Restoring Endodontically Treated Teeth (RET

RESTORATIONRESTORATION
OFOF
ENDODONTICALENDODONTICAL
LY TREATEDLY TREATED
TEETHTEETH
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

Table of Contents
•History
•The endodontically treated teeth
•Treatment planning to restore an endodontically treated tooth
•Basic components used in the restoration of an endodontically treated tooth
•Dowel classification
•Post materials
•Core and core materials
•Principles for preparation of an endodontically treated tooth
•Effect of ferrule on the resistance form of the tooth preparation
INTRODUCTION

•Techniques for Dowel and Core fabrication
•Cast Dowel and Core fabrication techniques
- Direct techniques of fabrication
- Indirect techniques of fabrication
•Provisional restorations for an endodontically treated tooth
•Failure and removal of posts.
•Summary and conclusion
•References

HISTORY
•The replacement of missing tooth structure has been practiced by various
cultures for thousands of years.
•Talmud (AD 352-457)…….. a supporting wire…
•Franks (AD 200-737) ……...a wooden dowel….
•Pierre Fauchard, in 1747, gave the first documented procedure of ‘pivoting teeth’.
He used posts fabricated of gold or silver that were held in place with the heat-
softened adhesive called “mastic”.

Wooden vs. metal posts
•There was much controversy over the type of post to be used.
•Wooden posts, made of hickory or box tree...self-retentive…..less wear to the
canal.
•Metal posts retained with cotton or silk thread or with wedges were detrimental
to the root…...abrasion of the canal walls.
•Although ,posts made of fine gold or platinum corroded less than copper,
brass or silver.
•The following years…. hippopotamus, sea horse and ox teeth were used to
replace lost tooth structure…….replaced with porcelain.

• In the 1870’s, Richmond Crown (integrated dowel crown) given by T.W.
Richmond….
•In the 1960’s….changeover from the single porcelain crown…..separate, well-
retained component, ‘the core’….
•In the 1970’s,composite and amalgam were introduced as direct core buildup
materials. Pin retained composite and amalgam restorations as alternatives to
post and core began to be practiced.
•In 1980 , Arun Nayyar described the amalgam coronal – radicular dowel and
core system.

•In 1990, Duret et al introduced a non-metallic post, based on carbon-fiber
reinforcement principles, which showed high tensile strength and modulus of
elasticity similar to dentin.
•In 1994 , Sandhaus and Pasche introduced the prefabricated zirconia ceramic
endodontic post and suggested use of zirconia ceramic core build up.
Thus, over 200 years of research by various clinicians and investigators
has increased the longevity and serviceability of endodontically treated teeth.

Review of literature

•Guzy G E et al in 1979 conducted an vitro study to compare the
failure loads of 59 intact endodontically treated teeth with and without
post reinforcement. The purpose of this study was to determine if the
post reinforces the root against fracture.
No statistically significant reinforcement was demonstrated by
cementing a post into a sound endodontically treated teeth.
•Sorensen and Martinoff (1984) evaluated 1273 endodontically
treated teeth to (1) compare the clinical success rate of six coronal-
radicular stabilization methods, (2) record the failure of dowel systems
and the effect on endodontically treated teeth, and (3) determine the
effect of dowel length on the clinical success rate. The 6 categories
were: tapered cast dowel and core; Parapost and amalgam or
composite resin core; cast-Parapost and core; threaded post; pin-
amalgam core and pin-composite resin core.

Results showed that:
The cast parallel-sided serrated dowel with an amalgam or composite
resin core recorded the highest success rate.
The tapered cast dowel and core displayed a higher failure rate than
teeth treated without intracoronal reinforcement.
The parallel-sided serrated dowel did not have failures caused by
tooth fracture, whereas failure of the tapered cast dowel and core
required extraction in approximately one third of the fractured teeth.
Teeth that had a dowel length equal to or greater than the crown
length had a success rate that exceeded 97%.

