POST AND CORE (2).ppt

The structure and
composition of teeth is
perfectly adapted to the
functional demands of the
mouth and are superior in
comparison to any artificial
material…
So first of all, DO NO HARM.

CONTENTS
History
Alterations in endodontically treated teeth
Pre Treatment assessment
Definitions and Classifications
Materials Aspects
Biomechanical principles

1747: Pierre Fauchard
Wooden/metal posts
1870: T. W. Richmond
Richmond’s Crown
1930: Custom cast
post and core

20th century: the modern face
1960:Core concept
1961: Ferrule concept
1967: Peter Kurer:Kurer post
1970: Baraban: Parapost
1980: Aesthetic Posts
1990: Duret: Composipost
1994: Sandhaus Pasche: zirconia post
2000 : All Ceramic posts

How are endodontically
treated teeth different?
Loss of tooth structure
results in loss of
stiffness
5% in ideal access
cavity
40%- for class II
60%- for MOD
Coronal dentin
Stress bearing areas
Radicular dentin
removed
Caries, destruction Stress peaks cervically in endo
treated teeth

How are endodontically
treated teeth different?
Altered physical characteristics:
Moisture : 9% less (Helfer et al)
Collagen: Decreased (Rivera et al)
14% reduction in strength
Altered esthetic characteristics
Altered light refraction
Degradation of pulp tissue
Medicaments, fillings
Loss of proprioception

Indications: why do we need
posts?
Resistance
Retention

PRE TREATMENT ASSESSMENT
Endodontic evaluation
Periodontal evaluation
Restorative evaluation
Esthetic evaluation
Prosthetic evaluation

Endodontic evaluation
Dense uniform three dimensional
obturation of the root canal system.
Fluid impervious apical seal.

Periodontal evaluation
Periodontal disease should be treated prior
to placement of definitive restorations.
If there is substantial loss of tooth structure,
crown lengthening procedures should be
considered to maintain the BIOLOGIC
WIDTH.
Any destruction in this width leads to
resorption of the alveolar crest, which is not
desirable.

Biologic width relates to the amount of tooth
structure coronal to the osseous crest upto
the gingival attachment apparatus. It is
about 2.04mm.

Restorative evaluation
Amount of remaining tooth structure
Anatomical position of the tooth
Functional load on tooth

Esthetic evaluation
Must be done before initiation of post
endodontic therapy.
Discoloration from gutta percha can be
visible in the coronal aspects of root filled
teeth.
Tooth coloured posts should be used in
anterior regions.

Prosthetic Evaluation
Extent of tooth destruction.
Method and material used in core build up.

LEVELS OF CORONAL DAMAGE IN ANTERIOR AND POSTERIOR TEETH
Smith & Schuman

Anterior teeth
Minimal damage: no complete
coverage
Composite resin, GIC
Moderate to severe damage:
Post n core, full coverage
crown
(Smith and Schuman)
Esthetic considerations
Type of canal

Posterior teeth
Require occlusal coverage
Minimal damage
Moderate damage:
Cuspal coverage
Full coverage
Pin retained amalgam
Severe damage
Minimal damage
Moderate damage

BASIC COMPONENTS
OF A POST AND
CORE SYSTEM

A: 4-5 mm apical seal
B: Post
C: Residual root
attachment apparatus
D: Core
E: Final restoration

DEFINITIONS (GPT)
POST/ DOWEL is a relatively rigid,
restorative material placed in the root of the
non vital teeth. The foremost purpose of the
post is to provide retention for the core and
coronal restoration.
CORE is defined as properly shaped and
well restored substructure which replaces
missing coronal structure and retains the
final restoration.

Indications for POST
Extensively damaged natural crown of root filled
teeth.
Inadequate resistance form of the coronal
portion of the tooth to support the crown.
Large MOD cavities with a lingual endodontic
access opening.
Where a change in axial position greater than
1mm is required, as in malaligned teeth.

Contraindications for POST
Severe curvature of the roots.
Persistent periapical lesion.
Poor periodontal health.
Poor crown to root ratio.
Weak/ Fragile roots.
Teeth with heavy occlusal contacts.

Functions of the POST
To provide retention for the core which in turn provides
retention for the coronal restoration.
Distribute masticatory forces along the long axis of the
tooth thus preventing the tooth from fracture.

