POST AND CORE

-Dr. SAURAV PAUL
SENIOR LECTURER
RAMA DENTAL COLLEGE

Introduction
Why to restore endodontically treated teeth
Definitions
History
Goals For Restoration of Endodontically
Treated Teeth
Pre-Treatment evaluation
The post
Classification
Types of Post & core systems
Clinical protocols
Biomechanical principles
Factors influencing post selection
Clinical techniques
Core & Core materials
Fabrication
Cementation
Removal of existing
posts(Re-treatment)
Conclusion
References
2

Root canal therapy cannot be summarized by saying, “fill it,
shut it, forget it”.
The final restoration over an endodontically treated tooth is
as important or probably even more important than the
actual root canal therapy itself.
The main aim of endodontics and restorative dentistry is to
retain the natural teeth with maximal function and pleasing
esthetics.
3

The permanency of endodontically involved teeth has been greatly
enhanced by continuing developments made in endodontic therapy and
restorative procedures including the use of intraradicular devices.
These devices vary from a conventional custom cast post and core to one
visit techniques, using commercially available prefabricated post
systems.
In the last few decades, various prefabricated posts systems have been
developed.
The selection of post design is important, because it may have an
influence on the longevity of the tooth (Sorensen JA et al 1990).
4

Endodontically treated teeth
the tooth structure has already been weakened by previous
episodes of caries, trauma, restorative procedures and tooth
preparations.
more prone to fractures than the vital teeth
Fracture occurrence- posterior teeth > anterior teeth
the masticatory forces are higher
5

impaired neurosensory feed- back mechanism because of the
lack of pulpal tissue i.e. the protective property of
'proprioception' is lost.
This renders the tooth more vulnerable to fracture under
normal masticatory forces.
So, a person can un-intentionally bite too hard on the RC
treated tooth compared to a vital tooth, which can lead to its
fracture and failure.
6

Dowel / Post: a post usually made of metal or fiber-reinforced composite
resin that is fitted into a prepared root canal of a natural tooth; yttria-
stabilized zirconia is also used as a post material; when combined with a
core, it provides retention and resistance for an artificial crown; it is also
used as a platform for retentive attachment systems and for a non-retentive
overdenture post-coping
Core: the foundation restoration which restores sufficient coronal anatomy of
a vital or endodontically treated tooth
The Glossary of Prosthodontic Terms (GPT- 9) 7

 Ferrule
 GPT-9: A band or ring used to encompass the root or crown of a tooth
 Weine: A ferrule is a metal ring or cap placed around the circumference of the tooth, giving
it added strength & increasing resistance to wedging forces.
 Rosen (1961): A subgingival collar or apron of gold which extends as far as possible beyond
the gingival seat of the core and completely surrounds the perimeter of the cervical part of
tooth.
 Richmond crown: (Richmond CM. New method of attaching gold crowns to natural roots of teeth. Am J Dent Sci
1878;79:425)
a post-retained crown made for an endodontically treated tooth that uses a porcelain facing;
an artificial crown with an attached metal post that fits the prepared natural tooth and inserts into the
endodontically treated root canal
The Glossary of Prosthodontic Terms (GPT- 9) 8

 200-737 AD: Frank described the use of a wooden dowel placed in the roots to provide an anchor for
artificial crowns.
 1728: Pierre Fauchard described the use of “TENONS” which were metal posts screwed into the roots
of teeth to retain the prosthesis.
 1839: Harris proposed that gold and platinum were superior to brass, silver and copper which can
corrode.
 1849: Dr. F.H. Clark developed “spring loaded dowel” a retentive device consisting of a metal tube in
the canal and a spilt metal dowel which was inserted into it. It was designed to allow for the easy
drainage of suppuration from within the canal or apical areas.9
 G.V. Black developed porcelain fused to metal crown held in by a screw inserted into canal filled with
gold foil.
9

1871: Harris introduced wooden posts. However they swelled and caused root
fracture. “Pivot crown” – a wooden post fitted to an artificial crown and to root
canal.
1878: Richmond crown – a single piece post retained crown with a porcelain
fusing was engineered to function as a bridge retainer.
1930: Custom cast post and core replaced the one piece post crown or Richmond
crown.
1966: Prefabricated post and composite resin core system introduced.
1990: Duret, Reynaud & Duret introduced a non metallic material for the
fabrication of posts based on carbon fiber reinforcement principle.
10

1991: Kern and Knode introduced post and core made up of glass infiltrated
aluminous oxide ceramic.
1995: Pissis proposed a Monobolc technique for the fabrication of post and core
and crown as a single component made out of glass ceramic material.
1994: Sandhus and Pasche introduced prefabricated Zirconia ceramic
endodontic posts to restorative dentistry.
1996: Purton and Pyne suggested that carbon fiber posts could potentially
replace stainless steel and other metal posts in many clinical situations due their
inherent rigidity, which allows smaller sizes to be used for equivalent strength.
11

1998: Ahmad described the practical application of zirconia posts as a support to
leucite- reinforced cores in practice.
1999: Mannocci, Ferrari & Watson reported that fiber post reduced the risk of root
fractures of teeth restored to a minimum with quartz fiber, carbon quartz fiber and
zirconium dioxide ceramic posts.
2000: O’Keefe, Miller & powers evaluated tensile bond strength of adhesive systems to
stainless steel, titanium, carbon fiber and zirconium dioxide root canal posts.
12

Protect the
remaining tooth
from fracture
Replace the
missing
tooth
structure
Prevent
reinfection
of root canal
system
Goals For Restoration Of Endodontically Treated
Teeth
Pathways of the pulp Cohen, Ninth ed. 13

Endodontic
Periodontal
Biomechanical
14

Inspection of the quality of existing endodontic treatment.
Good apical seal
No sensitivity to pressure
No exudate
No fistula
No apical sensitivity
No active inflammation
15

A. the amount of remaining tooth structure;
B. the anatomical position of the tooth;
C. the functional load on the tooth;
D. the aesthetic requirements of the tooth.
16

Teeth with minimal remaining tooth structure are at increased risk for the following severe
clinical problems.
These include,
 Root fracture.
 recurrent caries, coronal-apical leakage and endodontic failure as a result of loss of the
restorative seal.
 Dislodgment or loss of the final prosthesis.
 Periodontal injury from biologic width invasion during margin preparation.
17

 Anterior teeth with minimal loss of tooth structure may be restored conservatively with a bonded
restoration in the access opening.
 Anterior teeth do not need posts and full coverage crowns unless the teeth are heavily restored or
there is a lack of coronal tooth structure to retain the core
 Molars must resist primarily vertical forces. In those molars that do require a post, the post should
be placed in the largest, straightest canal, which is the palatal canal in the maxillary molars and a
distal canal in the mandibular molars.
 Premolars are more likely than molars to be subjected to lateral forces during mastication. The
remaining tooth structure and functional demands are, once again, the determining factors
18

