost white
• Largely used for highly esthetic
restorations, these posts
typically are bonded with resin
luting cements and utilize
composite cores.
These posts should not be used if there is
less than 2-3 mm of supra-gingival tooth
structure present, if there is parafunction or
a deep overbite.

Ceramic posts
ADVANTAGES :
Esthetic - dentin like shade
Radioopaque , biocompatible
Low solubility
DISADVANTAGES :
Low tensile strength – fracture easily – thicker post needed – more dentin removal
Low fracture strength and fracture toughness .
Removed by grinding if retreatment necessary but is a tedious & risky procedure.
1989, Kwaitowski & Geller described clinical application of
glass ceramic posts.

Zirconia posts
1994, Sandhaus and Pasche
ADVANTAGES :
Esthetic
Extremely radioopaque , biocompatible
Low solubility
High flexural strength & fracture toughness
DISADVANTAGES:
Zirconia posts cannot be etched - not possible to bond a composite core
material to the post, making core retention a problem.
Grinding is impossible if retrieval necessary for retreatment
Higher incidence of root fracture fiber posts

Metal v. Fiber Reinforced
Metal
Coronal impact is
transmitted to remaining
tooth
Fiber reinforced
Coronal impact is dispersed
through the post alleviating
force on remaining tooth

ACTIVE VS PASSIVE POSTS :
• Active posts are more
retentive than passive posts,
but introduce more stress
than passiveinto the root
posts
• They can be used safely,
however, in substantial roots
maximum remainingwith
dentin
Active posts should be limited
to short roots in which
maximum retention is
needed.
ACTIVE
•Self threaded
•Pretapped posts
PASSIVE
•Tapered smooth sided
•Parallel sided
•Parallel with tapered
apical ends

SELF THREADED POSTS:
• Eg: DENTATUS SCREW, FLEXI-POST
• Self-threading posts have a shank (shaft) that is
fractionally narrower than the post channel that is cut
into the root and has a thread of wider diameter. Thus,
as the post is screwed into place the threads cut their
own counter-channel into the dentine.
They can be either tapered or parallel in
design of which tapered ones are more
retentive but induce high stresses due to
the wedging effect and may result in
fracture of the tooth

A novel post type( the Flexi Post) , has been•
designed in an attempt to overcome the
stresses that self-threading posts induce into
the root structure .
This is a parallel-sided threaded post with a
split in its apical half. As the post is screwed in
place, the split closes, transforming into a
tapered post, absorbing some of the potential
stresses
The coronal half of the post is not split and it is
in this area that the highest strain has been
recorded in the root

PRETAPPED POSTS
Eg: Kurer Anchor post
• It has a high frequency thread around a parallel-sided
shank.
• The system also provides a Kurer Root Facer which
flattens the root face onto which the head of the post
seats.
• This unfortunately removes coronal tissue, which is
important in creating a ferrule for the final restoration.
• During insertion of the post, the threads fit into the
counter-threads. This design creates large stresses in the
root which can lead to catastrophic root fracture

• Advantages:
High retention
• Disadvantages:
Stresses generated in canal may lead to fracture
Not conservative of coronal and radicular tooth structure
• Recommended Use:
Only when maximum retention is essential
• Precaution:
Care to avoid fracture during seating

TAPERED SMOOTH SIDEDPOSTS
eg: kerr endo post
• Smooth sided tapered posts conform to the
original taper of the root canal preparation,
thus conserving tooth tissue and reducing
the risk of post-perforation apically,
• It has been suggested that tapered smooth-
sided posts have a ‘wedging’ effect under
functional loading and it is this, that leads to
increased risk of root fracture.
Recommended Use of Tapered Posts: Small
circular canals and Very tapered canals
Precautions of Tapered Post: Not recommended for
excessively flared canals

PARALLEL SMOOTH SIDED POSTS
Eg: Whaledent Para post, Boston post
• Parallel posts produce uniform
distribution of stress along
length and are reported to
root fractures
the root
be less
thanlikely to cause
tapered posts
• They are cemented in to prepared
parallel channels.
• Parallel posts are proven to be more
retentive than tapered posts in case of
both metal and fiber posts

PARALLEL-TAPERED DESIGN
• The post is parallel throughout its length except for the most apical
portion, where it is tapered. This design permits preservation of the
dentin at the apex and at the same time achieves sufficient retention
because of parallel design
• Advantages:
Minimal stress production within
root
Ease of placement
• Disadvantages:
Precious material post expensive
Corrosion of stainless-steel
Less conservative of tooth structure
• Recommended Use:
Small circular
canals
• Precaution:
Care during
preparation

Retention:threaded>serrated> smooth

MATERIAL COMPATIBILITY
• Dissimilar alloys of the post and the core may create galvanic action, which
can lead to corrosion of the less noble alloy.
• Alloys containing brass have lower strength and lower corrosion resistance
and, hence, are less desirable Noble metal alloys are corrosion resistant, but
their cost is higher.
But with the availability of nonmetallic post materials, the corrosion factor is
eliminated.