•Isidor and Brondum (1992) compared the resistance to intermittent
loading of teeth with tapered, individually cast posts and cores or
prefabricated parallel-sided posts (Para-Post, Whaledent) and composite
cores. Teeth with prefabricated posts and resin composite cores showed a
significantly higher resistance to intermittent loading than did teeth with
tapered individually cast posts and cores.
•Stankiewicz and Wilson (2002) described a ferrule as a metal ring or
cap used to strengthen the end of a stick or tube. They proposed that the
use of a ferrule as part of the core or artificial crown may be beneficial in
reinforcing root-filled teeth. A review of the literature investigating this
effect is presented. The literature demonstrates that a ferrule effect occurs
owing to the artificial crown bracing against the dentine extending coronal
to the crown margin. Overall, it can be concluded that a ferrule is desirable,
but should not be provided at the expense of the remaining tooth / root
structure.

The Endodontically Treated Teeth
The major changes in these teeth include:
• Architectural changes
• Altered physical characteristics
• Altered esthetic characteristics

Architectural changes
• Endodontic access into pulp chamber destroys structural integrity……allows
greater flexing of the tooth under function.
• With reduction of the inner cuspal slopes….greater chances of fracture exist.
• In case of significantly reduced remaining tooth structure, normal functional
forces…..
• Additionally, if these teeth have extensive restoration or caries, their strength
and structural integrity are further compromised .

Altered physical characteristics
•Calcified tissues of pulpless teeth have 9% less moisture content than in vital
teeth.
•The shear strength and toughness of dentin….
•Changes in collagen crosslinking and dehydration of the dentin…
Altered esthetic characteristics
A darkened endodontically treated tooth is a common clinical phenomenon.
•Biochemically altered dentin modifies light refraction...
•Inadequate endodontic cleaning and shaping of the coronal area….
•Medicaments and cements of root canal fillings…..

Treatment Planning
Pre-treatment evaluation
Assessment of Restorability:
Endodontically treated teeth need to be carefully assessed and definitive
treatment should not be initiated if the tooth exhibits:
• Poor apical seal.
• Active inflammation.
• Pressure sensitivity.
• Exudate.
• Fistula.
• Periodontal disease – Moderate to severe periodontitis.
• Severe loss of sound tooth structure – where the tooth would not benefit
from crown lengthening or orthodontic extrusion.

The choices of action then, depending on the case, include:
1. Re-treatment
a) Endodontic re-treatment – can reverse inflammation, permitting
the tooth to receive restorative treatment.
b) Periodontal re-treatment – the tooth may require stabilization.
2. Monitoring – time to assess progressive healing.
3. Extraction – in unrestorable cases.

Considerations for restoring anterior teeth:
• Endodontically treated anterior teeth do not always need complete
coverage as studies have shown that intact root treated anterior teeth are
stronger than those restored with post and core.
• Post and core is not required when there is minimal coronal
damage…..restoration of access opening….
• If the tooth is discolored a non-vital bleaching technique…..
• Indications for post and core….

Considerations for restoring posterior teeth:
• All endodontically treated posterior teeth require a full occlusal
coverage restoration. This is because due to loss of the roof of the
pulp chamber (which provides structural integrity) the occlusal forces
tend to wedge the cusps apart, which may lead to tooth fracture.
• Minimal coronal damage…. crown/onlay.
• Moderate coronal damage…. Foundation (core) restoration…
• Extensive coronal damage.... Post and core.
• Premolars……lateral forces….smaller cross sectional area at
CEJ….smaller pulp chamber…..post and core.

Basic components used in the restoration of an ET tooth
The final configuration of the restored tooth includes four parts:
• Residual tooth structure and periodontal attachment apparatus.
• Post material, located within the tooth.
• Core material, located in the coronal area of the tooth.
• Definitive coronal restoration.