Posterior teeth carry greater occlusal loads and therefore require greater
protection against possible fracture.
The literature reports that average biting forces vary between 25 and 75 N in
the anterior region and between 40 and 125 N for the posterior region
19

metal or dark carbon fiber posts or amalgam placed in the pulpal chamber
can result in unacceptable aesthetic results, such as a grayish appearance of
the overlying prosthetic restoration
Tooth colored composite core material, translucent glass or quartz fiber
posts should be selected for esthetic cases.
Discoloration from gutta percha can be visible in the coronal aspect of an
endodontically treated tooth and thus should be limited to an apical level in
the root.
20

Healthy gingival tissue
Normal bone architecture and attachment levels to favor periodontal health
Maintenance of biologic width and ferrule effect before and after endodontic
and restorative phases
21

 The post can be a rigid restorative material placed in the canal of a non-vital tooth.
(cohen)
Function:
The post has got 2 main functions:
 Retention of core
 Protection of the tooth by dissipation of forces along its long axis to the surrounding
periodontal tissues and the alveolar bone.
22

 Extensive coronal tooth structure loss/ >50% loss of tooth structure including
important landmarks such as marginal ridges, cingulum, reciprocating walls etc.
 Teeth which are going to be used as abutments for FPD’s, overdentures etc.
 If an endodontically treated anterior tooth is to receive a crown, a post often is
indicated.
 Patient exhibiting any parafunctional habits which can cause excessive amounts of
load on the tooth.
23

Contraindications:
Endodontically treated teeth having a questionable prognosis requiring
possible re-treatment.
Teeth having minimal canal dentin
Teeth having unusual anatomy such as extreme curvatures and fragile roots.
24

Maximum protection of the root.
Adequate retention within the root.
Biocompatible / noncorrosive
Maximum retention of the core and crown.
Maximum protection of the crown margin-cement seal.
Pleasing esthetics
Radiopaque
25

 Fabrication:
 Custom made cast
 Prefabricated
 Esthetics:
 Esthetic
 Non-esthetic
 Retention mode:
 Active / threaded(which actively thread into
the dentin to attain retention. )
 Passive/ cemented(which rely on a cementing
media for their retention )
26

 Shape:
 Parallel
 Tapered
 Parallel with apical taper
 Surface configuration:
 Smooth
 Serrated
 Threaded
 Shank configuration:
 Solid
 Hollow
 Split
27

Venting:
Vented
Non-vented
 Resiliency:
Rigid
Flexible
28

 Materials used:
 Metallic
 Custom-cast posts
 Gold alloys
 Chrome-cobalt alloys
 Nickel-chromium alloys
 Prefabricated posts
 Stainless Steel
 Titanium
 Brass
 Non-Metallic
 Carbon-fiber
 Fiber-reinforced
 Glass fiber
 Quartz fiber
 Woven Polyethylene fiber
 Ceramic and zirconia
29

INGLE AND BAKLAND)
 Custom-cast Posts
 Prefabricated Posts
A. Tapered, smooth-sided
B. Parallel-sided
C. Tapered, self-threading screws
D. Parallel-sided, threaded
E. Parallel-sided, tapered apical
30

SHILLINBURG AND KESSLER)
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
31

WEINE)
A. Tapered smooth sided –Endowel(Star Dental)
B. Parallel, serrated and vented- Parapost ( Coltene/Whaledent).
C. Tapered, self threading- Dentatus ( Dentatus USA).
D. Parallel, threaded- Radix anchor, Kurer anchor (Dentsply Maillefer).
E. Parallel, threaded, split shank- Flexi post (Essential Dental Systems).
32

(W.ROBBINS, DCNA;2002)
 I. Metallic Posts
A. Custom-cast Posts
B. Prefabricated Posts
 Passive Tapered Posts
 Passive Parallel Posts
 Active Posts
 II. Non-metallic Posts
A. Carbon Fiber Posts
B. Tooth Colored Posts
 Fiber reinforced posts.
 Ceramic and zirconia posts
33

CLASSIFICATION (COHEN)
ACCORDING TO 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
34

 Dowel design
 Shape
 Parallel, tapered, parallel with tapered, parallel with increasing coronal diameter
 Diameter
 Metal (small), non metal (not small)
 Dowel composition
 Stiffer than dentin
 Metal, zirconia, ceramic
 Similar to dentin
 Carbon fibre, carbon core, fibre reinforced , woven fibre ribbond
 Dowel design for damaged roots
 Light transmitting dowel
 Cusom dowel and integrated core : ribbond and composite
ACCORDING TO PROTECTIVE QUALITIES OF DOWEL
AGAINST FRACTURE
35

ACCORDING TO ESTHETIC QUALITIES OF DOWELS
Ceramic dowel
Zirconia dowel
Fibre glass reinforced dowel
Carbon core dowel
36

CUSTOM-CAST METAL
POSTS
 developed in 1930’s to replace the one piece post crowns.
 gold, silver, palladium and base metal alloys are most commonly used metals.
 long history of clinical success
 excellent for endodontically treated teeth with moderate to severe damage…90.6% success rate
(Bergman B et al; 1989),
 when it is compared to parallel prefabricated posts, both in vitro (Chan RW et al; 1982, and
Lovdahl PE et al; 1977) and in vivo (Sorenson JA et al; 1984, and Torbjorner A et al; 1995) its
superiority is questionable;
 this can be attributed to the severe damage of teeth restored with the cast post.
38

39
Indications (Robbins JW et al; 1990):
• 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. Prefabricated posts
should not be bent; therefore the custom cast post best fulfills this requirement.
• In excessively flared and elliptical canals.
• Cast posts and cores are the restorative method of choice for endodontically treated
anterior teeth with moderate to severe destruction (Morgano M et al; 1993).

minimum tooth structure removal.
superior adaptation to the root canal,
associated with little or no stress with
installation,
high strength in comparison to the
prefabricated post.
40

time consuming complex procedure,
less retentive than parallel-sided posts, and acts as a wedge during occlusual
load transfer.
It requires two-visits and laboratory fabrication.
41

Adequate post length
This will assist retention, and distribution of coronal forces through the
roots.
The ideal post is approximately two thirds the length of the root, leaving 4 to
5 mm of root cal filling within the canal.
Minimal alteration of the internal root canal anatomy
essential to leave adequate dentin for support and distribution of post
stresses.
42

 Protection of the root against vertical root fracture
 The post and core should have a positive occlusal seat to avoid the wedge like action of
the post (Schnell FJ; 1978).
 Cohen et al (1976)concluded that a metal margin should surround and protect the root
from vertical fracture (the ferrule effect).
 The post should have a passive fit without a wedging effect.
 Anti rotational features
 the cast post for round canals, such as the maxillary incisor requires locking notches or
keyways incorporated into the canal to resist rotational movement.
43