BONDING CAPABILITY
• The bonding of a post to the tooth structure should improve the prognosis of
the post-core restored tooth by increasing post retention and by reinforcing
the tooth structure.
• Studies have shown that resin luting agents have good adhesion to carbon
fiber posts and glass fiber posts.
• The adhesion to zirconia posts was found to be unsatisfactory as it requires
surface treatment

CORE RETENTION
• Studies have reported that prefabricated metal posts with direct cores made of
glass ionomer, composite, or amalgam are less reliable than a one-piece cast post
and core because of the interface between the post and the core.
• As the number of interfaces increase, the potential for failure also increases.
• Thayer has expressed concern that post and core separation is more likely to
occur when composite is used as core material
RETRIEVABILITY
•Ideally, the post system selected should be such that if the endodontic
treatment fails or the post fractures, it is easy for the clinician to retrieve the post
without substantial loss of tooth structure
•Carbon fiber posts have an advantage over metallic,ceramic,zirconia posts in
that the removal is relatively easy, rapid, and predictable.

CROWN MATERIAL
• The metal ceramic crown will permit the clinician to use any post and
core material.
• All ceramic crowns are translucent and allow metal to show through.
• The influence of nonmetallic carbon fiber and zirconia post systems on
all-ceramic crowns depends on the substructure and thickness of
crown.
• When crown thickness is reduced, the color of foundation restoration
shows through a nonopaque thin crown.

2) REMOVAL OF ROOT FILLING MATERIAL
Mechanical removal by a non-end
cutting bur such as a Gates-Glidden or
Peeso reamer
Chemical removal by solvents such as oil
of eucalyptus, oil of turpentine and
chloroform
.
Thermal removal by a
heated instrument such as
a lateral compactor

3) PREPARATION OF THE CORONAL TOOTH STRUCTURE
• After the post space has been prepared, the coronal tooth structure is
reduced for the extracoronal restoration.
• Ignore any missing tooth structure (from previous restorative procedures, caries,
fracture or endodontic access) and prepare the remaining tooth as though it
were undamaged.
• Remove all internal and external undercuts that will prevent withdrawal of
the pattern.
• Be sure that part of the remaining coronal tissue is prepared perpendicular
to the post because this will create a positive stop to prevent over seating
and splitting of the tooth.
• Complete the preparation by eliminating sharp angles and establishing a
smooth finish line.

A) Direct technique
• Lightly lubricate canal and make sure plastic dowel extends to
full depth of post space
• Use the bead brush technique and add resin to canal space,
add “speedy post” inside the canal and seat completely
• Do not allow resin to set completely. Loosen and reset it
several times while it is still rubbery
• Once resin has polymerized, remove the pattern
• Inspect for any undercuts in pattern and trim away
• Measure and verify pattern post is same as prepared post
length
• Check that pattern goes in and out of canal without binding
• Additional resin is added for the core

b)Indirect Procedure
An orthodontic ‘J’ shaped wire
is selected & coated with an
adhesive
Canal is lubricated.
• Seat the wire and syringe in
impressionmore
cover coronal preparation
material to
and
insert the impression tray
Remove the impression and Pour the cast and fabricate
the post and core on the cast
•
with
material
elastomeric
using a
Fill canal
impression
lentulospiral

5) CORE FABRICATION
• It can be shaped in resin or wax and added to the post pattern before the assembly
is cast in metal.
• This prevents possible failure at the post-core interface.
• The core can also be cast onto most prefabricated post systems.
• A third alternative is to make the core from a plastic restorative material such as
amalgam, glass ionomer or composite resin.

Direct procedure for single-
rooted teeth
• Add a additional wax to form a
core
• Shape the core with carvers
• Remove the pattern, invest
immediately.
• If acrylic resin used – after
polymerization shaping done
with carbide burs.
Direct pattern for multi-rooted teeth
• The core is cast directly onto the post of one canal.
• Into the other canals - prefabricated posts are passed
through holes in the core
• One post (to which core is cast onto) is
roughened and rest are left smooth &
lubricated
• Fit prefabricated posts into the prepared canals
• Build up the core
• Grip the smooth lubricated posts with force and
remove them.
• Remove the pattern, invest and cast, the core with
the roughened post .