Post
The post is defined as a metallic or non metallic material inserted into
the root canal to aid in retention of a core component.
Function
•Retention
•Protection
Post design characteristics
•Length
•Diameter
•Shape
•Surface configuration
•Method of attachment
•Material

Classification
Ingle and Bakland
I. Custom-cast Posts
II. Prefabricated Posts
a) Tapered, smooth-sided
b) Parallel-sided
c) Tapered, self-threading screws
d) Parallel-sided, threaded
e) Parallel-sided, tapered apical end

Shillinburg and Kessler
I. Custom-cast Posts
II. Prefabricated posts
a) Tapered, smooth-sided posts
b) Tapered, serrated posts
c) Tapered, threaded posts
d) Parallel, smooth-sided posts
e) Parallel, serrated posts
f) Parallel, threaded posts

Robbins
I. Metallic Posts
A. Custom-cast Posts
B. Prefabricated Posts
1. Passive Tapered Posts
2. Passive Parallel Posts
3. Active Posts
II. Non-metallic Posts
A. Carbon Fiber Posts
B. Tooth Coloured Posts
1. Fiber reinforced posts.
2. Ceramic and zirconia posts

Materials Used
Metals
(a) Custom-cast posts
(i) Gold alloys
(ii) Chrome-cobalt alloys
(iii) Nickel-chromium alloys
(b) Prefabricated posts
(i) Stainless Steel
(ii) Titanium
(iii) Brass
Non-metals
(a) Carbon-fiber
(b) Fiber-reinforced
(i) Glass fiber
(ii) Quartz fiber
(iii) Woven Polyethylene fiber
(c) Ceramic and zirconia

Custom-cast metal posts
Indications:
• When multiple posts and cores are being placed in the same arch.
• When posts and cores are being placed in small teeth,
• When the angle of the core must be changed in relation to the post
• When an all-ceramic 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 on in a high-stress situation, resin composite….deform under a load.
So, post and core is cast….The core porcelain can then be etched with
hydrofluoric acid, and the all-ceramic crown can be bonded to the core.
• In excessively flared and elliptical canals….
• Cast post and cores…..easy to retrieve….

Drawbacks
•Requirement of temporary restoration…
•Lower fracture resistance…. Tapered design…wedging forces.

Pre-fabricated posts
Different post designs
a) Tapered, Smooth-Sided Posts
The oldest and most widely used design.
Eg : Kerr Endopost, Mooser post and all custom-cast posts.
Post Retention: The tapered, smooth-sided, cemented post is the least
retentive of all post designs.
Used in teeth not subjected to high functional or parafunctional loads
and where other designs are contraindicated.
Stress from Installation: Because of their taper, these posts are self-venting
and easily cemented. Hydrostatic pressures do not develop during
cementation because a taper does not act as a piston.
Stress from Mastication. Tapered-smooth posts are wedges and, as such,
exert a wedging pressure upon roots during function…

b) Tapered Posts with Self-Threading Screws
Eg : Dentatus
Post Retention: More retentive……gains its retention by spreading into the dentin
as it self-threads….
Stress from Installation: Sets up fracture lines as it “cuts” and spreads its way
into the dentin.
Stress from Mastication. The wedge configuration of the screw design is
accentuated under load when occlusal forces are added to the installation forces
described above.
Self-threading tapered screws possess the worst installation and occlusal
stress-producing characteristics of all existing designs.

c) Parallel-sided Posts
Examples are Whaledent posts which has introduced three post designs: the
original Para-Post, Para-Post Plus, and the Unity System. All are passive,
parallel, vented posts made of either stainless steel or titanium.
The Para-Post System
Post Retention: The parallel-sided, serrated, vented post provides
substantially greater retention than the smooth tapered design.
Consequently, these posts can be effectively employed in situations where
higher applied forces are expected.
Stress from Installation: The Para-Post has a vertical groove cut along the
length of its serrations, allowing axial venting. This design allows cement to
escape….
Stress from Mastication: Provide the most equitable distribution of
masticatory forces of all available post designs.
Avoids the wedging effect of tapered posts. The transfer of occlusal
forces of the tooth occurs via the cement layer, which serves to buffer the
forces. Together, these two factors result in a uniform distribution of stresses
in the supporting tooth. www.indiandentalacademy.comwww.indiandentalacademy.com

d) Parallel-sided Posts with Tapered Apical Ends
Provide the greater retention of parallel posts and also better conform to the
tapered apical portion of the canal.
Come in 2 variations. Degussa & Unitek BCH System..
Post Retention: Lower retention potential than regular parallel posts of
comparable length and diameter.
Stress from Installation: Produce little or no installation stress.
Stress from Mastication: Produce a definite wedging effect in the area of the
apical taper….cause root fracture than parallel-sided posts of comparable
length and diameter.