PRE-FABRICATED POSTS
Prefabricated posts are popular because of
 their ease of placement,
 less chair time,
 the ability to restore a tooth for immediate crown preparation;
 they also rely principally on cement for retention (Goerig AC et a1983).
DISADVANTAGES
 The root is designed to accept the post rather than post being designed to fit the root.
 Their application is limited when considerable coronal tooth structure is lost.
44

(1) The post should be of sufficient length
 To ensure adequate retention the post should be sufficiently long to extend two thirds of the way
down the canal and allow for sufficient length for the core (Standlee JP et al; 1972 & 1978, and
Trabert KC et al; 1978), it should be 10 to 15 mm in length.
(2) The post should be parallel in shape
 A parallel post has shown greater resistance to dislodgment than a tapered post. Tapered posts have a
wedge like shape which may lead to fracture of the root due to high stresses (Standlee JP et al; 1972),
and it becomes slightly dislodged because it does not remain in contact with the canal walls and loses
all resistance form (Goerig AC et al; 1983).
45

(3) Cemented rather than screwed
A post that is screwed into place causes greater internal stress in an already vulnerable
root and could lead to fracture (Standlee JP et al; 1972, Perel ML et al; 1972, and
Johnson JK; 1975
(4) Standardized to the size of existing drills
This allows for accuracy and ease in placement.
46

(5) Posts should be vented
To allow the extrusion of excess cement and to alleviate the hydraulic
pressure during cementation. Venting also reduces the tendency of the post to
rise from the channel during cementation (Standlee JP et al; 1972)
(6) Surface characteristics
A serrated or roughened post has greater resistance to dislodgment than a
smooth post.
47

 Tapered posts
 Smooth-sided posts –
 Endowel (Star Dental)
 Endopost(Kerr Dental)
 Colorama(Metalor Dental USA)
 Stress-Free Post (Denovo)
 Serrated Posts –
 Unimetric (Dentsply Maillefer)
 Whaledent Parapost dowels (Whaledent international,New York, N.Y.).
 NuBond (Ellman Internatinal)
 Self-threaded posts-
 Dentatus Classic post( Dentatus USA)
 Ventra-post (Ellman International)
48

 Parallel Posts
 Smooth sides Posts-
 C-Post (Bisco)
 CTH Beta Post (CTH)
 CTH R Series (CTH)
 Serrated Posts-
 ParaPost (Coltent/ Whaledent)
 ParaPost XP (Coltent/ Whaledent)
 ParaPost XH (Coltent/ Whaledent)
 ParaPost Plus (Coltent/ Whaledent)
 Threaded Posts-
 Compo- Post(Henry Schein)
 Boston Screw(Roydent Dental Products)
 Radix-Anchor (Dentsply Maillefer)
 ParaPost XT (Coltent/ Whaledent)
49

 Carbon Fiber Posts
 C-Post
 Aetheti Post
 Tooth colored Posts
 Glass fiber Posts
 Luscent anchor post system (Tapered smooth)
 Twin Luscent anchor post system(Tapered smooth)
 Luminex Post Technology(Tapered Serrated)
 Parapost fiber white system(Parallel Serrated)
 Fiber Kor post techinique (Parallel Serrated)
 Quartz fiber Posts
 Double taper post systems
 Aestheti Plus Post (Parallel Smooth)
 Woven Fiber Posts
 Ribbond
 Ceramic posts.
50

52
Different post designs
 a) Tapered, Smooth-Sided Posts
 The oldest and most widely used design.
 Eg : Kerr Endopost, COLOROMA KIT(J.Aderer, Inc)
 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:
taper ranging from 1.1ºto 6.2º
only evidence of stress is seen where the tapered post contacts irregularities produced
in the canal wall during preparation of the post channel.
Stress from Mastication:
Tapered-smooth posts are wedges and, as such, exert a wedging pressure upon roots
during function.
53

b) Tapered Posts with Self-Threading Screws
54
Eg : Dentatus
Post Retention: More retentive……gains its retention by threading
into the dentin
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.
55

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.
56

 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.
57

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. Eg:- 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. 58

e) Self-Threading Parallel Posts
Eg: Radix Anchor System.
They have low frequency sharp threads, and are vented to reduce cementation stress.
Like the other active-retentive posts, Radix Anchor posts gain their primary retention
by self-cutting counter threads in the dentin. It is vertically vented.
59

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.
60

CLASSIFICATION OF FIBRE BASED POSTS
BASED ON COMPOSITION
CARBON SILICA POLYETHYLENE ZIRCONIA
GLASS QUARTZ
62

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

 Introduced in 1990 by Duret and associates in France.
 They consist of continuous, unidirectional, pyrolytic
carbon / graphite fibres reinforced in an epoxy resin
matrix with 64% carbon.
 Available as:-
 Parallel sided, smooth post, (wider coronally and
tapers towards the apex).
64

ADVANTAGES
 Better strength
Stockson et al 1999: Retention of CFP = Metal posts.
 High flexibility
 Easy retrievability
 Better redistribution of stresses
 High fatigue resistance
65

DISADVANTAGES:
Aesthetics– the black colour of post has a negative effect on the
final aesthetic result of all ceramic crown
Poor adhesion to composite resins as the heat processed carbon
fibre posts have little free resin available for chemical reaction
causing failure of post / cement interface.
Lack of radioopacity
66

The disadvantage of carbon fiber overcomed-by replacing them with glass fiber.
Glass fiber supported resin dowel system was introduced in 1992.
They are made of glass or silica fibers (white or translucent).
These posts can be made of different types of glasses.
i. Electrical glass
ii. High strength glass
TYPES OF GLASS FIBER POSTS
1. Luscent anchor post system.
2. Twin Luscent anchor post system.
3. Luminex post technology.
4. Parapost fiber white system.
5. Fiber kor post technique.
67

 ADVANTAGES
 modulus of elasticity is close to that of dentin.
 They distribute the stress over a broad surface area, increasing the load threshold.
 Capability of glass fibers to conduct light which may improve polymerization of resin cement.
 Removed from root canal with ease.
 DISADVANTAGES
 Variable radiopacity among brands.
 Strength degrades significantly after stored in water, thermo cycling and cyclic loading.
68

Snow post (Carbotech, France)
Developed by Bios et al. at Lyon, composing of 60% of silica zirconium glass fibers in an
epoxy resin matrix. Silane surface treatment is performed to enhance bonding to resin
cements. Has a three-degree taper and a cylindrical shape. Available in different diameters
– 1, 1.2, 1.4, and 1.6 mm.
Parapost fiber white (Coltene/Whaledent)
Designed to complement and extend the existing parapost system, having glass fibers
which are longitudinally arranged. The small steps on the post aid in better mechanical
retention to core material. The color-coded ring around the head helps in identification.
Available in four diameters – 1.14, 1.25, 1.4, and 1.5 mm.
69