INGLE AND BAKLAND / WEINE
Custom cast posts
Pre fabricated posts
Tapered smooth sided
Parallel sided
Tapered self threaded
Parallel threaded
Parallel sided with tapered
end

WALTON AND TORABINEJAD
According to shape
Parallel
Tapered
According to construction
Custom made
Preformed
According to nature of fit
Passive
Active
According to surface configuration
Smooth
Serrated
Threaded

Cohen: Classification according to
desired physical properties:
Retentive Qualities of Dowels
Dowel design:
Dowel to root retention
Parallel,tapered,threaded,chemically bonded
Dowel to core retention
One piece, large dowel head, small dowel head
Dowel composition:
Dowel to root retention
Metal, carbon fibre, fibre reinforced, ceramic , zirconia
Dowel to core retention
One piece dowel n core, dissimilar dowel n core, monobloc
Dowel cementation:
Mechanical
Cement bonding to tooth only
Cement bonding to tooth and dowel

Cohen’s classification
Protective qualities of dowel against fracture
Dowel design
Shape
Parallel, tapered, parallel with tapered, parallel with increasing
coronal diameter
Diameter
Metal (small), non metal (large)
Dowel composition
Stiffer than dentin
Metal, zirconia, ceramic
Similar to dentin
Carbon fibre, fibre reinforced , woven fibre ribbond

Cohen’s Classification
Esthetic qualities of dowels
Ceramic dowel
Metal dowel
Zirconia dowel
Fibre glass reinforced dowel
Carbon core dowel

Classification according to
Mitra Hegde
Custom cast posts- custom made for an
individual case.
Prefabicated posts- used in the root canal by
altering the shape of the root canals to fit the
post into the canal.

Mitra Hegde
Prefabricated posts
Geometry Retention Material used
Shape Configuration Metal Non metal
Tapered Smooth
Parallel Serrated
Active Passive

Mitra Hegde
Based on composite material reinforced
Carbon Fibres Silica Fibres Polyethylene Fibres
Examples
Composipost
Endo Post
Carbonite Post
Mirafit Carbon
Glass Fibre Quartz Fibre
Examples Examples
Snow Post Aesthetic Post
Fibre White Aesthetic Plus
Glassix Style Post
Mirafit White Light Post
Lucent Anchor
Fibre Kor
Examples
Ribbond
Construct

According to materials used
Metals
Custom-cast posts
Gold alloys
Chrome-cobalt alloys
Nickel-chromium alloys
Prefabricated posts
Stainless Steel
Titanium
Brass
Non-metals
Carbon-fiber
Fiber-reinforced
Glass fiber
Quartz fiber
Woven Polyethylene fiber
Ceramic and zirconia

MATERIAL PROPERTIES
OF POST AND CORES

Custom made posts
Materials used:
Type III , type IV gold alloys
Ni-Cr, Co-Cr
Titanium alloys
Platinum- palladium alloys

Custom cast metal posts
Indications
1. When multiple post cores are placed
in the same arch.
2. When post and cores are to placed
in small teeth and it is difficult to
retain the core material on the post.
3. When angle of the core is to be
changed in relation to the post.

ADVANTAGES
1. Custom fit
2. Better geometric
adaptation
3. Excellent core retention
4. Greater strength
5. Good marginal
adaptation
6. Minimum tooth
structure removal
DISADVANTAGES
1. Root fractures
2. Poor aesthetics
3. Biocompatibilty
4. Two appointment
5. Laboratory fee
6. Risk of casting
inaccuracy
7. Difficult retrieval

PREFABRICATED POSTS
Indications
1. Sufficient width and length of root
structure present.
2. Roots of circular cross section.
3. Gross undercuts in root canals
which make pattern fabrication
difficult.

Prefabricated metal posts
Materials:
Stainless steel
Nickel chromium
Titanium
Brass
Titanium alloy and S-S post
Radiographic appearance of titanium

ADVANTAGES
1. Simple to use.
2. Less time consuming.
3. Easy retrieval.
4. Available in various
shapes and sizes.
5. Radiopaque.
6. Cost effective.
DISADVANTAGES
1. Not conservative
as the root is
designed to accept
the post.
2. Can not be placed
in tortuous canals.
3. Very rigid.
4. Prone to corrosion
5. Tapered posts can
have wedging
effect.