e) Self-Threading Parallel-Threaded Posts
Eg: 1) Radix Anchor System.
They have low frequency sharp threads, and are vented to reduce hydraulic
cementation stress.
Like the other active-retentive posts, Radix Anchor posts gain their primary
retention by self-cutting counter threads in the dentin. They have sharp low-
frequency helical blades that extend only partly down the shaft. It is vertically
vented. The Radix post is designed to fit snugly in a channel prepared for it in
the root.
Post Retention: Because of the limited number of threads, the Radix Anchor
has less retention than other actively retained posts.
Stress from Installation: A fully seated Radix Anchor induces severe stress due
to surface irregularities and the non-perpendicular alignment of the post and
coronal dentin.
Stress from Mastication: Since there are so few threads on the Radix Anchor,
the localized stress concentrations are raised under load because of the lowered
surface contact.

2) Parallel Flexi-Post
A variation of the self-threading screw is the Flexi-Post, which has become
one of the most popular post systems. Flexi-Post is a prefabricated, split-
shank, parallel-sided, threaded post that reportedly absorbs the stresses of
insertion (by gradually closing during placement) while providing maximum
retention. As the apical half “collapses”, it becomes a tapered post.

f) Parallel Threaded Posts with Pre-Tapped Channels
Eg :The Kurer Anchor posts, that fit into pre-tapped counter-threads in the
dentin. They are the most retentive posts available.They have rounded high-
frequency threads that fit into counterthreads “tapped” into the dentin with a
manual thread cutter.
Another unique feature of the Kurer Anchor is the Kurer Root Facer that
prepares a flat seat in the root face into which the coronal portion is to fit
perfectly. This obviates the problem of Radix Anchor (fitting against an
uneven root surface).
Post Retention: More retentive than the Radix Anchor simply because of the
higher frequency of threads.
Stress from Installation. Kurer posts produce severe apical stress levels if the
apex of the post fully engages the bevel produced by the twist drill at the
channel apex, similar to the Radix Anchor.
Stress from Mastication: The high-frequency threads of the Kurer design lower
the localized stress concentrations under load because of the increased
surface contact…differ from the low-frequency thread Radix posts.www.indiandentalacademy.comwww.indiandentalacademy.com

Non-metallic posts
Fiber reinforced posts
In 1990, Duret et al introduced a non-metallic material based on the carbon-
fiber reinforced principle, called the carbon-fibre posts. Posts made of this
material consisted of fibers of carbon surrounded by a matrix of polymer resin,
usually an epoxy resin.
Carbon-fiber posts are black in color…. introduction of silica-fiber posts that
are translucent and tooth colored. These posts are glass-fiber (S glass) and
quartz-fiber posts.

Advantages
•Greater flexure and fatigue strength .
•Modulus of elasticity close to dentin.
•Ability to form a single bonded complex within the root canal for a unified
root-post complex (monobloc)
•Potential to reinforce a compromised root and to distribute stress more
uniformly on loading to prevent root fracture.
•Easy to remove by cutting through the post. The fibers keep the bur
centered.
•These posts will yield to stress, before root fracture occurs, better than cast
or prefabricated metal posts.

All-Ceramic Post and Core
•The major advantage of an all-ceramic post and core is its dentin like
shade. It transmits a certain percentage of the incident light to the ceramic
core and post on which it had been placed. Thus the color of the final
restoration will be derived from an internal shade similar to the optical
behaviour of natural teeth.
•A ceramic post does not reflect intensively through thin gingival tissues,
and it provides an essential depth of translucency in the cervical root
areas.
•They are also biocompatible and do not exhibit galvanic corrosion.