FRC posts (Ivoclar/Vivadent)
These posts are composed of a methacrylate composite matrix and
parallel glass fibers. These fibers transmit light toward the apical
part of the tooth when dual curing composites are used. The post is
silanized with Monobond-S. They are available in two sizes and
can be processed chairside or in the laboratory. They are translucent
naturally looking and can be removed with rotary instruments.
70

Additionally glass fiber post can
also be made of quartz fibers.
Quartz is pure silica in
crystallized form.
It is an inert material with a low
co-efficient of thermal expansion.
71

Advantages
Flex with the tooth structure
Easy to retrieve, if retreatment is required
Aesthetic compatibility
Greater fracture resistance
Useful in polymerization by transmitting light through the
post.
Physical properties of these posts is similar to carbon fibre posts.
72

Aesthetipost (from RTD, France) retains a core of carbon fibre bundle
surrounded by quartz fibres similarly arranged longitudinally.
Aestheti Plus also from RTD, France is composed entirely of Quartz Fibres.
Snowpost from Carbotech, France –composed of 60% longitudinally arranged
Silica Zirconium glass fibres is an epoxy resin matrix.
73

Use of cold gas plasma treated, polyethylene woven
fibres embedded in conventional resin composite
Consists of woven fibre ribbons
It conforms to the natural contours and undercuts of
the canal and provides additional mechanical retention.
No stress concentration at the tooth post interface.
They undergo degradation on repeated loading and
moisture contamination
74

1989: Kwaitkonski and Geller described the clinical application of glass ceramic
post and core.
1991: Kern and Knode introduced post and core made of glass infiltrated
aluminous oxide ceramic.
1995: Pissis proposed a “Monobloc” technique for the fabrication of a post and
core and a crown as a single component made out of glass ceramic material.
1994: Sandus and Pasche introduced prefabricated zirconia ceramic endodontic
posts to restorative dentistry.
75

CERAMIC BASED POSTS
Ceramic posts are aesthetic as well as biocompatible.
They also exhibit improved strength and durability for the use with all-ceramic
restorations.
Advantages:
 Dentin like shade.
 It does not reflect intensively through thin gingival tissues, and it provides an
essential depth of translucency in the cervical root areas.
Disadvantage:
 High cost
76

Zirconia posts are gaining popularity as an ideal all-ceramic post as they
provide optical properties for post/core similar to that of all-ceramic crowns.
Extremely radio opaque, biocompatible, possess high flexural strength and
fracture toughness.
Low solubility.
For teeth with severe coronal destruction composite restorative materials are
known to lack the strength to resist deformation when used to support
crowns. Zirconia posts with zirconia enriched glass ceramic cores are selected
for adequate strength.
77

 Shape
Cylindroconical shape
 Smooth surface
May have grooves , serrations to enhance mechanical retention
May not bond well to composite resins

79
• One of the production methods of ceramic restorations is CAD-CAM. There are different
methods for preparing ceramic CAD-CAM post core systems.
• The core can be constructed separately and adhesively luted to post and tooth, one piece post
and core complex can also be constructed, and the core can be constructed using heat pressed
technique.
• Such an all ceramic single unit post and core restoration can help in the aesthetic and
functional rehabilitation of damaged anterior teeth.
• In addition, the use of CAD-CAM technology for the fabrication of ceramic restorations
allows the fabrication procedure to be carried out expeditiously and precisely.

80
 Following the endodontic treatment of the tooth, a portion of the gutta-percha was
removed preserving the adequate apical seal using Gates Glidden drills and/or Peeso
reamers.
 The coronal portion of the teeth was prepared to prevent acute angles between the post
surfaces and the apical surface of the core-post junction because the laser scanner of the
CAD-CAM systems can read rounded internal line angles better.
 Water irrigation prior to acrylic resin placement in the root canal is performed also to
prevent posts from getting stack in the canal.
 To record the anatomies of the canal, the plastic posts (Spee Dee Plastic Pins; Pulpdent
Corp) were covered with autopolymerizing acrylic resin (GC Pattern Resin; GC Corp)
and then inserted into the canals. The posts were kept in position for a few seconds and
quickly removed to check their accuracy..

81
 To prevent the post from getting stuck in the canal, the pots were completely moved in
and out of the canal until they were completely polymerized.
 The post patterns were then placed in the canal and the cores were completed using
acrylic resin. The teeth and the polymerized post and cores were finished using diamond
cutting instruments
 To guarantee the correct alignment at the junctions, the post and core systems were
placed in the scanning ring of the CAD system horizontally.
 The scanned post and core patterns were milled from a zirconia block and were then
placed in the sintering furnace. The sintering process was completed at 1430°C in
approximately 6hrs.

82
 Following the sintering, the fit of the post and core with the teeth were controlled and then can
be later cemented using dual cure resin cement.
 For the cementing process, 37% orthophosphoric acid was applied inside the canals and washed
after 30secs. Following this, enamel and dentin bonding systems are used according to
manufacturer’s instructions.
 The adhesive resin cement luting paste is mixed in 1:1 ratio and were applied accordingly. The
excess cement can be removed using a probe.
 To fabricate zirconia-based crowns, impressions were taken using silicone impression materials.
Crowns were manufactured using same CAD-CAM procedure used for zirconia-based post and
cores.
 After both the marginal fit, and the internal fit, occlusal and proximal contacts were examined
during the try-in and the crowns can be luted using the same dual cure adhesive resin cement
used earlier as well.

83
 Advantage of using zirconia as a post material lies in its translucency and tooth-colored shade,
thereby rendering the material usable with all-ceramic crowns in the anterior region.
 In particular, a patient who has high lip line and thin gingival tissue would require the use of
zirconia post with an all-ceramic crown to optimize the esthetic effect at the root, while
maintaining an adequate level of strength.
 In addition, zirconia is indicate for teeth with severe coronal destruction, because composite
materials lack the strength to resist deformation when used to support crowns
 Where as, disadvantage of zirconia post system is because of the higher rigidity as compared to
FRC posts which could act as an predisposing factor leading to vertical fracture.
 Besides, it is almost impossible to retreat teeth restored with zirconia posts because it is too
difficult to grind away the zirconia post and remove it from the root canal.