PREFABRICATED POSTS
Passive
Tapered smooth sided
Parallel sided
Parallel with tapered
apical ends
Active
Posts with self threading
screws
Self threading parallel
posts
Posts with Pretappered
threads Parallel/tapered

PASSIVE POSTS: tapered
smooth sided
Examples:
Kerr endopost ( 1.1- 6.2 degree taper)
Mooser post
Ellman Nu bond (tapered knurled post)
Post retention : least
Stress from installation : self venting
Stress from mastication : wedging effect

PASSIVE POSTS: parallel
sided posts
Examples:
Whaledent posts : parapost
Boston post
Parkell parallel post

PASSIVE POSTS : parallel
sided posts
PARAPOST SYSTEM:
Parapost
Parapost plus
Unity system
Post retention
Stress from installation
Stress from
mastication

sided posts
BOSTON POST SYSTEM (Goldman and
Nathanson, Tufts university)
99.6% titanium
Horizontal non engaging serrations
Rough surface
Increased Post retention

sided posts
PARKELL PARALLEL
POST SYSTEM
Passive, vented,
serrated
Anti-rotational lock
Available in Plastic
burn out pattern for
casting.

PASSIVE POSTS: Parallel
sided with tapered apical
ends
These were designed to achieve better
retention from parallel posts along with
tapered end conforming to the tapered
apical portion of canal.
Examples:
Degussa
Unitek BCH
Post retention: lower than regular
Stress from mastication: wedging effect
apically

ACTIVE RETENTION POSTS :
Self threading posts
Dentatus post
Radix anchor post
Flexipost
Tapered Dentatus
Post retention: high
Stress from installation:
very high
Stress from mastication

ACTIVE POSTS: Self
threading screws
FLEXIPOST SYSTEM
(tapered)
Split shank, parallel
sided
Post retention
Threads cut into
dentin 0.1-0.2mm
Stress from
mastication

ACTIVE POSTS: Self threaded
parallel posts
Examples:
Parallel V lock drill and
post system
Parallel Radix Anchor
post
Post retention: maximum
Stress from installation: high
Stress from mastication
Radix anchor post

ACTIVE POSTS: Parallel threaded
posts with pre-tapped
channels
Examples:
Kurer anchor post
Pre-tapped , non
vented, parallel
Kurer root facer
Retention : highest
Stress from
mastication
Kurer root facer

NON METALLIC
PREFABRICATED POSTS
Fibre reinforced posts
Carbon fiber posts
Silicon fibre posts
Woven polyethylene
fibre (Ribbond)
Ceramic and zirconium
post systems

Fibre reinforced posts
Composition:
Carbon fibre posts
(Duret 1990)
Silicon fibre posts:
Glass fibre posts
Quartz fibre posts
Woven polethylene
fibre : Ribbond
Fibre posts
Ribbond

Carbon fiber posts :
It was introduced by Duret et al in 1996.
it consists of bundles of stretched carbon fibers
embedded into epoxy matrix.
This was the 1st nonmetallic post introduced to the
dentistry.
The original form of carbon post was black &
unaesthetic.

ADVANTAGES
1. Strong but low stiffness
& strength tan ceramic
metal post.
2. Easily retrievable.
3. Less chair side time.
4. Modulus of
elasticity is similar to
dentin.
5. Biocompatible
6. Good retention.
DISADVANTAGES
1. Unaesthetic
2. Radiolucent so
difficult to detect
radiographically.
3. On repeated loading,
show reduced
modulus of elasticity.
4. Moisture
contamination
decreases strength.

GLASS FIBRE POSTS
 It was introduced in 1992.
 It consist of glass fibers embeded in resin
matrix which strengthens the dowel without
compromising the modulus of elasticity.

ADVANTAGES
1. Esthetically acceptable.
2. Modulus of elasticity is
similar to dentin
3. Biocompatible.
4. Easy retrieval.
5. High resistance to
fracture.
6. Distributes stresses a
broad surface area,
thus increases load
threshold.
DISADVANTAGES
1. Poor radiographic
visibility.
2. Expensive.
3. Technique sensitive.

Contents and mechanical
properties of some fibre posts
POST CONTENTS FLEXURAL
MODULUS
FLEXURAL
STRENGTH
Composi-
post
Carbon fibre
64%,epoxy
145 GPa 1500 Mpa
Light-post Quartz fibre
60%,epoxy
46GPa 1400Mpa
Luscent Quartz fibre
70%, polyester
40GPa 890 Mpa
Parapost Glass fiber 42%,
filler 29%,
methacrylate
resin 29%
29GPa 990 Mpa

Zirconia posts
1994 by Sandhaus Pasche.
Esthetic : dentin like shade
Made from fine grained tetragonal
zirconium polycrystals.