Disadvantages
Weaker than metal posts, so a thicker post is necessary, which requires
removal of additional radicular tooth structure.
Fracture resistance is low.
Zirconium posts cannot be etched with hydrofluoric acid; therefore, it is not
possible to bond a composite core material to the post, making core
retention a problem.
Retrieval of zirconium and other ceramic posts is very difficult if endodontic
retreatment is necessary or if the post fractures.

THE CORE
The core is defined as a restorative material placed in the coronal area of a
tooth to replace the missing coronal structure. The core is anchored to the
tooth by extending into the coronal aspect of the canal, or through the
endodontic post.
Ideal properties of the core material
•High compressive and tensile strength.
•High modulus of elasticity (rigidity).
•High fracture toughness.
•Dimensional stability.
•Ease of manipulation.
•Short setting time.
•The ability to bond to both tooth and post.
•Biocompatibility.
•Inert (no corrosion).
•Natural tooth color, when indicated.
•Low plastic deformation.
•Low cost. www.indiandentalacademy.comwww.indiandentalacademy.com

Core materials
• Cast core
-single unit
-root fracture, expensive, lab procedures
• Amalgam
-high comp. strength…easy to manipulate, rapid set
-color, discoloration of gingiva and dentin.
• Composite
-bonding characteristics.. high comp & tensile strength, easy to
manipulate, rapid set
-shrinkage, isolation required, water sorption…
• Glass ionomer cement
• Resin modified glass ionomer cement.

Principles for preparation of an endodontically treated tooth
1) Conservation of Tooth Structure
• Root canal
• Coronal tissue
As much of the coronal tooth structure should be conserved as possible
because this helps reduce stress concentration at the gingival
margin…..more than 2mm of coronal tooth structure….
2) Retention Form
Ability of a post to resist vertical dislodging forces.
• Preparation geometry and post design.
• Post length.
• Post diameter.
• Surface texture.
• Luting agent.
• Number of posts.

3) RESISTANCE FORM
Resistance is defined as the ability of the post and tooth to withstand lateral
and rotational forces.
Stress distribution
One of the functions of a post and core restoration is to improve resistance
to laterally directed forces by distributing them over as large an area as
possible.
•Stress is reduced as post length increases. But excessive length
•High stress...smooth parallel-sided posts that have no vent….
•Tapered posts are self-venting…
•Threaded posts can produce high stresses…half back turn..
•Fiber (carbon and glass) reinforced posts produce more even stress
distribution along the lengths of the root than the metal posts.

Rotational Resistance
It is important that a post with a circular cross section not rotate during
function. Where sufficient coronal tooth structure remains, this should not
present a problem because the axial wall then prevents rotation. When
coronal dentin has been completely lost:
•A small groove placed in the canal, where the root is bulkiest….
•An auxiliary pin on the root face can prevent rotation.
•Rotation of a threaded post can be prevented by preparing a small
cavity -half in the post, half in the root - and condensing amalgam into it
after cementation of the post.
•Additional cemented posts in multirooted teeth.
•Oval or elliptical canals.

Ferrule effect
• The walls and margins of the crown or cast telescopic coping encasing the
gingival 2mm of the axial walls of the preparation form the ferrule.
• A properly executed ferrule significantly reduces the incidence of fracture
in the non-vital tooth by reinforcing the root at its external surface and also
by dissipating force that concentrates at the narrowest circumference of
tooth.
• Stress in the radicular dentin during function is concentrated to the
circumference of the tooth, whereas the stress level is lowest within the
root canal….
• The ferrule also resists lateral forces from posts and leverage from crown
in function, and it increases the retention and resistance of the restoration.
• To be successful, the ferrule must encircle a vertical wall of round tooth
structure above the margin and must not terminate on restorative material.