84
o The literal meaning of the word Monobloc is ‘single unit’. It has been variously defined as
either a forging or casting made in a single piece, rather than being fabricated from separate
components.
o In endodontics, the concept of monobloc is used to signify a scenario where in the canal
space is perfectly filled with a gap-free, solid mass that consists of different material and
interfaces with the purported advantages of simultaneously improving the seal and fracture
resistance of the filled material.
o This gap free solid mass may imply either a root canal obturating material or a post and core
system. In fact, this philosophy was first popularized in 1996 with bonding of epoxy resin-
based, carbon fibre-reinforced posts to root dentin as a mechanically homogenous monobloc.

85
o Monoblocs created in root canal space are classified as primary monobloc, secondary
monobloc, and tertiary monobloc depending on the number of interfaces present between
the boding substrate and the bulk material core.
o The classification can be applied to both, the root canal obturating materials as well as the
post and core systems. In fact, the mentioned qualities ultimately determine the long term
prognosis of endodontic treatment.
o Teeth with significant loss of tooth structure require posts in the interest of retaining the
core. Since the currently favored fibre posts are passively retained into the root canal, an
adhesive cement is important for a good seal.
o These resin cements play a very integral role in achieving a monobloc.

87
 Includes root filling materials that have one interface that extends circumferentially between the
material and the root canal wall. E.g.: Mineral Trioxide Aggregate (MTA), Polyethylene fibre
post-core systems.
 Polyethylene fibre post systems make use of ultra-high molecular weight braided polyethylene
fibres coated with a dentin bonding agent to build-up endodontic post and cores.
 Components of woven fibre have a modulus of elasticity (MOE) similar to that of dentin.
Moreover, fibres adapt well to wall of root canal hence significant root canal enlargement is not
necessary.
 A study by Singh et al reported that cyclic loading reduced the retention of all posts but was lesser
for the polyethylene posts as a result of formation of the primary monobloc.

89
 These materials consist of two circumferential interfaces, one between cement and dentin and the other
between the cement and the core material. E.g. Resilon based systems, fibre-reinforced posts.
 Conventionally, root canal obturation may be regarded as secondary monobloc systems on account of
two interfaces (one between sealer and dentin, second between sealer and conventional gutta-percha
condensed into a homogenous mass).
 First implied existence of mechanically homogenous monobloc was seen with the bonding of epoxy
resin-based, carbon fibre-reinforced posts to root dentin.
 The strongest carbon fibres have a tensile modulus 500-1000GPa which is 2.5 times than that of steel.
Studies claim that carbon fibre posts having similar MOE to that of dentin, could achieve a tooth post-
core monobloc.
 But over the years, carbon fibre posts were replaced by quartz and glass fibres including zirconia which
were bondable to methacrylates based resin sealers under physiological conditions.

91
 These systems involve the introduction of a third circumferential interface between the bonding
substrate and the abutment material. E.g. Endorez (Ultradent Products), Fibre posts + external
silane.
 Fibre post that contain an external silane coating (DT Light SL, VDW). Another example
include Anatomic Post R (TD, St.Egeve), silane coated ceramic post.
 Coating made of silane or silicate is applied to the post. The additional surface treatment is
advisable for better adhesion.
 Although, introduction of tertiary interface is problematic as in gaps ere found to be present
between the fibre post and the remaining adhesive cement.
 These gaps may act as stress raisers and result in eventual adhesive failure and dislodging of the
fibre post.

93
 The core is defined as a restorative material placed in the coronal area of a tooth to
replace the missing coronal structure
 Materials used for core build-up include:
 Cast core : metal, ceramic
 Amalgam
 Composite
 Glass ionomer
 Resin modified glass ionomer

94
Desirable properties for a core material:
 Compressive strength to resist intraoral forces
 Flexural strength to prevent core dislodgement during function
 Biocompatibility with surrounding tissues
 Ease of manipulation
 Ability to bond to tooth structure, pins and posts
 Dimensional stability
 Short setting time to allow tooth preparation and core placement to be carried out in the same visit
 No adverse reaction with temporary crown materials or luting cements
 Cariostatic potential
 Contrasting color to tooth tissue unless being used for anterior cores

95
 Traditional core build-up material
 Advantages:
 High compressive strength.
 High modulus of elasticity.
 Stable under thermal and functional stresses and therefore, transmits minimal stress to
the tooth and cement and crown margins.
 Bonded amalgam improves the seal at the tooth and alloy junction.
 Amalgam is easily manipulated and has a rapid setting time.
 Disadvantages:
 Potential for corrosion and subsequent discoloration of the gingiva or remaining
dentin.
 Dark coloured, so cannot be used in anteriors.
 Its use is declining worldwide because of legislative, safety and environmental issues.

96
 Core is an integral extension of the dowel
 Can be metal or ceramic
 Requires post for retention and a substantial degree of coronal destruction to be used as an
option.
 Advantages:
 Avoids dislodgement
 Metals are more noble
 Disadvantages:
 Cast post and core are shown to have a higher rate of root fracture than prefabricated
post and core.
 Expensive.
 Laboratory phase is technique sensitive.
 Casting a core to a prefabricated stainless steel post degrades the physical properties of
the post

97
Advantages:
1. Bonded: retention
2. High compressive strength
3. Easy to manipulate
4. Tooth coloured
5. One step procedure
Disadvantages:
1. Polymerization shrinkage
2. Water sorption, thermocycling
3. Plastic deformation
4. Adhesion to radicular dentin is less
5. Isolation required

98
Advantages:
• Anticariogenic
• Small buildups/undercuts
Disadvantages:
• Poor physical props
• Low retention to prefabricated posts
• Sensitive to moisture
Resin modified: hygroscopic expansion

In general, rigid posts made of stiff materials (metal and ceramics) are
indicated for teeth with minimal tooth structure that rely on the post to hold
the core and crown.
In structurally compromised teeth, which lack cervical stiffness from dentin,
excessive post flexion can be detrimental to the marginal seal and prosthesis
longevity, so fiber posts are generally contraindicated.
In structurally sound teeth, nonrigid posts flex with the tooth under
functional forces, reducing the transfer of force to the root and reducing the
risk of root fracture.
99

Conservation of tooth structure
 Preparation of the canal
 Preparation of coronal tissue
Retention form
 Anterior teeth
 Posterior teeth
Resistance form
 Stress distribution
 Rotational resistance
103

Preparation of canal
When creating post space, great care must be used to remove only minimal
tooth structure from canal.
 Excessive enlargement can perforate or weaken the root, which then may
split during cementation of post or subsequent function.
 Thickness of remaining dentin is the prime variable in fracture resistance
of the root.
 Larger diameter post caused more fractures them smaller posts, and also
induced more stresses.
104