ADVANTAGES
1. Teeth with severe
coronal destruction,
zirconia post provides
adequate strength.
2. Combination of glass
ceramics & zirconia
ceramic can be used
because of similar
coefficient of
thermal expansion.
DISADVANTAGES
1. Adhesion to tooth &
composite is
compromised.
2. Brittle.
3. Expensive.
4. Weaker

Comparative properties of all
types of posts: RETENTION
According to shape
Parallel >
tapered
According to type
Active > passive
According to length
Long > short

Stress during cementation
Parallel posts exert more stress than
tapered posts during cementation.

Stress under mastication
Under function tapered posts exert a wedging action
and more stress
Threaded posts

THE CORE:
Cast core : metal, ceramic
Amalgam
Composite
Glass ionomer
Resin modified glass ionomer

CAST CORE : METAL, CERAMIC
Advantages
Avoids dislodgement
Metal more noble.
Disadvantages:
More root fracture
Expensive
Time consuming

AMALGAM CORE
Advantages:
Good physical properties
Bonded amalgam: seal
Minimal stress
transmitted
Easy to manipulate and
sets rapidly.
Disadvantages:
Tarnish and corrosion
Dark colored
Environmental issues

COMPOSITE RESIN CORE
Advantages:
Bonded: retention
High compressive strength
Easy to manipulate
Tooth colored
One step
Disadvantages:
Polymerization shrinkage
Water sorption
Plastic deformation
Adhesion to radicular dentin is
less
Isolation required

GLASS IONOMER CORE
Advantages:
1. Anticariogenic
2. Small buildups/undercuts
3. Less microleakage compared to
composites.
Disadvantages:
1. Sensitive to moisture
2. Tensile & flexural strength is less
3. Fracture toughness is low
4. Low retention

FINAL RESTORATION
Functions:
Function and esthetics
Prevent microleakage
Protection
Maintain periodontal health
Choice:
Anterior
Posterior
Margins

CONTENTS
 Biomechanical principles for post and core
preparation.
 Clinical Direct and Indirect techniques for post and
core fabrication and cementation.
 Failures of the post core systems.
 Removal of the Post core systems.

BIOMECHANICAL PRINCIPLES OF
POST AND CORE PREPARATION

Biomechanical principles
RETENTION is defined as that which resists a
tensile or pulling force.
RESISTANCE is defined as that which opposes any
force.

Factors affecting RETENTION of post
systems
1. Post length
2. Post diameter
3. Post design
4. Luting agents
5. Luting methods and Venting
6. Canal Shape
7. Surface roughness

POST LENGTH
Equal to or greater then crown length.
2/3rd of the total root length
Atleast half the distance between alveolar bony
crest and root apex.
Minimum 4-5 mm apical guttapercha should be
remaining

APICAL SEAL >>> POST LENGTH
After RCT, the apical gutta percha is the
only barrier against reinfection of the
periapical region.

POST DIAMETER
 Increase in post diameter increase the
retention but it also increases the risk of
root fracture.
 There are 3 theories regarding the post
diameter
1) The conservationist
2) The preservationist
3) The proportionist

THE CONSERVATIONIST
It suggests the narrowest diameter that
allows the fabrication of a post to desire
length.
It allows minimal instrumentation of canal
for post space preparation.
According to this, teeth with smaller dowels
exhibits greater resistance to fracture.

THE PRESERVATIONIST
It advocates that at least 1mm of sound
dentin should be maintained
circumferentially to resist the fracture.

THE PROPORTIONIST
It advocates that post width should not
exceed 1/3rd of the root width at its
narrowest dimensions to resist fracture.
The guideline for determining appropriate
diameter of post involves mesiodistal width
of the root.

POST DESIGN
Custom made parallel sided with apical taper
and prefabricated parallel sided threaded post
with apical taper are considered where added
retention is required.

LUTING AGENT
Adequate film thickness.
Good Bonding.
LUTING METHODS AND VENTING
Because of intraradicular hydrostatic pressure
created during cementation of the post, a means for
cement to escape must be provided. Hence, a vent
must be incorporated in the pattern before casting
or cut into the post with a bur prior to cementation.

Methods of applying luting agent into the
canal space-
1. Lentulospiral
2. Paper point
3. Endodontic explorer.