Requirements
•A maximum of 2mm of dentin axial wall height.
•Parallel axial walls.
•Metal must totally encircle the tooth.
•It must be on sound tooth structure.
•It must not invade the attachment apparatus.

Steps in tooth preparation
Removal of the Endodontic Filling Material
• It is recommended that the root canal system should first be completely
obturated and then space made for a post. This will ensure that the
lateral canals are sealed.
• Silver point..
• The two commonly used methods for gutta-percha removal are:
• With a heated endodontic plugger.
• With a rotary instrument.
Enlargement of the Canal
• This is accomplished with instruments, Peeso reamers or a low speed
drill. The purpose is to remove undercuts and prepare the canal to
receive an appropriately sized post without excessively enlarging the
canal.
• Before starting canal preparation, remove any existing restorations,
caries, bases and thin or unsupported walls of tooth structure,
preserving as much tooth structure as possible.www.indiandentalacademy.comwww.indiandentalacademy.com

For Pre-fabricated Posts
• Set the stopper on the instrument to the predetermined length. Enlarge
the canal one or two sizes with a drill, endodontic file or reamer that
matches the configuration of the post.
• Enlarging the canal in 0.2mm increments diminishes the possibility of
the instrument straying from the canal.
• Care should be taken not to remove more dentin at the apical extent of
the post space.
• In case of a threaded post, a tap (to make threads in the dentin)
follows the appropriate drill, unless self-threading screws are being
used.
• To provide anti-rotational resistance, a pin may be used. Drill one or
two 0.6mm pin holes to a depth of 2mm, in the area of the greatest bulk
between the canal and the periphery of the tooth (usually on lingualwww.indiandentalacademy.comwww.indiandentalacademy.com

For Custom-made Posts
• Often very little preparation will be needed for a custom-made post.
• However, undercuts within the canal should be removed and some
additional spacing is usually necessary.
Preparation of 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 and prepare the remaining tooth as
though it was undamaged.
• The facial surface (in anteriors) should be adequately reduced for good
esthetics.
• Remove all undercuts that will prevent removal of pattern.
• Preserve as much tooth structure as possible.
• Prepare the finish line at least 2mm gingival to the core. This establishes
the ferrule.
• Complete the preparations by eliminating sharp angles and establishing a
smooth finish line.

Post Fabrication
Prefabricated posts
•These have to be selected to match the dimensions of the canal.
•They must be seated till full depth.
•Any discrepancy between the coronal part of post and canal wall can be
filled with core material during the build up of core.
•Shorten the length of the post:…

Custom-made posts
•A custom-made post can be cast from a direct pattern or an indirect one.
•A direct pattern utilizing autopolymerizing resin is recommended for
single canals whereas an indirect procedure is more appropriate for
multiple canals.

Direct procedure

Indirect procedure

Core Fabrication
Cast-metal core
These are 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. In addition to cast posts, they can also be cast directly onto most
prefabricated post systems.
Direct procedure for single-rooted teeth
• Use a prefabricated metal or custom acrylic resin post.
• Add resin by “bead” technique, dipping a small brush into monomer and
then into polymer and applying it to the post. Light cured resin may be used.
• Slightly overbuild the core and allow it to fully polymerize.
• Shape the core with carbide finishing burs. Use water spray to avoid
overheating of acrylic resin correct any small defects with wax.
• Remove the pattern, sprue and invest immediately.

Direct pattern for multi-rooted teeth
A single piece core with auxiliary posts is used. The core is cast directly onto
the post of one canal. The other canals already have prefabricated posts
that pass through holes in the core. Smooth sided parallel or tapered
posts are used as auxiliary posts.
• Fit prefabricated posts into the prepared canals. One post is roughened
(to which the core is cast onto); others are left smooth and lubricated…
• Build up the core with cold cure resin.
• Shape the core to the final form with carbide burs.
• Grip the smooth lubricated posts with force and remove them.
• Remove, invest and cast, the core with the roughened post or resin
pattern. When this is done, the holes for auxiliary posts can be refined
with the appropriate twist drill.
• After verifying the fit, cement the core and auxiliary posts to place.