Preparation of coronal tissue
 Endodontically treated teeth have often lost much coronal tooth structure as a
result of caries, previously placed restoration and preparation of endodontic access
cavity or trauma.
If cast post and core is to be used, further reduction is needed to accommodate a
complete crown and to remove undercuts from the chamber and internal walls.
This may leave very little coronal dentin.
Preservation of coronal tooth structure is necessary to reduce stress concentration
at gingival margins which is also necessary for creating a ferrule.
Crown lengthening does provide a ferrule but it results in an unfavorable crown
to root ratio thus increasing the leverage on the root during function.
105

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.
106

Preparation of coronal tissue :
Milton P and Stein R S 1992 if more than 2 mm of coronal tooth
structure remains, the post design probably has a limited role in
the fracture resistance of restored tooth.
A key element of tooth preparation when using a dowel and core is the
incorporation of a ferrule. 107

A ferrule is a metal band or ring used to fit the root or crown of a tooth.
FERRULE
• Increased fracture
resistance
• Antirotational
108

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.
109

 Rosen (1961): “ A subgingival collar or apron of gold which extends as far as possible beyond the gingival seat of
the core and completely surrounds the perimeter of the cervical part of tooth”
 Sorensen and Eagleman(1990)
 2 types of ferrule:
 Crown ferrule
 Core ferrule

FERRULE EFFECT
Without ferrule With ferrule
It originates from combining the Latin for Iron (ferrum) & Bracelets
(viriola).
111

The walls and margins of the crown or cast telescopic coping encasing
the gingival 2mm of the axial walls of the preparation forms 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.
112

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.
113

Advantage of ferrule
 Reduces the incidence of fracture in the non-vital tooth by reinforcing the
tooth at its external surface and dissipating force that concentrates at the
narrowest circumference of the tooth.
 Fracture resistance is increased with increasing ferrule length.
 It resists the lateral forces from dowels and leverage from crown in
function and it increases the retention and resistance of the restoration.
 It helps to bind the remaining tooth structure.
114

Insufficient crown length – What to do?
a. Insufficient crown height
b. No ferrule effect
c. Ferrule effect achieved after
crown lengthing
115

Surgical crown lengthening
Gingivectomy Procedure
Insufficient Crown Height
Gingivectomy Done
Crown Height Increased
and Crown Given
116

Surgical Crown Lengthening
Insufficient Crown Height
Sulcular Flap Elevated and
Apically Repositioned
(Front View)
(Occlusal View)
117

ORTHODONTIC TOOTH EXTRUSION
3 weeks after rapid eruption.
Adequate root structure exposed
Sulcular fiberotomy done
every 4 days
Inadequate Crown Height
Eyelet Post Cemented and
Tooth Pulled Out
118

Pre-eruption Radiograph Post- eruption Radiograph
119

Post retention refers to the ability of a post to resist vertical dislodging forces.
Post retention is affected by
the preparation geometry,
post length,
post diameter,
post surface texture, and
the luting agent.
121

Threaded posts > parallel-sided posts > tapered posts
Circular parallel-sided post systems are effective only in the most apical portion of the
post space, because the majority of prepared post spaces demonstrate considerable flare
in the occlusal half.
Similarly, when the root canal is elliptical, a parallel sided post is not effective unless
the canal is considerably enlarged, which would significantly weaken the root
unnecessarily
Tapered posts produced the greatest stress at the coronal shoulder, and parallel posts
generated their greatest stress at the apex of the canal preparation. (Cooney J P et al. Retention
and stress distribution of tapered-end endodontic posts. J Prosthet Dent 1986;55:540-6.)
122

maintain a 4-5-mm apical seal.
if a post is shorter than the coronal height of the clinical crown of the tooth, the
prognosis is considered unfavorable, because stress is distributed over a smaller surface
area, thereby increasing the probability of radicular fracture.
A post that is too long may damage the seal of the root canal fill or risk root
perforation if the apical third is curved or tapered.
123

The post length should equal the incisocervical or occlusocervical dimension of the crown
(Harper RH et al; 1976,)
The post should be longer than the crown (Silverstein WH et al; 1964)
The post should be two thirds of the root length (Christy JM et al; 1967).
The post should be as long as possible without disturbing the apical seal (Henry PJ et al;
1977).
The post preparation for molars should be limited to a depth of 7mm apical to the canal
orifice (Abou-Rass M et al; 1982).
124

According to cohen 10th edition :-
Length of the post should be:-
1) IN CASE OF METAL POST:-
 a) two third the length of the canal
 b) a radicular extension at least equal to coronal length of the crown
 c) one half the bone supported length of the root.
125

2) IN CASE OF FIBRE POST :-
 a) one third to one half the length of the canal, maximum.
 b) a radicular extension about the coronal length of the core
126

different approaches regarding the selection of post diameter:
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.
128

Preservationist (Halle EB et al; 1984) proposed that the
post should be surrounded by a minimum of 1mm of sound
dentin.
Pilo and Tamse (2000) advocated minimal canal
preparation and maintaining as much residual dentin as
possible (conservationist approach).
129

130
A serrated or roughened post is more retentive than a smooth one, and
controlled grooving of the post and root canal considerably increases the
retention of a tapered post.

Ideally, cements should be biocompatible, offer resistance to dissolution in oral fluids,
and possess favorable physical and mechanical properties.
Properties such as tensile strength, compressive strength, and adhesion to dentin are
important, and the potential for plastic deformation, water sorption, and microleakage
are also critical factors that must be considered
Cements used for posts should have a relatively long working time to facilitate
manipulation of the cement and a short final setting time to permit tooth preparation
relatively soon after cementation of the post.
131

Zinc phosphate cements or polycarboxylate cements are still used for cementation of posts
and crowns.
They are generally supplied as a powder and a liquid, and their physical properties are
highly influenced by the mixing ratio of the components.
Their compressive strength is about 100 MPa, and elastic moduli are lower than that of
dentin (5 to 12 GPa).
Zinc phosphate cement is mostly used for cementing metal restorations and posts; film
thickness of the zinc phosphate cement is less than 25 μm.
These cements provide retention through mechanical means and have no chemical bond to
the post or to dentin but provide clinically sufficient retention for posts in teeth with
adequate tooth structure. 132

can be classified as either conventional or resin-modified glass ionomer
cements.
Conventional glass ionomer cements have compressive strengths ranging
between 100 and 200 MPa; the Young modulus is generally about 5 GPa.
They are mechanically more resistant than zinc phosphate cements, and
they can bond to dentin with values ranging between 3 and 5 MPa.
133

Some authors still recommend the use of glass ionomer cements for the
cementation of metallic posts. Major advantages of conventional glass
ionomer cements are their ease of manipulation, chemical setting, and ability
to bond to both tooth and post.
On the contrary, older generation, resin-modified glass ionomer cements are
not indicated for post cementation, because these cements exhibit hygroscopic
expansion that can promote fracture of the root.
134