CORE MATERIALS
IDEAL REQUISITES OF A CORE MATERIAL
o High compressive strength
o High tensile strength.
o High modulus of elasticity (rigidity).
o High fracture toughness
o Dimensional stability
o Ease of manipulation
o Short setting time for cement
o An ability to bond to both tooth and
dowel.
o Biocompatible
o Natural tooth color, when indicated.
o Low plastic deformation.
o Low cost

CORE MATERIALS
Cast core
• Metal
• Ceramic
Plastic core
• Amalgam
• Composite
• Glass ionomer
• Resin modified glass
ionomer

Cast core: Metal
Advantages
•High strength
•Avoids dislodgement
Disadvantages
•More root fracture
•Casting inaccuracies
•Time consuming
•Expensive

Amalgamcore
Advantages:
• High compressive strength
• High modulus of elasticity
• Easy manipulation and placement
• Stable to thermal and functional
stresses
Disadvantages:
• Unesthetic
• mercury toxicity
• Tendency to discolor adjacent gingiva
• Tendency to corrode
• Low early strength –preparations
cannot be done immediately

Composite resincore
Advantages:
• High compressive strength
• Easy to manipulate
• Esthetic
• Bondable
• Adequate strength
• Command set- preparation can be
done immediately
Disadvantages:
• Microleakage due to
• polymerization shrinkage
• Dimensionally unstable
• Tendency to deform plastically and thus
cannot be used in high stress areas
• Isolation

Glass ionomercore
Advantages:
• Anti cariogenic
• Chemically adhesive to the
tooth
• Small buildups/undercuts
Disadvantages:
• Low fracture resistance
• Low retention to
prefabricated posts
• Sensitive to moisture

Resin modified glassionomer
core
Advantages:
• Properties lie in between composites and
GIC
• Anticariogenic
• More adhesive than GIC
• Decreased moisture sensitivity
• Decreased microleakage
Disadvantages:
• Tendency to expand in presence of moisture-
can lead to fracture of ceramic crowns.

6) TEMPORIZATION/PROVISIONAL RESTORATION
• If a cast post-and-core is made, an additional provisional restoration is
needed while the post and core is being fabricated.
• This can be retained by fitting a wire (e.g. a paper clip or orthodontic wire)
into the prepared canal.
• The restoration is then conveniently fabricated with autopolymerizing
resin by the direct technique.

7) CEMENTATION
Five main groups of dental materials are used to cement posts
o
o
o
o
o
zinc phosphate
polycarboxylate,
glass ionomers
resin-modified glass ionomers
composite resins
Retention provided by luting cements: zinc phosphate <
polycarboxylate< GIC< adhesive resin cements

LUTING METHOD
Place the luting agent on the post and
also in the canal with a lentulospiral, a
paper point, and an endodontic explorer.
After the luting agent is placed in the
canal, the post is coated with the luting
agent and inserted.

FAILURES IN POSTAND CORE
Root perforationRoot fractures
Apical lesion and cariesPost loosening

POSTREMOVAL TECHNIQUES
1) Masserann technique
• Masserann developed and designed an instrument for
extracting posts or rigid instruments that are broken
deeply within the roots with minimum damage.
• The method involves gripping the object through a
tube or trephine which acts as a tube-vice.
• This method is relatively harmless to the tooth and
periodontium

2) Eggler post remover
• The Eggler device can be easily applied
to anterior teeth and to most first
premolar teeth, but its size prevents it
from being used in most second
premolars and virtually all molar teeth 3) Ultrasonic scalers
• For posts that extend into the pulp
chamber, vibrations from the
ultrasonic scaler are able to break the
cement bond between the canal and
the post by touching the post with the
ultrasonic tip.

Gonon post removal technique:
• Free the head of the post from the
coronal tooth structure
• The high strength trephine is used to
bore and gauge the protruding post to
the exact size of a corresponding
mandrel which is specially
manufactured to thread the post
• The extracting pliers are fixed on the
mandrel and jaws of the pliers are
expanded by tightening the knurled
knob

CONCLUSION
• Use of post-and core restorations has changed markedly
in the past several decades.
• The evolution from wooden to metal to the most recent
fibre ones or from the custom cast to the pre fabricated
ones, they have been very promising in restoring
endodontically treated tooth
• It is possible to achieve high levels of clinical success
through the application of sound biomechanical principles,
maximum preservation of healthy tooth structure and use
of restorative materials with mechanical properties similar
to dental structure

REFERENCES
• Shillingburg – Fundamentals of fixed prosthodontics 3rd ed.
• Cohen – Pathways of the pulp 9th ed.
• Robbins JW. Guidelines for the restoration of endodontically treated teeth. J Am Dent
Assoc 120:558–566, 1990.
• Schwartz: Post Placement and Restoration of Endodontically Treated Teeth: A
Literature Review JOE Vol. 30, no. 5, May 2004
• Fernandes AS, Shetty S, Coutinho I. Factors determining post selection: literature
review. J Prosthet Dent 2003;90:556-562.
• Tait CME, Ricketts DNJ, Higgins AJ. Post and core systems, refinements to tooth
preparation and cementation. British Dental Journal 2005;198:533-541.
• Cheung W A review of the management of endodonticallytreated teeth Post, core and
the final restoration JADA, Vol. 136 www.ada.org/goto/jada May 2005

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