CANAL SHAPE
Custom cast post- Ovoid and elliptical canals
Prefabricated posts- Straight and parallel root
canals

SURFACE TEXTURE
Surface roughening, such as air abrading or
notching of the post increases post retention.

Factors affecting RESISTANCE of post
systems
1. The ferrule effect
2. Natural remaining tooth structure
3. Antirotation feature

THE FERRULE EFFECT
The term ferrule is often misinterpreted.
It is often used as an expression of the amount of
remaining sound dentin above the finish line.

A FERRULE is a metal ring or covering intended for
strenthening.
FERRULE= FERRUM (iron) + VIRIOLA(bracelet)

A dental ferrule is an encircling band of cast
metal round the coronal surface of the tooth .
It can also be defined as ‘the 360 degree metal
collar or crown surrounding the parallel walls
of the dentin extending coronal to the
shoulder of the preparation’.

It is not the remaining tooth structure that is the
‘ferrule’ but rather the actual bracing of the
complete crown over the tooth structure that
constitutes the ferrule effect.

Coronal extension of dentine above the
shoulder provides an effective ferrule effect

The cervical collar along the post has definite
benefit in increasing the resistance of the post
and core to various forces.
Minimum ferrule length= 1-1.5mm
The fracture resistance is increased with the
increase in ferrule length which may not be
achieved by increasing post length.

FACTORS THAT INFLUENCE THE
FUNCTIONALITY OF THE FERRULE
1]Ferrule height
2]Ferrule width
3]Number of walls and ferrule location
4]Type of tooth and the extent of lateral loads
5]Type of post
6]Type of core material

To achieve the full benefit of ferrule effect, it should
be a minimum of 1-2 mm in height, have parallel
dentine walls totally encircling the tooth, and ending
on sound tooth structure.
The consensus is that:
A properly constructed ferrule significantly reduces
the incidence of fracture in non vital teeth by
reinforcing the teeth at its external surface and
redistributing the applied forces, which concentrate
at the narrowest point around the circumference of the
tooth.
It helps to maintain the integrity of the cement
seal of the crown.

Preparation of ferrule
Vertical wall around tooth
structure
Must fulfill following
requirement:
Minimum of 2mm of dentin
axial wall length
Parallel axial walls
Encircle the tooth
Sound tooth structure
Should not invade the
attachment apparatus

Preparation of ferrule
4-5mm height, 1mm
thickness of suprabony
tooth structure should
be available
Orthodontic
extrusion
Crown lengthening

Natural Remaining tooth
structure
Traditionally, it was
thought that the tooth
structure should be
flattened prior to
construction of post and
core.

ANTITOTATION FEATURES
Antirotational groove
Auxillary pin
Keyway preparation
Additional cemented posts in
multirooted teeth

STEPS FOR POST AND CORE
PREPARATION

1. Proper Tooth Preparation
Conservation
Ferrule
Reduction
Undercuts

2. Removing the Gutta percha
Mechanical
Chemical
Thermal
Combination

Mechanical removal of gutta percha is
efficient and probably the most common
technique.
Coronal/cervical 2-3mm of GP- removed by
rotating the round bur in slow motion.
Peaso reamers are used next till the desired
length maintaining the apical seal.

A radiograph should be taken to check the
accuracy of the preparation depth and to make
any necessary adjustments in the peaso
reamer length.

Peaso Reamer
- Sharp but non cutting tip which follows the
path of least resistance.
- It conforms more consistently to the original
canal in the apical region.
- Numbered 1-6, range in diameter from 0.7-
1.7 mm in graduated increments of 0.2mm.

Chemical removal– Softens the gutta percha
for easy removal.
Oil of eucalyptus
Halothanes
Oil of turpentine
Chloroform
Endosolv-R
Endosolv- E

Disadvantages
1. Difficult to control the depth of softening of
gutta percha.
2. Potential leakage of the solvents into the
periradicular tissues.

Thermal Removal
A file is warmed and gently
inserted in the gutta percha and
allowed to stay till it cools down.
The file is then rotated
anticlockwise removing the
entangled gutta percha. This
process is repeated till the
required length is achieved.

When should the gutta percha
be removed??

3. Preparation of the canal
space
The final preparation of the canal should be
completed with the peaso reamers.
In order to distribute stresses properly, a
key way is prepared in the root canal.

The prepared post space should be thoroughly
irrigated and evaluated radiographically.
The prepared post space should not be left
empty for long to avoid chances of
reactivation of micro-organisms.
In case the impression making procedure is to
be delayed, the post space should be properly
closed with dressing.