The rationale for using adhesive cements is based on the premise that bonding
posts to root canal dentin will reinforce the tooth and help retain the post
and the restoration.
Contemporary resin-based luting cements have been shown to exhibit
compressive strengths around 200 MPa and elastic moduli between 4 and 10
GPa.
These materials may be polymerized through a chemical reaction, a
photopolymerization process, or a combination of both mechanisms.
Photopolymerization of these resin-based materials is often necessary to
maximize strength and rigidity
135

most resin cements have a dual-curing process that requires light exposure to
initiate the polymerization reaction.
Dual-curing cements are preferred because there are concerns as to whether
light-curing materials are properly cured, especially in areas of difficult light
access such as the apical portion of the root canal.
136

alternative to conventional resin-based luting cements.
Self-adhesive luting cements contain multifunctional phosphoric acid
methacrylates that react with hydroxyapatite and simultaneously
demineralize and infiltrate dental hard tissue.
They do not require any pretreatment of the tooth substrates, and their
clinical application is accomplished in a single step.
137

Resistance refers to the ability of the post and tooth to withstand lateral and
rotational forces.
1. Stress distribution
2. Rotational resistance
138

The influence of post design on stress distribution has been tested & the
following conclusions have been drawn:
The greatest stress concentrations are found at the shoulder, particularly
interproximally, and at the apex.
Dentin should be conserved in these areas if possible.
Stresses are reduced as post length increases.
139

Parallel-sided posts may distribute stress more evenly than do tapered posts,
which may have a
wedging effect. However, parallel-sided posts generate high stresses at the
apex.
Sharp angles should be avoided because they produce high stresses during
loading.
High stress can be generated during insertion, particularly with smooth,
parallel-sided posts that have no vent for cement escape.
140

Threaded posts can produce high stress concentrations during insertion and
loading, but they have been shown to distribute stress evenly if the posts are
backed off a half-turn and when the head contact area is of sufficient size.
The cement layer results in a more even stress distribution to the root with
less stress concentrations.
141

To minimize the risk of dislodgment, it is important that
preparation geometry prevents a post with a circular
cross-section from rotating during function
Where coronal dentin has been completely lost, a small
groove placed in the canal wall can serve as an
antirotational element.
The groove is normally located where the root is bulkiest,
usually on its lingual aspect.
142

1) Removal of
root canal filling
material
3) Preparation
of the coronal
tooth structure
2)Enlargement
of the canal
FABRICATION TECHNIQUE

There are two commonly used methods to remove gutta-
percha:
Thermal
Mechanical, using a rotary instrument, sometimes in
conjunction with chemical agents.
145

 Touch n’ heat
 System B
 Placed for 2-3 sec
 Takes 7-10sec to cool down
THERMAL REMOVAL

Gates-Glidden
 Peeso reamer
Disadvantages
It can weaken the root
Damage the periodontium
Lead to root perforation
MECHANICAL REMOVAL

Chemical agents
 Oil of eucalyptus
 Oil of orange
 Chloroform
 Xylene
 Disadvantages
Difficult to control the depth of softening of the GP
Potential leakage of the solvents into the periradicular tissues

Although more time consuming, the warmed endodontic plugger is preferred
because it eliminates the possibility that the rotary instrument will
inadvertently damage the dentin.
If it is more convenient, the gutta-percha can be removed with a warmed
condenser immediately after obturation. This does not disturb the apical seal.
149

Before removing gutta-percha,
calculate the appropriate length of the post.
As a guide, make the post length equal to the height of the anatomic crown (or two-
thirds the length of the root), but leave 5 mm of apical gutta-percha.
On short teeth, it is not possible to meet both these restrictions, and a compromise
must be made.
An absolute minimum of 3 mm of apical fill is needed.
If this cannot be achieved without having a very short post, the tooth’s prognosis is
seriously impaired.
150

Avoid the apical 5 mm if possible.
Curvatures and lateral canals may be found in this segment.
If the working length of the root canal is known, the length of the post space
can be easily determined.
Therefore, the incisal or occlusal reference point must not be lost as a result of
premature removal of coronal tooth structure.
151

End-cutting instruments should never be used to gain length because root
perforation will result!
Peeso-Reamers and Gates Glidden drills are often used for this purpose.
The football shape of the cutting head of the Gates-Glidden drill often results in
small concavities in the wall of the post space.
These are avoided with the more cylindrically shaped Peeso-Reamer.
Both are considered “safe-tip” instruments because they are not end-cutting burs.
153

The friction generated between the fill and the tip of these burs softens the
gutta-percha, allowing the rotary instrument to track the canal with
reasonable predictability.
Make sure the instrument follows the center of the gutta-percha and does not
cut dentin.
When the gutta-percha has been removed to the appropriate depth, shape the
canal as needed.
This can be accomplished by using an endodontic file or a low-speed drill.
154

This procedure removes undercuts and prepares the canal to receive an
appropriately sized post without excessively enlarging the canal.
The post should be no more than one-third the root diameter, with the root
and walls at least 1 mm thick.
155

Prefabricated posts
Enlarge the canal one or two sizes with a drill, endodontic file, or reamer
that matches the configuration of the post
A tapered post conforms better to the canal than a parallel-sided post and
requires less removal of dentin to achieve an adequate fit.
However, it is slightly less retentive and causes greater stress
concentrations.
158

Custom-made posts
Use custom-made posts in canals that have a noncircular cross-section or
extreme taper.
Often very little preparation is needed for a custom-made post.
Enlarging canals to conform to a preformed post may lead to perforation.
However, undercuts within the canal must be removed, and some
additional shaping usually is necessary.
161

Be most careful on molars to avoid root perforation.
In mandibular molars, inter-radicular root concavities make the distal wall of
the mesial root and the mesial wall of the distal root, particularly susceptible.
In maxillary molars, the curvature of the mesio-buccal root makes mesial or
distal perforation more likely
162

After the post space has been prepared, the remaining coronal tooth structure is reduced
for the extracoronal restoration.
Specific reduction depends on the type of crown that is planned.
Ignore missing coronal tissue (from previous restorative procedures, caries, fracture, or
endodontic access) and prepare the remaining tooth structure as if the crown is intact.
163

Meeting the same specifications that would be applied otherwise (i.e., if a metal-
ceramic crown with a porcelain labial margin is planned, a facial shoulder and
lingual chamfer are placed).
The prepared walls are the starting point for the core materials, and ensuring that
the configuration is correct facilitates achieving correct preparation form in the
core.
164

Be sure that the facial structure of the tooth is adequately reduced for good
esthetics.
Remove all internal and external undercuts that will prevent withdrawal of
the pattern.
Remove any unsupported tooth structure, but preserve as much of the crown
as possible.
165