Indirect pattern for multi-rooted teeth
• When there is limited access, indirect approach is easier to use. A multi-
piece post and core is made by this method (Split casting).
• In the final cast wax the custom-made posts.
• Build part of the core around the first post.
• Remove any undercuts adjacent to other post holes and cast the first
section.
• Wax the additional sections and cast them. Each section should be waxed
to ensure that no undercuts are created.
• Cast each section separately.
• Alternatively, interlocking sections can be made by using dovetails to
interlock the sections. But this makes the procedure more complicated and
is of limited benefit, especially because the final buildup is held together by
the fixed cast restoration.

TECHNIQUES FOR FIBER POSTS
Two categories of fiber reinforced posts are available:
1) Prefabricated posts.
2) Chairside-fabricated posts.
Prefabricated Systems
• Intraradicular Rehabilitation
• Luscent Anchor Post Technique
• ParaPost Fiber White Technique
• FibreKor Post Technique
• Aestheti-Plus Technique
Chairside Fabricated Post
This technique utilizes polyethylene woven ribbon (Ribbond) fibres along
with a composite resin.

Provisional Restorations
•After endodontic treatment, if a cast post and core is planned, a
provisional crown with attached temporary post can be fabricated for the
teeth with limited supragingival structure.
•A provisional restoration is also needed while the post and core is being
fabricated to prevent drift of adjacent and opposing teeth.
•The final post, core and crown should be fabricated as soon as possible,
because microleakage can contaminate the post space and endodontic fill.

Investing and casting
•The post-core pattern is sprued on the incisal or occlusal end.
•1.0 to 2.0cc of extra water is added to the investment and a liner is omitted
to increase the casting shrinkage. This results in a slightly smaller post that
does not bind in the canal, and it also provides space for the cement.
• When resin is used, the pattern should remain for 30 minutes longer in the
burnout oven to ensure complete elimination of the resin

Try-In and Cementation
• Any cement may be used if retention and resistance of the post are
adequate. When resin cements are used, the post should be cemented
with auto-cure or dual-cure resin cement because of limited light
penetration into the root.
• Irrigation with 2.5cc of 17% EDTA to chelate calcium followed by 2.5cc of
5.25% NaOCl ….
• Check the fit
• The core portion of the casting should be polished. If required, a vertical
groove
• The canal should be cleaned with a cavity cleaner
• Cement the post
THE FINAL RESTORATION
Choice of restoration depends on the type of tooth and esthetic demands…

FAILURE AND REMOVAL
The main causes of post and core restoration failure are:
• Dislodgement of post (loss of retention).
• Root fracture.
• Fracture of post.
• Caries.
• Periodontal disease.
Removal of existing posts
Post removal by high-speed bur
Post removal by extractor
Post removal by ultrasonic device
Masserann technique for the removal of fractured posts

Summary and conclusion
•There is not one post, core, or final restoration that can be used in all
clinical situations.
•When we understand the basic concepts of how to retain the various
restorative components and how to protect remaining tooth structure,
our ability to answer the numerous questions that arise during the
restorative process will be facilitated.
•This could result in final restorations that are based on sound design
principles

• References
• Ingle and Bakland. Endodontics. 4th Ed; Williams and Wilkins,
Malvern, 1994.
• Cohen and Burns. Pathways to the Pulp. 8th Ed; Mosby, St. Louis,
2002.
• Rosenstiel, Land and Fujimoto. Contemporary Fixed Prosthodontics.
2nd Ed.; Mosby, St. Louis, 1995.
• Shillinburg. Fundamentals of Fixed Prosthodontics. 3rd Ed.;
Quintessence, Chicago, 1997.
• Walton and Torabinejad. Principles and Practice of Endodontics. W.B.
Saundedrs, Philadelphia, 1989.
• Freilich et al. Fiber Reinforced Composites. Quintessence, Chicago,
2000.
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