4. Impression of the prepared
space.
Depends upon the type of the post used.
Custom cast post
1. Direct method
2. Indirect method
3. Two piece custom post
4. Post-inlay system

DIRECT METHOD
Fabricated in the prepared tooth in vivo
using resin or wax pattern.
Central reinforcement
1. Wooden stick
2. Hard plastic stick
3. Thin metal needle
4. Old/ broken file or reamer
5. Orthodontic wire

Trim the sprue so that it fits freely in the
canal to the exact desired length.
Mark the labial surface.
Heat a stick of inlay wax over the flame.

Start coating the plastic sprue with the fluid
wax uniformly.
Seat the wax covered sprue in the canal until
it has touched the apical end of the of the
post preparation.

More wax is added to the coronal portion of
the pattern to provide the bulk for the core.
After the wax has set, the post is removed
from the canal and the length is checked.
It is reseated in the canal and the coronal
portion is shaped so as to mimic the tooth
anatomy which it replaces.

Replace the pattern from time to time to
ensure that the contours being shaped are
consistent with the remaining coronal tooth
structure.
After complete finishing of the core, the wax
pattern is dispensed to laboratory for
casting procedure at the earliest to prevent
distortion.

INDIRECT METHOD
Cut ortho wire to length and shape of letter J.
Verify the fit of the wire in the canal (should
fit loosely and extend to full depth of post space).
Lubricate canal to facilitate removal of impression
material.

Using a lentulo spiral, fill the canals with
elastomeric impression material.
Seat the wire reinforcement to the full depth
of each prepared teeth and insert the
impression tray.

Remove the impression and evaluate it.
Pour the working cast.

Roughen a loose fitting plastic post.
Make sure it extends to depth of the canal.
Add soft inlay wax in increments on the
plastic post and insert it in the canal space.
Wax the core.

ADVANTAGE
As the pattern is made in the laboratory by a
lab technician, it saves a lot of time of the
dentist as well as the patient.

3. TWO PIECE CUSTOM POST
Molars - key tooth.
- Extensively damaged.
- in cases of FPD where more
retention and resistance is required.
Because of the divergent roots in molars, fabrication
of a single piece post and core is difficult. Hence, a
multiple piece post and core with separated posts
should be employed.

Mandibular molar- mesial and distal.
Maxillary molar- facial and palatal.

4. POST INLAY SYSTEM
Indicated in teeth with crowns requiring
endodontic treatment.
Removing the crown may lead to fracture of the
coronal portion of the tooth or the crown or
both.
Thus, it becomes mandatory to initiate RCT
through the cast restoration.

An endodontic access through the crown is often
larger because the crown obscures the
morphology of the tooth and makes it difficult to
locate the root canal.
After completion of the RCT, the remaining un
restored part can be restored with cast post with
an attached inlay to close the access opening.
Retentive and can withstand laterally directed
forces without fracture.

CEMENTATION OF THE POST
Objectives-
1. To help in retention.
2. Allow proper sealing along the root canal.
3. Promote a layer of cushioning that
contributes to the uniform distribution of
stress between the post and root canal wall.

Characteristics of the cement
1. High resistance
2. Small coating thickness (< 20 µm)
3. Low solubility
4. Good adhesion capacity
5. Good marginal seal
6. Easy manipulation

Zinc Phosphate
Glass Ionomer
Resin cements

ZINC PHOSPHATE CEMENT
Long history of clinical success.
Only disadvantages
1. Solubility in oral fluids.
2. Lack of true ahesion.

GLASS IONOMER CEMENT
Disadvantages
1. Weak adhesion to dentin.
2. Highly susceptible to humidity.
3. Does not reach its maximal strength for many
days due to the long setting reaction.
4. Risk of expansion after setting can be a risk
factor for root fracture. ( Resin modified GICs)

RESIN CEMENTS
Conflicting results.
The setting reaction of most dental resins is
adversely affected by the presence of
eugenol and most endodontic sealers
contain eugenol.
Technique sensitive and difficult to use for
cementation of posts in the canals.

Small film thickness.
Extended working time.
Excellent compatibility with eugenol.
Good handling properties.
Modulus of elasticity near to dentin.
Proven clinical record.
Low risk of root fracture.
ZINC PHOSPHATE

NO CONFLICTS
If fundamental biomechanical principles are
followed when designing and placing a post, it
seems unlikely that the type of cement used for
cementation plays a significant role in the
overall prognosis of a post and core restored
tooth.