In addition, be sure that part of the remaining
coronal tissue is prepared perpendicular to the
post (see step 4 in Fig.), because this creates a
positive stop to minimize wedging and
subsequent splitting of the tooth.
Similarly, rotation of the post must be
prevented by preparing a flat surface parallel to
the post (see step 5 in Fig.).
166

If insufficient tooth structure for this feature
remains, an anti-rotation groove should be placed
in the canal.
Complete the preparation by eliminating sharp
angles and establishing a smooth finish line.
167

Direct method
Indirect method
169

Acrylic resin Inlay wax
DIRECT METHOD

Remove the root canal filling material to the required depth and diameter. It is
neither necessary nor desirable to make the post space round.
Most custom cast posts and cores will possess a slightly tapered form, so prepare a
flat area in remaining coronal tooth structure if one is not already present in the
existing morphology.
This flat area (formed perpendicular to the long axis of the post) will serve as a
positive stop during cementation of the post and during subsequent application of
occlusal forces, thereby helping to minimize any tendency for the post to wedge
against the tooth.
171

Select a solid plastic post that fits within the
confines of the post preparation without binding.
Leave the post sufficiently long that it can be
easily gripped.
Lightly lubricate the canal with a periodontal
probe and petroleum jelly.
Create notches in the side of a plastic post
pattern if the post is smooth and seat it to the
depth of the prepared canal.
172

Using a brush, apply pattern resin to the prepared
canal as well as the body of the plastic post.
Seat the post to the full depth of the canal.
Do not allow the resin to completely harden within the
canal.
Wait for 30 to 45 seconds and then remove and reseat
the post and attached resin several times while the resin
is still in its rubbery stage so that the pattern does not
inadvertently become locked into the canal.
Remove the polymerized pattern and inspect the resin
for integrity and lack of voids.
Reseat the post and test for adaptation and passivity
173

Add additional coronal resin to form the desired dimensions
of the core.
Remove and reseat the pattern as previously described to
prevent it from becoming locked into coronal tooth structure.
Add a slight excess of core resin so that the hardened core can
be prepared with a high-speed diamond and water spray to
resemble a complete-crown tooth preparation.
Remove the resin pattern post and core and then invest and
cast it.
Try in the post and core and adjust it as necessary, then
cement it.
174

Select an orthodontic wire or a prefabricated plastic pin as a
means of supporting the impression material.
The coronal portion of the wire should be bent to form a handle
and to help retain it in the impression material.
Coat the wire with tray adhesive.
Lubricate the canals to facilitate removal of the impression
without distortion (die lubricant is suitable).
Fill the prepared canal with impression material using a
lentulospiral accompanied by an up-and-down motion.
176

Seat the wire or plastic post through the impression
material to the full depth of the canal, syringe additional
impression material around the supporting device as well
as the prepared tooth, and seat the impression tray.
Remove the impression, evaluate it, and pour a cast.
Roughen a loose-fitting plastic post (a plastic toothpick is
suitable) and, using the impression as a guide, make sure
that it extends into the entire depth of the canal.
177

Apply a thin coat of sticky wax to the plastic post and, after
lubricating the stone cast, add soft inlay wax in increments.
Start from the most apical and make sure that the post is
correctly oriented as it is seated to adapt the wax.
When this post pattern has been fabricated, the wax core can
be added and shaped.
Use the impression to evaluate whether the wax pattern is
completely adapted to the post space.
179

Recommended For multirooted teeth with divergent roots having grossly
decayed coronal tooth structure.
Where to Prepare?
1. Maxillary molars:
Primary canal – Palatal canal
Secondary canal – Mesiobuccal or Distobuccal
2. Mandibular molars:
Primary canal – Distal canal
Secondary canal – Mesiobuccal or Mesiolingual canal

After removing the gutta percha material the canals are prepared with
the help of the peezo reamer while leaving 4 to 5 mm gutta percha for
the apical seal.
Lubricate the primary canal (distal) and notch the loose-fitting plastic
dowel. It should extend to the full depth of the prepared canal.
Add resin to the dowel and seat it in the prepared canal.

Do not allow the resin to harden fully within the canal.
Loosen and reseat it several times while it is still rubbery.
Once the resin has polymerized, remove the pattern.
The same procedure was being performed for the fabrication of the post
pattern for the secondary canal, i.e. the mesiobuccal canal.
Once the pattern has been made additional autopolymerizing resin for the
fabrication of the core is used.

 patterns for the both the canal is now sprued,
invested and casted.
 Finishing of the casting, both post with a metal
core can be adjusted inside the primary (distal)
and secondary (mesiobuccal) canals one by one.
 The posts are cemented.
 Final restoration fabricated

Remove the root canal filling material using a warm endodontic hand instrument or
a small-diameter rotary instrument until the desired post length and remaining
gutta-percha length are achieved .
Enlarge the canal using the rotary instrument that corresponds to the final
dimension of the selected post. The post should fit passively in the post space but be
sufficiently proximate that it does not exhibit substantial movement in the canal.
At least the apical half of the post must possess good approximation to prepared
tooth structure. The coronal half of the post may not fit as well because of root canal
flaring.
189

However, this lack of adaptation can be corrected when the core material is
placed around the cemented post.
If the root canal cannot be prepared so that it conforms to the round shape of
the post and has adequate approximation to the root canal walls, then a
custom cast post may be preferable.
Do not remove more dentin at the apical end of the post space than is
necessary.
When necessary, take radiographs to confirm appropriate seating and length
of the post.
Shorten the incisal or occlusal end of the post so that it does not interfere
with the opposing occlusion but extends occlusally sufficient to provide
support and retention for the restorative core material (2 to 3 mm).
190

If nonmetallic prefabricated posts are being used, do not use scissors to cut
the posts; instead, shorten them with a diamond rotary instrument.
When metal posts are used, bend them slightly coronally, if necessary, to
align them within the core material. Always remove the metal post from the
tooth and bend it outside the mouth with orthodontic pliers.
Cement the post in the root canal using resin bonding procedures.
191

Condense restorative material around the post or bond the restorative
material to the post and remaining tooth structure, depending on the material
used to form the core.
Place a slight excess of material so that it can be prepared to the desired
crown preparation form after hardening.
Complete the definitive tooth preparation and make an impression for the
crown.
192

The luting agent must fill all the space within
the root canal system.
A rotary (lentulo) paste filler or cement tube is
used to fill the canal with cement.
The post and core is inserted gently to reduce
hydrostatic pressure, which could cause root
fracture.
194

If a parallel-sided post is being used, a groove should be placed along the
side of the post to allow for improved escape of excess cement.
Use of venting procedures has also been shown to reduce the necessary
seating force.
195

POST AND CORE

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to POST AND CORE

Similar to POST AND CORE (20)

Recently uploaded

Recently uploaded (20)

POST AND CORE

Editor's Notes