SEATING OF THE POST
Pre treatment of root dentin
1. Post space should be cleaned with a
chelating agent followed by rinsing with
NaOCl and dried with paper point.
Advantages-
1. Makes the post space walls to be free of root
canal sealant, debris and dentinal smear
layer.
2. Enhances the bonding between the cement
and root dentin.

Only the core portion of the casting should
be smoothened to a satin finish.
Insert a thin mix of luting cement into the
canal with a lentulospiral.

It gives better spreading and spinning of the
cement because of centrifugal dispersion of
cement.
It also reduces voids and increases the
contact of the cement with the walls which
helps to distribute stresses evenly
throughout the entire root canal.

Liberally coat the post with the fluid cement
and insert the post in the canal.
Post should be free of any residue.
The post should be seated slowly with finger
pressure, allowing the cement to escape
ahead of the post. Never mallet the post to
place.

When the cement has set, the axial surfaces
of the core and tooth structure should be
merged with a fine grit diamond bur to
remove any minor undercuts near the
margin of post-core.

INTEGRA POST SYSTEM
Aesthetic post reinforced
over titanium alloy.
Biocompatible and
corrosion resistant.
Innovative, round flow
through head to
optimize composite core
materials.

FIBREFILL POST SYSTEM
The uniqueness of this system is the
simultaneous obturation of the prepared
root canal with the insertion of fibre
reinforced post system.
Increased strength.
Time and cost effective.

ALL CERAMIC and ZIRCONIA
POSTS
Major advantage is its dentin like shade.
The positive contribution of the dentin
shade ceramic core is related to the deeper
diffusion and absorption of the transmitted
light in the core mass.
The final restoration is derived from an
internal shade similar to the optical
behaviour of natural teeth.

FOUR TECHNIQUES
1. Slip casting technique
2. Copy milling technique
3. Two piece technique
4. Heat Press technique

Copy milling technique
Two piece technique concept
Heat pressed

Advantages
Dentin post provide excellent biocompatibility
and resilience that is comparable to the original
tooth.
Excellent adhesion to the natural tooth.
Low cost, as dentin posts are made from
donated extracted natural teeth.

Post mishaps during
preparation
Perforations :
Root anatomy
Choice of root
Choice of post
Too big posts
Orientation of bur

Types of failures
Prosthodontic failures
Periodontic failures
Endodontic failures

Types of failures
Loss of retention
Root fracture
Post fracture
Caries
Periodontal disease
Failure mode

Ideally post system selected should be such
that if an endodontic treatment fails, or
failure of post & core occurs, it should be
retrievable.
Post can be removed by :
1. Use of rotary instrument & solvent
2. Use of ultrasonics

SPECIAL RETRIEVAL KITS
Little Giant Posy Puller designed by
Skinner
S.S.White Post Extractor (S.S.White
Dental Mfg.Co.,Philadelphia,Pa)
Post Puller (Star Dental Mfg. Co.,
Conshohocken, Pa.) designed by Kahn et
al.

Saca Pino post extractor
Messeran kit

TO CONCLUDE…..
The pain taken for successful completion of
endodontic therapy is of no use if a proper
post endodontic restoration which
completely houses the tooth is not given.
Numerous studies have proven long term
prognosis of post and core restored root
filled teeth provided proper technique and
materials are used.

In this wide arena of the world, failures and
success are not accidents as we so frequently
suppose……
But strict justice to nature…..

REFERENCES
1. Endodontic science, volume II
2. Mechanism and risk fractures of
endodontically treated teeth. Endodontic
topics 2006.
3. Indirect restorations, Vimal Sikri.
4. Restoration of endodontically treated teeth,
DCNA 2002
5. Rethinking ferrule, British dental journal
2010.
6. Ferrule effect : a literature review, JOE
2012

7. Textbook of endodontics, Anil Kohli.
8. Ingle’s Endodontics, sixth edition.
9. Textbook of Endodontics, Mitra Hegde.
10. Restoring endodontically treated teeth
with post and core- A review, Quintessence
International 2005.
11. Endodontic Therapy, Weine.
12. Pathways of the Pulp, Cohen.
13. Restoration of endodontically treated
teeth, Dentistry Topics, 2011.
14. Grossman’s Endodontic Practice, 12th
edition.

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